14th European LS-DYNA Conference 2023

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• A Comparative Study of Modeling Approaches for External Structures in Mine Blast Simulations of an Armored Military Vehicle

  İsmet Kutlay ODACI, Samet Emre YILMAZ, İlker KURTOĞLU

  External structures are known to be critical in ensuring the protection of occupants in military vehicles during mine blast events. There are variety of modelling approaches that can be employed to represent external structures in mine blast simulations of armored military vehicles. This study aims to present an accurate configuration considering the modelling efforts and tight project schedules by comparing different modeling techniques applied to external structures, such as add-on armor plates and other external subsystem components. A whole vehicle finite element model is utilized for an on-going research and development project to evaluate the effectiveness of these modeling approaches by comparing simulation results with live fire test data of Hybrid III dummy and plastic deformations of the hull structure. The findings emphasize that the modelling approach of not only primary protective structures but also other external components significantly contributes to better representation of the tests. Configurations featuring accurately modeled external structures demonstrate improved accuracy in occupant safety assessment. The outcomes of the study contribute to enhancing the efficiency and reliability of the conceptual design phase by providing faster and relatively reliable finite element solutions, specifically in terms of representing external structures in the simulations.

• A data-driven methodology for the automated analysis and explanation of system behavior in crash simulations

  Janis Mathieu, Michael Di Roberto, Michael Vielhaber

  Attributable to model size and complexity of numerical crash simulations, it is not feasible for the engineers to analyze each area or component in detail, especially when these are not the core subject of investigation. In the field of occupant safety, the main explanatory objective is given by the signals of anthropometric test devices (ATD), as they are relevant for the fulfillment of legal regulations and consumer protection guidelines. Hence, this study proposes a data-driven methodology to automatically determine deviations in ATD behavior in a set of simulations and provide possible causes for the prevalence helping the engineer to understand simulations faster and to ensure quality.

• A New Approach to Contacts and Rigid Body Inter- actions in LS-DYNA

  Frederik Bengzon, Thomas Borrvall, Anders Jonsson, Gert Petersen

  Traditionally in LS-DYNA (almost) all contact definitions use a penalty formulation. This means that penetration in the contact is required to obtain a contact force between interacting entities. It is then up to the user to verify that the penetrations are small enough not to influence the results. The Mortar contacts [1], which have become the preferred choice for implicit analyses, is of penalty type. Also, the rigid walls (*RIGIDWALL) use a penalty method in implicit analyses. To find a good penalty stiffness setting may be problematic if solid elements (especially tetrahedra), or soft materials, such as rubber or plastic, are involved. It can be hard to find a good trade-off between reasonably small penetrations and implicit convergence.

• A New Model Reduction Method for Vehicle Crash Simulation

  Shinya Hayashi, Shinya Hiroi, Norio Shimizu

  When major design changes are required to satisfy product performance late in the development process, significant cost and time are required to implement them. This is a particular problem in automotive development which requires a large amount time and cost. To alleviate this, automotive manufacturers have adopted the concept of "front-loading" to identify problems early-on in the development process. “Front-loading” is defined as "the distribution of development costs or time in large proportions in the early stages of the design process”.

• A Numerical Investigation on the Ballistic Performance of Ceramic Composite Armors against EFP Threats

  M. Emin Akca, M. Bartu Ünal, Koray Kaya, H. Hüseyin Türkmen

  The increasing destructiveness of explosive-formed penetrators or projectiles (EFPs) in modern warfare has posed significant challenges in developing effective armored solutions incorporating advanced ceramics as crucial components, offering enhanced protection against high-velocity-formed projectiles. [1] In other words, Explosively Formed Penetrators pose a significant threat to military vehicles, necessitating the development of advanced armor solutions to counteract their destructive potential. Thus, Finite Element Analysis (FEA) research is crucial for the armor system against this threat. In addition, since EFP tests are costly and time-demanding, performing these experiments with FEA provides significant cost and performance efficiency. This study analyzes the composite armor system integrating Nurol Teknoloji [2] ceramics against EFP threats utilizing LS-DYNA, a program for nonlinear dynamic analysis of structures in three dimensions.

• A Study of RC Beam-Column Against Close-in Blast Loading Using 3D ALE Mapping to S-ALE Technique

  Zoey Lim Siew Fern, Sun Jian Yun, Heng Zi Jing, Ang Choon Keat

  Mapping technique has been developed to allow the decomposition of a calculation in several steps. The transitions are allowed 1D to 2D/3D, 2D to 2D/3D, or 3D to 3D/2D etc [1], that the data from the model’s latest cycle is saved in a binary file and can be mapped into another model using the “map” command in the expression. This technique has a wide range of application since it allows to adjust mesh length or model size, as well as include Lagrangian or Eulerian Parts.

• A study on the bolt modeling with pre-load for field application

  Han Deok Hee, Kim Dong Hyeon, Kim Young Joon

  When fastening a structure with a bolt, an axial force is generated by the tightening torque of them. This axial force acts as a friction force by the friction coefficient of the fastening part, and becomes a factor that directly affects the deformation of the fastening part. For this reason, there have been many studies on how to make the bolt models for applying preload and users are using various methods. What is common is the construction and evaluation of bolt models with preload requires a lot of working by user. So this study was conducted because it was necessary to easy and exact method for with preload bolt models.

• A Systematic Approach Towards Integrated Safety Modelling for Aerospace Applications – Preliminary Results on Rigid Seat Simulations

  Nina Wegener, Christoph Sauer, Paul Schatrow, Matthias Waimer

  In the aviation sector, the historically evolved crashworthiness requirements prescribe seat certification separately from the airframe structure. Based on historical test and accident data the airframe crash behaviour is presumed in terms of crash pulses, which are applied to the seat structure for seat certification (e.g. EASA CS-23/25.562). Certification authorities have recently started to change the regulations from a prescriptive to a performance-based certification, considering the crash performance with the seats integrated in the airframe structure (EASA CS-23 Amendment 5). With this, occupant safety and structural crashworthiness is combined to an integrated safety approach. Due to the high cost of full-scale testing in the aviation sector, extensive use of simulation is of interest. Modelling methods are continuously being developed for crash loading conditions relevant to aerospace, which significantly differ from automotive ones. The German Aerospace Center (DLR) Institute of Structures and Design has extensive experience in developing simulation methods for aircraft crash analysis. In an effort to develop an integrated safety modelling approach for aviation, a research initiative was launched to incorporate advanced passenger safety considerations.

• A user-defined Folgar-Tucker-based fiber orientation material model for compression molding of fiber/polymer-compounds

  Dominic Schommer, Miro Duhovic, David May, Joachim Hausmann, Heiko Andrä, Konrad Steiner

  LS-DYNA® provides an ever-increasing portfolio of material models covering a wide range of material behavior for solving multi-physics problems. The software also provides users the opportunity to implement their own user-defined material models via FORTRAN code, to describe the behavior of very specific materials. In this work, a user-defined material model has been developed to describe the compression molding behavior of sheet molding compounds (SMCs). A SMC is a composite material based on a thermoset resin reinforced by chopped long fibers. During the compression molding of SMCs, very complex material behavior involving elastic compaction and plastic flow (depending on material composition) occurs, which is dependent on the local fiber orientation, temperature and strain rate. One way to describe the processing behavior of SMC materials as simply as possible is using a building block approach. Following the identification of the most relevant material effects, individual building blocks are created containing the respective mathematical solutions (e.g. compaction and plastic flow behavior).

• Abuse Characterization and Simulation of Battery Cells Using Layered Approach

  David Poulard, Prakhar Amrute, Pierre L’Eplattenier, Kevin Kong, Vidyu Challa, Inaki Caldichoury

  The adoption of electric vehicles (EVs) has brought renewed attention to battery safety, particularly in scenarios where batteries are subjected to mechanical abuse, such as car crashes. The potential for battery cells to catch fire or exhibit thermal runaway under such conditions necessitates a comprehensive understanding of the underlying physics. The complex interplay of structural, thermal, electrical, and electrochemical phenomena presents a formidable challenge for accurate simulation and prediction of battery behavior. In this context, the integration of multiphysics coupling within Ansys LS-DYNA® has emerged as a crucial tool for studying battery abuse and enhancing safety measures.

• Accelerating elastoplastic material models with spare nonlinear regression: A hybrid approach

  G. Bokil, D. Koch, André Haufe, Holger Steeb

  Evaluating material models in Finite Element (FE) simulations is computationally expensive. Recently, Machine Learning (ML) techniques have been explored for accelerating elastoplastic algorithms. One such method includes replacing a part of the algorithm with an ML model which is called the “hybrid” approach. One of the most commonly used algorithms for ductile materials is the J2-based von Mises hardening elastoplasticity. To improve the performance of this model, an ML-based hybrid algorithm was sought. In this algorithm, the expensive iterative plastic correction step was replaced with a single-step prediction from a SINDY-inspired sparse nonlinear regression model.

• Advanced Plasticity & Fracture for Structural Car Body Metals in Crashworthiness CAE analysis: SAMP-1 plus GISSMO

  Alejandro Domínguez, Pablo Cruz, Lluis Martorell, Adrián Ros, Eduardo Martin-Santos

  This paper describes an engineering process to generate material cards for forefront crashworthiness CAE analysis that properly capture both plastic and fracture behaviour of car body structural metals. The main objective of the paper is to show that advanced plasticity approaches can be used without significantly increasing the complexity of the overall material characterization process. The paper is mainly centred in metals plastic characterization for shell elements although some important relationships with the fracture characterization will be also discussed. Before defining the engineering process, it is necessary to tackle some misleading general ideas that the automotive CAE community normally assumes as correct for metals like steel or aluminium alloys.

• An Interprocess Communication based Integration of AI User Materials into LS-DYNA

  Joachim Sprave, Tobias Erhart, Andr´e Haufe

  Machine Learning (ML) driven material models have been investigated for some time now. The respective ML models can be trained outside of the Finite Element solvers by means of given strain paths and corresponding stress results which have either been recorded from simulations, drawn from distributions, or even measured from hardware tests. The trained models can be easily evaluated regarding their performance based on an-other set of strain paths with results that have not been presented to the model during training. When a model has reached a promising prediction accuracy on the validation data, the natural next step is to test it in a finite element simulation by integrating the trained model as a user material.

