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This paper is concerned with numerical simulation utilizing LS-DYNA MAT54 for axial crush of glass-fiber mat/PA6 composite tubes. The crush simulation aims at reproducing the crush energy absorption capability measured from dynamic drop tests. The adopted MAT54 has a merit as a widely commercialized model of composite materials to simulate a progressive failure mode. Parameters of MAT54 are calibrated to reduce difference of the crush energy absorption capability between experiment and simulation on the basis of parametric studies. The calibration is performed for major parameters considering effect of energy absorption and stability of crush simulation first, and other parameters are determined by a trial and error method. In order to evaluate the calibrated parameters of MAT54, results are compared for specific energy absorption and crush depths measured from simulation and experiment. Consequently, the presented simulation shows good agreements with experiments, and its applicability is verified under various impact speed and impactor mass conditions.

In this paper, the results are present of an experimental investigation into quasi-static and dynamic crushing responses and crashworthiness characteristics of round-hat-shaped crash tubes made with glass long-fiber-mat/PA6 laminates of around 45 vol%. These characteristics were explored using a high-dynamic hydraulic test machine. The crash tubes failed by the progressive splaying mode except for some tubes in the quasi-static tests, which failed by the mid-length collapse mode. The specific energy absorption (SEA, 42.0 J/g) in the quasi-static tests increased to around 52 J/g in the dynamic tests. The increased energy absorption at the higher test speed was analyzed through the microscopic behavior of the small bending radius of the splayed laminar bundles and fragmentation of the lamina bundles. The drop-tower tests show that the dependency of the performance of the crash tubes on the test speed appears only at relatively low speed (1 m/s in the limited tests reported in this paper), but the performance becomes relatively steady at much higher impact speeds. The impactor mass and tube length had almost no effect on the crash characteristics of the mean crushing load, SEA, and peak load.