Numerical Simulation of CFRP Thin-Walled Tubes Subjected to Quasi-Static Axial Crushing 2017-01-0465

Carbon Fiber Reinforced Plastic (CFRP) tube is an important material for the lightweight design of automotive structures. Simulation method of CFRP thin-walled tubes subjected to axial compression using MAT54 in LS-DYNA was investigated. Based on the two-layer shell model combined with MAT54, failure strategy and the parameters sensitivity of the model were discussed in detail. Then the simulation model was verified by using duplicate specimens comprised of carbon fiber/epoxy unidirectional prepreg tape. Furthermore, the modeling methods of crush trigger and different types of loading speed were analyzed. In addition, based on the method of equal energy absorption, energy absorption performance of thin-walled circular and square tubes made from four materials including mild steel, high strength steel, aluminum alloy and CFRP were also compared. The results showed that the method of modeling crush trigger and loading speeds had an important influence on the simulation results, especially on the peak load and the energy absorption of trigger zone. Simulated chamfers can be modeled by either directly deleting the first lap of elements of outer tube or by utilizing the inclining elements with a thinned thickness. The simulated results using abruptly stepped loading speeds or the gradually increasing loading speeds, can agree well with the experimental data. Taking convenience into consideration, the chamfer using deleting elements and the loading speeds using abruptly stepped velocity are better ways to simulate CFRP under axial compression. The circular tubes have better energy absorption ability than the square tubes. Compared with steels, CFRP is less sensitive to the shape of the cross section in terms of energy absorption ability. Within the limitation of this study, the weight of CFRP can reduce by 75.08%, 69.78% and 41.12% when compared with that of the mild steel, high strength steel and aluminum alloy, respectively.