• Anatomically accurate finite element model of a human head for crash applications

  Alberto Tacchi, Ivan Colamartino, Gabriele Canzi, Giorgio Novelli, Marco Anghileri

  Every year road traffic accidents are responsible of approximately 1.3 million deaths in the world, resulting in one of the main causes of mortality. According to the World Health Organization (WHO), by the 2020s road traffic accidents will be the leading cause of premature death. Moreover, between 20 and 50 million people involved in incidents suffer non-fatal injuries, most of them leading to disabilities [1]. These injuries considerably affect individuals, their families, and nations from both social and economic points of view. Over the last 60 years, experimental activities focused on the impact behavior of the human body were carried out with crash dummies and human cadavers, expanding the available injury database, exposing the most common injury scenarios and allowing the development of effective predictive criteria. The most frequently injured body regions resulted to be head and lower limbs; however severe to fatal injuries (Abbreviate Injury Scale values AIS 3+), are more commonly related to head impacts, as shown in Figure 1 [2].

• Assessment of Abdominal and Skeletal loadings and Kinematics during Frontal Impacts through a Novel Tool for HBM Variants Generation Based on the Occupant’s BMI

  Zouzias D, Fokylidis A, Lioras A, Rorris L

  HBM variant generation tools are solely based on morphing techniques to adjust the shape of the external surface to a target depending on the BMI of interest. Even though this approach can quickly produce HBM variants, downgrades the model’s mesh by stretching the elements and compromising their quality. Furthermore, the dependence of the abdominal organs morphology on the occupant’s BMI is rarely, taken into account. This paper presents a novel tool for automatic HBM variant generation, that respects elements’ quality taking also into account the volume of the abdominal organs.

• Automatic Generation of Accurate Material Models for Long Fiber Reinforced Plastics in Crash Simulations

  Timo Schweiger, Jörg Lienhard, Hannes Grimm-Strele, Matthias Kabe

  Long fiber reinforced plastics (LFRPs) offer excellent mechanical properties and are widely used in automotive and aerospace industries. Accurately modeling the behavior of LFRPs under crash conditions is crucial for designing lightweight and safe structures. However, creating reliable material models for LFRPs is challenging due to their complex microstructure and anisotropic nature. This study presents an automatic method to generate highly accurate material models for LFRPs, specifically tailored for crash simulations.

• Blast Mitigation Seat Simulations Using LS-DYNA®

  Buğra Balaban, Ahmet Mete Sabah

  Military vehicles are exposed to mine and explosive loads in operational conditions and the vehicle must have the appropriate protection level to prevent personnel injuries. Blast mitigation seats represent a critical component in ensuring personnel safety. In this study, we conducted mine blast simulations using the non-linear finite element code LS-DYNA® to examine the structural behavior of blast mitigation seats. The blast simulations were carried out in accordance with the requirements of NATO AEP-55 STANAG 4569 VOL-2. We employed the Structured Arbitrary Lagrangian-Eulerian (ALE) method for these simulations. The model encompassed an ALE domain, including soil, air, explosive definitions, and a Lagrange domain for the 4x4 military vehicle. To assess the impact of the explosive charge on the occupant, we utilized the LSTC Hybrid III 50th dummy. We measured force and acceleration outputs from the dummy and compared them with the allowable limits defined in NATO AEP-55 STANAG 4569 VOL-2.

• Characterization of a cohesive zone model for adhesives with *MAT_240 and curve mapping method in LS-OPT

  Nicole Betz, Tobias Behling, Martin Holzapfel, Mathieu Vinot, Nathalie Toso

  The importance of adhesives in automotive structures exposed to high crash loads has increased over the years. To improve the structural sizing, it is necessary to predict the behavior of bonded joints under dynamic impact and crash loads. Cohesive zone models have proven to be suitable for numerically representing adhesive behavior in Finite-Element simulations. However, the manual determination of the model parameters requires experience with the material model and a corresponding amount of time to derive the various parameters. The present work aims at developing an optimization scheme with LS- OPT for the effective and automated identification of input parameters for the material card *MAT_240 (*COHESIVE_MIXED_MODE_ELASTOPLASTIC_RATE) [1] which is used to represent the behavior of the adhesive layer. The present work focuses on a curve mapping process with LS-OPT.

• Coil Winding Simulations of Electrical Machines

  Stavroula Stefanatou, Johannes Heydenreich

  The winding of coils on stator teeth is a central process in the manufacture of electrical machines. The quality of the windings and the associated copper fill factor are important factors for the efficiency of electrical motors. While the copper winding process was manual labor some years ago, this process has meanwhile been completely automated and has been taken over by machines and robots. What is still left for manual labor is the setup of the machines for series production. This can be quite time consuming and costly. To support this setup process, fully understand it in all its details and speed it up, BROSE has used LS-DYNA to develop simulation models for the setup of new coil windings.

• Comparative Study of Positioning HBM to Cycling Postures Based on Experimental Data

  Maria Oikonomou, Athanasios Lioras, Lambros Rorris, Thomas Nikodelis, Athanasios Mihailidis

  The objective of Crash Analysis is to ensure the safety of a diverse spectrum of road users through the utilization of several finite element (FE) crash simulations. While a considerable number of studies have focused on evaluating the motion and the potential injuries of occupants and pedestrians, the investigation of two-wheel vehicle users remains underrepresented, even though they are considered vulnerable road users and two-wheelers are common personal transportation. Therefore, studying their kinematic behavior in multiple collisions is crucial to ensure safe and convenient travel.

• COMPARING PLATE-LEVEL BLAST ANALYSIS USING ALE, S-ALE AND CONWEP METHODS

  Ahmet Salih Yilmaz, Barkin Sonmez, Ulas Ozcan Erkan

  The simulation analyses of the explosion were performed using three different methods: LBE (Lagrangian-based Eulerian), PBM (Particle-based Method), and ALE (Arbitrary Lagrangian-Eulerian). The reference point cloud data obtained from the scanning process after the explosion tests conducted on a 12 mm thick M400 steel plate indicated a deformation of approximately 12.5 cm at a Y-directional distance between the measured points. Based on this measurement, the explosion analyses were simulated using the aforementioned three methods. The scenario involved the detonation of 6 kg of TNT beneath the structure.

• Comparison of Polyurethane and Epoxy Adhesive High Strain Rate Performance Using Cohesive Zone Model

  Devon Downes, Manouchehr Nejad Ensan, Chun Li

  It is known that the ballistic performance of ceramic composite personnel armour is highly dependent on the thickness of ceramic and backing material. Recent studies have begun focusing on the effect of adhesive bonding between the ceramic and the backing plate, because failure of the adhesive layer can cause separation between the ceramic and backing. This debonding between substrates causes the ceramic to underperform by shattering early due to an imperfect transmission of the stress wave to the backing material. Given that the adhesive plays such an important role in armour, it is important to better understand the underlying physics.

• Comprehensive Digital Twin of a Beverage Can Body Forming Process and Performance Evaluation

  Sebastijan Jurendic, Maximilian Weiser

  Novelis is a world leader in aluminium flat rolled products and a major supplier to the beverage can-making industry. As such, Novelis is deeply involved in supporting the can-making industry to help shaping a more sustainable future together. Reducing the amount of metal used for each beverage can is a major driver for improving sustainability of the beverage can packaging, thus Novelis is actively investigating and developing state of the art modelling tools and approaches to support further optimization of the beverage can.

• Computational Modeling of the TPU Shock Absorber using LS-DYNA

  Ahmet Mete SABAH, Buğra BALABAN

  In this study, various analysis and test activities are presented, which were carried out for the development of shock-mitigating floor mats. These impact-absorbing floor mats are produced from hyperelastic materials and are designed to absorb high-amplitude, short-duration shock loads in defense or civil applications. Throughout the study, the *MAT027 model is examined for its suitability in modeling hyperelastic materials in both static and dynamic analyses, conducted using the non-linear finite element code LS-DYNA®. The *MAT027 model accurately describes the behavior of hyperelastic materials and is often preferred for this type of material. To correctly apply this model, specific parameters pertaining to the hyperelastic material must be determined. This study primarily focuses on the determination of these material parameters through tests conducted on samples made of Thermoplastic Polyurethane (TPU) material. In the initial phase of the study, a literature review concerning TPU material was conducted, and material parameters were obtained using the test data presented in this study. The material parameters were then optimized using LS-Opt® to achieve the best material behavior. Following the determination of material parameters, dynamic simulations were performed using LS-DYNA®, and the simulation results were subsequently compared with experimental data. With the material parameters in hand, the second phase of the study involved the design of cellular structures with various geometric shapes. The force-displacement graphs of these newly designed shapes were analyzed through dynamic analyses.

• Correlative Approach to Mine Blast Effects via Conducting Real Test Campaigns and Simulating in LS-DYNA

  İzzet ÖZCAN, Buğra ISIKER

  In this study, pressure data were collected by conducting free field blast tests with explosives placed inside the steel pot to verify the explosive model. Free field blast analysis was performed using the Structured Arbitrarily Lagrangian -Eulerian (SALE) method in the LS-DYNA® software under the same boundary conditions, and the pressure values obtained from the test were compared. Plate tests were performed in consideration of the verified explosive model with explosives placed inside the steel pot. Tests were carried out for 3 different designs, which consist of flat plate, twisted plate, and plate with deflector. Elastic and plastic displacement measurements were taken during the tests. LS-DYNA® software was used to perform analyses using the Johnson-Cook material model obtained from Split Hopkinson bar tests for plate materials and the SALE method. The effect of the distance between the plate and the explosive, the behavior of the source during the explosion, the effect of plate geometry, and the comparison with analysis results were investigated as a result of the plate tests.

• Crash Simulation of Public Transport Vehicle Traction Battery

  J. Dohnal, M. Šebík, M. Popovič

  Nowadays, lithium-ion batteries are considered as most efficient source of power for electric vehicles (EVs). With the increasing utilization of EVs, the requirements for higher performance, lower weight and improved safety also growing. These demands can be fulfilled by an improved traction battery design, which consists of decreased battery frame mass or higher number of battery cells. However, with these improvements come several negative aspects, such as higher risk of battery frame intrusion or reduction of space between the cells. Due to these factors, the risk of battery damage is rising and it is crucial to predict and better understand the behaviour of the battery cells during critical situations, such as vehicle crash.

• Creating Machine-Learning-Friendly Training Data from Crash Simulation Data

  Sarah Zenne, Joachim Sprave, Markus Stoll

  A method is presented for generating training data from FEM meshes based on element prop-erties. Learning at the element level is often indicated when larger structures, especially parts, are too inhomogeneous in size or geometry. At the element level, quality metrics and other infor-mation are gathered from the neighborhoods of elements, just as convolutional neural networks for image processing gather information from the neighborhoods of pixels. But in general, neigh-borhoods of elements are not as well structured as pixels in images. Instead, they form irregular graphs which cannot be processed by standard Neural Network (NN) architectures directly.

