Preparation and high temperature load-carrying performance of polyimide composites with embedded defects

Polyimide composites with embedded defects were successfully prepared by inclusion-embedding method with autoclave molding. By testing and simulation, the influence of defects was investigated on the static strength and fatigue performance of the equal-thickness open-small-hole typical part and the varied-thickness open-large-hole typical part at a high temperature. The high temperature static and fatigue residual strengths of the equal-thickness open-small-hole typical part remain above 92% when a Z=60 mm (Z represents half of the sum of the long axis and short axis dimensions of the defect) defect is embedded. There is no explicit influence of a Z=125 mm defect on the fatigue residual strength of the varied-thickness open-large-hole typical part at high temperature. The load-carrying capacity of this composite is more sensitive to the defects near its edge. This study may provide a basis for evaluating the defect allowance and optimizing the internal quality inspection standard for polyimide composites.