Experimental investigation on mechanical properties and failure mechanisms of polymer composite-metal hybrid materials processed by direct injection-molding adhesion method

Multi-material hybrid application is an effective way of automotive weight reduction. This paper proposes and validates a direct injection-molding adhesion process for polymer composite metal hybrid (PMH) materials to overcome several limitations of existing PMH technologies. The fundamental tension and bending properties of PMH materials are investigated by experiments. The force-displacement curves of PMH coupons present a multi-stage feature, which is the cumulative results of two constituent materials, and a typical stepwise progressive failure process was observed. Furthermore, scanning electron microscopy and digital image correlation observations reveal the failure mechanisms of PMH materials at micro-scale, including polymer composite metal interface debonding, brittle fracture of thermoplastic matrix, glass fiber breakage or pull-out from matrix, and ductile failure of steel. The convex concave interlocking mechanism plays an important role in PMH interface bonding. Under tension and bending loads, the rule of mixture prediction method for modulus and strength of PMH coupons have a high precise compared with the test results. These basic material characteristics may serve as a foundation for the future engineering applications of PMH load-bearing components.