• Designing Shock Absorbers for Nuclear Transport Packages

  A Sean Duvall

  Across the world, radioactive sources are used for a variety of applications. From X-rays and radiotherapy in hospitals, to generation of heat in a nuclear power station. All these sources, however small or large, need to be transported to the point of use and away from there for eventual disposal or recycling. It is more often the case that when the sources are transported to the site, before use, they are not particularly radioactive, but after use they can pose a serious health hazard if not handled correctly. Special, specifically designed transport packages are manufactured and tested to ensure they meet the regulatory requirements for the transport of radioactive materials [1]. Part of the regulatory requirements is that the package withstands a 9m drop on to an unyielding target without loss of containment. The external shock absorbers of a transport package are designed to absorb the energy from this impact, as well as provide other functions not covered in this paper. This paper looks at methods to assist in the designing of these shock absorbers and how LSDYNA can be instrumental in the design and testing phase.

• Development of a 2020 SUV vehicle FE model

  Rudolf Reichert, Umashankar Mahadevaiah, Cing-Dao (Steve) Kan, Lukas Fuchs

  Finite element (FE) vehicle models allow researchers to conduct diverse simulation studies. Members of the Center for Collision Safety and Analysis (CCSA) at the George Mason University (GMU), that also built the core team of the formerly known National Crash Analysis Center (NCAC), have been developing a fleet of publicly available FE vehicle models [1] over the past 25 years. This paper describes the latest model, representing a 2020 Nissan Rogue SUV vehicle, shown in Figure 1. Note that the vehicle has been named as the Nissan X-Trail in all countries it is sold, except for the United States and Canada, where it called Nissan Rogue.

• Development of a Data-driven Surrogate Model for Scale-bridging in Battery Modelling Application

  Harshwardhan Dhumal, Tobias Aubel, David Koch, Nils Karajan, Karsten Keller, Andre Mielke

  In numerous mechanical engineering applications, the use of multiscale computational modeling and simulations is imperative. Nevertheless, the computational challenge persists in addressing complex multiscale systems due to the vast dimensionality of the solution space. The field of machine learning (ML) has experienced ongoing development as a feasible option that might potentially expedite, substitute, or complement traditional numerical techniques.

• Development of Effective Taylor-Quinney Coefficient Table of *MAT_224 for Aluminum 2024-T351

  Chung-Kyu Park, Kelly Carney, Paul Du Bois, Cing-Dao Kan

  In this research work, the effective Taylor-Quinney Coefficient (TQC) table of *MAT_224 for Aluminum 2024-T351 alloy was developed to replace the current constant TQC. The methodology to create the effective TQC table was developed by using a two-step approach. In Step 1, the thermal-structural analyses of tensile tests were conducted to verify the referenced TQC values and generate the additional temperature-strain curves at additional rates which were not covered by the physical tensile tests. In Step 2, the structural-only analyses of tensile tests were conducted to calibrate the effective TQC values at all the rates for the effective TQC table and validate the calibrated effective TQC table.

• Development of Far-Side Sled Simulation Model with Airbag for Virtual Testing

  Hisaki Sugaya, Yu Kanayama, Kanae Matama, Nanami Kobayashi, Takashi Kikuchi

  Currently, Euro NCAP announced a virtual test to improve safety performance robustness. Starting with the Far-side sled test, robustness will be evaluated at different angles and seat positions. Since robustness is evaluated only by simulation, it is crucial to improve the accuracy of the model. Therefore, the objective of this study is to verify the model accuracy level by comparing the simulation with the far-side SLED test with airbag as a benchmark for the virtual test.

• Developments in *MAT_WINFRITH_CONCRETE and Application to Modelling of Segmented Concrete Tunnel Linings

  Richard Sturt, Gianmarco Montalbini, Hyuk-Il Jung, Marc Tatarsky

  Tunnels constructed by Tunnel Boring Machines are lined with precast reinforced concrete segments. The joints between the segments must resist a combination of compressive load and bending moments induced by non-uniform pressure from the soil. Failure modes to be considered during design include splitting of the joint face under concentrated compressive load, spalling of the exterior or interior faces of the segments under bending actions, and impacts of bolt connection details on the stability of the joints. The capacity of the segments to resist such failures may be explored in detail using LS-DYNA’s nonlinear concrete models. The paper includes examples from an investigation into a tunnel that partially collapsed shortly after construction. The failure modes revealed by the site investigation of the collapsed tunnel matched well with those shown by the model.

• Die Attach Process using Adaptive ISPG in LS-DYNA

  Ayush Kumar, Vivek Pawar

  The die-attach process is a crucial step in electronic packaging, where semiconductor chips (dies) are securely bonded onto substrates (e.g., lead frames or printed circuit boards). The process typically in-volves applying an adhesive or solder material to join the die and substrate. It ensures electrical con-nectivity, dissipates heat, and protects the delicate semiconductor components. Precise die-attach (DA) techniques are vital to guaranteeing the reliability and performance of electronic devices, as improper bonding can lead to connection failures and reduced overall functionality of the packaged components.

• Dynamic Explicit SPH Simulation and Material Characterization of Road Tankers using LS-DYNA

  C. Robb, G. Abdelal, P. Mckeefry, C. Quinn

  Crossland Tankers is a significant manufacturer of bulk-load road tankers from Northern Ireland. Thirty thousand litres of liquid are carried over long distances and varying road conditions. The effect of sloshing within the tank can significantly impact the driveability and lifespan of the tanker. As part of this project with Crossland Tankers, we will develop a model using LS-DYNA to investigate the applications as part of the design process.

• Efficient processing method for material card definition of AHSS and UHSS to predict fracture in crash analysis and its application to vehicle crash model

  Kang Hee Lee, Dae Young Kim, Chul Woong Jun, Kyoung Teak Lee

  Crashworthiness of the vehicle body is getting importance to meet the enhancing vehicle crash safety regulations. To improve the vehicle body crashworthiness, application of Advanced high-strength steels (AHSS) and Ultra high-strength steels (UHSS) are continuously increasing due to their superior strength than conventional high-strength steels (HSS).

• Enabling Productive Use of Isogeometric Shells in LS-DYNA

  Lukas Leidinger, Stefan Hartmann, Frank Bauer, Dave Benson, Attila Nagy, Liping Li, Marco Pigazzini, Lam Nguyen

  Isogeometric Analysis (IGA) [1] is a novel Finite Element Analysis (FEA) technology based on splines known from Computer Aided Design (CAD). In an isoparametric sense, IGA uses the higher-order and higher-continuity spline basis functions, e.g., Non-Uniform Rational B-Splines (NURBS), not only to describe the model geometry, but also the solution field. This may yield a more accurate geometry description, higher solution accuracy and a larger time step in explicit analysis compared to conventional FEA.

• Ergonomic optimization of rowing seats using personalized Human Body Models

  Manuela Boin

  Seat-related discomfort and health problems, which occur especially during long rowing tours or training sessions, can be reduced by rowing seats with a surface geometry that is ergonomically optimized for the particular rower. This seat optimization can be done by analyzing measured pressure distributions and modifying the standard seat surface geometry for a specific person based on these results using CAD tools. The project presented here focuses on the purely virtual development of the optimal geometry for specific rowers. FE simulations were performed using Human Body Models (HBMs) to define seat geometries for specific individuals.

• Event Detection Methods for Multi-Sensor CAE-Data

  R. Iza-Teran, D. Steffes-lai, Anh-Duy Pham, M. Pathare, J. Garcke

  Virtual product development especially in car development requires the evaluation of multiple sensors signals in the simulations as one of the tasks; the sensor data is also needed for comparison with the real product. Comparing many virtual sensors manually from many simulations turns out to be a time consuming and challenging task. We propose a methodology and workflow setting that address this challenge, allowing a similarity comparison of hundreds of sensors from hundreds of simulations detecting similar events (clusters) or very different behavior as outliers. The approach uses a method of dimensionality reduction combined with different type of clustering methods including hierarchical clustering. The dimensionality reduction reduces the virtual sensor data information such that a visual comparison of thousand sensor signals can easily be performed in 3D, the hierarchical clustering on the other hand allows a localized comparison of sensor signals. The approach is demonstrated using binout Ls-Dyna data from a frontal crash example with many model variants containing many sensor data per simulation as well as for head impact computation.

• EXPERIENCE WITH CRASH SIMULATIONS USING AN IGA BODY IN WHITE

  Frank Bauer, Tian Yugeng, Lukas Leidinger, Stefan Hartmann

  With the IGA (Isogeometric Analysis) technological approach [1], the transfer processes from CAD to CAE can be simplified in the future and false predictions due to discretization effects can be reduced. In recent years, IGA and the corresponding toolset has increasingly developed into a setup that comes close to industrial use [2]. In order to test the use of IGA in industrial environments, a body in white (BIW) that was previously modelled with a „classic“ FE approach was also modelled with IGA and installed in a so-called hybrid model in a full vehicle crash simulation. For this purpose, the CAD data used as the basis for the FE model creation was used to directly create IGA surfaces. The aim of implementing a body in white using IGA was, on the one hand, to look at the processes in terms of usability, automation capability and implementation quality; and, on the other hand, to understand how hybrid crash simulations behave in terms of computing time and stability. In order to see different design effects in crash simulations, a front crash and a side crash were carried out and compared with existing FE models. The investigations show the entire process, from geometry conversion to full vehicle simulation and explain the findings in comparison with the FE model.

• Experimental Procedure and Hardening Model for Simulation Considering Forming and Baking Effects

  JiHo Lim, Haea Lee, Jisik Choi

  The automotive body is manufactured by assembling parts made by forming, and then going through a painting process. Sheet metal parts formed by press have the plastic strain, and bake hardening that material strength increases according to the plastic strain during the baking process of painting, occurs. Therefore, the actual assembled automotive parts are stronger than the original materials due to the combined effects of work hardening and bake hardening. Automobile crash analysis generally applies the properties of the original material, but the change of material properties in real parts acts as a factor of error in crash analysis. Especially, these characteristic is more pronounced in giga-steel. Considering the increasing trend of giga-steel for weight reduction, it is necessary to consider the change of material properties due to work hardening and bake hardening in crash analysis.

• Exploring the Potential of ARM Processors: Evaluating LS-DYNA Performance for Cloud-Based High-Performance Computing

  Eric Day

  In the realm of high-performance computing (HPC), x86_64 architecture has traditionally dominated, driven by its robust performance and extensive software support. However, recent benchmarks indicate the emerging viability of ARM processors for compute-intensive workloads, particularly when running LS-DYNA software. This study explores the performance of LS-DYNA on ARM-based chips, specifically evaluating its effectiveness on Amazon Graviton in the HPC cloud environment and Apple M, Cavium ThunderX2, Ampere Altra, Fujitsu A64FX and Amazon Graviton in standalone computing. Power efficiency, high throughput, cost-effectiveness, and scalability position ARM processors as compelling options for cloud-based LS-DYNA computations.

