October 2025, Munich, Germany
A Constitutive Model for the Simulation of Fabric-Reinforced Materials under Automotive Crash Conditions
Eduardo Martin-Santos (Applus IDIADA, Universidad Politècnica de Catalunya), Alejandro Dominguez, Alfredo Alameda, Ángel Sillero (Applus IDIADA), Tomohiko Max Miura (TOYOTA GAZOO Racing Europe)
This work presents an advanced constitutive model for simulating fabric-type fibre-reinforced composite materials under automotive crash conditions. Operating at the mesoscale level, the model balances computational efficiency for full-vehicle simulations with accurate representation of complex damage through the combination of different mechanisms. This modelling strategy features multi-stage damage laws with optional fracture toughness regularisation, ensuring mesh-independent results during crack propagation.
Key innovations include quadratic-exponential plasticity for in-plane shear, stress coupling for compression mechanisms, and multi-stage damage evolution capturing peak, post-peak, and residual stress behaviours. The model incorporates an algorithm preserving permanent strain after load release, improving predictability of final component shape and managing reaction force during unloading scenarios—critical for pedestrian safety applications.
Implementation as a UMAT in LS-DYNA demonstrates superior predictability compared to standard models whilst maintaining consistent performance across varying mesh refinements, enabling seamless integration into automotive development processes where efficiency and accuracy are paramount.
A Flexible Method to Integrate AI Models (PyTorch) into LS-DYNA User Defined Material Subroutines
Cristian Saenz-Betancourt (BMW Group, Ludwig-Maximilians-Universität München), Dustin Draper, Balazs Fodor (BMW Group), Fabian Duddeck (Technical University of Munich), Steffen Peldschus ( Ludwig-Maximilians-Universität München)
Artificial Neural Networks (ANNs) are universal approximators capable of modeling material behavior for Finite Element Method (FEM) simulations. This work aims to enable the efficient coupling of AI material models into LS-DYNA subroutines. The architecture of ANNs varies depending on the problem type. For instance, feedforward models are suitable for path-independent cases, such as linear elasticity. In contrast, path-dependent cases require architectures capable of handling material history, such as Gated Recurrent Units (GRUs) or Long Short-Term Memory (LSTM) networks.
Moreover, changes in architectural hyperparameters—such as the number of layers and neurons, input/output size, and activation functions—occur frequently during the development process. AI models are typically coded in Python using libraries like PyTorch. However, user-defined material subroutines (UMAT) require Fortran, necessitating a direct coupling to avoid the time-consuming process of recoding in Fortran and manually implementing changes to the model and its parameters. To bridge this gap, FTorch, a new open-source library, is linked to the LS-DYNA solver. This library enables seamless model updates, Torch tensor transformations, and output computations within the UMAT subroutine. In our research work, the functionality is demonstrated using a GRU as an elastoplastic material model.
A New Eikonal Solver for Cardiac Electrophysiology in LS-DYNA
Pierre L’Eplattenier, Karim El Houari, Olivier Crabbe, Francesc Levrero-Florencio, Inaki Caldichoury (Ansys, part of Synopsys)
Heart disease is among the leading causes of death in the Western world; 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 the electrophysiology (EP) part of the physics, which describes the propagation of the cell transmembrane potential in the heart. In LS-DYNA, EP can be coupled with the mechanics and the fluid solvers for a Multiphysics simulation of the heart, but pure EP is also often used to investigate complex phenomena such as cardiac arrhythmias 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. 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).
In this paper we introduce new computationally efficient eikonal and reaction-eikonal solvers. The eikonal method is very general and describes the propagation of a wavefront in a medium with given propagation velocities.
The eikonal solver will be presented and different examples will be shown.
Advanced characterization of airbag fabrics for *MAT_FABRIC including permeability
Daniel Munoz, Alberto Regidor, Javier Ferrer (Newgentechs)
The airbag fabric is a highly complex material and has a great influence on the behavior of the restraint system in crashworthiness events. LS-DYNA offers multiple possibilities to simulate it, including dependencies with Triaxiality, strain rate or permeability, among others.
To take advantage of these capabilities, a highly specialized experimental characterization program, including different types of mechanical loading and specific permeability tests is required.
Dynamic permeability tests used so far for the characterization of airbag fabrics have been limited to low pressures and room temperature. At Newgentechs, an experimental system has been developed to reproduce the high pressures encountered in the airbag at the earliest stages of the opening and at different temperatures, providing new information on the behavior of these materials.
This presentation describes state-of-the-art experimental and analytical techniques for characterizing airbag fabrics for simulation, including this new system for determining permeability.
Application of the LS-DYNA Implicit Solver for Battery Regulatory Load Cases
Katie Lampl (Oasys), Simon Hart (Ove Arup & Partners)
In a short timeframe, the automotive industry has swiftly adapted to the demand for clean sustainable transportation, aiming to reduce CO2 emissions and enhance air quality. Leading this transformation is the shift from internal combustion engines to electrified powertrains, primarily using Lithium-ion batteries for energy storage.
Simulation engineers face new considerations in vehicle design. The battery system has become an integrated part of the structure and must be included in safety and durability assessments. Extensive simulation is essential for designing competitive, safe vehicles and the available tools have quickly responded to the transition from internal combustion to electric powertrains.
Ansys LS-DYNA has always been at the forefront of this effort. While some of the global regulatory requirements for battery pack safety fall neatly within its core explicit capabilities, its implicit capabilities are often overlooked for cases such as vibration fatigue or thermal shock. Clearly, maximising the number of requirements that are assessed with a single solver will result in a more efficient analysis workflow.
This presentation will describe how Arup’s engineers use LS-DYNA and Oasys software tools to analyse battery systems using the explicit and implicit solvers, to benefit from these powerful solvers and provide efficient outcomes for their clients.
Application of the Soft-Factor Concept to Metallic Materials
Sebastian Bencker, Thomas Zink, Philipp Henn, Patrick Hager, Niklas Prange (Dr. Ing. h.c. F. Porsche AG)
Crack initiation and propagation in metallic materials significantly impact crash test outcomes, making this a critical area of research in finite element crash simulations. While damage evolution and crack initiation are effectively modeled by the established GISSMO features in LS-Dyna, accurately predicting crack propagation remains challenging. This study presents an experimental investigation into crack behavior across various metallic materials and its integration into dynamic finite element simulations. Through compact tension tests, the authors introduce a strategy to utilize and calibrate the GISSMO SOFT-factor, enhancing the prediction of crack propagation for press-hardened steels.
Automated Evaluation of Forming Limit Curves Using 3D-DIC and LINOVIS for Sheet Metal Forming Simulations
M. Schwab, S. Riemelmoser (4a engineering)
This work presents a streamlined and highly automated methodology for deriving forming limit curves (FLCs) using 3D digital image correlation (3D-DIC) in combination with the LINOVIS testing system. Nakajima-type tests are conducted on downscaled specimens to simplify handling and material extraction. A pneumatic clamping system ensures high throughput and repeatable boundary conditions. The test setup accommodates a wide range of strain rates and forming speeds – from quasistatic up to more than 3m/s – using a single machine configuration.
Two high-speed cameras capture the local strain evolution during deformation, enabling precise evaluation of the forming behavior. The 3D-DIC data is processed automatically to extract forming limit curves with minimal user intervention. Finally, the resulting data is seamlessly integrated into an automated workflow to generate complete material cards for use in metal forming simulations. This approach significantly reduces manual effort and enhances the reliability and reproducibility of material characterization for forming process design.
