An experimental investigation of static and fatigue behaviour of GFRP sandwich beams with a web reinforced wood core

Three-point static and fatigue bending experiments were performed on 51 composite sandwich beams with glass fibre reinforced polymer (GFRP) face sheets and paulownia wood cores. Specimens with no lattice, one lattice and two lattices were prepared, and the fatigue bending failure mode, fatigue life distribution and stiffness degradation model of the sandwich beams were obtained. The results show that the specimens with no lattice exhibit two brittle failure modes, i.e., interface debonding and core shearing. The failure modes of the specimens with one lattice are local buckling and crushing, while the specimens with two lattice webs only exhibit tensile failure of the bottom face sheet. Moreover, the specimens with webs exhibit ductile failure characteristics. Based on the Weibull model, the Weibull distribution equations of each specimen under different survival rates were established, and the engineering fatigue curve was drawn. Furthermore, the secant stiffness curve of the specimens with webs was established based on the fatigue cumulative damage theory, and the fatigue lives of three specimens were predicted.