17th International LS-DYNA Conference 2024

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• A New Eikonal Solver for Cardiac Electrophysiology in LS-DYNA

  Pierre L’Eplattenier, Karim El Houari, Olivier Crabbe, Francesc Levrero-Florencio

  Heart disease is among the leading causes of death in the western countries; hence, a deeper understanding of cardiac functioning will provide important insights for engineers and clinicians in treating cardiac pathologies. In this paper we will concentrate on electrophysiology (EP), which describes the propagation of the cell transmembrane potential in the heart. In LS-DYNA, EP can be coupled with solid and fluid mechanics for a multiphysics simulation of the heart, but pure EP is also often used to investigate complex phenomena such as cardiac arrhythmia or fibrillations. The gold standard model for EP is the “bi-domain” model, along with the slightly simplified “mono-domain”. These were introduced in LS-DYNA a few years ago [1]. They give very accurate predictions, but the associated computational expenses are significant, which can be an issue for patient-specific predictions, for example, cardiac activation patterns for complex procedures such as cardiac resynchronization therapy (CRT).

• A physically based strength prediction model for glass

  Jonas Rudshaug, Odd Sture Hopperstad, Tore Borvik

  The strength of glass has been a subject of great interest for more than one hundred years. Due to the stochastic nature of glass, originating from microscopical surface flaws, glass plates exhibit large variations in fracture strength. The aim of this work is to present a new strength prediction model for glass, named the Glass Strength Prediction Model (GSPM) that captures the nature of fracture initiation in glass, spanning from rate dependence to size effects. We aim for the presented model to be applicable in modern design processes and provide a procedure to facilitate input parameter calibration for glass plates from different suppliers. GSPM is a Monte-Carlo based model that combines the theories of linear elastic fracture mechanics (LEFM) and sub-critical crack growth (SCG) to generate virtual tests on a representative sample of glass plates. The stress evolution in the glass plates is obtained from finite element (FE) simulations. The model results in representative fracture strength distributions that span the probable fracture initiation instances with respect to time, location and stress level. We demonstrate how the GSPM can be used to trigger fracture in the constitutive model MAT_280 in LS-DYNA. This feature provides the option to investigate scenarios including multiple glass plates with interdependent fracture initiation behavior. The GSPM displays great promise in terms of usability and prediction capacity. It can capture the fracture initiation behavior of glass plates of varying geometries exposed to load cases spanning from, e.g., quasi-static four-point bending to blast pressure. The model has the potential to reduce the number of physical experiments and numerical FE simulations in modern development processes of glass structures.

• A systematic study on Ansys Forming® performance

  Dr.-Ing Kang Shen

  Mesh adaptivity refines the blank mesh as needed in stamping simulations. Users do not need to anticipate where a dense mesh will be required. Despite its universal use, it demands significant effort due to serialization and the need to carry a dense mesh through subsequent iterations. In-Core adaptivity and Mesh fusion assist the solver in conserving effort, thereby enhancing performance. This paper will demonstrate best practices for utilizing In-Core adaptivity and Mesh fusion in Ansys Forming through practical cases. In addition, for different model, we should find an optimum number of CPUs to run the job. Beyond this number, the scalability will not see any obvious improvements.

• Accelerate Ped-Pro assessments using SimAI

  Srikanth Adya, Akshay Jawale, Pierre Yser

  Deep learning methods have had a significant impact on design process in the recent past. SimAI is a deep learning-based AI platform that has shown to be very effective in approximating the behavior of fluid flow applications, especially fully developed steady state flows simulated by CFD solvers. The underlying neural networks in SimAI are very versatile and can be easily extended to structural applications as well. This study aims at demonstrating the applicability of SimAI for non-linear transient structural simulations like pedestrian protection. We start with a simple Tube Crush model to demonstrate the use of SimAI to predict the deformed shape of the Tube at any time instance. We then train a model on different Tube shapes to show SimAI’s ability to learn from non-parametric geometry. Finaly, we demonstrate how SimAI can be used to accelerate Ped-pro evaluations. The NCAC Accord model is used to generate 96 training points. This dataset is used to train a SimAI model and the resulting trained model can predict the full field hood deformation as well as the HIC value for the corresponding hit location within 10% relative error on any point on the vehicle hood. SimAI is many orders of magnitude faster in predicting the HIC than direct numerical simulation and hence can be very effective in evaluating designs upfront in the vehicle development process.

• Accidental Fuel Drop on Spent Fuel Pool Storage Racks

  Ragunath SANKARANARAYANAN

  Spent Fuel (SF) storage racks are fully submerged in water and stand freely at the bottom of the Spent Fuel Pool (SFP). The water column acts as a coolant for residual heat removal from nuclear fuel and provides radiation shielding. Due to the storage of large quantities of nuclear material, Appendix D to NUREG-0800 Section 3.8.4 [1] specifies that the functionality of the SF racks be demonstrated for the D + L + Fd load combination, where Fd is the force caused by the accidental drop of the heaviest load from maximum height. D and L are the dead and live loads acting on the SF racks.

• Adaptive FEM-DEM simulation of a soft missile impact on a reinforced concrete slab

  Yury Novozhilov, Eric Piskula

  Modeling the behavior of reinforced concrete (RC) structures under the action of destructive loads, considering the non-linear material properties and the strain-rate effects, are prescribed according to the requirements of The International Atomic Energy Agency (IAEA) in the design of buildings and structures of Nuclear Power Plants (NPP) [1]. A soft impact of a body imitating an aircraft engine missile is considered according to experiments [2]. Such a study can determine the ability of RC structures to withstand the impact of an engine or other large aircraft fragment. The paper describes an approach to solving such a problem, especially for a large-thickness under-reinforced slab made of low-quality concrete. Such a combination of design parameters may prove challenging for FE modeling due to significant mesh distortions and the need to model material erosion.

