Isogeometric Analysis for Shell Structures: Capabilities, Limitations and Industrial Applications for Numerical Simulations with LS-DYNA Software GDTech

Abstract

Automotive crash simulations are a core activity in the engineering industry, where accuracy and workflow efficiency are critical. In the classical finite element analysis, the mesh generation process is time-consuming and introduces geometric approximation errors, which motivates the investigation of isogeometric analysis as an alternative. IGA uses the same NURBS basis functions that describe the CAD geometry to approximate the solution fields, eliminating the meshing step and preserving the exact geometry throughout the analysis. This thesis represents a first step toward the adoption of IGA in industrial crash simulations at GDTech, using LS-DYNA as the simulation environment. Since most parts in crash simulations are modelled as thin-walled structures, this study focuses on shell elements. The study follows a progressive approach, starting from simple elastic benchmarks and increasing the complexity toward dynamic crash scenarios, comparing IGA with classical FEM at each stage. The results demonstrate that IGA correctly reproduces the mechanical behaviour in elastic, plastic, and dynamic crash cases. For equivalent mesh sizes, IGA provides smoother and more accurate stress fields, and can achieve similar accuracy with coarser meshes and fewer degrees of freedom. However, the computational cost is significantly higher, driven by denser system matrices, contact treatment through an interpolation mesh, and the critical time step limitation imposed by the patch boundary elements. IGA is a promising method for industrial crash simulations, but its adoption should be carefully considered. It is most beneficial when geometric accuracy and smooth results are required, and when meshing time savings justify the increased simulation cost.