Automated Injury Metrics Evaluation and Visualization for the HANS Human Body Model using Generator4 and Animator4
Leyre Benito Cia (GNS mbH)
The HANS model is a high-fidelity structural human body model designed for use in LS-DYNA simulations, enabling biofidelic analysis of occupant injury in crash scenarios. With growing demands for accuracy and efficiency in safety assessments, automating pre- and post-processing steps has become crucial for improving simulation workflows and ensuring consistent results.
This work presents an automated framework for visualizing and evaluating injury metrics in HANS model simulations, utilizing Generator4 and Animator4. Generator4 facilitates efficient pre-processing through a user-friendly GUI, enabling rapid model positioning and setup in crash test environments. Post-processing is handled in Animator4 using the Human Body Modeling (HBM) GNS Tool, which automates the extraction of injury metrics such as the Head Injury Criterion (HIC), Brain Injury Criterion (BrIC), rib fracture assessment, and other key indicators. The tool also supports detailed visualization and customizable report generation. This framework enhances handling and visualization of complex models, whether involving a single body part or multiple components, through an automated process.
By reducing manual intervention and minimizing user error, the workflow improves analysis speed, reliability, and repeatability. The integration of Generator4 and Animator4 provides a robust solution for engineers and researchers performing occupant injury evaluation and iterative safety design within LS-DYNA environments.
Automated process chain for calibrating material cards of punctiform and planar joint connections for explicit finite element simulations
Tim Wirtz (German Aerospace Center)
In the automotive industry, point and surface joining techniques are often used. These include clinching, self-pierce riveting, flow drilling screws and adhesive joints. To accurately model the joints in FE-Models, especially for crash simulations, properly calibrated material cards are required. A great amount of manual effort is required for the generation of the material card parameters. Automating this process can reduce the costs currently required for the generation of validated numerical descriptions.
For this purpose, an automated process chain is developed. Using shear and head tensile tests the quasi static and dynamic characteristics of joints will be determined. New clamping concepts and simulation models are developed to receive the static and dynamic responses of the joints. Various initial values for the material card parameters are determined based on the measurement results of the tests. These values are crucial for rapid optimization by a following optimization algorithm. With these initial parameters, FE simulations are performed to generate a metamodel that is used to accelerate the identification of optimal material card parameters. Once the optimization algorithm converges, the generated material card is verified, validated and simulated again. After successful validation, it is then approved for further use in other FE simulations.
Avoiding Volumetric Locking in Ten-node Tetrahedral Finite Elements for Explicit Finite Element Simulations
Tolga Usta, Malte von Scheven, Manfred Bischoff (University of Stuttgart)
Simulations involving nearly incompressible materials require particular attention during the setup phase, as volumetric locking phenomena might significantly distort the results. Researchers have proposed various methods to address this issue. One widely adopted technique for eight-node hexahedral solid elements is to combine reduced-order integration with hourglass stabilization. However, this method relies on a mesh composed of hexahedral elements, which for complex structures often cannot be achieved. Complex structures typically require tetrahedral elements to ensure an accurate representation, and automated meshing algorithms tend to generate meshes dominated by tetrahedral elements for such structures. Therefore, removing volumetric locking for tetrahedral elements is especially important.
This work revisits the method proposed by Lo and Ling [1], which decomposes the element stiffness matrix into constant and higher-order parts. Preserving the constant part ensures element consistency, while the higher-order part is specifically treated using a modified material property known as the bulk modulus. This modification directly targets the root cause of the unwanted volumetric locking. The proposed approach is extended to support explicit time integration schemes and it is integrated into LS-DYNA for ten-node tetrahedral elements with five integration points as a user-defined isotropic linear elastic material model. A series of numerical simulations validates the effectiveness of the proposed method.
We gratefully acknowledge the support for this research from the DigiTain project (19S22006K), funded by the Federal Ministry of Economic Affairs and Energy (BMWE), following on a resolution of the German Bundestag.
Beyond Simulation: AI’s Role in Future Crash Studies
Srikant Adya, Celalettin Karadogan, Shyam S. Vasu, Nikolay Lazarov, Martin Husek, André Haufe (Ansys, part of Synopsys)
In recent years, artificial intelligence (AI) has begun to significantly influence the field of computer-aided engineering (CAE). Technologies like Ansys-SimAI have been successfully deployed to develop surrogate models of complex finite element (FE) simulations, enabling rapid system behavior predictions. Despite these advancements, the conventional iterative design process remains slow due to the time-intensive task of generating new design variants.
To address this limitation, Ansys has introduced a generative design solution that automates the creation of design alternatives. Starting from seed geometries, the tool generates hundreds of new, physically plausible variants within the original design space. When combined with SimAI, this forms a comprehensive pipeline for rapid design generation and evaluation, enhancing product development efficiency.
This paper demonstrates training a SimAI model to predict vehicle behavior under side impact loading using high-fidelity LSDYNA simulations as database. The sill in-lay designs from these simulations serve as seed geometries for the generative design tool, which then creates new geometries within physical constraints. Both tasks are completed in seconds, showcasing AI’s potential when combined with legacy CAE data to accelerate product development cycles and improve design efficiency and innovation.
Behavior of Variant Human Body models on different restraint systems with the aid of ANSA HBM toolset
Savvas Kelidis, Athanasia Sakka, Athanasios Fokylidis, Lambros Rorris, Athanasios Lioras (BETA CAE Systems)
Restraint systems have traditionally been developed based on the anthropometric characteristics of the average male, potentially reducing safety for individuals with different body proportions. Expanding simulations coverage to a wider range of body types is essential, but current Human Body Models (HBMs) lack high anthropometric diversity due to the high cost and time required for development.
To address this limitation, BETA CAE Systems introduces in ANSA the HBM Scaling Tool designed to adapt existing HBMs to variant anthropometric profiles. A comparative analysis is carried out between two human body models (HBMs) defined using LS-DYNA keywords: the baseline THUMS AM95 and a THUMS AM50 model scaled to AM95 anthropometrics using the Scaling Tool. The comparison focuses on multiple criteria, including mass distribution, center of gravity (COG), body morphology, bone dimensions, and elements quality.
The scaled model validation involves conducting sled test simulations with various restraint systems, meticulously configuring LS-DYNA keywords for accurate testing. These simulations are closely modeled after Vezin et al.’s (2001) study. Acceleration in the head, spine, and pelvis—are analyzed, along with major principal strain patterns in the ribs. The results are compared with those from the original THUMS AM95 model and available experimental data from the Vezin study.
This research highlights how the scaling approach proposed by BETA CAE Systems enables more representative occupant simulations, supporting the development of restraint systems better suited to a diverse population.
CPG – Application beyond airbag modeling
Edouard Yreux, Jason Wang, Iñaki Caldichoury (Ansys, part of Synopsys)
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.
Comprehensive 3D Wear Analysis in Drilling process Using Smoothed Particle Galerkin Approach in LS-DYNA
Pulkit Rana, Hariramkumar Vennilavan Thenmozhi, Thomas Schall (Mercedes-Benz AG)
Efficient drilling operations directly impact manufacturing productivity and product quality in the automotive industry. Understanding tool wear during drilling operations is crucial for improving manufacturing efficiency. This research work focuses on simulating the drilling process using LS-DYNA to study the wear of cemented carbide tool without coating. The simulation combines Lagrange Element Formulation and Momentum-Consistent Smoothed Particle Galerkin (MC-SPG), using the Johnson-Cook material model for material behavior under the effects of strain, strain rate and temperature on the material flow stress. The workpiece was of bainite steel, and the tool was made of ISO-K10 hard metal. Usui tool wear model was used for the wear analysis. Experiments were conducted on the CNC machine to validate the simulated forces, moment and tool wear. Additionally, simulated chips were compared with the experimentally produced chips. The study confirms the reliability of the simulation model by the comparison of simulated data with experiments. In general, this research highlights the importance of advanced simulation techniques in the evaluation of tool wear performance, contributing to better drilling process simulation, thus enhancing tool life in manufacturing facilities.