• Failure model calibration of a DP1000 dual phase steel using solid and shell elements for crash simulation

  Florence Andrieux, Silke Klitschke, Andreas Trondl

  With the trend towards lightweight construction, advanced high-strength steel (AHSS) is increasingly being used in automotive structural components. Since the ductility of high strength steels is relatively low, damage behaviour of these materials must be accurately modelled. In automotive structures AHSS components are usually discretized with shell elements. With the increase of computation capacity attempts with solid elements are made to capture the loading state more accurately, especially after necking. For this reason, it is convenient to develop a method which enables a systematic model calibration from the 3D to the 2D loading situation. The failure strain of metallic materials depends on stress state. In the past years several studies have shown that the stress triaxiality is not sufficient to describe failure and empirical models were extended to consider the effect of Lode parameter. Recently it was also shown that the amount of bending seems to influence failure, namely i.e. the failure strain increases with the amount of bending.

• Far side crash correlation and sensitivity study for virtual testing

  Roland Schirmer, David Ide, Carlos Gonzáles

  In 2024 the monitoring phase of the virtual far side occupant assessment is going to start. The vehicle manufacturer will carry out the physical sleds and virtual tests. Variations of the impact angle and the seat position are going to be assessed with purely virtual tests. The car manufacturer has to show that the correlation level of his simulation model is sufficient. For that the ISO score rating according to ISO/TS18571 and the selected ATD (‘dummy’) injury criteria are used on the two validation tests. To be prepared for this challenge, Stellantis put together a cross functional, international CAE team of methods development and safety department members. The task was to test if the existing model content and the level of detail in the subsystems fulfill all performance requirements and to identify the key enablers to reach the correlation targets.

• Fatigue assessment of an adhesively bonded EV battery enclosure, using LS-DYNA implicit tools

  David McLennan, Michael Magnier, Simon Hart

  Adhesively bonded aluminium structures are becoming increasingly popular within the automotive industry. Bonded connections are continuous, and therefore can avoid the stress concentrations which arise in discrete connections such as spotwelds, rivets or bolts, and thus have the potential to perform better from a fatigue perspective. However, bonded structures have their own challenges to analyse, particularly for predicting fatigue life, where limited data exists in the public domain.

• Finite element modelling of textile-soft material interaction using 3D/4D scan data

  Ann-Malin Schmidt, Yordan Kyosev

  The interaction between textile and soft material occurs in different areas. It can be found in the clothing, medicine or automotive sector. In this paper the textile-soft material interaction has been investigated using the example of the breast-bra interaction. 4D scan data of a test person dressed with a bra and unclothed were acquired in two scan poses. The scans were analysed by cross section comparisons. A finite element model was developed from these scans. Three different meshing methods were modelled. A FEM model of a bra compressing the female breast was successfully developed. The breast deformation is modelled the best with a solid body model. In the validation comparison of the modelled breast deformation and the original breast deformation, a very good agreement can be seen.

• Fluid added mass modeling in LS-DYNA and its application in structural vibration

  Yun Huang, Tom Littlewood, Francois-Henry Rouet, Zhe Cui, Ushnish Basu

  Many structures, machines, or devices are operated partially in water, like surface ships, vessels, semi-submersible platforms. Some others may work completely in water, like submarines. For any of them, water has an important influence on their dynamic response. For most cases, a strong coupling between structures and surrounding water is required to get a good simulation of vibration response of structures subjected to shock or wave loadings. Unfortunately, a fully coupled simulation involving both structures and water explicitly can be expensive. Besides, with the traditional finite element method, meshing a large volume water body and defining non-reflection boundary conditions (e.g., Perfectly Matched Layer [1]) on the truncated boundary can be challenging and needs some experience.

• Fluid-Structure Interaction Simulations of Mechanical Heart Valves with LS-DYNA ICFD

  Mariachiara Arminio, Dario Carbonaro, Sara Zambon, Rodrigo Paz, Facundo Del Pin, Umberto Morbiducci, Diego Gallo, Claudio Chiastra

  The aortic valve is responsible for allowing blood flow from the heart left ventricle into the aorta during the systolic phase of the cardiac cycle and for preventing backflow during the diastolic phase. The aortic valve is composed of three leaflets attached to the aortic root in proximity of three aortic dilations named sinuses of Valsalva. Leaflets open and close as a result of transvalvular pressure drop. Specifically, when the ventricular pressure is higher than the aortic pressure the leaflets open, whilst they close the valve orifice when the aortic pressure is higher than the ventricular pressure. Valve functionality may be impaired due to several conditions, such as aortic valve stenosis and aortic valve regurgitation, with a consequent increase in the risk of left ventricle hypertrophy and cardiac failure [1]. Among treatment options for aortic valve disease, a major role is played by the surgical replacement of the native valve with a prosthetic device.

• From automatic event detection to automatic cause correlation

  Nouran Abdelhady, Dominik Borsotto, Vinay Krishnappa

  Reaching and fulfilling several design and crash criteria during the development process is what makes the engineer adapt and redesign the simulation model over and over again. Ideally resulting in new simulation runs with in best case improved performance, matching the intention of the applied changes. For the more demanding case of unforeseen results which do not necessarily fit to the expectations of the actual changes, methods and a workflow are being introduced here, which allow to identify the root cause of this behavior.

• FSI simulations to study eye biomechanics during a Non Contact Tonometry

  Elena Redaelli, Begoña Calvo, José Felix Rodríguez Matas, Giulia Luraghi, Jorge Grasa

  Understanding the corneal mechanical properties has great importance in the study of corneal pathologies and the prediction of refractive surgery outcomes. Non-Contact Tonometry (NCT) is a non-invasive diagnostic tool intended to characterize the corneal tissue response in vivo by applying a defined air-pulse. The development of a strong FSI tool amenable to model the NCT, applied to different structural and anatomical configurations, provides the basis to find the biomechanical properties of the corneal tissue in vivo. This paper presents a high-fidelity finite-element model of a patient-specific 3D eye for in-silico NCT. A fluid-structure interaction (FSI) simulation is developed to virtually apply a defined air-pulse to a patient-specific eye model comprising cornea, limbus, sclera, and humors. Three different methodologies are tested to model the humors and the best approach is chosen. Then, a Montecarlo simulation is performed varying both the parameters describing the mechanical behaviour of the corneal tissue and the IOP. The analysis reveals that the mechanical properties of the corneal tissue and the IOP are perfectly coupled. A stiffer material with a low IOP can give the same deformation result on the cornea as a softer material with an higher IOP.

• FSI Simulations with LS-DYNA ICFD Solver: Capabilities, and Best Practices

  Satish Kumar Meenakshisundaram, Facundo Del Pin

  This document presents an overview of the LS-DYNA ICFD (Incompressible Computational Fluid Dynamics) solver and best practices for its efficient use in solving complex Fluid-Structure Interaction (FSI) problems from a user's perspective. LS-DYNA ICFD solver is a powerful tool for simulating the interaction between fluids and solid structures, allowing for accurate predictions of real-world phenomena. This paper will cover the underlying principles of the ICFD solver, its unique features, and practical applications, along with tips for efficient use. The content presented is crafted to ensure that engineers, regardless of their level of experience with FSI simulations, can easily understand and benefit from it. This document aims to provide a clear and concise guide for researchers and engineers who seek to utilize LS-DYNA ICFD solver for their FSI simulations, enabling them to achieve the expected throughput and save time in the process.

• Full Electric Vehicle Crash Simulation Using Coupled Thermal-Electrical-Mechanical Analysis

  Chenxi Ling, Leyu Wang, Cing-Dao (Steve) Kan, Chi Yang

  The safety of electric vehicles (EVs) has become increasingly important as the number of EVs has grown rapidly in recent years. This work presents a system solution to model the full EV structural crash analysis together with its active battery cells using a thermal-mechanical-electrical coupled analysis. This multi-physics analysis predicts the sequence of events that could lead to thermal runaway and battery fire. In previous work, a representative battery cell model was first developed based on matching the cell dimensions and the total amount of material in a realistic cell. Each battery component was modeled separately with realistic mechanical, electrical, and thermal material models.

• High-throughput Simulation and Machine Learning Approaches for Can Body Design

  Maximilian Weiser, Sebastijan Jurendic

  Novelis is a world leader in aluminium flat rolled products and a major supplier to the beverage can-making industry. As such, Novelis is deeply involved in supporting the can-making industry to help shaping a more sustainable future together. Reducing the amount of metal used for each beverage can is a major driver for improving sustainability of the beverage can packaging, thus Novelis is actively investigating and developing state of the art modelling tools and approaches to support further optimization of the beverage can.

• Higher-Order 3D-Shell Elements and Anisotropic 3D Yield Functions for Improved Sheet Metal Forming Simulations: Part I

  Maximilian Schilling, Tobias Willmann, Alexander Wessel, Alexander Butz, Manfred Bischoff

  Sheet metal forming simulations are crucial in various industries, such as automotive, aerospace, and construction. These simulations are commonly carried out using Reissner-Mindlin shell elements, which involve certain simplifying assumptions about zero normal stress in shell normal direction and cross-sectional fibers remaining straight during deformation [1]. Because of this, the material model needs to be modified and no three-dimensional material model can be used. However, in critical forming situations such as bending with small radii relative to the sheet thickness, these assumptions do not hold, resulting in inaccurate simulation results. To address this issue, a higher-order 3D-shell element that incorporates a full three-dimensional constitutive model and that can account for cross-sectional warping and higher-order strain distributions has been developed [2].

• Higher-Order 3D-Shell Elements and Anisotropic 3D Yield Functions for Improved Sheet Metal Forming Simulations: Part II

  Alexander Wessel, Maximilian Schilling, Tobias Willmann, Alexander Butz, Manfred Bischoff

  This two-part series focuses on the industrial application of higher-order 3D-shell elements and anisotropic 3D yield functions in sheet metal forming simulations. In the second part, the effect of plastic anisotropy with respect to the in-plane and out-of-plane behaviour on sheet metal forming simulations is analysed. To this end, parameters of the anisotropic 3D yield function Yld2004-18p were identified by a crystal plasticity modelling approach for an AA6014-T4 aluminium alloy. Different loading conditions related to the plane and full stress state were carried out to study the plastic anisotropy with respect to the in-plane and out-of-plane behaviour.

