유한요소법을 이용한 CFRP 구조 부재의 동적거동에 관한 연구

Abstract

Carbon fiber reinforced plastic (CFRP) are widely used in a large number of industries by virtue of its light weight and excellent strength as compared to metal or other materials. In particular, unidirectional CFRP prepreg inter-layer structure with excellent compression strength is in wide use in aircraft building and lightweight vehicles. This CFRP is an isotropic material and the material properties of the CFRP is determined by stacking sequence. So The CFRP shows different collapse characteristic then isotropic material. In addition, It shows local buckling, inter-laminar cracks and intra-laminar cracks during collapse. Thus, it is hard to predict and analysis behavior under various load. But the progress of computer performance and the FEA(Finite Element Analysis) program help to predict behavior of CFRP member under dynamic load. Thus many researchers are studying the FEA method of CFRP structural members. According to researches, FEA of the CFRP structural members has several difficulties. And the representative difficulty on FEA of the CFRP structural members is implementation of brittle fracturing and inter/intralaminar cracks. In this paper, the FEA method of the CFRP structural members under dynamic load is studied with using the LS-Dyna3D and the result obtained from this study is as follows ;

1. The crushing response of composite member can be categorized into three basic modes: Lamina Bending, Transverse Shearing, and Local Buckling. But the biggest intra-lamina crack was broke out on the center interface of specimen on the almost case of experiment.

2. A split on corner and intra-lamina crack were shown on this simulation. Thus, an analysis method using 2 layer shell model with Contact interface algorithms is reasonable for analysis CFRP member with Mode I, Mode II and intra-lamina crack.

3. The load-displacement plot of simulation result is similar to the load-displacement plot of experiment. But the range of load-displacement plot of simulation is larger then the range of load-displacement plot of experiment. It seems that the TFAIL Parameter, which is time step size criteria for element deletion, influenced the result of simulation.

4. Simulation results shows 1.4∼33.63% of the difference on absorbed energy, 2.6∼14.61% of the difference on maximum load and 1.4∼33.63% of the difference on mean load comparison with experiment result.