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Crashworthiness analysis involves highly nonlinear transient dynamic problems with large deformation of thin shell structures, elastic-plasticity, surface contact, etc. Accuracy, robustness and efficiency are always the fundamental requirements for engineering applications. Adaptive methods of finite element analysis are considered powerful tools for many engineering applications, to obtain good accuracy efficiently. This paper is to report a preliminary study on the application of h-adaptivity to crashworthiness analysis using LS-DYNA. The performance of the component axial crash simulation using adaptive method is presented with comparisons to uniform refinement. The roles and effects of the control parameters of the software are discussed. It is found that the error indicator based on shell element normal rotation is effective for the solutions of bending dominated crashworthiness applications.

In the past twenty years, the explicit finite element method has been successfully employed for crash simulation. At present, crashworthiness analysis is still basically a calibration based engineering practice, but not a fully predictive process. The increasing expectations and requirements on CAE are even more challenging. To develop a predictive and reliable CAE tool, it is important to investigate the root causes that affect the numerical accuracy and the availability of the analytical method. Some of the challenging issues are discussed here from both theoretical and engineering aspects, such as convergence of explicit finite element method, locking-free shell element, analysis of material rupture, and modeling of spot weld.

To have better confidence on CAE prediction of crashworthiness analysis, the process of verification and validation for the explicit finite element method is essential. Selected examples are presented to study the convergence behavior and the quality of the explicit finite element method for transient dynamics. For the axial vibration of a rod, the computed displacement and velocity, and the frequencies calculated by using Fast Fourier Transform achieve the optimal convergence rates when mesh is refined. For a clamped rectangular plate subjected to lateral load, the elastic deflection and rotation calculated by using Reissner-Mindlin plate element, achieve the optimal convergence rates within a range of thickness. For the motion excited by initial velocity, when the thickness is reduced however, the deterioration in convergence of velocity related terms is observed.