Continuum-based Particle Gas for Airbag Deployment
Satish Pathy, Edouard Yreux, Inaki Caldichoury, Amit Nair (Ansys, part of Synopsys)
The new continuum based particle gas method has opened up the possibility to simulate other load cases that is beyond airbags. CPG method can be used to design door pressure sensors, battery gas venting and heat propagation are few examples.
Crash Simulation of Lattice Structure
Dr.-Ing. Horst Lanzerath, Sasa Bach (Ford-Werke GmbH), Prof. Dr.-Ing. André Haufe, Vincent Suske (Ansys, part of Synopsys), Jonas Rohrbach (RWTH Aachen University), Emre Ertugus (fka GmbH)
his presentation will cover the crash simulation of 3D-printed lattice structures, with a focus on the following key areas:
a. Model Creation Strategies:
•Comparison of solid and beam element modeling techniques.
•Application to fundamental lattice geometries (e.g., cubes).
•Application to complex automotive structures (e.g., crash boxes).
b. Material Characterization and Fracture Modeling:
•Overview of experimental techniques for characterizing 3D-printed lattice materials.
•Discussion of fracture modeling approaches suitable for lattice structures.
c. Material Model Validation and Comparison:
•Comparative analysis of CrashFEM and LS-DYNA (GISSMO) material models.
•Validation against experimental data.
•Systematic validation of material card parameters.
d. Application Example: Passenger Vehicle Crash Box:
•Demonstration of lattice structure implementation in a crash box design.
•Simulation results and performance analysis
Development of a set of finite element models to assess the performance of a beverage can body in dome reversal pressure and drop tests
Mouaad El Mouss, Gilles Guiglionda, Camille Linardon, Laurent Nguyen (Constellium Technology Center, C-TEC), Lukasz Brodawka, Maciej Kociolek (CANPACK S.A.)
The aluminium beverage can is a highly engineered product providing excellent beverage conservation and combining impressive mechanical resistance with minimal weight and infinite recyclability.
In this work, a numerical approach to predict the mechanical performance of a beverage can body is presented. Using the finite element method, two standard performance tests used in the industry, namely the dome reversal pressure (DRP) test and the drop test, are modeled. To study the influence of the can bottom geometry on its mechanical performance, the key can body forming steps are first modeled. In addition to the can body geometry, this allows to capture the material deformation history and thus any local thinning or work hardening.
Successively linking the forming and performance finite element models has allowed to reproduce experimental results. As an example, the evaluation of the influence of the internal reforming diameter of a can body on its performance in DRP and drop tests is presented.
Energy-Based Regularization Approaches for GISSMO
Thomas Zink (Dr. Ing. h.c. F. Porsche AG, Karlsruhe Institute of Technology (KIT)), Dr.-Ing. Frank Burbulla (Dr. Ing. h.c. F. Porsche AG),Prof. Dr.-Ing. Thomas Böhlke (Karlsruhe Institute of Technology (KIT))
The Generalized Incremental Stress-State dependent damage MOdel (GISSMO) is widely used in crash simulations to model the damage and failure of ductile materials. Since its inception, significant effort has been devoted to regularization schemes that minimize mesh dependence. However, regularization for arbitrary stress states remains a challenge. The work of Andrade et al. (2022) introduced a proportional loading strategy for element patches, i.e. loading with constant triaxiality. Building on this strategy, the present study proposes a new iterative scheme that ensures equal energy to failure for all mesh sizes in arbitrary stress states. The implications of the resulting regularization are investigated in virtual component tests.
Exploration of Asymmetric Ligament Behaviours of Lower Leg injury in Automotive Pedestrian Impact
Ben Crone, Jean Bout (Arup)
During physical testing for ECE R127 lower leg impact on a sports vehicle, a pronounced asymmetry was observed in Flex-PLI PCL knee elongation between impacts on the left and right sides of the vehicle. This paper investigates the potential causes of this asymmetry, examining its sensitivity to variations in vehicle geometry, impact conditions, and pedestrian orientation. Using Ansys LS-DYNA, simulations are performed across a range of vehicle morphologies and impact configurations, including both leading-leg and trailing-leg scenarios. The study is further extended to aPLI and Human Body Model (HBM) impactors to assess whether similar trends emerge across different impactor types. These investigations aim to highlight considerations for interpreting test outcomes and may inform future discussions around the selection of outboard test locations in regulatory protocols.
Fluid Structure Interaction Modeling of an Artificial Heart Membrane Test Bench
Alex Sanaei, Nicolas Van Dorsselaer (Dynas+), Charlotte Toureng, Yannick Tarnowski (CARMAT), Loic Mées, Nathalie Grosjean (CNRS)
Understanding fluid-structure interaction (FSI) phenomena is crucial in numerous engineering and biomedical applications, particularly when compliant structures are immersed in internal flows. CARMAT is now embarking on an ambitious exploration of next‐generation artificial heart architectures, using high‐fidelity simulations to evaluate novel geometries crafted from cutting‐edge biomaterials. Integrating advanced material property data into the numerical workflow makes it possible to virtually stress‐test each design under severe hemodynamic loads, mapping pressure fields, shear stresses, and deformation profiles. By fusing empirical data with virtual prototyping, the team will be able to quantify both shear-induced red blood cell damage (hemolysis) and thrombosis risks under worst-case conditions, accelerating design optimization and de-risking the system prior to clinical translation.
To lay the groundwork for a comprehensive hemodynamic evaluation of the total artificial heart, the LMFA, in collaboration with CARMAT, performed an intensive test campaign on the device’s hyperelastic membrane which is the interface between the blood and the oil that is used as a pump in the artificial heart. LMFA predicted the fluid-structure interactions behaviors of the Membrane with an experimental device along with Particle Image Velocimetry (PIV) and Particle Tracking Velocimetry (PTV) methods. The PIV was carried out on three laser sections and the PTV was carried out on small dots, printed on the Membrane surface.
This experimental rig was then paired with a high-fidelity incompressible fluid–structure interaction (FSI) model conducted by Dynas+, enabling correlation between bench measurements and virtual simulations. By calibrating the membrane’s mechanical and fluidic response with the experimental data from LMFA, Dynas+ showed LS-DYNA capabilities in reproducing such FSI behavior with a good level of precision before scaling up to the complete artificial-heart prototype.
Full-field calibration from DIC: a way to analyze fibre orientation deviations in composites?
Christian Witzgall, Sandro Wartzack (Friedrich-Alexander-Universität Erlangen-Nürnberg)
In the literature, full-field calibration has so far mainly been used for the identification of yield parameters of metallic materials, mostly steel. These offer the clear advantage that very large strain values and localised necking occur. In the case of brittle laminate materials, none of this is to be expected; instead, spontaneous material failure must be reckoned with even if the strain is small. However, it is also possible to calibrate material models for composites using this method. A mat58 is used here.
