Mechanical properties and failure mechanisms of metal-woven composite hybrid structures under three-point bending

Abstract

In order to solve the problems of delamination failure and fiber destruction in the traditional metal-composite hybrid forming method, a new hybrid structure combining metal additive manufacturing, composite weaving and stitching processes was designed. The metal skeleton and woven composite materials were co-cured and formed after completing normal stitching, which increased the bonding strength among heterogeneous materials. Flexible forming and stable connection between metal and composite materials on macroscopic scale were also realized. The in-plane bending performance of the new hybrid structure was investigated by a three-point bending test. The damage morphology of the sample parts and their failure mechanisms were analyzed by non-contact image measurement. The results show that: hybrid structural failure is a combination of multiple failure modes, including compression fracture on the upper side of the fiber layer and tensile fracture on the lower side of the fiber layer, interlaminar failure of heterogeneous materials and plastic damage of metals; the interlaminar delamination is caused by the presence of matrix cracks and interlaminar shear stresses next to the interface, as well as incompatible stiffnesses between adjacent layers; the structural bending strength and bending modulus of elasticity of the samples increase with the increasing structural thickness in the experimental range; the stitching fibers introduced at the openings can inhibit the expansion of delamination cracks to a certain extent and improve the structural resistance to delamination.

Keywords

• metal additive manufacturing
• woven composite
• stitched joint
• hybrid structure
• mechanical property
• failure mechanism