Investigation of the effect of Z-pin reinforcement on the collapse of foam-cored sandwich panels

Z-pin reinforced foam core sandwich is fabricated by reinforcing lightweight foam with a truss network of pultruded carbon fiber rods, and then laminated between composite facesheets to produce sandwich structure. Experimental and analytical studies on this novel sandwich composite under three-point bending were presented in this paper, and the failure models were investigated and compared with that of the unreinforced one. It is found that the bending properties of foam core sandwich are enhanced significantly by pins. The predictor formulas were developed to obtain the collapse loads of Z-pinned sandwich, and then the influence of pins on the flexural properties were presented. The collapse load is clearly affected by the inclination angle, volume fraction and Young's modulus of pin. The Z-pinned core was subsequently optimized from a minimized weight standpoint subjected to various failure constraints.