Interface constitutive modeling and failure propagation mechanisms of integrated polymer-metal hybrid (PMH) structures

This paper studies the polymer-metal hybrid (PMH) structures, formed by direct injection over-molding the glass fiber-reinforced polymer (GFRP) composite on the surface of high-strength steel (HSS), which integrate the advantage of HSS and GFRP, and have been applied in the lightweight design of vehicles. However, the existence of an interface between GFRP and HSS weakens the ultimate carrying capacity of the overall PMH structures, and hence, the interface needs further improvement. First, five kinds of PMH specimens with different micro -interlock features were designed and fabricated, and the corresponding interfacial tensile and shear strength (oIc and ocII) and fracture toughness (GCI and GcII) were characterized experimentally. An interface constitutive model suitable for describing different mechanical interlocks was established, and the general program for parameter identification was developed in a finite element code. Using this model, the crack evolution mecha-nisms of PMH structures under tensile and bending loading were revealed. Finally, the micro-macro mapping rule between the interlock features and the ultimate loading of overall PMH structures is proposed. These results are conducive to the lightweight design and performance prediction of PMH structures.