Time-dependent deformation of ROHACELL-core CFRP sandwich panels.

In this study, we experimentally and analytically investigated time-dependent deformation of carbon-fiber reinforced plastic sandwich panels with three kinds of polymer foam-core ROHACELL, with the deformation caused by moisture absorption. Tensile tests for the ROHACELLs before and after moisture absorption were performed using the digital image correlation method, and we obtained a stress–strain relationship for each condition. Surface deformations of sandwich panels were calculated using finite element analyses to examine the elasto-plastic deformation of the ROHACELLs based on the tensile test results. Experimentally measured deformation in the sandwich panels varied depending on the cell size of cores, and the largest measured deformation after the moisture absorption was approximately 100 μm. This was much larger than the analytical result. On the basis of this study, we suggest that the main reason for the deformation may be an irreversible shrinkage of the ROHACELLs caused the absorption of moisture during exposure to high-temperature and high-humidity environments. [ABSTRACT FROM PUBLISHER]