Finite Element Analysis of Compression Behavior of Composite Egg-Box Panel with Non-Orthogonal Constitutive Model

In the current study, thermoforming and compression analysis were carried out for the woven composite egg-box panel with the non-orthogonal constitutive material model, which is proposed by Xue et al (Composites: Part A 34 (2003) 183–193). The material model is implemented in commercial engineering software, LS-DYNA, with user subroutine. Xue et al obtained the nonlinear Young’s modulus and shear modulus from the experiment test, but the constant Young’s modulus and shear modulus for fiber are used in this woven composite egg-panel compression analysis for the convenience. Directional properties in non-orthogonal coordinates are detected using the deformation gradient tensor and the material modulus matrix in local coordinate is updated at each time step.

After the implemented non-orthogonal constitutive model was verified by performing bias extension test, the egg-box panel simulation was performed. The egg-box panel simulation is divided into two categories: thermoforming (draping) and crushing. For thermoforming process, the only die compression effect is considered and the temperature effect is ignored in this study. The finite element model for compression test can be obtained using the displacement result of thermoforming process. Isotropic transverse shear modulus is assumed for the compression simulation. The results from simulation are compared with the experimental tests and also compared with the result using the isotropic material model in order to help understanding the directional property.