Composite materials like fiber reinforced plastics (FRP) are becoming more widely used in the automotive industry and have been found very effective in reducing vehicle weight. Recently, discontinuous long carbon fiber reinforced plastics are increasingly used for lightweight structural parts with high stiffness, strength and energy absorption performance. Compression molding is considered one of the most efficient manufacturing processes to mass produce FRP parts for automotive applications. Compression molding can form discontinuous long fiber reinforced plastics into complex shapes with relatively low manufacturing cost and short process time. LST and JSOL developed new compression molding simulation techniques for discontinuous long fiber reinforced plastics using a beam-in-adaptive EFG coupling function in LS-DYNAⓇ. Then JSOL developed a modelling tool called J-CompositesⓇ/Compression Molding to generate an input deck for this new compression molding simulation. In this paper, new functions of J-Composites/Compression Molding Version 2.0 are introduced and two compression molding simulations using hybrid lay-up composites are presented.
The efficient staging and storing of home appliances in warehouses are critical to avoid human injuries and huge losses to the company. After manufacturing the packaged product needs to be stored for a particular duration in the warehouse before it’s shipped out to suppliers. For optimum space management, those products are stacked one over the other. So it is important to have a robust packaging design to ensure even distribution of stacked product loads maintains their stability. Considering the constant loading over a longer period there is a high possibility of creep effects in packaging material, and it becomes even more crucial when packaging material is Expanded Polystyrene (EPS). So it's imperative to study material creep behavior in designing product packaging. In this study creep behavior of EPS material is evaluated with standard test setup, where precise measurement is done to get creep curves. The results were obtained for long-term constant compressive loading at different stress levels for multiple material densities, at ambient temperature 23°C.
In the event of an explosion in a populated urban area, fragmentation from glass is a significant contributor to human injury. The mitigation of glass fragmentation hazards is well-established through the use of laminated glass featuring a polymer interlayer, such as DuPont Sentry Glass Plus (SGP) or polyvinyl butyral (PVB). These interlayers work by exploiting the inherent viscoelastic and adhesive properties of the polymer, providing a mechanism to dissipate the energy of the blast through work done in deformation of the interlayer while retaining fragments of broken glass. This behaviour is fundamental to limit the projection of fragments of otherwise brittle glass, thereby reducing or eliminating highly hazardous secondary fragmentation associated with glazing.
Injection-molded short-fiber-reinforced composites (SFRC) have been widely used for structural applications in automotive and electronics industries. Due to the heterogeneous microstructures across different length scales, the nonlinear anisotropic behaviors of SFRC are very challenging to model. Therefore, an effective multiscale approach that links the local microscopic properties (e.g., fiber orientation, fiber volume fraction) to the global behaviors is required. To this end, multiscale analysis functions are recently developed in the engineering simulation software LS-DYNA to enable high-fidelity micromechanical finite element analysis, mechanistic machine learning-based reduced-order modeling, and accelerated concurrent multiscale simulation of SFRC composite structures.
This work presents a multiscale simulation framework that will be used for the simulation and experimental validation of eigenstresses in composite materials generated via laser-dispersion. These materials are obtained by adding tungsten carbide particles into the melt pool of a base metal to generate surface coatings. Such coatings are used to boost wear-resistance, more precisely to protect metallic surfaces against abrasion, erosion or corrosion. The coating significantly extends the part's lifetime due to the outstanding material characteristics of the locally produced metal matrix composite (MMC). Eigenstresses, which are the residual stresses left in the MMC material after the coating process, shall be investigated and predicted within the framework of this project and their effect on the lifetime shall be estimated.
The objective of this work is to create an FEM-based model for the inductive heating of carbon fiber reinforced thermoplastic composite (CFRTPC) laminates. A macroscale simulation model was created using the multi-physics capabilities of LS-DYNA®. Material model parameters were largely determined by micromechanical considerations. In order to further increase the accuracy of the FEM model, dynamic differential calorimetry (DSC) measurements were also carried out to determine the temperature dependence of the heat capacity of the laminates investigated. The model was then validated for laminates reinforced by non-crimped fabrics (NCF) with fiber volume contents (FVC) of 32%, 47% and 60% via induction heating tests. In general, the heating experiments could be approximated well both qualitatively and quantitatively. Furthermore, analyses were carried out in order to investigate the influence of individual ply orientations in the laminate on one another as well as the influence of the layer thickness on the resulting heating behavior.
The automotive industry is facing stronger requirements for crash safety and environmental friendliness of passenger cars from legislators, society and customers. This is reflected in legal requirements that regulate CO2 fleet emissions over the next few years as well as the relevance of CO2 emissions and vehicle safety as purchase criteria for vehicles [1, 2]. Fiber-reinforced plastics (FRP) offer a great potential to meet these requirements due to their high specific strength and stiffness as well as energy absorption capacity [3]. In particular, fiber-reinforced thermoplastics (FRTP) are suitable for large-scale production owing to their good recyclability and short cycle times [4].