• Advancements in Eigenvalue Technology

  Daniel Bielich, Roger Grimes, Francois-Henry Rouet

  The standard eigenvalue problem for Implicit Mechanics in LS-DYNA is ΚΦ = ΜΦΛ , where Κ and Μ , the stiffness and mass matrices, are real and symmetric positive semi-definite in most applications. LS-DYNA offers three main algorithms for this problem, chosen with EIGMTH (field 7 of line 1 of *CONTROL_IMPLICIT_EIGENVALUE). The three algorithms currently available are • Lanczos (EIGMTH=2); • LOGPCG (EIGMTH=102); • Fast Lanczos (EIGMTH=103). This paper will give an overview of these methods, guidelines on when each should be used, performance comparisons, and recent enhancements. For non-symmetric problems, LS-DYNA also has an SMP solver, which relies on ARPACK [1,2]. An MPP solver relying on a different algorithm is being actively developed and is briefly mentioned in the last section.

• An Application of Shape Similarity Recognition Using PCA based Dimensional Compression

  Masahiro Okamura

  In recent years, the demand for faster product development has been increasing year after year. In addition, as requirements and their levels become more sophisticated, data-driven development that makes use of past data is attracting attention. Compared to experiments, simulations are characterized by the ease of retaining data that can be used for analysis, but this creates the problem of handling huge amounts of result data. In order to overcome this challenge, we propose a method to detect similar behaviors based on the distance in the modal space obtained from the animation results of past calculations with a reduced dimension reduction technique.

• Ansys Forming® - The New GUI for Forming Simulations with LS-DYNA: An Overview and Outlook

  Chris Robinson, Pablo Hernandez Becerro, Kang Shen, Xinhai Zhu, Madhu Keshavamurthy, Volker Steininger

  We are motivated by being the engine behind human innovation that leads to more efficient manufacturing and digital engineering. As we lead out in providing world class simulation solutions, we provide an avenue for individuals and companies to develop products that can improve the quality of life across the globe, by enabling safer more efficient products to be brought to market at a lower overall cost and energy footprint in less time than using traditional methods. In short, digital engineering solutions help improve life, save the environment, and reduce costs.

• Application of Machine Learning technique to incorporate manufacturing and Testing variation for Robust BIW design for Crash performance

  Shinoj Narayan Nair, Yoshinori Sugimoto, Susheel Khanna, Kei Nagasaka

  In vehicle development CAE plays crucial role in arriving at optimum structural design to meet various vehicle performance targets in different domain such as Crash, NVH, Durability etc. Accurate CAE methodology can aid in reducing the number of physical tests & reducing overall vehicle development time. However, there are instances where there are gaps observed between test results and CAE predictions. These gaps get amplified in crash simulations as the event is highly dynamic and non-linear behavior simulation is always challenging. In order to enhance CAE methodology, it was decided to incorporate the effect of manufacturing and testing variations in crash CAE simulations. Manufacturing process accounts for variations due to inherent variation in material properties, spot weld nugget diameter, manufacturing processes such as stamping etc. whereas Physical Testing houses variation in barrier positions, test speed etc. within specified tolerance defined by regulatory bodies. These variations affect structural performance and negating these issues in early design phase will help to arrive at robust structural design.

• Application of the ISPG Method in Various Manufacturing Processes Simulation

  Li Zhang, Xiaofei Pan, Tung-Huan Su, Jingxiao Xu, C.T. Wu, Philip Ho

  The Incompressible Smooth Particle Galerkin (ISPG) theory was proposed by the R&D team Computational and Multi-scale Mechanics Group (CMMG) at LSTC in 2017 [1]. It developed a new Incompressible Navier-Stokes solver to model free-surface Newtonian and Non-Newtonian fluid flow with surface tension and adhesion force. The Lagrangian particle method was employed to discretize the ISPG part to approximate the Navier-Stokes equation, coupled with surrounding rigid structures. The ISPG method is fully implicit, and in its dynamic mode, it simulates in real time fluid behaviors in many manufacturing processes. The ISPG’s robust, in-core, and smart mesh adaptivity allows fluid flow in complex geometry, accurately capturing and aligning the ISPG surfaces with the structure surfaces while keeping the model size down. It also allows for separation and fusion within the ISPG fluid. The ISPG advanced material models allow for the simulation of fluid behavior with various viscosities from liquid to near solid state.

• Application of the MAT 213 Composite Impact Model to NASA Problems of Interest

  Robert K. Goldberg, Trenton M. Ricks, Troy Lyons, Javier Buenrostro, Jacob Putnam, Daniel Slaughter

  As composite materials are gaining increased use in aircraft components where impact resistance under high-energy impact conditions is important (such as the turbine engine fan case), the need for accurate material models to simulate the deformation, damage, and failure response of polymer matrix composites under impact conditions is becoming more critical.

• Application of Trimmed Solid in Isogeometric Analysis to Aluminum Diecast Part

  Tadashi Naito, Shinnosuke Nishi, Takafumi Ohya

  With the changes in the global environment such as global warming, automobile OEMs and their affiliates have an urgent need to address carbon neutrality and resource circulation to reduce the environmental impact of their products and their corporate activities. Under such circumstances, as part of the effective use of materials, companies are considering the adoption of large aluminum diecast (ALDC) parts aimed at weight reduction through part integration, and enhancement of material recycling rates. Some OEMs have already introduced such parts to the market. Since prototyping and testing of large ALDC parts require enormous costs and time, it is important to be able to predict and evaluate the part performance through simulations. Crash calculations are no exception.

• CAD-integrated Untrimmed Body-fit Unstructured Spline LS-DYNA Preprocessing for Isogeometric Analysis and Digital Twins

  William W. Charlesworth, Richard H. Crawford, Daniel L. Keller, Benjamin Urick

  Isogeometric Analysis (IGA) has emerged as a next generation advancement in the field of Computer-Aided Engineering (CAE) and simulation thanks to its ability to utilize geometric representations native to Computer-Aided Design (CAD) models. Ansys LS-DYNA®’s proven capabilities for IGA have made it the premier solver for the technology. While the direct benefits for analysis are well documented, industrial adoption has been hampered by the difficulty in producing IGA-ready models from CAD data. Trimmed multi-patch IGA preprocessing approaches have seen advances at the industrial level but the desire for untrimmed body-fit unstructured splines has remained an unsolved approach in IGA preprocessing. In this paper, we discuss an IGA preprocessor for Ansys LS-DYNA® that not only produces untrimmed body-fit unstructured splines but does so in a process that is integrated directly into a CAD application.

