Temperature and structure effects on the impact damage distribution of 3D braided composites

Abstract

Three-dimensional braided composite materials are prepared by fiber bundle braiding and composite material forming. These materials can realize the integration of material structure to manufacture complex structural parts in a near net-shape way and reduce the number of assembly connections. This material has been widely used in the aerospace industry, high-speed vehicles, and important civil facilities. Computed tomography (CT) and finite element method (FEM) were used to characterize the relationship between the internal damage distribution of 3D braided carbon fiber/epoxy resin composites under multiple transverse impact loading, ambient temperature, and microstructure. It is determined that with an increase in the temperature, the failure mode of resin changes from brittle failure to ductile failure, the interface bond strength decreases, and the failure mode changes to fiber/resin interface cracking and resin debonding. With an increase in the braiding angle, the failure mode changes from interface cracking to resin debonding cracking; interface cracking simultaneously occurs, impact tolerance increases, and local temperature increases with an increase in the absorbed energy. With an increase in the number of impacts, the accumulation of impact damage leads to the clear cumulative effect of reinforcement deformation, interface cracking, and resin debonding.