As is usual, an optimisation problem is solved during material parameter identification, whereby the material parameters such as modulus of elasticity and similar are treated as free parameters. However, if a reliable material map is already available, it may be conceivable that the fibre orientations in the simulation model are variable and that these are adapted with the optimisation in LS-OPT.
This method seems very interesting for the deviation analysis of laminates, which can go hand in hand with non-destructive loading and DIC measurement and may save complex methods such as CT radiography.
High-Fidelity DEM-CFD Simulation for Optimized Dental Powder Delivery
Luca Antonin (Parametric Design Suisse Sagl)
Ensuring a controlled delivery of abrasive powder to the teeth is fundamental for efficient dental prophylaxis. The powder is typically recruited by a high-velocity air stream from a reservoir whose design might significantly affect the device’s performances. Given the complexity of this phenomenon, a digital representation of the powder mixing process would enable the identification of design-related criticalities, such as the presence of powder stagnation zones that could prevent a constant delivery, that are challenging to assess through experimental analysis. For this purpose, a numerical LS-DYNA simulation coupling the Discrete Element Method (DEM) with Computational Fluid Dynamics (CFD) was developed to accurately replicate particle-particle, particle-wall and particle-air interactions within the reservoir. Specifically, DEM parameters were tuned to replicate powder experimental behavior, while CFD computes air flow dynamics, allowing the measurement of powder consumption rate. The numerical outputs of the mixing process and powder recruitment inside the reservoir were rigorously validated against experimental data, demonstrating the high accuracy and reliability of the integrated DEM-CFD approach in predicting the powder consumption rate. This simulation framework offers a powerful tool for optimizing powder reservoir designs, enabling a predictive performance analysis under different operating conditions, improving patient care and procedural efficiency.
High-Voltage Cable Modeling using *DEFINE_CABLE: Optimization and Validation for Automotive Crash Applications
Maximilian Beck (BMW Group), Raphael Heiniger (Ansys, part of Synopsys)
The increasing complexity of high-voltage cable systems in automotive applications demands advanced modeling techniques to accurately predict their mechanical behavior under various load conditions. This study investigates the potential of the in LS-DYNA R16 introduced *DEFINE_CABLE keyword as a novel approach to cable modeling. By focusing on axial tension, three-point bending, and radial compression load cases, the research aims to assess the capabilities and limitations of this method compared to existing techniques. The motivation lies in improving simulation accuracy and efficiency, particularly for complex load scenarios, while addressing the challenges posed by material behavior and mesh dependencies in high-voltage cable systems.
Higher-Order 3D-Shell Elements in LS-DYNA – Enhancing Stress Prediction in Laminates
Maximilian Schilling, Malte von Scheven, Manfred Bischoff (University of Stuttgart)
Accurate stress prediction in fiber-reinforced laminates is crucial for anticipating damage like delamination in lightweight designs. While standard Reissner-Mindlin shell elements are computationally efficient for large-scale explicit simulations, they are inaccurate due to simplifying assumptions like zero transverse normal stress and straight cross-sectional fibers. Conversely, fully 3D solid element discretizations, while accurate, are computationally prohibitive for industrial-size models.
This contribution presents the application of higher-order 3D-shell elements, implemented as a user-defined element in LS-DYNA, to bridge this gap (T. Willmann et al., 2021). Unlike standard shells, these higher-order 3D-shell elements can capture cross-sectional warping and a higher-order strain distribution in thickness direction, providing a fully 3D stress state.
Through a variety of comparative analyses against standard LS-DYNA shell elements (e.g. Shell 2), our studies demonstrate significantly improved stress prediction for the higher-order 3D-shell elements. This includes a substantially more accurate prediction of transverse shear stress and normal stress in the thickness direction. Results align closely with detailed stress distributions from fully 3D solid simulations yet maintain a significant computational advantage. These studies utilize fully anisotropic 3D material models (*MAT_COMPOSITE_DAMAGE) across various laminate configurations and loading conditions, extending on M. Schilling et al. (2025).
In conclusion, our contribution highlights a promising and viable approach to achieve more reliable stress predictions for composite structures in LS-DYNA, crucial for robust design and damage assessment, without the prohibitive cost of fully 3D discretization.
We gratefully acknowledge the support for this research from the DigiTain project (19S22006K), funded by the Federal Ministry of Economic Affairs and Energy, following on a resolution of the German Bundestag.
Human Body Modelling for Aerospace Impact Applications
Dipesh Chouhan, Jean Bout, Qiu-Rui Zai, Jia-yi Zhong (Arup), Galal Mohamed (Oasys)
In the aviation sector, dynamic seat certification involves applying crash pulses to seats to assess their structural performance and evaluate injury criteria using Anthropomorphic Test Devices (ATDs). Specifically, dynamic seat certification requires two prescribed crash pulses for sled tests: a horizontal pulse and a 60-degree backward pitch. The SAE Aerospace Recommended Practice 5765B provides guidelines for modelling techniques and evaluation criteria for virtual ATDs, supported by validation data from the National Institute for Aviation Research (NIAR).
The primary objective of this study is to develop and validate modelling methodologies for assessing occupant kinematics and injuries using industry-leading Human Body Models (HBMs). The entire modelling workflow is conducted using the Oasys LS-DYNA Environment and Ansys LS-DYNA. The first phase involves positioning industry-leading HBMs on a rigid seat according to SAE Recommended Practice 5765B, with landmark points extracted from NIAR test data. Simulation-based positioning is achieved using pre-configured positioning tree files in Oasys PRIMER, a powerful LS-DYNA pre-processor. Cables are attached to stiff parts of the HBM for simulation-based positioning, where the cables shrink to zero length and pull the HBM into position.
The HBM model is then fitted with a two-point belt, and an acceleration pulse is applied to the rigid test fixture. Occupant kinematics and injury metrics are evaluated and compared against previously run virtual ATD (v-ATD) studies and test data. Organ-level injury assessments, such as the Cumulative Strain Damage Measure (CSDM), are also considered.
Initial simulations show that the methodologies closely replicate physical test conditions, with HBMs providing detailed insights into occupant kinematics and injury mechanisms. This research will contribute to the wider application of HBMs in the aviation industry and promote biomechanical research into aircraft occupant safety.
IGA on 3D Parts : 1st application on Bolt assembly
Franck Norreel (Stellantis), Pierre Glay, Julien Lacambre (Ansys, part of Synopsys), Ilka Schwarzer, Anantharam Sheshadri (Stellantis)
The initial deployment of IGA for shell structures at Stellantis on Body-in-White is delivering promising results.
Building on this success, solid elements will follow once solver capabilities and modeling techniques reach sufficient maturity.
Bolt assemblies were identified as a key initial application: While 3D meshing of bolts improves assembly representation, issues such as mesh dependency (contact facet effects, mesh-dependent failure) and mass scaling remain challenging. IGA technique should help to take-up these technical challenges.
This study will address key topics:
1- Finite Element (FE) Representation: Establish baseline results and highlight limitations tied to traditional FE approaches.
2- IGA for Bolts:
a. Assess mesh and IGA grid sensitivity
b. Calibrate material and failure models
3- Explore hybrid IGA/FE modeling on full assemblies
4- Next Steps:
1. Integrate expected solver enhancements in LS-Dyna
2. Define a scalable, automated deployment process for broader industrial rollout
Introducing a System Coupling solution including LS-DYNA and Fluent
David Aspenberg, Isheng Yeh1, Oleg Chernukhin (Ansys, part of Synopsys)
System Coupling has been used for many years, connecting multiple Ansys software to create multi-physics solutions. Although LS-DYNA includes many multi-physics solutions within a single code, it would sometimes be beneficial to access more advanced solver features from other specialized software.