• Combining Physical Test with Structural FEA to Develop Package-Specific Failure Models for Electronic Components

  Mike Howard, Tyler Ferris

  The use of electronics in harsh environments has increased significantly in the past few decades. For example, in automobiles, where electronic assemblies experience wide temperature extremes, temperature cycling, and shock, the cost of electronics was 18% of the total vehicle cost in the year 2000 and 40% of the total vehicle cost in 2020 [1]. Automotive electronic assemblies experience mechanical shock in a variety of scenarios such as a door slam, a vehicle crash or going over a pothole. In addition to the impact of component power dissipation on component temperatures, the automotive environment can include significant temperature variation due to diurnal solar loading, climate control, and engine heating/cooling cycles. The solder joints that connect electronic components to circuit boards are common failure locations in electronic assemblies, particularly in high shock/vibration environments and extreme temperature cycling conditions. Solder joint failure behavior is heavily influenced by the component’s package construction and materials.

• Comparative Evaluation of Material Models for Crush Simulation of Cast Aluminum Alloy Wheel

  𝑌𝑢𝑤𝑎𝑟𝑎𝑗 𝑆, 𝐷𝑒𝑒𝑝𝑎 𝐴𝑟𝑖𝑔𝑎𝑙𝑎, 𝑉𝑒𝑛𝑘𝑎𝑡𝑒𝑠ℎ 𝑃𝑟𝑎𝑏ℎ𝑢 𝐶, 𝐻𝑒𝑙𝑚𝑢𝑡 𝐺𝑒𝑠𝑒, Philipp van der loos

  Wheels play a critical role in vehicle safety, especially during severe crash scenarios such as small overlap frontal impacts. In these situations, energy typically absorbed by components like bumpers and crash boxes is instead transferred directly to the wheels, which can intrude into the passenger compartment and pose severe risks to occupants. However, most of the current research related to wheels are mainly focusing on the light-weight design, next-generation material selection (HSS, AHSS, DP, etc.), wheel fatigue life improvement, and standards, such as the SAE J175 [1] lateral impact test and the SAE J3203 [2] radial

• Computational modeling of tensile split-Hopkinson bar tests on carbon-carbon composites using continuum and mesoscale approaches

  Christopher Sorini, Roberto Enriquez Vargas, Alexander Carpenter, Drew Hackney, Sidney Chocron

  The high strength, toughness, quasi-ductility over monolithic ceramics, and elevated temperature oxidation resistance make carbon-carbon (C/C) ceramic matrix composites (CMCs) excellent candidates for hypersonic vehicle components, which will experience high temperatures and oftentimes high strain rates in service. However, accurate characterization of the material behavior under such extreme/harsh conditions presents significant challenges.

• Continuum-based Particle Gas (CPG): A New Approach for Airbag Deployment Simulations

  Edouard Yreux, Jason Wang, Inaki Caldichoury, Mohammed Mujtaba Atif

  The evolution of automotive safety systems has witnessed a remarkable journey over the past few decades, with airbags emerging as pivotal components in mitigating the severity of injuries during vehicle collisions. Initially conceived as relatively simple passive restraint systems, airbags have undergone a profound complexification in their design and functionality, driven by the relentless pursuit of enhanced occupant protection and regulatory compliance. Today, modern vehicles incorporate a diverse array of airbags strategically positioned throughout the cabin to address various collision scenarios. From front and side airbags to curtain and knee airbags, this proliferation underscores the nuanced approach to occupant protection adopted by automotive manufacturers.

• Data preparation for the Euro NCAP far-side ISO/TS 18571 rating calculation with tools from the DYNAmore Eco System

  Alexander Schif, Venkata Krishna, Yupeng Huang, Sebastian Stahlschmidt

  In 2024 the Euro NCAP Virtual Testing far-side protocol was introduced with a monitoring phase. The protocol defines all the requirements in precise detail. To obtain an assessment for the virtual testing, the OEM needs to pass two validation load cases. The assessment is conducted using ISO/TS 18571 ratings. Euro NCAP is responsible for the ISO/TS 18571 rating calculations. The OEM must provide the simulation and test data in a predefined ISO MME data format. If the ratings meet the defined criterion, the virtual testing assessment is deemed successful. This paper presents a straightforward workflow for preparing ISO MME data, illustrated by a case study of a far-side test involving the open-source Toyota Yaris car and the DYNAmore WorldSID 50th dummy model in LS-DYNA. The DYNAmore Eco System tool DM.binout2isomme is used to create the required ISO MME files for sharing with Euro NCAP. Furthermore, the ISO/TS 18571 scores are calculated with a Python script with the same procedure as defined by Euro NCAP.

• Development of a coupled electro-mechanical model of cylindrical cell LR61 batteries with LS-DYNA ®

  Abigail Schauer, Megan Gober, William O’Donoghue, Nathan Spulak, George Nelson

  In-depth characterization of the mechanical and electrical response of an LR61 alkaline battery is performed, for incorporation into a coupled electro-mechanical battery model using LS-DYNA. Tension tests are performed on the outer metal casing to develop a plasticity model, and a Bayesian Model Calibration analysis is performed to determine crushable foam model parameters for the interior anode, cathode, and separator battery components. Electrochemical impedance spectroscopy, distribution of relaxation times, and Kramers-Kronig analysis are used to determine the electrical response of the battery during incremental crush tests. X-ray imaging is also utilized to determine the dimensions of the inner battery components, and to gain insight into the geometric changes to these individual components that occurs during crushing and the corresponding changes to the electrical behavior. This data is used to determine the required order of a Randles circuit necessary to accurately model the electrical behavior. This experimental data is then incorporated into a solid element LS-DYNA model of the battery utilizing the MAT_24 and MAT_63 material models and the EM_RANDLES_SOLID electrical circuit model.