• Importance of Plasticity for GISSMO Calibration in Automotive Safety Applications

  Richard Burrows

  GISSMO has become an incredibly flexible tool since its inception. An overview is not to be presented here owing to the fact it is coved extensively by other authors. This body of work aims to show that even using simple techniques and features a robust GISSMO card is possible using only *MAT_024 and *MAT_ADD_EROSION, that can be useful in automotive safety, even with larger type 16 shell elements 3-6mm in edge length for gauges approx. 1-2mm. 3-6mm quad elements are a very useful size for automotive structures and allows accurate meshing of holes, flanges and joints for example.

• Improvements of LS-DYNA ICFD’s two-phase level-set solver

  Z. Solomenko, F. Del Pin, I. Caldichoury, R. Paz, P. Huang

  Numerical simulation of two-phase flows with interface capturing consists in solving a single set of Navier-Stokes equations with variable material properties. Here, we use the level set method for interface capturing [1]. That gives a simple representation of the interface – the level-set scalar field is continuous and allows easy access to geometrical properties at interfaces. That function evolves in time as it is transported by the flow velocity. As the velocity is not uniform in general, the level-set function may need be reinitialized while maintaining the position of interfaces. Numerical methods that are deployed to solve those problems must be chosen meticulously. Depending on the type of flow, advanced numerical techniques must be used to avoid unphysical motion of interfaces. Combinations of numerical methods have been tested on several benchmark tests.

• Incremental Forming Simulation of Dimples for Solar Mirror Supports using Isogeometric Analysis

  Wade Evans, Johannes Pottas, Lukas Leidinger, Amit Nair, Fabian Knieps, Benjamin Liebscher, John Holmes, Joe Coventry

  Heliostats are concentrating mirrors which track the sun to direct light onto a receiver in concentrating solar power (CSP) systems. Heliostat cost and performance are major contributors to the capital cost of CSP systems and their levelised cost of energy. For this reason, several existing heliostat mirror facet designs utilise low-cost stamped supports which are laminated to glass mirrors to impart stiffness and maintain shape accuracy of the optical surface, whether curved or flat.

• Inductive and Radiofrequency (RF) heating in LS-DYNA for medical and other industrial applications

  Iñaki Çaldichoury, Pierre L’Eplattenier

  Inductive and radiofrequency heating both rely on an electromagnetic power source to generate heat. However, they are based on different frequency scales that trigger different electromagnetic behavior and make some terms predominant over others. Inductive heating can be viewed as a “contactless” form of heating where a current source (typically a copper coil) with a frequency in the range of 𝐾𝐾𝐾𝐾𝐾𝐾 or MHz approaches another conductor thus triggering induced currents (Eddy currents) in nearby conductors which can generate heat, depending on the material’s properties (resistivity, permeability). In this paper, radiofrequency heating can be viewed as an extension of traditional Resistive heating where an electrode is plugged between two ends of a specific material. Contrary to resistive heating, the material’s electrical conductivity is usually very low, or the material can be an insulator, but the input source is in a high frequency range (𝐺𝐺𝐾𝐾𝐾𝐾 or higher) which triggers molecular displacements that generate heat via friction. This dielectric heat source term becomes the dominant factor rather than the Ohmic losses term.

• Investigation of Improvised Explosive Device Effects on a Section Hull of Armored Military Vehicle

  İsmet Kutlay ODACI, Samet Emre YILMAZ, İlker KURTOĞLU

  Military vehicles and their occupants in conflict zones face a significant risk from improvised explosive devices (IEDs). Simulating IED risks on armored military vehicles requires employing various modeling approaches. However, to ensure the accuracy and effectiveness of these approaches, it is crucial to accurately transfer the explosive load onto the vehicle structures. This study aims to address this critical point by developing a methodology for selecting the appropriate vehicle components for load transfer and evaluating the proximity of the analysis model to live fire test results.

• Investigation of Mechanical Behavior of Lithium-ion Battery under Loading and Suggestion of Simplified Modelling Approach

  Atsushi Takahashi, Shinichi Amano, Kei Saito, Yasuhito Aoki

  Ensuring battery safety is one of the key issues in the design of electric vehicles. In many cases, batteries are designed to be placed in strong cases or with sufficient clearance to prevent serious damage. On the other hand, to develop a vehicle which is lighter and can run longer, it is necessary to reduce the weight of battery cases and the clearance between cells. To meet the above requirements, it is important to fully understand the mechanisms leading up to the occurrence of short circuits that cause thermal runaway, and to feed such information back into the design.

• Latest ANSA developments for IGA modeling

  Lambros Rorris, Ioannis Chalkidis

  During the last years the capabilities of both LS-DYNA and ANSA are in continuous progress in terms of creating and analyzing IGA models, especially in crash and safety discipline. Automotive industry studies the behavior of ever more complex mechanical parts by running simulations using both FEA and IGA within a context where robustness and automation are probably the most important keywords. Pre – processing such parts with Isogeometric Analysis gives more accurate results in terms of displacements but robustness is yet to come. Describing and analyzing the parameters of an IGA simulation singularities, plays an important key role in the latest developments of the ANSA pre – processor, opening the way to study new models of high complexity and build hybrid models.

• Machine learning using a hybrid quantum-classical algorithm

  Maximilian Spiegel, Sebnem Gül-Ficici, Ulrich Göhner

  The industrial sector uses artificial intelligence (AI) in many ways. E.g. anomaly detection to identify and examine abnormal behavior of machines, such as voltage and current fluctuation. To develop self driving cars AI is used to perform segmentation of the environment to navigate the vehicle and make decisions, preferably in real-time. Quantum computers are already being used for special machine learning processes, achieving, in some instances, better results than a regular machine learning algorithm. This paper will elaborate on the upsides of a machine learning model consisting of a hybrid between a quantum machine learning (QML) algorithm and a classical machine learning algorithm.

• Meshless Methods in Workbench LS-DYNA

  Ulrich Stelzmann, Yury Novozhilov, Alexander Pett, Erik Plugge

  CADFEM Germany GmbH is working to create an open library of Ansys LS-DYNA [1] industrial use cases. Two new Industrial Use Cases for Ansys LS-DYNA have been developed by CADFEM in 2023. They focus on using meshless methods and the Eulerian approach for real-world applications: SPG usage with GISSMO damage model to simulate material separation and SPH/S-ALE solver usage for inertia-dominated fluid-structure interaction (FSI).

• Modeling Aluminum Honeycomb Under High Velocity Impact

  Murat KAMBEROGLU

  Aluminum Honeycombs are classified as advanced engineering solution for specific requirements and utilized as composite core material, thermal isolator, optical aligner, floor mat, packaging filler and energy absorber for different industries. Many materials may be mentioned here as cheaper and simpler alternative that can offer similar or maybe higher performance for these purposes even with lower cost, however none of them can come close to the weight advantage of honeycombs thanks to the extensive air space and load path provided by its peculiar shape.

• Modeling composite materials with respect to reinforcement textile construction

  P. Böhler, M. Gubser, J. Ravic, O. Döbrich

  To address the ongoing efforts to virtually design complex composite materials and their high-perfor-mance structures and to contribute to the increasing developments towards Industry 4.0, research and development of fiber-reinforced composites is shifting from an experimental domain to a virtually con-trolled environment. Material models to account for the specific failure mechanisms of layered fiber-reinforced materials have been developed and can be used for largescale numerical structural simula-tions. However, these models do not account for the individual properties of the reinforcing materials and therefore lack information on microstructural effects and behavior.

• Modeling Net Capture of an Object in LS-DYNA

  Lee-Hee Drory, Aviner Shreiber, Matan Elbaz, Omer Livneh

  One way of capturing a moving object is by using a hanged cage-like net. The process is to be reliable under various impact velocities and orientations of the captured body. Thus, accurately modeling its dynamics is vital due to the need to account for multiple probable outcomes while including the complex net structure. The focus of the present work is on the modeling, characterization and calibration of the net and its motion. To best represent the geometric properties of the net, its initial state, motion, and body capturing procedure, the following stages were carried out. First, a beam-element-based model of the net was constructed in MATLAB® using a generative function, that allows simple generation of a multiple-parameter dependent net structure. This was due to the need for flexibility in dimensions, geometric properties, part allocation and base unit cell shape. Second, mechanical properties of the hyper-elastic unique net structure were characterized by a series of tensile experiments followed by properly choosing LS-DYNA elements and material formulations. Finally, two sets of finite element analyses (FEA) were conducted, where the first included folding the net to determine its initial state for the successive impact simulation. Both folding and impact procedures required careful consideration and examination of different aspects, such as contact types and formulations, mechanical forces and damping.

• Modeling of Directional Focused Fragmentation Charge (DFFC) – Investigation of Different Approaches

  İsmet Kutlay ODACI, Samet Emre YILMAZ, İlker KURTOĞLU

  The aim of this study is to examine the effects of explosion-accelerated clusters of projectiles, which is in literature referred as Directional Focused Fragmentation Charge (DFFC), on target armor structures. The primary challenge in this study is to develop an accurate model for the explosive and fragments configuration, since the scenario involves a close-range explosion and fluid-structure interaction (FSI) due to the direct contact of fragments with the explosive. To find an appropriate and stable solution to this challenge, various techniques are explored for modeling both the explosive and the cluster of fragments.

• Modelling Delamination in Fibre-Reinforced Composites subjected to Through-Thickness Compression by an adapted Cohesive Law

  Moritz Kuhtz, Johannes Gerritzen, Jens Wiegand, Andreas Hornig, Maik Gude

  A special form of failure in impact loaded Fibre-Reinforced Composites (FRP) structures is delamination, in which individual layers of a laminate get separated from one another. In contrast to the continuum mechanically formulated models of damage mechanics, the description of delamination processes is based on concepts of fracture mechanics. Here, delamination initiation is due to interlaminar stresses [1], whereby the tolerable interlaminar shear stresses can be increased by a simultaneous through thickness compression (TTC) [2-4]. Furthermore, an increase in the critical energy release rate with increasing out-of-plane compressive load is described [5-6]. Failure to consider the compressive superposition can lead to an overestimation of the delamination failure in impact loaded FRP structures such as three-point bending beams [7].

• Modelling of laser impact on typical composites aeronautical structures for bonding quality assessment

  Julie Rougier, Teddy Maillot, Charlotte Michel, Vincent Lapoujade

  Massively used in aeronautical structures, composites are nowadays essential in the search for a more ecological and successful industry. Their low density enables weight reduction and then decreases airplanes consumption. However, the current composites assembly process represents a limitation in their use. In fact, we do not have any reliable, industrialized and non-destructive technology to control the adhesive quality. Then composites are also riveted which adds weight and a drilling process during which fibres can be locally damaged. For about 10 years, the LASAT (LAser Shock Adhesion Test) technology appears to be a promising alternative as a non-destructive control mean to asses bonding quality. The laser impact creates a plasma that induces shock waves propagation in the structure. The LASAT technology can also be used to generate damage anywhere in the assembly thickness. The experimental technology is mature but is lacking a numerical tool in order to calibrate the input laser parameters depending on the targeted results.