For that reason, this presentation introduces the soon to be released coupling between LS-DYNA and Fluent. As a first step in this development, the developed coupling exchanges force and displacement data. The workflow to accomplish this coupling within System Coupling’s graphical user interface is demonstrated on a benchmark model, including the steps that need to be performed on each solver side. The presentation also includes technical information regarding the coupling.
L7 Class Electric Vehicle Crash Performance Study
Ahmet Salih Yilmaz (ISUZU), Hakan Balaban (BLB Mühendislik)
The objective of this study is to assess the performance of a L7 Class electric vehicle (EV) in a range of crash scenarios. The tests encompass a range of scenarios, including frontal crashes into a rigid wall, a deformable barrier, a road barrier, and a road blocker bollard. Given that no mandatory safety requirements have been established for this category of vehicle, the necessity for such a requirement is called into question. The aforementioned crash test scenarios were simulated using ANSYS LS-DYNA software, featuring two distinct crash protection systems: a stationary prevention system and a replicable concept bumper system. An examination of the results of the collision tests reveals that the replicable bumper provides significant benefits, particularly in the case of low-speed impact collisions with a deformable barrier. In such instances, the bumper can be repaired without compromising the integrity of the main structure. The objective of this study is to underscore the significance of safety for this class of vehicles. In consideration of these types of collisions, the study will propose cotilion-based safety standards for future implementation.
Lifetime Prediction of Hygro-Thermo-Mechanically Loaded Adhesive Joints Using LS-DYNA and User-Defined Material Models
Maxim Rodschei, Gunnar Possart, Paul Steinmann, Julia Mergheim (Friedrich-Alexander-Universität Erlangen-Nürnberg)
Ensuring the long-term performance and safety of adhesive bonds under cyclic mechanical, thermal, and hygroscopic loading requires advanced computational models. We aim to present our simulation method, which enables the prediction of the lifetime of hygro-thermo-mechanically loaded adhesive joints. We hereby propose an approach for addressing coupled three-field problems involving mechanical, thermal, and diffusion processes, while improving numerical efficiency. Next, our user-defined material model for adhesives is introduced. A viscoelastic constitutive law, which incorporates the effects of temperature and water concentration through the time-temperature-concentration superposition principle, is coupled with a local damage formulation to model the degradation of adhesives. The damage evolution equation thereby includes contributions from creep damage, fatigue damage and hygroscopic damage. Numerical examples are presented to demonstrate the model´s ability to simulate the effects of hygro-thermo-mechanical loads on the lifetime of adhesive joints. Furthermore, parameter identification methods are introduced, aimed at calibrating the model to real adhesive materials.
Maximizing LS-DYNA MPP Performance
Eric Day, Jason Wang (Ansys, part of Synopsys)
This presentation explores proven practices for achieving consistent, high-performance LS-DYNA MPP simulations across a variety of hardware platforms. It covers how to select the optimal LS-DYNA binary for your system, as well as techniques for detecting parallel inefficiencies and resolving them through user-defined domain decomposition. Attendees will gain practical insights into maximizing performance on existing hardware through system settings, undersubscription, hybrid MPI/OpenMP execution, and processor pinning. The session also highlights recent LS-DYNA benchmarks on the latest x86 and Arm-based chips, options for running in the cloud via Ansys Gateway and Ansys Access, and new MPP features—such as OneMPI.
Modeling Forming Effects for Crash Simulation: Recent Advances in HYCRASH
Kei Saito, Takanori Katsuta, Rika Tateiwa, Yasuyoshi Umezu (JSOL Corporation)
Modeling the effects of plastic forming on thin metal components is essential for accurate performance prediction in automotive simulations. HYCRASH, a fast one step solver that estimates strain and thickness distributions caused by forming processes from product geometry, has been continuously developed to improve crash simulation accuracy and streamline modeling workflows.
Recent crash simulations require handling of large-scale vehicle models, diverse component geometries, and complex physical phenomena such as fracture. Addressing these challenges is key to advancing simulation-driven design.
This presentation outlines the latest HYCRASH developments, including support for anisotropic materials, pipe-shaped components, and damage transfer between forming and crash analyses. We also highlight efforts to further accelerate the solver and improve usability through a more efficient modeling environment.
These enhancements aim to improve the accuracy and practicality of incorporating forming effects into crashworthiness analysis. The continued development of HYCRASH supports more reliable and efficient virtual vehicle development.
Modular Contact in LS-DYNA: Progress and New Capabilities
Matthias Birner, Brian Wainscott, Albert Ziegenhagel (Ansys, part of Synopsys)
In this talk, we present an update on the “Modular Contact” framework in LS-DYNA, initially introduced at last year’s conference. Last year we highlighted performance benefits of the new implementation. This year we will present recent advancements, including support for eroding contacts with significant performance advantages compared to the existing implementations.
MODAL BEHAVIOR ASSESSMENT USING IGA ON AUTOMOTIVE NVH ANALYSIS
Felipe Vieira, Lluis Martorell, Ovidi Casals, Angélica Sánchez (Applus+ IDIADA), Courtesy of: Xabier Larrayoz (SEAT-CUPRA)
Isogeometric Analysis (IGA) has gained significant traction in automotive simulation, with OEMs demonstrating its capabilities for BiW structures using shells and trimmed solid elements. Despite these advancements, industry adoption remains primarily focused on crashworthiness applications. This research investigates IGA’s potential for NVH performance, where its inherent characteristics offer compelling advantages.
IGA’s exact geometry representation and higher inter-element continuity are particularly beneficial for modal prediction and vibration analysis. To our knowledge, no comprehensive studies have evaluated implicit IGA for automotive modal analysis using LS-DYNA under production vehicle conditions, a gap this work addresses. We aim to assess IGA’s readiness for NVH applications and identify improvements needed for widespread implementation.
Our methodology follows a progressive approach from basic benchmarks to full BiW analysis. We first established optimal IGA modeling parameters through benchmarking with free and clamped plate configurations with varying polynomial degrees and knot spans. The investigation then advanced to component-level, where we evaluated IGA assembly modeling techniques using a B-Pillar model to compare traditional finite element and IGA approaches. Finally, we transformed a production NASTRAN BiW model to LS-DYNA as a baseline, converting selected components to IGA shell representations to create a hybrid model. This approach allowed us to assess modal frequency accuracy, computational efficiency, and implementation feasibility at the full vehicle structure level, completing our evaluation from simple benchmarks to production-level BiW structures.
Multiphysics Simulation of AC Contactor Closing Dynamics with Nonlinear Ferromagnetic Behavior and Eddy Current Effects
David Poulard, Trang Nguyen, Inaki Caldichoury1, Pierre L’Eplattenier (Ansys, part of Synopsys)
AC contactors are essential for controlling electrical circuits but often reopen when AC current crosses zero. This issue can be reduced by using a shading coil, which generates a delayed induced current to maintain holding force. However, the changing distance between moving and fixed parts affects the magnetic field, and the nonlinear magnetization of ferromagnetic materials adds further complexity.
To address these challenges, we use LSDYNA’s Multiphysics coupling to study the closing dynamics of AC contactors. Our approach captures both electromagnetic and mechanical interactions. We integrate the eddy current solver in LSDYNA through BEM EM soler and define magnetic permeability using a B-H curve to accurately model ferromagnetic behavior.
