Three-point bending characteristics of all-composite sandwich panels with different core configurations

With cores of the hexagonal honeycomb (HH), staggered corrugated lattice (SCL), bidirectional corrugated lattice (BCL), reinforced hexagonal honeycomb (RHH), and reinforced staggered corrugated lattice (RSCL) made by cutting, bonding, arranging and weaving the trapezoidal corrugation (TC) formed by mold hot pressing, six types of composite sandwich panels of the same macro size were proposed. The failure processes of the six sandwich panels in three-point bending experiments were compared and analyzed, and the effects of core configuration and reinforced stiffener on the bending response were evaluated. A general analytical model was established to predict the bending stiffness and failure mode of six sandwich panels, which was also visually presented by a three-dimensional numerical model. The numerical and experimental results validated the effectiveness of the analytical model. The effects of ply parameters and corrugated sizes on bending responses were studied by a combing application of experiment, analytical and numerical models. The three-dimensional failure mechanism maps were displayed to evaluate the failure mode and failure load. The longitudinal discontinuity of the bonding zone of the core could significantly weaken the bending performance and bonding strength of BCL, SCL, RSCL, and HH. The peak load of SCL and HH was enhanced by 45.97% and 60.29%, respectively, by setting stiffeners. Both RHH and TC could achieve bending stiffness of more than 3.5 kN center dot mm(-1), while the failure load of the latter could be up to 25 kN. The design parameter space of bending stiffness, failure load with respect to ply orientation angle, core wall thickness, corrugated web angle, and horizontal segment length was provided intuitively.