• Modelling the Dynamics of Well Perforation

  Marco Serra, John P. Rodgers

  One of the crucial steps in the completion of many oil wells is their perforation, required to establish communication with the target reservoir. Perforation is a very short duration, high energy event in which a series of explosive shaped charges is fired to produce corresponding perforations into the hydrocarbon-bearing formation. This event gives rise to violent pressure and structural dynamics that die out within a second or two, depending on the specific completion design. During this time, the nature of the pressure dynamics and resulting fluid response determine the initial quality of the communication between the well and the formation, which has significant consequences for the overall productivity over the well’s lifetime, as well as the integrity of the tool string components during the perforation event.

• Monopile damage assessment from impact with a sub-sea boulder, using an LS-DYNA methodology

  David McLennan, Francesca Palmieri, Andrew Cunningham, James Go, Richard Sturt, Paul Morrison, César Tejada, Georgios Perikleous, Jacob Brandt, Mikkel Lubek

  During the installation of monopiles (MP) for the offshore wind turbine industry, there is a site-specific risk of impact with submerged sub-sea boulders, depending on the nature of the site geology. Factors such as boulder size, boulder depth, soil properties, and impact angle, will influence the level of damage experienced by the MP due to the boulder impact.

• Multi-phase welding simulation, experimental validation and exploratory bending simulation of structural steel weldments

  Tobias Girresser, Tobias Loose

  To predict the load-bearing capacity of a welded joint, it is necessary to know the structure that will be formed. In recent decades, welding simulation has evolved and now offers the possibility to determine the required material properties after welding [1]. Computational welding mechanics (CWM) is a calculation method that can be used to calculate distortions, mechanical stresses, and strains as well as microstructure states and microstructure transformations in thermally joined components [2, 3].

• Multi-stage Analysis Approach to Low Speed Vehicle Impacts using the *SENSOR Keywords

  Hari Patel, Ben Crone

  The low speed impact tests outlined in ECE R42 and FMVSS 581 consist of multiple consecutive impacts on a vehicle bumper to assess vulnerability to damage and repairability. Typical CAE approaches to assessing multi-stage analyses involve running each stage of the analysis individually, inputting deformations, stresses, and strains from the end of the previous analysis. This approach typically requires manual model editing before each analysis, which is time consuming and increases the risk of human error.

• New Eigen Solver Technology in LS-DYNA

  Roger G. Grimes, François-Henry Rouet

  The Linear Algebra Team of Ansys LST has added two new eigen solver technologies for the standard vibration analysis problem of structural mechanics. The first, LOBPCG, is based on iterative solution technology to reduce the cost of the direct solution used by the default eigen solver Lanczos. The second, Fast Lanczos, is a new innovative implementation of the Block Shift and Invert Lanczos algorithm targeting the computation of thousands of eigenmodes with less accuracy for the Noise-Vibration-Harshness (NVH) application.

• Numerical Dynamic Characterization of a Xenon Satellite Propellant Tank Employing Discrete Element Spheres

  Thomas PIERROT, Antoine GUILPIN, Tess LEGAUD, Vincent LAPOUJADE, Jean-Emmanuel CHAMBE, Miguel CHARLOTTE, Yves GOURINAT

  The ecological emergency makes the use of cryogenic or supercritical fluids more and more relevant. However, experimental tests and associated modelling of those liquids dynamic vibratory behaviour remain extremely challenging. Indeed, security, control and conditioning are critical issues due to the intrinsic fluid instabilities. Among those fluids, liquid hydrogen and supercritical xenon are both highly used in the spatial propulsion domain. Because of their hazardous behaviour, only few experimental dynamic tests have been performed to improve the knowledge of their behaviour inside a vibrating tank.

• Numerical Modelling of Sheet Metal Damage in LS-DYNA using GISSMO

  Erik Stålbrand, Axel Hallén

  In this paper, a strategy for numerical simulation of cutting during concurrent pressing of stainless steel sheet metal is investigated while accounting for the stress triaxiality and Lode angle parameter. An inverse modelling approach is used, where both a material model and a damage model are calibrated. The damage model is developed using the GISSMO damage model (Generalized Incremental Stress State dependent damage Model).

• Numerical simulation of shock events and associated response of satellite

  Tess Legaud, Nicolas Van Dorsselaer, Vincent Lapoujade, Simon Lemay

  The paper presents CNES’ and Dynas+ partnership recent activities to improve shock events simulation and predict shock propagation in structures and equipment. The last activities presented here have been focused on shock test prediction by numerical analysis (i.e. virtual shock testing). The simulations were performed using LS-DYNA®, whereas the use of explicit non-linear computation codes is not common in the space industry to deal with spacecraft mechanical environments. Especially, the activities aimed at modelling physically the shock event generated by one of CNES’ pyrotechnic test device and to predict the acceleration levels generated by this source on the structural model of a microsatellite. To do so, multiple intermediate steps had to be studied, beginning by the modelling of a simple sphere impacting a plate. The model complexity increased progressively to reach the modelling of a satellite vibrations induced by shock sources. In order to assess model predictability, all the tests were performed at various shock energies and compared to experimental results. This paper will present the results and comparisons with experimental SRS (Shock Response Spectrum) obtained starting with “simple” cases up to cases integrating complex structures and shock sources.

• Numerical Structural Design and Optimization of Free-Form Hydrogen Vessels in the Context of Metal-Organic Frameworks

  Markus Bellmann, Ruben Krischler, Ruben Czichos, Peter Middendorf

  Development regarding storage solutions for hydrogen is crucial to enable its widespread adoption as a sustainable energy carrier especially in the mobility and transportation sector. The application of Metal-Organic Frameworks in carbon fiber composite wound pressure vessels leads to a reduction in operating pressures and allow both a cost and CO2 footprint reduction by enabling glass fiber as a valid material choice and the exploration of free form tank designs in order to better utilize challenging design spaces in automotive vehicles. This study explores the capabilities and limitations of these tank designs using numerical multi stage optimization in LS-OPT in conjunction with LS-DYNA, BETA CAE, MATLAB and Python for the fully automated, detailed optimization of the geometry and laminate of these tanks.

• Numerical study on a new forming method for manufacturing large metallic bipolar plates

  David Briesenick, Maxim Beck, Kim Rouven Riedmueller, Mathias Liewald

  Fuel cell technology offers a sustainable power supply solution for heavy-duty vehicles, aviation and shipping as well as stationary application. Manufacturing of metallic bipolar plates (MBPP) as a key component of fuel cells is nowadays one of the main topics in production-based research and processing industry. One reason for this is that although stamping of thin stainless-steel foils enables an economic large-scale production of metallic bipolar plates, tooling and press technologies required for embossing and shear cut operations are highly demanding and thus continuously being developed. Particular challenges are posed by the embossing of the complex flow field structure, which can cause forming defects and pronounced springback phenomena.

• Parametric optimization of cellular materials through LS-OPT

  Alessandro Giustina, Ivan Colamartino, Paolo Franzosi, Marco Anghileri, Marco Virginio Boniardi

  Cellular materials, characterized by a repetitive pattern of unit cells, feature many advantages with respect to conventional monolithic materials, that make them especially desirable for structural and energy absorption applications. First of all, the intrinsic cellular architecture, characterized usually by an interconnected network of solid struts and sheets results in a lightweight material [1], which at the same time is able also to dissipate large amounts of energy through the deformation of plastic hinges and local buckling phenomena [2], achieving a superior structural efficiency. Moreover, some recently developed geometries allowed to achieve highly desirable and unprecedented structural properties, such as negative Poisson’s ratio, bistability, or recoverable deformation.

• Parametric Projection-based Model Order Reduction For Crash

  Mathias Lesjak, Fabian Duddeck

  Modern passive safety development is associated with numerous simulations and hardware tests. In virtual development, multi-query analysis such as optimization, sensitivity analysis and robustness studies are performed. These methods require many simulation evaluations, which can make their application impractical for large simulation models. An approach to make the development process more efficient is Model Order Reduction (MOR) which uses already generated simulation data to build a Reduced-Order Model (ROM) and accelerate future simulations.

• Prepreg forming, curing and structural analysis for an aero engine component

  Dennis Wilhelmsson, Jesper Eman, Vivekendra Singh, Anders Bernhardsson, Mats Landervik

  Carbon fibre composites have the potential of reducing weight and thereby the carbon footprint of an aero engine component due to the high strength and stiffness of the material relative to its weight. In this paper, a process simulation chain, consisting of forming, curing and structural simulations, is proposed. The demonstrator here is an outlet guide vain (OGV) which is part of an electric fan aero engine demonstrator, See Fig.1 below. This electric ducted fan (EDF) has been developed by GKN Aerospace Sweden in collaboration with the Royal institute of technology (KTH).

• Process simulation in LSDYNA from the viewpoint of a materials supplier: towards an integrated approach for performance and process

  Christos Derdas, Raoul Abas, Michael Klotz

  Electromobility and sustainability are the current megatrends that drive the market development of the automotive industry. In order to be conforming to these megatrends, one solution exists, and this is the lightweighting of automobile structures. More specifically, with advancing metal technology, the trend is for automotive Original Equipment Manufacturers to reduce the thickness of outer, non-load bearing panels of closures like doors and hoods. However, reducing the thickness of such panels creates an additional challenge, this being retaining both the Class A surface finish and the localized stiffness, which is crucial as it defines the experience of the end-user of the automobile. This can be achieved by leveraging 2D rubber or epoxy reinforcements that enable the bridging of the weight reduction and the localized stiffness competing requirements. Outer panel thickness reduction, however, makes them more prone to process induced permanent deformations due to temperatures of the oven required for curing coatings and paints.

• Pyheart-lib: A Python Library For LS-DYNA Multi-Physics Heart Simulations

  Martijn Hoeijmakers, Karim El Houari, Wenfeng Ye, Pierre L’Eplattenier, Attila Nagy, Dave Benson, Michel Rochette

  Physics-based computer simulations of the heart are gaining rising interest for optimizing the design of medical devices and for its treatment prediction and planning. LS-DYNA offers a powerful framework for modeling cardiac electrophysiology, mechanics, and fluid dynamics, as well as the coupling between the three physics. However, its wider adoption is hindered by several requirements among which: knowledge in cardiac function in health and pathology, expertise in numerical simulation, appropriate right modeling choices for the target application, availability of realistic heart geometries. In this paper, we present a free to use python package that allows for the generation of physiologically accurate heart models in an automatic and modular fashion. The architecture is organized in an abstract form that allows users to easily choose between the different physics, anatomical chambers of interest and parameters of interest and export the LS-DYNA keyword files ready for simulation. We also introduce the relevant heart modeling features that are available in LS-DYNA and present two exemplary models generated by the package: a full electrophysiology heart model and a bi-ventricular mechanical model.