• Effect of Hourglass Control on LS-DYNA® Concrete Constitutive Models in Low Velocity Impact Simulations

  Amirmohammad Samadzad, Matthew Whelan

  The performance of reinforced concrete structural components under impact loading has received significant attention over the past decade, with high fidelity numerical simulations supplementing the available experimental test data. Several studies have evaluated the prediction of impact force and displacement time histories, as well as cracking and spalling, using a number of constitutive models in LS-DYNA. Under-integrated hexahedral elements are typically used in these analyses with hourglass control introduced to suppress hourglass modes. Prior studies have demonstrated that finite element analysis of reinforced concrete beams to impact loading is sensitive to the hourglass coefficient, however several studies have limited their basis of selection of appropriate hourglass coefficients to relative hourglass energy and comparison of model predictions with experimental measurements of displacement and force time histories. Furthermore, studies contrasting the performance of different constitutive models have routinely used a single hourglass coefficient for all models [1, 2]. This may be problematic if individual constitutive models demonstrate unique sensitivity to the hourglass control.

• Enhancing Vehicle Safety Assessments through Advanced Virtual Testing Crashworthiness with the aid of ANSA and META

  Thanassis Lioras, Thanassis Fokylidis, Ioannis Stavrakis, Nikos Tzolas

  The automotive industry is continually evolving to meet stringent safety standards and enhance occupant protection in crash scenarios. With Euro NCAP supplementing far-side impact testing with Virtual Testing Crashworthiness (VTC) starting in 2024, real tests and CAE simulations come closer more than ever. The VTC protocol mandates the use of simulation and physical test data to robustly evaluate far-side impact protection, requiring detailed compliance with validation and quality criteria, as well as specific data formatting for submission. Consequently apart from far-side more protocols will be implemented in the virtual testing raising more challenges to the safety engineers. As a result there is an increasing need for efficient tools that streamline the assessment process offering ‘know how’ of the different protocols and simultaneously minimize the human interaction with the aid of automation.

• Ensuring conformity and high level productivity between ANSA and LS-DYNA during model and load case development

  Andreas Fotiou, Thanassis Fokylidis, Lambros Rorris, Emmanuella Baksiova, Ioannis Fourkiotis

  Simulations have been playing an increasingly significant role in developing Computer-Aided Engineering (CAE) models over the last decades. Virtual testing has become standard practice in the design process, with analysts striving to establish robust procedures to validate the final products. ANSYS LS-DYNA has become a leading solution in CAE simulations, proving indispensable for engineers. Simultaneously, the BETA CAE pre-processor ANSA offers a comprehensive solution for model building, load case definition, and generating the deck file for ANSYS LS-DYNA. This ensures full conformity with ANSYS LS-DYNA standards, facilitating easy setup and high-quality results. This presentation demonstrates ANSA's capability to handle all needs of a CAE engineer in a broad spectrum of use cases ranging from ID handling and solver deck file conformity up to high level inspection and editing of a complex crash model.

• Evaluation of Viscoelastic Material Models in LS-DYNA based on Stress Relaxation Data

  Gokula Krishnan M, Vesna Savic, Bryan Cordeiro, Surjayan Biswas

  Viscoelastic behaviour of a material is often used as a probe in the field of material science since it is sensitive to the material’s chemistry and microstructure. The behaviour enables understanding of the quantity of energy absorbed by the material’s internal structure and the energy dissipated to the surroundings. The viscoelastic properties can be determined experimentally by tests such as stress relaxation, creep, or Dynamic Mechanical Analysis (DMA).

• Exploring Ansys LS-DYNA's Battery Modeling Capabilities

  Iñaki Çaldichoury, Kevin Kong, Pierre L’Eplattenier, Vidyu Challa

  Over the past decade, considerable advances have been made on battery safety models but achieving predictive accuracy across a wide range of conditions continues to be extremely difficult. From a numerical perspective, the obstacles are numerous. Multiple physics can potentially be involved and interact with one another, electrochemistry, thermal, mechanical, fluid dynamics and so forth. The question of modeling scale also invariably arises. Is it reasonable to imagine a numerical model resolved at the micro scale being later used in a macro model such as car crash simulation?

• Facilitating Virtual Testing at an Industrial Level with Simulation Data Management

  Marko Thiele, Alexandru Saharnean, Ferenc Leichsenring, Masahiro Okamura, Alexander Gromer, Andre Haufe

  From an industrial or productive standpoint, the scale of simulation models, the number of involved simulation model components, and the complexity of the utilized processes with a vast amount of data are at a level that is challenging to manage manually. The introduction of virtual testing adds to the complexity of the development process and the quantity of data to be handled. Consequently, the use of a Simulation Data Management (SDM) system for this purpose can be advantageous or even indispensable. The introduction of virtual testing can be accomplished in several steps. The initial step is the automation of data preparation, encompassing both input data and produced result data for both the OEM and the testing authority. Subsequent steps involve the implementation of individual processes and security mechanisms against data manipulation. This paper primarily addresses the initial step and outlines a methodology for achieving the objective of safeguarding against data manipulation and intellectual property (IP) infringement by OEMs.

• Fast Study of Multiple Sizes Helmets and Design Shape Optimization using LS-DYNA, LS-OPT and DEP MeshWorks

  Armand Leglise, Antoine Guilpin, Charlotte Michel, Vincent Lapoujade, Matthieu Seulin

  For obvious security reasons, wearing a helmet is highly recommended when riding a bike or a skateboard. In order for the manufacturers to design safe helmets some regulations have been established and must be respected before any market release. The process enabling to meet the regulation targets can be quite long considering the numerous impact points and test configurations that have to be repeated for each helmet size. The use of simulation and the appropriate tools can be a real asset to save time and reduce experimental tests while increasing security and comfort. Indeed, the numerical simulation offers the opportunity to explore more designs and test almost an infinite number of impact configurations. Especially when the numerical tools are powerful enough to significantly speed up the product development process.

• Fluid Slosh Behavior for Crashworthiness – A Modeling Approach Validated with Experimental Data

  Prabhu Selvaraj, Vikas Sanghavi, Srikanth Adya, Onkar Akolkar, Vedant Joshi, Jeremy Seidt

  FMVSS301 mandates fuel system integrity for vehicles post-crash, so a detailed assessment of the fuel system is needed to validate its integrity. Modeling the fuel tank assembly for vehicle crashworthiness is very challenging due to the fuel slosh phenomenon which occurs in the dynamic crash event. The fuel slosh behavior affects the overall dynamics of the fuel tank and its interaction with surrounding vehicle structures. Extensive studies can be found in the literature to improve fuel tank modeling. However, there is limited information related to modeling fluid’s free surface and the pressure profile imparted by the fluid on the tank during the crash event.

