Effects of hygrothermal environment on the buckling and postbuckling performances of stiffened composite panels under axial compression

Effects of hygrothermal environment on the buckling and postbuckling performances of stiffened composite panels under axial compression were investigated experimentally and numerically in this paper. Hygrothermal aging experiment on stiffened composite panels was conducted in 70 °C distilled water and the moisture uptake was analyzed every 24 h until to moisture saturation. Moisture uptake process and moisture content distribution along the thickness direction were analyzed by using finite element (FE) method. Thin region and thick region of stiffened composite panels were defined and classified respectively according to moisture uptake process. Then the axial compressive experiments were performed on the hygrothermal aged specimens, with comparison of compression on virgin specimens. Strains, loads, out-of-plane displacements, shortening and failure modes were analyzed comparatively. The results indicate the hygrothermal environment impose much negative effects on the stability and carrying ability of specimens. In the end, a new approach for simulating the dynamic properties of unsaturated specimens was proposed, which considered the gradient of moisture content. Effects of various moisture content on buckling and postbuckling performances were determined.