The crushing performance of aluminum-CFRP (Carbon Fiber-Reinforced Plastics) hybrid generic crash components under axial compression load is experimentally investigated. Aluminum crash components, having similar geometry, are also crushed and compared with the hybrid components. The performance of the hybrid components is found to be twice as much as that of the aluminum components in terms of peak force and specific energy absorption (SEA). Finite element simulations of the crush tests are carried out in LS-DYNA®. The extended 3-parameter Barlat model (MAT36E) is used to characterize the anisotropic elasto-plastic behavior of aluminum sheet. The CFRP laminate is characterized by an orthotropic linear elastic material model (MAT54) with a progressive failure criterion (Chang and Chang). The aluminum-CFRP interface is modeled using tied contact with cohesive mixed mode failure criterion to capture the delamination behavior. Good agreement is found between experiment and simulation in terms of Specific Energy Absorption (SEA) as well as deformation pattern.
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 drilling process during which fibres can be locally damaged. For about 10 years, the LASAT (Laser adhesion test) technology appears to be a promising alternative. 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 so to calibrate the input laser parameters depending on the targeted results.
Define numerical analysis capable of predicting the behaviors of laminates composites is a research challenge for engineers and scientists from the first implementation of laminated model for shell elements in 1984 [1]. In these last 35 years all aspects of composite materials behavior have been evaluated such as for example, the impact response, crack propagation, crushing resistance. All contributions, for example from Abrate [2], Farley et al. [3], Botkin et al. [4] to actuals individuated a lot of ways to study numerically all aspects associated to related topic, as descripted and clearly resumed in the following picture.
This work focuses on an integrated modeling scheme of a sensor embedded woven composite structure which is created for the joint project “Digitaler Fingerabdruck” (DFA) or in English: “Digital Fingerprint” within the research campus ARENA2036 [4]. The process chain includes a draping simulation of a woven fabric and a trimming simulation using LS-DYNA®, optimization of a tailored-fiber placement process on top of this woven fabric structure using Optistruct®, fiber direction mapping from weaving simulation results using beam elements to shell element target meshes and handling of reinforcing patches using the mapping tool Envyo® [5]. The final goal is to establish an integrated process chain with parametrized variables using LS-OPT® for robustness analysis. A new feature of *MAT_REINFORCED_THERMOPLASTIC (*MAT_249) is also demonstrated to introduce fiber directions as an integration point history variable in global coordinate system to the subsequent simulations [7].
The accurate modelling of delaminations is necessary to capture the correct behavior of composite structures subjected to demanding loads. While the use of cohesive elements is valid when the discretization is smaller than the failure process zone [1], for many composite materials it implies using a fine mesh, typically smaller than 1.0 mm, leading to excessive computational cost for large structures. On the contrary, the Virtual Crack Closure Technique (VCCT) allows the prediction of delamination growth in larger elements [2] but lacks of an energy dissipation mechanism. Therefore, it leads to excessive vibrations when the delamination propagates in dynamic analyses. The present work aims to combine the best of both methods in order to develop a viable solution for large structures, allowing for coarser meshes than what is possible to use today. To do so, the VCCT is used as a failure criterion to predict damage initiation while a cohesive-like model is added to dissipate the released energy. The model has been implemented in LS-DYNA in the frame of an adaptive user element recently published [3,4]. The model has been validated with Double Cantilever Beam, End-Notched Flexure and Mixed-Mode Bending tests. It demonstrates the ability of the method to accurately model delamination with larger elements and higher stable time step.
Accurate representation of materials is an essential part of the quest for realistic and predictive simulation, not least for anisotropic materials such as short fiber reinforced plastic (SFRP). Still, it is common to neglect the anisotropic properties of SFRP components when evaluating the structural performance of the design in FE simulation, thereby often failing to predict a realistic mechanical behavior. Neglecting the anisotropic features of SFRP, especially at an early stage in the design development, may lead to a design that is not viable for the component in question.
The usage of composite materials in automotive body structures has the potential of reducing weight and thereby improving energy efficiency of the vehicles. Two key factors that limit their usage are long cure time for the material and the lack of simulation support. The recent development of snap-cure or rapid-cure prepregs can address the former problem. For the latter, LS-DYNA simulations can support the design of composite parts and production process which can improve both their structural properties and manufacturability, avoiding the economic and environmental costs of trial and error used today to obtain defect free parts. This paper concerns the simulation of the forming of parts using unidirectional (UD) carbon fiber prepreg.
J-Composites/Compression Molding Version 2.0: New Simulation Tool for CFRP Composites