• Raising the treasure of SPDMs – How data compression and automatized event detection support engineers

  D. Borsotto, V. Krishnappa, S. Müller, F. Natter, T. Roth, K. Schreiner, H. Talaat, C.-A. Thole, T. Weinert

  To cope up with the ever growing amount of simulation runs being performed, tools and techniques are needed to store the huge amount of simulation data and to make use of data being stored. While current Simulation Data Management systems allows managing and accessing datasets and would facilitate putting this into action for analysis, the demand on bandwidth and storage increases. Even with SPDMs, the users usually only had tools and time to make rather straight forward model to model comparisons, between current model versions and their immediate predecessors. To take analysis capabilities and model development a leap forward, it is necessary to also make use of whole model development branches to learn from the gathered simulation information. With the availability of such tools, the value of past simulation data increases.

• Realistic articulation, positioning and simulation of Human Body Models using Oasys LS-DYNA tools

  Manu Agarwal, Galal Mohamed

  The application of human body models (HBMs) in numerical simulation offers exciting opportunities in automotive development in areas such as comfort, ergonomics, and safety. These models are used to simulate human body kinematics and injury responses and risks in a variety of simulated impact scenarios. The industry leading THUMS and GHBMC family of models are usually provided in two standard postures – occupant and pedestrian. The occupant posture is typically a driving posture in an up-right position, whereas the pedestrian is a walking posture with fixed arm and leg angles. These standard postures are limiting and do not reflect the diversity of postures which an occupant or pedestrian can assume at the point of a collision. Furthermore, current trends in vehicle automation are also expected to give rise to new seating postures such as forward or backward facing reclined seats. A major challenge for users, however, is that these models are not provided with pre-configured information to aid positioning making it a very difficult and time-consuming effort.

• Recent Developments of the EM-Module in LS-DYNA

  Lars Kielhorn, Thomas Rüberg, Jürgen Zechner

  Since 2017, TAILSIT maintains a close collaboration with Ansys/LST. Our partnership focuses on the enhancement of LS-DYNA's electromagnetic (EM) solver module which is based on a coupling between Finite Element (FEM) and Boundary Element Methods (BEM).

• Reduced Order Model for enhanced EVAR Planning and navigation guidance

  Monica Emendi, Eirini Kardampiki, Karen H. Støverud, Pierluigi di Giovanni, Sigrid K. Dahl, Aline Bel-Brunon, Victorien Prot, Marco E. Biancolini

  Endovascular aneurysm repair (EVAR) is a minimally invasive procedure for the treatment of abdominal aortic aneurysms that consists in stent graft deployment through the iliac arteries [1]. During this procedure, a stiff guidewire is introduced from the femoral artery towards the aorta to support the proper deployment of the stent graft. The insertion of the stiff wire triggers a straightening effect on the iliac arteries, smoothing out their natural tortuosity [2]. This morphological alteration is hard to be measured intraoperatively or be forecasted preoperatively [3]. The main bottleneck is that the preoperative Computed Tomography (CT) does not get updated during the operation. Consequently, clinicians perform their maneuvers according to the initial aortic configuration and inject contrast in the vessel to visualize their configuration when it is needed. This practice could possibly lead to sub-optimal stent graft sizing, choice of the stent’s landing zone and to an increase in radiation exposure and contrast doses, especially in complex cases.

• Similar part identification integrating machine learning approaches with a SDM workflow

  Uwe Reuter, Marcelo Pintado, Marko Thiele, Akhil Pillai, Florian Moldering

  Machine learning (ML) approaches for geometric part recognition have been evaluated with 3D automotive data in [1], where only one vehicle was used (Toyota Yaris with around 200 parts) and the exact match was tested, which means that the model was able to identify only the particular part shown regardless of the other classes (one-to-one match).

• Simulating Shot Peening: Application on leaf springs

  Christos Gakias, Georgios Savaidis

  Shot peening (SP) is a widely used process of surface treatment, based on the impact of small spheres (shots) on the surface of a component. The impact results on a localized plastic deformation and the development of a compressive residual stress field, that can extend up to a depth of 300-400 μm. This stress field significantly improves the fatigue life of components and prevents the initiation of small cracks. SP treatment can be influenced by various parameters, such as the velocity of shot peening media, many of them, governed by stochasticity.

• Simulating Structural Resistance of D&I Food Cans to Open Up Downgauging Potential

  B. Liebscher, F. Knieps, I. Weinand

  To reduce cost and increase the efficiency of D&I food cans, a lighter can with the same axial stability and paneling resistance is required. Axial stability depends on wall thickness, bead geometry (mainly bead depth) and tensile strength in the wall, whereas paneling resistance is a function of wall thickness, Young’s modulus and bead geometry (mainly bead depth), with the bead depth having an opposite influence on paneling resistance and axial stability. FEA is used to find a bead geometry that satisfies both the paneling resistance and axial stability requirements. For a stable calculation of the paneling resistance, perturbation in the form of an eigenmode is required. The calculation time is significantly reduced by using an implicit solver with arc length method. When simulating axial stability, accurate modeling of the beginning of the flow curve is required. A weight reduction of 5% can be achieved by using next-generation high-strength D&I steel grades (e.g. rasselstein® D&I Solid).

• Simulating the hot press processing of structural thermoplastic foams

  S. Cassola, M. Duhovic, M. Salmins, P. Mitschang

  Thermoplastic foams allow the manufacture of lightweight parts with good thermal and acoustic insulation properties, particularly suited for aircraft interior and cabins structures. Such foams can be combined with skin layers of organic sheet materials (e.g. glass fiber (GF) polycarbonate (PC)) forming sandwich structures, enhancing the mechanical properties, but which unfortunately do not fulfil strict FST (Fire, Smoke and Toxicity) standards. An alternative approach uses the foam itself to create an integrated sandwich structure of an unmodified core and two skins of high density from the same material.

• Simulation of back-injection molded parts using MAT_058 and MAT_215

  Kai-Chien Chuang, Sanjay Kumar Sardiwal, Boris Cordero Porras, Patrick Scholz, Olaf Hartmann

  Within the modern automotive industry, long-fiber-reinforced polymers (LFRPs) have gained increasing popularity because of efficient production of complex geometries in combination with relatively high stiffness and strength. Increased mechanical performance can be achieved by combining LFRP with continuous fiber composites, such as UD-Tape while using back-injection molding. The combination of these two material types poses a challenge in CAE, because of their individual anisotropic behavior.

• Simulation of Hollow Embossing Rolling for Bipolar Plate Forming using LS-DYNA©

  Franz Reuther, Verena Psyk, Verena Kräusel, Martin Dix

  Hollow embossing rolling constitutes a promising forming technology for metallic bipolar plates due to the high achievable production rates. The simulation-based process optimization is impeded by the incremental forming character and modeling of fine channel structures, which leads to large model sizes and computation times. This paper presents a shell-based finite element modeling approach using LS-DYNA© for bipolar plate forming simulation. Essential boundary conditions of the modeling are discussed, and recommended setting parameters are derived.

• Simulation of Sheet Metal Forming – New Developments

  Dr. M. Fleischer, C. Babel, M. Guru, Dr. J. Strauß-Ehrl

  The use of finite element (FE [12], [16]) simulations to conduct a virtual validation of the forming process for sheet metal parts has been introduced in the mid 1990s and is state of the art in the automotive industry today. Two challenging tasks for determination of feasibility of a tool design and its process parameters [17] are the prediction of the material behavior during the forming process and the springback of the final part [2,3,4].

• Simulation of thermoplastic 3D-printed parts for crash applications

  Mathieu Vinot, Lars Bühler, Tobias Behling, Martin Holzapfel, Nathalie Toso

  The rapid development of additive manufacturing techniques in aeronautic and automotive industry opens new possibilities in the design of metallic or composite parts compared to traditional subtractive processes. In particular, 3D printing allows the design of complex parts with a high lightweight potential through optimal use of material along the load paths. In the composite field, various printing techniques emerged in the last decade such as Selective Laser Sintering (SLS) or Fused Deposition Modelling (FDM) [1]. On the downside, 3D printing is confronted to the large influence of process parameters on the geometrical and optical quality as well as on the mechanical properties of the manufactured structures [2]. Moreover, simulation techniques with finite-element methods are still at their very beginning and improvements should be achieved to predict structural performances in crash applications.

• Simulation of woven composite structures consider-ing manufacturing effects

  Mathieu Vinot, Tolga Usta, Christian Liebold, Martin Holzapfel, Nathalie Toso

  In recent years, advanced material models have emerged in finite-element codes for the simulation of composite materials reproducing realistic failure mechanisms. Through the increased reliability in simulation, less conservative designs of composite structures have been made possible. However, most of the current numerical solutions are considering the composite material independently of real manufacturing conditions, which can strongly affect the local material architecture and properties. To extend the potential of composite structures, it is therefore necessary to enhance the simulation models by including additional information from the production processes. To answer this problematic, many works have focused on the detailed simulation of these processes and on the transfer of information between the simulation steps [1, 2].

• Some New Features of the Dual CESE solver in LS-DYNA and its applications

  Grant Cook Jr, Zeng-Chan Zhang

  In this paper, we briefly review the dual-CESE solver that is an improved version of the regular CESE solver. For instance, compared to the regular CESE solver, it is more accurate and stable, and particularly more stable for triangle (2D) /tetrahedral (3D) meshes, all while maintaining the core features of the CESE method. Some of the new features of the Dual CESE solver in the R15 release will then be explained.

• Speeding Up LS-DYNA Implicit with Mixed Precision, Low Rank Approximations, and Accelerators

  Cleve Ashcraft, Jason Cong, Florent Lopez, Roger Grimes, Robert Lucas, Francois-Henry Rouet, Linghao Song

  The multifrontal method of Duff and Reid [1] dominates the runtime of most LS-DYNA im-plicit analyses. Its complexity will range from O(N1.5) to O(N2), depending on the model. This paper will give an overview of attempts to reduce the run time of solving large systems of linear equations, both on the host processor as well as with accelerators. Most of what is discussed herein is available today in the development version of LS-DYNA and should be released with R15. Everything discussed herein only applies to our symmetric indefinite solver.