• From automatic event detection to automatic cause correlation

  Nouran Abdelhady, Dominik Borsotto, Vinay Krishnappa, Clemens-August Thole

  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.

• HANS meets the GNS software Working with HBMs in Generator4 and Animator4

  Leyre Benito Cia

  New trends and developments in the automotive market have caused changes in the way we evaluate and analyze our vehicles. For example, the introduction into the market of vehicles with autonomous driving capabilities has led to an explosion in the number and variability of possible passenger positions within the vehicle cabin. Positions for which conventional dummy models have limitations due to the unidirectionality of their components and sensors.

• Highly Automated Springback Compensation of the Draw Die©

  Madhu Keshavamurthy, Junyue Zhang, Yiquan Tang, Xinhai Zhu, Volker Steininger, Thomas Schöbach

  Achieving a sheet metal part within dimensional tolerance without the need for tool recutting is the ultimate goal of every forming simulation. Several key factors are essential to reach this goal: an accurate forming simulation with precise material descriptions, correct friction val-ues, and an accurate binder model to determine the correct material flow and stress state of the part after forming. Additionally, an accurate springback calculation is required, considering the part clamped in the measurement device and the effect of gravity. With these results the new tool geometry has to be determined to compensate the springback of the sheet metal part.

• Introducing J-SimRapid, A New Reduction Modelling Tool for Vehicle Crash Simulation

  Shinya Hayashi, Shinya Hiroi, Norio Shimizu

  Demands for ever increasing efficiency of automotive crash analysis have continued to rise in the drive to reduce automotive development costs. When major design changes are required to satisfy product performance late in the development process, significant cost and time are required to implement them. To alleviate this, automotive manufacturers have adopted the concept of "front-loading" to identify problems early-on in the development process.

• Introduction of LS-DYNA® MCOL solver coupling with Ansys Aqwa for the application in shipbuilding analysis

  Zhe Cui, Yu Bi, Arwel Davies, Shuangxing Du, Yun Huang

  For the ship building industry, ship accidents continue to occur regardless of efforts to prevent them. Some extreme or accidental situations such as collision and grounding need to be considered at the design stage. The rigid body dynamic program MCOL was developed in LS-DYNA and used in simulation of ship collisions analysis. The MCOL solver requires an input file as .mco file containing the hydrodynamic parameters such as the rigid body added mass matrix, hydrostatic restoring matrix, buoyancy parameters, and wave damping matrices for the body, etc. These parameters were provided by third-party software previously. In this paper, the new development on LS-DYNA/MCOL-Aqwa coupling analysis has been implemented in which the Aqwa solver can automatically create the MCOL required hydrodynamic database, .mco file.

• LS-DYNA User-Defined Internal Ballistic Modeling

  Sirri Oğuz

  One of the challenges in modeling deflagration of solid propellants with LS-DYNA is its limited capability, which is mostly applicable to airbag systems that use gaseous nitrogen generated by burning sodium azide. To overcome this limitation and enable the modeling of custom propellant grains with specific geometries, perforations, surface inhibitors, impetus, burn rates, and co-volumes, a user-defined burn model must be defined. In this study, a custom internal ballistic analysis code is integrated into LS-DYNA to simulate kinematic systems driven by pyro-mechanical devices such as pyro pushers, cutters, thrusters, separations bolts, ejection seat catapults, etc. Step-by-step guidance is provided on implementing a user-defined loading subroutine and the requirements for compiling a custom LS-DYNA executable along with a simple pyro thruster example.

• Manage multi-disciplinary load cases in SDM: Model setup and evaluation of results

  Andreas Lohbrunner, Marko Thiele

  Due to the continuously increasing demand in Computer Aided Engineering (CAE), it is essential for high efficiency and transparency to automate and standardize processes. In many cases, Simulation Data Management (SDM) software is used for this purpose. To achieve all mechanical target values of a product, there are several standard disciplines in the field of CAE, such as Crash, Noise Vibration Harshness (NVH) or Fatigue. Assembly, solving and postprocessing for these disciplines can differ greatly from one another. For this reason, it is best practice in many companies to carry out the optimization of a model in each discipline separately and to compare the results and structural adjustments with other disciplines at regular intervals.

• Mitigating Risks at Bus Stops: A Study of the Effectiveness of Bollard Systems

  Jonathan Lazatin, Pouya Shojaei, Brendan O’Toole, Mohamed Trabia

  This work assesses the effectiveness of a proposed interconnected multi-bollard design in protecting bus stop occupants from incoming vehicles. A detailed model of a 3-bollard system was developed in ANSYS LS-Dyna®, which included the bollards, their underground support structures, and the rebars connecting the bollards. The bollard system was composed of 116 parts with a total of 443,799 elements. The system model was merged with a detailed model of a 2007 Chevrolet Silverado, 4-door crew cab pickup truck with 603 parts with 251,400 elements developed by the Center for Collision Safety and Analysis [1]. The vehicle was simulated to impact the bollard system at speeds between 15 and 90 mph at angles ranging from 0° (normal to the bollard system) and 90° (parallel to the bollard system). Impacts were also made at various degrees of centeredness, with cases showing response from impact at the center of bumper, as well as at the edge of the bumper. With each case, vehicle velocity and acceleration were monitored using virtual accelerometers, placed in the vehicle to assess the effectiveness of the bollard to stop the vehicle. Simulation results show that the bollard was able to stop a vehicle traveling normal to the bollard system, impacting the center of the bumper at speeds up to 45 mph. However, the vehicle would continue past the bollard system at higher speeds.

