Four-point bending behaviors of CFRP trapezoidal corrugated sandwich plates

The stiffness, failure load and failure mechanism of carbon fibre reinforced plastic (CFRP) composite trapezoidal corrugated sandwich plates (CTCSPs) subjected to four-point bending load were studied by experiment, modelling prediction and parametric analysis. With orthogonal anisotropic lay-ups containing ± θ plies (θ = 15°, 45° and 90°), three all-CFRP specimens were fabricated by mold hot pressing and secondary bonding. The four-point bending behaviors of specimens were tested and compared, and the analytical expressions of stiffness and failure load were provided. Four buckling failure modes and four strength failure modes were analytically considered. The spatial location and time sequence of eight failure modes were revealed by numerical linear buckling and progressive damage models established in ABAQUS. The modelling stiffness, failure load and failure process agreed with the four-bending experimental results. By increasing θ, the limit load of the specimens first increases and then decreases while the stiffness decrease. Correspondingly, the initial failure modes are shear corrugation fracture, debonding and face fracture. The variations in stiffness parameters and failure mechanism maps were presented; the latter can simultaneously predict the limit load and failure mode. The limit load and stiffness of CTCSPs can be improved more obviously by increasing the number of the face plies than by expanding the core plies.