We developed a generic model based on published research to simulate various scenarios and identify key performance factors. Optimization techniques are applied to enhance closure stability and reduce the chance of reopening.
This work introduces a practical, simulation-based method for improving AC contactor performance, aiming for more stable and reliable operation in real-world electrical systems.
Multiscale modelling of metal anisotropy using the viscoplastic self-consistent (VPSC) approach as a user-defined material model (UMAT) within LS-DYNA
Leo Schwarzmeier, Nikolaus P. Papenberg, Alois C. Ott, Johannes Kronsteiner (LKR Leichtmetallkompetenzzentrum Ranshofen)
Directional deformation processes of primary material, such as rolling and extrusion, lead to anisotropic mechanical properties of a workpiece. Such can be observed because of reoriented crystallographic grains, i.e. texture, along directions of preferred orientations. The anisotropy can strongly influence follow-up processes like deep drawing of metal sheets. Considering such properties in numerical simulations allows to investigate the effects of texture-dependent defects in forming processes. However, current applications of the finite-element (FE) method in forming simulations either neglect anisotropic material properties or incorporate a fixed texture by special material models. Often this is the case, because full-field crystal-plasticity (CP) FE models are too computationally demanding for industrial-relevant part sizes. This presentation shows the use of the visco-plastic self-consistent (VPSC) model as an efficient way of modelling a metal’s developing texture and mechanical response. Applying a multiscale approach by incorporating VPSC as a user-defined material model (UMAT) in the FE-solver LS-DYNA allows to consider texture evolution in large scale metal forming simulations. The resulting material properties of some simulated metal deformation processes are compared to experimental data to highlight the accuracy of the coupled FE-VPSC simulation model.
Near Side Impact: Experience with HANS
Simona Roka, Daria Di Costanzo (Applus IDIADA)
The Diffuse Axonal Multi-Axis General Evaluation (DAMAGE) criterion has proven effective in predicting brain injury risk during frontal impacts, showing better correlation with Maximum Principal Strain (MPS) than other criteria like BrIC and HIC. However, its applicability to lateral impact scenarios remained unexplored. This study evaluates the effectiveness of the DAMAGE criterion in near-side lateral impacts using the WorldSID 50th percentile male dummy (WS50) in Euro NCAP AE-MDB configurations, comparing responses between the anthropomorphic test device (ATD) and Human Body Model.
New application oriented workflow in LS-PrePost for short time dynamics with LS-DYNA
Daniel Hilding, Anders Jernberg (Ansys, part of Synopsys)
Many companies within aerospace and defence rely on high-resolution virtual testing for their success. LS-DYNA is one of Ansys’s flagship solutions in this area. It has a wealth of industry-specific features and multi-physics solvers, each allowing extensive user tuning and control.
The wealth of features in LS-DYNA presents a challenge, and many users spend a lot of time setting up their simulation model. Here, we present two recent developments to address this challenge and make it possible for users to set up models much faster and without having to be subject matter experts. We also show how this technology can be used for short-time dynamics applications, such as impact and penetration simulations.
The new developments also allow users to easily and without coding to extend the graphical user interface in LS-PrePost to automate repeated tasks and set up multi-physics models. These co called templates are also easy to create, distribute, and share.
Optimized Test Program for Calibration of 3D-GISSMO for Die-Cast Aluminum
Takumi Ban (ARRK Engineering), Aina Najwa Shamsuddin (King Mongkut’s University of Technology North Bangkok, ARRK (Malaysia)), Olaf Hartmann (ARRK Engineering)
The application of die-cast aluminum in automotive components is rapidly increasing due to its advantages in lightweight design, reduction of connections, and enhanced recyclability. These benefits make die-cast aluminum a key material for achieving both performance and sustainability goals in modern vehicle manufacturing. However, die-cast parts typically feature complex geometries with varying wall thicknesses, which require Finite Element Models (FEM) to be constructed using solid elements.
While shell elements, which assume a plane stress condition, allow for fracture model calibration using 2D-GISSMO, solid elements require more advanced failure modeling that accounts for three-dimensional stress and strain states. LS-DYNA addresses this requirement through the 3D-GISSMO model, which enables the definition of failure criteria dependent on the triaxiality and the Lode parameter.
This study focuses on investigating optimal specimen geometries necessary for the accurate calibration of 3D-GISSMO. We propose an effective test program that ensures reliable identification of failure parameters under various stress states characterized by the triaxiality and the Lode parameter, contributing to enhanced predictive accuracy in FEM simulations of complex automotive components.
Optimization of automotive part for better vibrational performance including Forming effects
Dharanivendhan T, Kang Shen, Mehul Muradia, Akhil KS (Ansys part of Synopsys)
Automotive parts are often manufactured using Stamping process which often involves significant plastic deformation in the components which affects the stiffness and strength of the component due to strain hardening. Not considering the prestress effects could result in inaccurately predicting the Mode shapes. Moreover, the forming parameters need to be optimized to get the desired vibration performance as well. In the current study, Ansys Forming has been used to simulate the Multistage process and the process parameters are optimized through optiSLang. The prestress results are exported to both LS-DYNA and Ansys Mechanical which are used to calculate the modal frequencies. The current workflow could be extended to other kinds of analysis like failure analysis of the component.
Parametric Study of High Velocity Ballistic Impacts on Composite Materials
Megan Hinaus, Torodd Berstad, David Morin (NTNU), Susanne Thomesen (NFM Group), Tore Brøvik (NTNU)
Ultra-high molecular weight polyethylene (UHMWPE) composites are increasingly used in lightweight, high-performance personal protective equipment for law enforcement. Current material performance evaluations rely on experimental testing, which is both time consuming and costly. To address this, numerical simulations using LS-DYNA offer a cost-effective alternative approach, minimizing material waste and reducing experimental testing time. However, there is limited research on numerical analysis on composites and even fewer resources specifically focused on numerical analysis on composite modeling in LS-DYNA.
This study presents a finite element model comprised of UHMWPE composites incorporating independent cohesive layers, based on defined ply properties and estimated interfacial strengths. The numerical model was calibrated through comparisons with ballistic experiments, methodically varying ply and cohesive material parameters to evaluate their influence on the simulated residual velocity. Parameters with the most influence were jointly optimized using LS-OPT, with reference to a Recht & Ipson ballistic limit curve from experimental testing, with the resulting model more accurately predicting a numerically simulated ballistic performance.
Perforation of reinforced concrete slabs with LS-DYNA
Eric Piskula (Ansys, part of Synopsys)
Modeling the nonlinear behavior of concrete and reinforced concrete (RC) structures under high-intensity loads is a complex challenge. These loads can cause material compaction, fragmentation, and cracking, making accurate simulations essential for the design of civil structures, especially when experimental data is unavailable. This study presents a methodology to evaluate both global and local strength of RC components using the LS-DYNA solver. In December 2008, the Committee on the Safety of Nuclear Installations approved a proposal from the Working Group on Integrity and Ageing of Components and Structures to launch the IRIS_2010 benchmarking study (Improving Robustness Assessment of Structures Impacted by MissileS). The goal was to compare different computational tools, modeling techniques, and results to analyze the structural response of nuclear power plant (NPP) structures to missile impacts, improving accuracy and fostering international collaboration without destructive testing. The IRIS_2010 study focused on RC elements, such as walls and slabs, subjected to missile impacts at medium velocities (100–200 m/s). Failure mechanisms like bending and punching were analyzed. it was considered more interesting (and exciting) to propose blind simulations in 2010 to test modeling capabilities. Initial simulation results were unsatisfactory, prompting a second phase in 2012 with additional experimental data to improve accuracy and bring results closer to real-world observations. This study revisits these simulations using the same data from 2010 and 2012 but with enhanced features of LS-DYNA as of 2025. The goal is to evaluate improvements in accuracy due to technological advancements. To reduce the number of simulations, this study focuses solely on the perforation of a reinforced concrete slab by a rigid missile, a critical failure mode in structural safety analysis, providing a test case for modern modeling techniques.