• Structural Optimization with the Incremental Equivalent Static Load Method for Nonlinear Dynamic Responses

  Hong Dong, Brian Watson, Juan Pablo Leiva

  This paper presents an efficient approach for optimizing structures under dynamic impact loading conditions. We introduce an improved method called the Incremental Equivalent Static Load Method that enhances the accuracy of the original ESL method. In the original ESL method, equivalent static loads are computed based on the initial geometry and nonlinear displacement results from a nonlinear analysis software. With the Incremental ESL method, we update the stiffness matrix at selected time steps using deformations from a base time step. This enables us to compute and apply equivalent static loads based on incremental displacements for ESL loadcases, resulting in a more precise capture of geometric and material nonlinearity.

• Study on Analytical Verification Method for Dynamic Load Profile-based Joint Design

  J.H. Kim, S.D. Kim, K.T. Lee

  Fastening is clamping and fixing objects using tensile force generated by applying torque to bolts or nuts. In this process, the applied torque doesn’t entirely convert to bolt’s axial force (clamping force); It is mostly lost due to friction, and only a portion is transmitted as axial force. Typically, around 90% of the torque is lost. These frictional losses are influenced by factors like the shape and material of the joint parts and surface finishing. As depicted in Fig.1, even small change in friction coefficient can have a significant impact on the resulting clamping force.

• Systematic assessment of isogeometric sheet metal forming simulations based on trimmed, multi-patch NURBS models in LS-DYNA

  Christoph Hollweck, Lukas Leidinger, Stefan Hartmann, Liping Li, Marcus Wagner, Roland Wüchner

  Isogeometric sheet metal forming simulation is a promising numerical technique utilized for predicting the behavior of sheet metal parts during the forming process, aiming to establish a stronger connection with Computer Aided Design (CAD) descriptions. This approach combines the well-established framework of traditional finite element analysis (FEA) with the power of non-uniform rational B-splines (NURBS), known as isogeometric analysis (IGA). Unlike the conventional FEA framework, IGA directly employs the ansatz space of the CAD geometry for analysis, thereby enabling analysis on the exact geometry. Additionally, the smoothness of NURBS basis functions offers enhanced simulation accuracy and a larger timestep in explicit dynamics.

• The influence of pretension on reinforced concrete beams subjected to fuel tanker explosions

  Joel Smith, James Bache, Jessica Klimenko, Ben Smith

  Pretension in reinforced concrete beams is commonly used within the construction industry to provide sufficient precompression to the tension face of an element, such that static dead and live loads develop low or no tension stress within the concrete components of the element. While this is advantageous for conventional structural design, allowing the element to carry more load over longer spans, beam elements subjected to significant uplift loading, such as those experienced during an accidental explosion, can develop additional tensile stresses on the element's top surface.

• Thermal Runaway in Electric Vehicle Crash Simulation using LS-DYNA

  Pierre L’Eplattenier, Inaki Caldichoury, Kevin Kong, Vidyu Challa, Dilip Bhalsod, Srikanth Adya, Mike Howard

  Safety is an important functional requirement in the development of large-format, energy-dense, lithium-ion (Li-ion) batteries used in electrified vehicles. Many automakers have dealt with this issue by enclosing the batteries into robust protective cases to prevent any penetration and deformation during car crashes. While this worked well for first-generation vehicles, consumers are increasingly interested in higher range, which makes overengineered heavy protective cases detrimental for range. A more detailed understanding of battery cell behavior under abuse becomes is therefore necessary to properly make design trade-offs.

• Towards the Solution of Cross-Talk in Explicit Isogeometric B-Rep Analysis

  Zeyu Lian, Lukas F. Leidinger, Stefan Hartmann, Frank Bauer, Roland Wüchner

  Driven by the increasing need for seamless integration between Computer-Aided Design (CAD) and Computer-Aided Engineering (CAE), Isogeometric Analysis (IGA) emerged with the groundbreaking research conducted by Hughes et al. [1] in 2005. Unlike standard Finite Element Analysis (FEA) that typically employs 𝐶0-continuous Lagrange polynomials as basis functions, IGA utilizes smooth spline-based basis functions, the same as the ones used to describe the CAD geometries. The usage of consistent basis functions offers the potential to bridge the gap between CAD and CAE.

• Trimmed IGA B-Spline Solids vs. Standard Tetrahedra Finite Elements

  Stefan Hartmann, Lukas Leidinger, Frank Bauer, Dave Benson, Attila Nagy, Liping Li, Marco Pigazzini, Lam Nguyen

  In 2005, Hughes et al. [1] introduced isogeometric analysis (IGA). As opposed to standard Lagrange polynomial-based finite element analysis (FEA), IGA utilizes the same shape functions employed in computer-aided design (CAD) for numerical analysis. In the last decade, the development of IGA in LS-DYNA was mainly focused on thin-walled structures modelled as either structured trimmed or unstructured isogeometric shells. Currently, there is growing interest in the analysis of more complex engineering parts. This requires the use of accurate solid finite elements. It is well known however that rather poor computational performance can be achieved by invoking low-order solid elements. Recently, the potential benefits of volumetric B-spline finite elements have been successfully demonstrated by Meßmer et al. [2], [3]. This led to an increased customer interest and thus to the development of trimmed isogeometric solids in LS-DYNA. This paper provides an overview of basic concepts and current capabilities of trimmed isogeometric solids in LS-DYNA.

• Uncertainty Sources in WorldSID-50M Dummy

  Stefan Kronwitter, Karin Birkefeld, Markus Kösters

  Full vehicle crash tests are never fully identical in terms of their results, even when conducted with the same configuration. This variability arises from the existence of a diverse set of uncertain input parameters, which induces uncertainty in the relevant quantities of interest (QoI). The classical engineering approach, dealing with scattering system behavior and QoI, is to introduce safety factors and thus ensuring the system’s robustness with respect to the adherence of performance-relevant criteria. However, using this strategy within the vehicle safety design process carries the risk that the margins to specific limits might be exceeded in initial hardware tests.

• Universal Data Space for Vehicle Development: Managing and Orchestrating Workflows via Policy-driven Data Transfer in Global Enterprises

  Nikhil Mitapalli, Nadine Riske, Christopher Woll, Sebastian Fink

  The car of the future thinks ahead - and, based on the analysis and processing of data, can do far more than humans alone behind the wheel. Radar, lidar sensors as well as cameras, already collect and evaluate large amounts of information in real time and detect hazards such as black ice, objects such as stationary cars or the ends of traffic jams. If desired, the automobile of tomorrow will even drive autonomously. But it will be some time before all offline vehicles have disappeared from the roads and most of all cars are navigating through traffic completely autonomously. A study by the Prognos research institute for the ADAC [1] shows that autonomous driving is not expected to become established until 2040. By the time the first driverless cars are on the roads in Germany, both the volume and variety of data will have exploded. According to estimates by the international market research and consulting firm IDC [2], the volume of data worldwide will grow to as much as 143 Zbytes by 2024. And an end to the flood of data is not in view. In its latest study, IDC forecasts a globally generated data volume of around 284 Zbytes by 2027.

• Update of a Linear Regression Model to Predict Forming Limit Curves from Tensile Test Data

  G. Trattnig, M. Schmid, H. Pauli, L. Wagner, A. Grünsteidl

  Forming limit curves (FLCs) are widely used for the feasibility analysis of deep drawn steel components and the final tool design. The experimental determination of the FLC is usually based on Nakajima tests, which are evaluated according to the ISO 12004-2 standard with the intersection line method. In recent years the additional determination with the time dependent method [1] is used since it more accurately describes the increased forming potential of modern high ductility steel grades found in practical experiments.

• Using Data from Physical Experiments to Train Machine Learning Material Models

  Daniel Sommer, Pauline B¨ohringer, Markus Stoll, Peter Middendorf

  Structural analysis of mechanical components, such as predicting the deformation behavior of sheet metal or assessing the crash safety of a vehicle, typically relies on finite element analysis (FEA). One critical aspect influencing the quality of these simulations are the material models that describe the relationship between strains and stresses. However, the development and selection of the most appropriate models is a significant challenge that involves costly and time-consuming testing and calibration procedures.

• Verification of Concrete Spalling Simulation with Wave Propagation Theory

  Sunao Tokura

  It is well known that spalling failure occurs when concrete walls are subjected to impact loading. This is explained by the fact that the compressive stress wave generated by the impact propagates from the front surface to the back surface and is reflected at the back surface as a tensile stress wave that exceeds the tensile strength of the concrete. Spalling failure is one of the most important failure modes in evaluating the response of concrete structures subjected to impact loading. Ansys LS-DYNA has several capabilities to simulate spalling failure, but whether the depth from the surface where spalling occurs is accurately simulated is an important indicator for predicting the actual response of the structure with high accuracy. Therefore, in this study, the accuracy of the simulation of spalling failure using LS-DYNA was investigated based on the wave propagation theory. As a result, it was confirmed that LS-DYNA could reproduce the behavior of spalling failure with high accuracy.

• Virtual testing developments of the LS-DYNA® WorldSID 50th dummy model

  Alexander Schif, Yupeng Huang, Sebastian Stahlschmidt

  In 2024 the European New Car Assessment Programme (Euro NCAP) Virtual Testing Crashworthiness (VTC) procedure for far-side impact is introduced. The LS-DYNA DYNAmore WorldSID 50th dummy model will be part of this procedure. Separate qualification criteria must be satisfied for the WorldSID model. They are specified in Technical Bulletin TB043-1 [1]. LS-DYNA DYNAmore WorldSID 50th version 8 will be the first model with the official certificate to satisfy all the defined criteria of TB043-1. TB043-1 includes three different stages of certification. Normative dummy requirements are checked in the first stage. Component level tests of head-neck and lumbar spine represent the second stage. The last stage includes a new full dummy sled test scenario representing the far-side load case. The dummy model must pass all three stages to be fully certificated.

• Worst-Case Topology Optimization

  Imtiaz Gandikota, Willem Roux, Guilian Yi

  This paper presents a worst-case design approach for the multidisciplinary topology optimization of an automotive hood design. The study considers the impact of a pedestrian’s head against the hood, static loads, and the minimum weight of the hood – all required to meet general design code requirements in automobile industry. Among the design code requirements of the hood design, the biggest challenge is to handle hundreds of head impact locations specified in the Euro NCAP pedestrian testing protocol, due to the high computational expense of hundreds and thousands of structural analyses demanded in the structural optimization. To overcome this challenge, we accordingly introduce a general framework for the worst-case topology optimization which investigates the worst impact locations on the hood by evaluating the maximum head injury criterion and the maximum deflection of the hood separately, reducing the burden to consider multiple disciplines simultaneously at hundreds of impact locations all at once. At the end, these worst impact locations are combined with a static load case and formulated into a single multidisciplinary design optimization problem that needs only tens of structural analyses per iteration for numerical gradients computation, enabling the proposed design framework suitable for large scale topology optimization problems.