• Modelling thick-walled aluminium extrusions in side- crash applications

  E. Teixidó-Marquès, D. Morin, O.S. Hopperstad, T. Berstad, B. Olsson, M. Costas

  In this study, the numerical modelling of a thick-walled aluminium extrusion which serves as a protective structure for battery trays in electric vehicles was studied. The thick-walled profile was modelled in a pole-crushing test. For this application, four aluminium alloys of different strength were considered: AA6063, AA6082, AA6005 air-cooled and AA6005 water-cooled. Shell elements proved to be inadequate in accurately describing the mechanical behaviour of thick-walled extrusions. Differences in the deformation mode and the computed force were observed between shell and solid models. Parametric studies were performed to evaluate the effect of fracture model, element formulation, contact formulation, and friction coefficient.

• More than 40% cost reduction through drop test simulation with Ansys LS-DYNA

  Manfred Maurer, Alain Capt, Yury Novozhilov

  The cost-sensitive development project for a new sewing machine series within Bernina International AG includes optimizing the packaging to the new logistical conditions and adapting it to the new product design. Packaging protection also had to be increased. Regarding specifications, no acceleration forces more significant than 100G may occur on the machine during a standardized drop test from a height of 0.9m. Furthermore, polystyrene should be reduced by at least 20% for cost and environmental reasons. For the end customer, the package should be easy to transport by hand and leave a tidy and logical impression when unpacked, which was difficult to specify and led to some loose ends concerning the arrangement of accessories.

• Multiphysics Analysis of Automotive Components for Product Portfolio Optimization

  Santiago José Javier Torres García, Eduardo David Berdeal Zertuche, Ramiro Elizondo Villarreal

  In this study, the pillars A, B and C from the Body-in-White (BIW) of a pickup passenger vehicle were considered, and the steels used for these components were identified based on the A2MAC1 platform, the SAEJ2947 standard, and state-of-the-art literature. Subsequently, these steels were compared with the client's product portfolio to propose a steel that meets the characteristics demanded by the automotive market for each of the components considered in the BIW. Next, the performance of each of the three pillars with these steels was validated and compared through crashworthiness simulations using Finite Element Analysis (FEA) with ANSYS LS-DYNA software. These simulations modeled the behavior of the pillars on side impact tests, with meshed parts based on the 2014 Chevrolet Silverado 1500 FEA model from the CCSA of the George Mason University. The impact speed was based on the Oblique pole side impact testing protocol from Euro NCAP; the time simulation was based on the Side impact Crashworthiness Evaluation 2.0 Rating Guidelines from the IIHS. To compare materials’ behavior, different curves were defined for each case. The tested materials were evaluated by comparing internal energy and displacement on each of the three pillars. Finally, results regarding the behavior of the different materials were discussed.

• Overview of LS-TaSCTM and New Feature Highlights

  Guilian Yi, Imtiaz Gandikota

  The general capabilities of LS-TaSC were designed to solve topology and shape optimization of large nonlinear problems involving dynamic loads and contact conditions applied to solid and shell structures. LS-TaSC can deal with huge models with up to 10 million elements, multiple load cases, and multiple disciplines. Three main categories of structural optimization problems can be addressed by LS-TaSC, including topology optimization, topometry optimization, and shape optimization. Topology optimization uses the relative densities of elements as design variables, minimizes the structural mass or a response, or maintain a target mass fraction at the global level, and maximizes the structural stiffness or the fundamental frequency at the local level. Topometry optimization uses the shell element thicknesses as the design variables, and it has similar setting options in terms of the definition of the objective function. Shape optimization chooses a free shape of the outer surface contour to design and finds the best surface shape that yields a uniform stress on the surface. The von Mises stress field is designed, and the uniform surface stress reduces the occurrences of stress concentration.

• Parametric ROM Technology for Fast Optimization of Crash Problems

  Radha Krishnan, Sridhar Bijjala, Rajasekaran Mohan

  The purpose of the Crashworthiness analysis is to assess how well a vehicle's structure can protect its occupants during a collision. This study involves transforming the vehicle Crash Model Partially into a Lumped Parameter representation using DEP MeshWorks’ - Reduced Order Modelling (ROM) technology. The ROM model shows an impressive 85-95% correlation with the original Detailed Finite Element model. The complex process of converting the Detailed Finite element model into lumped parameter representation is automated through the ROM approach. The ROM model is further parametrized with a broad ranging category of parameters involving a) shape, b) gage, c) material, d) spot welds, e) adhesives, f) seam welds, g) crush-initiators, h) reinforcements, i) darts, j) bulk-heads, k) slots/holes, l) laser welded blanking, m) ribbing and o) composite lay-up to convert it to an intelligent ‘Parametric ROM Dyna model’ using DEP MeshWorks. This parametric ROM model is integrated with a DOE (Design of Experiments) based Optimization scheme to obtain an optimized design that maximizes Crashworthiness performance and minimizes weight & hence cost. Thanks to the significantly reduced number of nodes/elements in the parametric ROM model, the entire optimization process can be completed in less than 50% of the time that detailed models would require.

• Preliminary Validation of New Continuum-based Particle Gas (CPG) Method for Airbag Deployment Simulations

  Hiromichi Ohira, Richard Taylor, Shinichi Arimoto, Kosho Kawahara, Hiroyuki Umetani, Edouard Yreux, Inaki Caldichoury, Shinya Hayashi, Masato Nishi

  CPM (Corpuscular Particle Method) is widely used as a standard simulation technique for airbag deployment simulation among users for a long time. It is very fast and robust for most of the cases. On the other hand, we may need additional effort to reproducing the realistic gas flow around narrow area such as curtain airbag, vents, and so on. A new fluid solver (CPG ; Continuum-based Particle Gas) has been developing to reproduce it by directly solving the Navier-Stokes equation. 3 types of simple airbag tests are suggested and conducted to validate the CPG solver. Due to inviscid and free slip assumption for now, the gas frontal speed is faster than tests, but CPG showed a good result in terms of gas flow around narrow area.