Prediction of Pedestrian Head Protection Performance Using VisionGNN
Osamu Ito (Honda Motor)
Pedestrian head protection is a critical component of vehicle safety assessment, particularly for minimizing injury severity in the event of a collision involving a pedestrian. Conventional evaluation techniques, such as physical crash tests and finite element simulations, although reliable, are often time-consuming, labor-intensive, and computationally expensive. To address these limitations, this study proposes a novel method that leverages Vision Graph Neural Networks (VisionGNNs) to predict head protection performance directly from the geometry of the bonnet hood. In the proposed approach, the structural features of the bonnet are represented as graph-structured data, allowing the model to effectively capture spatial relationships and topological characteristics. By exploiting the deep learning capabilities of VisionGNN, the system can accurately estimate Head Injury Criterion (HIC) values without the need for repeated physical or numerical simulations. The model was trained on a dataset generated from detailed CAE models and their corresponding simulation results. Experimental evaluation demonstrates that the VisionGNN approach achieves high prediction accuracy, significantly reducing computational costs and development time. This method presents a promising direction for integrating artificial intelligence into the early stages of vehicle design, facilitating rapid and efficient assessment of pedestrian safety performance across diverse design alternatives.
Reinforced Concrete Punching Failure Modeling with Ansys LS-DYNA
Ivaylo Klecherov (Fluid Codes)
Reinforced concrete (RC) structures have been used to protect critical energy infrastructure against accidental and malicious impacts. Wind-borne and man-made projectiles with high velocities can impact the outer shell structures, causing significant damage and potentially leading to a collapse. Studying the punching resistance of thinner and thicker slabs with and without shear reinforcement is an ongoing topic of research, and there are multiple full-scale impact tests available for validating the modeling techniques.
In our current studies, the punching failure of RC slabs, subjected to impacts with blunt-nosed hard or semi-hard steel projectiles, is investigated. The pre- and post-processing are fully performed using Ansys tools – SpaceClaim, Mechanical and LS-PrePost. The mesh-free Smoothed Particle Galerkin (SPG) method was employed for the concrete slabs, and it is coupled with the 3D beam-modelled layout of the reinforcement, to ensure close resemblance of the actual geometry.
The simulation results are compared against the results of multiple full-scale impact tests. The developed methodology is used for applying the techniques learned in more complex projectile-target interactions scenarios, where the severe scabbing, penetration, spalling and perforation failure of the reinforced concrete structures can compromise the functionality of the safety-critical infrastructure.
SimAI Application in Stamping Die Engineering
Li Zhang, Junyan He, Amit Nair, Ethan Rabinowitz, Ethan Thompson (Ansys, part of Synopsys)
In this paper, a modified 2005 NUMISHEET Crossmember was used to demonstrate SimAI’s use cases in stamping sheet metal formability prediction. The AI model is trained with 49 DOEs of LS-DYNA stamping simulation consisting of various die and punch radii changes. The formability results from the DOEs produced both failure and wrinkles, which is of interest in the SimAI prediction study.
CASE 1 focuses on prediction of thickness, strain and FLD in a “one-step” fashion. The last state of the incremental LS-DYNA simulation results on the blank are used to build the AI model. New part geometries are used to predict formability based on the trained model. This case consists of formability prediction with new part geometries on an AI model trained with trimmed panels, and prediction of new part geometries on an AI model trained with drawn panels. CASE 2 focuses on transient prediction of thickness and deformation. All states of 49 DOEs (a total of 490 training/test data sets) were used to train the AI model. Prediction results are discussed and SimAI application strategies in Stamping Die Engineering are discussed.
Simplified Finite Element Model of a Prismatic Cell for the Prediction of Short Circuit under Crash Loading
Anja Steiert, Benjamin Schaufelberger, Thomas Kisters, Sebastian Schopferer (Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institut (EMI))
The inclusion of a battery system in an electric vehicle presents significant challenges due to various requirements, such as low weight, integration into the load-bearing structure, and safety concerns. Allowing for deformation of the battery system, necessitates an understanding of potentially critical deformations, that may lead to short circuit and are therefore a potential source for thermal runaway. The failure of the separator foils is one trigger for short circuit, making it essential to evaluate its deformation. In this study, a simplified finite element (FE) model, comprising three components— can, homogenized inner part, and shell layers for the separator—is utilized. The model is calibrated using experimental data from a planar compression test and material parameters from the literature. The transferability of this comparatively simple model will be analyzed, by simulating different experiments, such as crush tests and three-point bending. Separator failure in the model and occurring short circuit in the experiment are compared to assess the validity of the proposed physical based short circuit criterion.
Simulation of high-velocity impact onto a liquid filled container
Shashanka Subrahmanya, Georg A. Heilig, Michael May (Fraunhofer EMI)
At EMI an experimental series to study the deformation and failure of tab water filled tanks subjected to high speed impact loading has been performed. These experiments investigate the Hydrodynamic RAM (HRAM) effect, which plays an important role in the safety of aircraft. During service life, an aircraft may encounter various foreign object impact scenarios including birds or drones impacting the leading edges of its wings, which may lead to the undesirable HRAM effect.
In the laboratory, HRAM is realized through high-speed impacts of solid projectiles onto tanks filled with tap water, as water shares similar physical properties with fuel but eliminates fire hazards. HRAM is a complex phenomenon, characterized by several physical processes occurring simultaneously, e.g. a cavity behind the impacting projectile builds up; it is filled with atmospheric air, which flows into the tank through the penetration orifice.
The experiments are simulated with the two hydrocodes Ansys AUTODYN-3D and Ansys LS-DYNA, fully coupled in the Fluid-Structure-Interaction mode. The paper gives a comparison between the experimental and numerical results for a scenario with impact velocity V0 = 645 m/s. The main focus is velocity-decay of the cylindrical aluminum projectile (L/D = 2) in the water and the growth and decay of the induced cavity.
Standardized Determination of Dynamic Loads Transmitted to Structures – Exploration of Alternative Approaches
Antoine GUILPIN, , Vincent LAPOUJADE, Jérémy POURCELOT, Julie ROUGIER (Dynas+), Clément GOUBEL, Romain CARRETTA (EDF DT), Ludovic CORVOL (ROUSSEAU)
In civil engineering, structural design has traditionally been based on static load assumptions. However, the increasing use of numerical simulation in adjacent fields—such as vehicle restraint systems (VRS) on bridges or tornado protection structures—raises new challenges. These domains generate highly dynamic loads, which are often reduced to a peak value and then directly applied as static loads to civil engineering components. While simple, this conservative practice tends to produce significant overdesigns, conflicting with today’s goals of structural optimization and energy/material efficiency.
This paper explores strategies to bridge the gap between dynamic simulations and static design in civil engineering. It draws on two practical cases: (1) the development of the FD P98-435 methodology, a simulation-based approach to quantify loads transmitted by bridge-mounted safety barriers, and (2) EDF’s use of LS-DYNA to assess the anchorage performance of protective structures.
