Time-dependent Out-of-plane deformation of symmetric laminate including small fiber misaligned

In this study, we focused on the geometrical change of symmetric laminates that are widely used for the composite structures. The behavior of time-dependent out-of-plane deformation under high temperature and humidity was examined with high accuracy. The geometries of the CFRP plates were measured after constant time. It was obvious that the main factor which causes geometrical change was moisture absorption at 80°C, 90%RH environment. The geometrical change was calculated based on Finite Element Analysis considering fiber misalignment. Coupling analysis including stress and diffusion analysis was performed to reproduce the time-dependent deformation. In this analysis, we rotated the layer of the symmetric laminate about 5 degrees, so specifically the model was asymmetric, and the coupling effects that arose bending by tension took place due to moisture absorption. Quasi-isotropic laminate model including small fiber misalignment deformed into saddle shape and twisted saddle shape. It was predicted that it must be needed to control fiber alignment strictly when we product CFRP laminate with high dimensional stability.