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.