Beyond full dynamic modeling—accurate but resource-intensive—alternative strategies are considered: an equivalent static force approach, energy-based impulse methods, and validation-based extrapolation techniques. These aim to retain the richness of dynamic simulations while enabling realistic and efficient static design in engineering practice.
Swelling and module pre-loading considerations in EV battery crash models
Sriram Seshadri, Alexis Wilson (Automotive Cells Company)
Electric vehicles are deemed necessary for the transition to sustainable transportation, but the growing demand in safety regulations and need for cost effective batteries are essential in making this transition successful. One of the critical aspects involve the prediction of battery performance in various crash/impact scenarios and thereby evaluating the risks to the occupants. One key area concerning a battery module in addition to standard crashworthiness assessment is the pre-loaded state of the module, including cell swelling, gas pressure and module assembly effects. This paper presents a methodology to consider pre-loading in a battery module which is compatible with and included in crashworthiness simulations. Module deceleration and crush simulations are performed to validate the implementation of pre-loading phenomena and compared to available test data to illustrate the improvement against non-pre-loaded simulation models. The results highlight the need to include pre-loading in the module simulation to accurately represent the module stiffness for crash assessments by demonstrated improvement in the prediction of component displacement, stress and damage values..
Testing and verification of the new CPG method for complex internal structures in airbags
Ercan Usta, Sebastian Stahlschmidt, Edouard Yreux (Ansys, part of Synopsys), Alexander Diederich, Michael Freisinger (Toyoda Gosei Europe NV), Peter Csizmadia, Doris Ruckdeschel (BMW AG)
Developments of the airbag’s complexity in the last couple of years for occupant safety, such as new detailed geometries, different gas generator characteristics and internal fabric or steel diffusors keep LS-DYNA always to continue its airbag method developments.
Towards a 3D hybrid active skeletal muscle for Ansys Hans Human body model in LS-DYNA
Mukund Thirugnanasambanthar (Ansys, part of Synopsys), Michael Ditthardt, Christian Kleinbach (Mercedes-Benz AG), Oleksandr Martynenko (University of Stuttgart), Alexander Gromer (Ansys, part of Synopsys), Syn Schmitt (University of Stuttgart)
Human Body Models (HBMs) are being widely used to investigate injury biomechanics and the development of vehicle safety systems. To simulate active human responses, muscles are typically represented by 1D Hill-type materials. However, muscle tissue is a complex material that exhibits anisotropy and hyperelasticity, and its properties drastically change when it contracts after activation through electrical signals. Therefore, traditional active HBMs with 1D elements face key limitations such as inaccurate muscle moment arms due to subjective routing and an inability to model lateral muscle expansion during contraction.
The Ansys Hans HBM features a detailed, biofidelic 3D muscle structure that can address these limitations. As part of the publicly funded CARpulse project, a hybrid muscle modelling methodology is being developed to introduce active musculature into Hans using LS-DYNA. The proposed approach additively decomposes the muscle characteristics: active behaviour is captured by the 1D elements, and the 3D solids capture passive mechanical response coupled through shared nodes. The stress transfer between elements enables increased muscle stiffness during contraction, a feature absent in purely 1D models.
The modular nature of the approach allows future integration of muscle controllers that monitor joint angle or muscle length paving the way for simulating goal-directed motion with higher biofidelity and computational efficiency.
Trimmed IGA Solids in LS-DYNA: CADFEM Findings
Yury Novozhilov (CADFEM), Lukas Leidinger (Ansys, part of Synopsys)
The application of the Trimmed IGA Solids approach has the potential to revolutionize the entire industry of structural analysis. The implementation of this method in LS-DYNA has seen rapid development in recent years. CADFEM has been studying the practical applicability of this approach in solving engineering problems, identifying both its strengths and weaknesses. This presentation will focus on the findings of this research.
Update on EM Solver
Inaki Caldichoury, Pierre L’Eplattenier, Trang Nguyen (Ansys, part of Synopsys)
The LS-DYNA Electromagnetism solver (EM solver) specializes in coupled Electro-thermal-mechanical simulations. Its application range covers a wide spectrum, from magnetic metal forming, magnet snapping and inductive heating to battery abuse and electrophysiology. The objective of this presentation is to provide an overview of some new developments introduced in R17 and discuss the requests that prompted them. Specifically, the discussion will focus on electric cable management problems, electrostatics and provide an update on magnet simulations.
Using JFOLD and *AIRBAG_CPG to Study the Effect of Fold Pattern on Curtain Airbag Deployment
Shinya Hayashi, Mayumi Murase (JSOL Corporation), Richard Taylor (Arup)
JFOLD is a software tool for simulation-based airbag folding in Ansys LS-DYNA. *AIRBAG_CPG is a new gas dynamics solver that shows great promise for deployment prediction through accurate simulation of gas flow within complex airbag structures. Curtain airbags are an important part of a vehicle’s safety system. Carefully folded to fit within the trim and roof side rail, they must deploy very quickly into the narrow gap between occupants and doors, once a side collision is detected. Any wayward interaction of the curtain airbag on trim or brackets during deployment can greatly impede speed and direction, negatively affecting occupant protection. To avoid this, engineers spend a long time optimizing the fold pattern to ensure a clean break out and deployment. In this presentation we show how different folding patterns of one curtain airbag can be easily designed and optimized using the latest JFOLD features. The deployment performance of each fold pattern is then assessed using *AIRBAG_CPG, after validation of a baseline to physical tests.
Utilization of Surrogate Models for Enhanced Crash Simulation Accuracy of Fiber-Reinforced Plastic Parts
Yoshikazu Nakagawa, Osamu Ito (Honda Motor)
In recent years, the application of resin in automotive parts has been expanding as a replacement for steel plates, aiming for greater shape flexibility and weight reduction. Among resins, fiber-reinforced resin with glass fibers as reinforcement exhibits anisotropy, where the strength characteristics vary depending on the orientation of the fibers. To perform highly accurate crash simulations, it is necessary to reproduce this anisotropy in the LS-DYNA model.
Whisker sensor based on magnetostrictive material modeling in LS-DYNA
Thu Trang NGUYEN, Inaki Caldichoury, Pierre L’Eplattenier, Loic Ivaldi (Ansys, part of Synopsys)
Recently whisker sensors have been widely investigated for tactile sensing in bionic robots, automatic vehicles and so forth, due to their advantages of working under static or low frequency. The structure of the whisker sensor presented in this paper consists of a Galfenol/berybellium-bronze/galfenol cantilver beam and a fixed magnet. A loading deflection is applied at the beryllium-bronze beam’s free end which induces some stress in the galfenol magnetostrictive beams. Since the permeability and B-field of the galfenol material depends on the applied stress, the magnetic flux density B in the galfenol beams generated by the magnet will depend on the applied deflection. The B-field can then be measured by a Hall sensor. In this paper, a whisker sensor is simulated using LS-DYNA mechanical and EM solvers, with “magnetostrictive” non-linear B-H curves depending on the external stress.
An external force is applied to the structure, leading to the deflection of both the beryllium-bronze beam and the galfenol beams. A mechanical implicit simulation is done to get the shape and stresses of the deflected beams, and the EM solver is then used to get the B-field at the sensor’s locations. Given the sensibility of the Hall sensors, a voltage is obtained by multiplying the magnetic flux density with Hall sensor sensitivity.