• Recent development in Ansys LS-DYNA’s NVH solvers

  Yun Huang, Tom Littlewood, Zhe Cui, Ushnish Basu

  LS-DYNA has been used in automotive industries for many years, especially in vehicle crashworthi-ness and occupant safety analysis areas. Besides that, LS-DYNA also provides many useful features for NVH (Noise, Vibration and Harshness) analysis. During the past few years, based on the feedback and suggestions from users, many updates and enhancements in the NVH solvers have been imple-mented, including - Fast FRF analysis with reduced eigenvectors. - Frequency dependent adaptive remeshing for BEM acoustics. - Frequency interpolation for BEM acoustic solvers. - Fluid added mass computation and its application in modal and vibration analysis. - Coupling of acoustic spectral element method and piezoelectric materials for ultrasonic sensor simulation. - Enhanced d3max output. - New options in fatigue solvers. - Other enhancements.

• Sequential drop test simulations through automated process in Workbench LS-DYNA

  Yury Novozhilov, Ulrich Stelzmann

  Modeling drop tests of various goods has always been one of the classic problems for explicit structural dynamics. Current requirements for such tests often require the consideration of multiple sequential impacts, such as the procedures described by the International Safe Transit Association. CADFEM is investigating the possibilities of automating such sequential drop tests in the Workbench LS-DYNA environment. With the automated calculation of sequential drop tests, these can be integrated into optimization cycles.

• Simulating Safe Landing : A Deep Dive into Parachute Inflation and Float with LS-DYNA

  Suraj Dhomase, Chandra Sekhar Kattmuri, Rodrigo Paz, Karthik Chittepu

  Parachutes for aerospace application is a new research area in the current era of space science. The scope of our project includes parachute design and inflation techniques. The current research project focuses on the following application areas: ● Parachutes for Re-entry Capsule ● RLV Parachutes Parachutes are used as aerodynamic decelerators in airdrop systems, so inflation is a significant fluid-structure interaction (FSI) phenomenon. New patterns of parachutes are constantly being developed and tested for airdrop systems but this research into parachute inflation is heavily reliant on historical experimental data. Till now, no parachute inflation model that is not based on this experimental data was developed. Material and instrumentation have changed significantly since the early experimental testing, yet the methods to develop the parachutes can still be traced to the same techniques used over ninety years ago. Rapid development of computational technology and modern computational mechanics combined with numerical simulation techniques have become more widespread in parachute research field and would enable us to develop the parachutes that are more optimized.

• Simulation of Sheet Metal Forming Using Solid Elements using ANSYS LS-DYNA©

  Mikael Schill, Xinhai Zhu

  Simulation of sheet metal forming has long been a fundamental application of ANSYS LS-DYNA, predominantly relying on shell elements under a plane stress assumption. While effective in many cases, situations arise where a full 3D representation becomes imperative, particularly when modelling thicker sheets or parts with tight radii. However, transitioning from shell to solid elements poses immediate challenges related to e.g. element size and the simulation model size.

• Simulation of viscoelastic two-phase flows with LS-DYNA ICFD

  Z. Solomenko, F. Del Pin, I. Caldichoury

  Simulations of viscoelastic flows are presented. Viscoelasticity is accounted for by solving a constitutive equation for the conformation tensor - the viscoelastic stress tensor is directly related to the conformation tensor [1] and the divergence of the viscoelastic stress tensor yields an extra momentum source. The Oldroyd-B constitutive model is here considered [1]. Results of several benchmark tests are presented. Implementation is first tested on a two-dimensional lid-driven cavity flow. Results of two-dimensional and three-dimensional Oldroyd-B liquid jets are then presented. Viscoelastic models are used in applications like food-processing, polymer melt processing, blood flow modeling.

• Sonic weld characterization and FEA modeling method development for automotive applications

  ABM Iftekharul Islam, Salvador Beltran Ruelas, Lisa Koch, Onkar Akolkar

  Joining is a critical part of any structure for transferring load and maintaining integrity for the product. Ultrasonic weld is one of the popular methods for joining plastic parts in automotive industry. Along with providing a visually demanding finish, the method has been established for tight, strong, and dimensionally accurate joints. With the increase of complexity and integration of electrical and sensing instrumentation in autonomous and electric vehicles, sonic weld provides a necessary means of attaching plastic parts without compromising visual impact. However, the sonic weld performance is yet to be quantified, and the criteria for capturing weld separation, and losing this connected load path during structural vehicle analysis, has not been studied extensively. Sonic welds, even though it is a very effective joining method, the whole tooling process is expensive and time consuming. Ideally, to optimize the welding spot number and develop future cost-effective welding methods, it is crucial to understand the actual weld performance under several variables such as material type, temperature, strain rates, etc.

• SPH Coupled Simulation for Blast and Impact study on Reinforced Concrete Bunker buried under Soil

  Priya Gautam, Hrishkesh Sharma

  This study examines how concrete structures respond to extreme conditions, particularly coupled simulation for blast and impact analysis, using LS-DYNA software for simulations. By analyzing displacement, pressure, strain, and stress, we aim to understand failure mechanisms and quantify damage in buried bunkers, providing insights for structural design and resilience assessments. In addition, coupled simulation for blast impact analysis, we consider durability and survivability under extreme conditions. This includes assessing long-term structural integrity, understanding environmental effects on material properties, and ensuring structures can function effectively after extreme events.

• Spotweld Modeling Methodologies and Failure Characterization of Aluminum Resistance Spotwelds (RSW) using LS-DYNA

  Akshay Kulkarni, Ashwin Yeagappan, Joao Moraes, Lily Slabbert, Martin Vézina

  With an increased use of aluminum in automotive body structures, developing a deep understanding, and capability to model failure of aluminum resistance spotwelds (RSWs) is critical [1]. This paper discusses failure card development of aluminum RSWs using LS-DYNA for certain 5000 and 6000 series flat rolled sheet alloys used in automotive structural applications.

• Study of Vehicle Aerodynamics with the ICFD Solver and its Application to the Quarkus P3 Pikes Peak Version

  Nicolas Van Dorsselaer, Morgan Le Garrec, Vincent Lapoujade

  The study of external aerodynamics is now an integral part of the development of new vehicles. Indeed, in the current context of reducing energy consumption, it is essential for a vehicle to minimize losses wherever possible. Optimizing external aerodynamics limits the aerodynamic drag generated by the vehicle and therefore optimizes its energy efficiency. Moreover, in a car race context, it is also important to improve downforce to keep the vehicle on track in corners.

