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Modeling the Axial Crush Response of CFRP Tubes using MAT054, MAT058 and MAT262 in LS-DYNA®

Predictive capabilities of three LS-DYNA composite material models – MAT054, MAT058 and MAT262 – were investigated and compared with respect to modeling of axial crushing of CFRP energy absorbers. Results of crush simulations with non-calibrated material models were compared with available experimental data, and then parameter tuning was conducted to improve correlation with experiments. Furthermore, calibrated material models were used to conduct independent crash simulations with a distinct composite layup. Simulations with calibrated MAT054 predicted axial crush response of the energy absorbers with a reasonable accuracy. MAT058 was found to be intrinsically less accurate in predicting the peak force due to its inability to account for reduction of longitudinal compressive strength of a ply in the case of transverse compressive failure. It was also found that simulations with pre-calibrated MAT058 can predict non-physical failure modes, such as e.g. global buckling instead of stable axial crushing. Owing to complexity of its constitutive model, MAT262 required extensive calibration before a satisfactory agreement with experimental data could be achieved, which constitutes the major limitation of this material model. Instead of simple trial and error approach employed for other models, it was found more practical to use response surface approximation and gradient optimization in order to tune the parameters of MAT262.