• Study on Impact Loading Reduction Performance of "Origami Hat"

  Sunao Tokura, Toshie Sasaki, Ichiro Hagiwara

  With the enforcement of the revised Road Traffic Act, wearing helmets has become a mandatory effort for all cyclists since April 1, 2023 in Japan. However, there are still many people who do not wear helmets. Therefore, we considered developing a foldable helmet that can be easily carried by applying the concept of origami engineering. Origami engineering is a research field proposed with the aim of developing lightweight, high-strength structural components based on the idea of origami, a traditional Japanese paper craft in which various shapes are created by folding paper-like materials. Under the same conditions of the safety test for industrial helmets, a 5 kg striker was dropped from a height of 1.0 m onto a dummy head wearing the hat in which impact energy absorption material was installed, and the impact load received by the dummy head was computed in the simulation. As a result, it was confirmed that it was possible to reduce the impact load by devising the proper material properties and folding shape.

• Template-driven management of model and loadcase variants for LS-DYNA simulations

  Irene Makropoulou

  In recent years, crash and safety simulations have reached a very high level of accuracy in the prediction of the crashworthiness of the vehicle and the probability of injury for occupants and pedestrians under a multitude of loading scenarios. Among several factors, this achievement is also attributed to the fine resolution of finite element models that enables the precise representation of even the smallest parts and geometric features affecting the simulation results and the increase in the number of simulated loadcases. However, accuracy does come with a cost: Model size and variability have considerably increased, together with the number of loading scenarios that need to be simulated on each model variant.

• Topology Optimization for Giga-Casting Design in Automotive Bodies Using LS-TASC & LS-DYNA

  Akshay Kulkarni, Chaithanya Rachayyanavar, Carrie McGowan

  Topology optimization plays a crucial role in generating initial design concepts during the early stages of vehicle development. It is a Finite Element Analysis (FEA) based technique that helps to optimize the shape and distribution of the material in a desired packaging space. This paper explores the application of LS-TaSC and LS-DYNA for topology optimization of giga casting in a vehicle’s underbody. This paper touches on the importance of topology optimization in the design development process and elaborates how the LS-TaSC tool can be used to get directional guidance before initiating detailed design (CAD) work. BIW (Body-in-White) global static bending and torsional stiffness load cases were considered while setting up the optimization model. Various optimization setting parameters, constraints, and post-processing tools available in LS-TaSC were explored and have been elaborated in the paper. The use of LS-TaSC and LS-DYNA in this project enabled the generation of an initial giga casting design concept, indicating the critical areas where material is needed or can be removed. These design concepts were further refined by the design team using CAD tools, considering more realistic manufacturing and performance constraints.

• Trim Curve Development in Forming Simulation

  Pablo Hernandez-Becerro, Xinhai Zhu

  Numerical simulations are increasingly used to design and optimize sheet metal forming manufacturing processes [1]. ANSYS FORMING® [2] offers a comprehensive, process-centric solution for metal stamping simulation. It simplifies the setup of multi-stage forming simulations, making it accessible and efficient for users. Relying on the ANSYS LS-DYNA® multiphysics solver, the platform offers easy job submission and monitoring. The interface integrates post-processing capabilities that allow for detailed analysis of the resulting part.

• Updates on trimmed IGA B-Spline Solids

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

  Recently, trimmed Isogeometric B-Spline solid elements have been introduced in Ansys LS-DYNA ® nonlinear dynamics structural simulation software [1]. The numerical analysis methodology Isogeometric Analysis (IGA) dates to the paper by Hughes et al. [2] in 2005. While in standard Finite Element Analysis (FEA) polynomial basis functions are typically used for the discretization of the geometry and the unknown fields, IGA aims to use the same shape functions employed in the Computer Aided Design (CAD) environment for numerical analysis. This paper reviews the main ideas and concepts of the trimmed IGA B-spline solid finite elements in LS-DYNA and provides an update on the available capabilities. The current modeling workflow for these new element types will be first introduced. Modeling strategies for boundary conditions, contact and connections, and in-core refinement possibilities will be presented, and some recommendations and best practices will be discussed. The potential benefits of this new type of solid finite elements will be illustrated by two numerical examples. The paper closes with a summary and an outlook on future development activities.

• Utilizing a Validated Laminated Glass Model to Simulate Pedestrian Head Impact on a Windshield

  Marc Tatarsky, Ben Crone, Daniel Aggromito

  The authors have previously published a paper characterizing a laminated glass pane to simulate the delamination and fragmentation response of glass in a blast event. In this study, a computational model in LS-DYNA was developed and correlated with physical testing of laminated safety glass panes subjected to blast loads. To generate an accurate model, validation of the component parts including Polyvinyl Butyral (PVB), adhesion and glass that make up the laminated safety glass was completed.

• Validating wear simulations in heat exchanger plate stamping process through comparative analysis for enhanced productivity and quality

  Donghui Fang, Kang Shen, Xiaolong He

  Tool wear is a common problem in the manufacturing process of heat exchanger plates. The shape of HP changes due to tool wear, causing issues in subsequent processes such as welding, brazing, and assembling. In this paper, a simulation model of heat exchanger plates using Ansys Forming® is created to predict tool wear. It provides guidance for the shape design of heat exchanger plates, aiding in the planning of tool repair and replacement.

• Virtual Testing Protocols and LS-DYNA – Pre and Post Processing Solutions in the Oasys LS-DYNA Environment

  Alasdair Parkes, Rory Bradshaw

  The Oasys LS-DYNA Environment is a key part of many LS-DYNA workflows, used to ensure quality models and results. The introduction of virtual testing crashworthiness (VTC) protocols is changing how CAE teams create and process LS-DYNA crash models and poses several challenges for CAE workflows. Good correlation is moving from beneficial to mandatory, and we can no longer rely on conservative assumptions. The format and quality of outputs is increasingly important to meet the requirements of regulatory bodies. CAE teams will need to work more with physical test data, and safety teams will need to work more with simulation data – how do we improve collaboration and processing? How can we manage large amounts of data for virtual testing?