高强高模聚酰亚胺纤维/环氧树脂复合材料力学性能与破坏机制

以高强高模聚酰亚胺（PI）纤维为增强体，以航空级环氧树脂（EP）为基体，通过热熔法制备预浸料并采用热压罐成型技术制备了PI/EP复合材料层合板，对其力学性能和破坏形貌进行了分析。结果表明:高强高模PI纤维与EP具有良好的界面结合力，PI/EP复合材料的层间剪切强度为65.2 MPa，面内剪切强度为68.6 MPa；良好的界面结合状态能充分发挥PI纤维优异的力学性能，PI/EP复合材料的纵向拉伸强度达1 835 MPa，弯曲强度为834 MPa；PI/EP复合材料纵向拉伸破坏模式为散丝爆炸破坏，同时由于高强高模PI纤维还具有优异的韧性和较高的断裂伸长率，PI/EP复合材料从受力到失效断裂的时间较长；PI/EP复合材料纵向压缩破坏模式为45°折曲带破坏。高强高模PI/EP复合材料为航空航天先进复合材料增加了一个全新的选材方案。 

Mechanical properties and failure mechanism of high strength and high modulus polyimide fiber/epoxy composites

The polyimide fiber/epoxy (PI/EP) composite laminates were prepared by hot-melt method combined with autoclave molding technology using high strength and high modulus PI fiber as reinforcement and aviation grade EP as matrix. The mechanical properties and failure morphology of the PI/EP composites were analyzed. The results show that PI fiber exhibits good interfacial bonding strength with epoxy resin. The interlaminar shear strength of the PI/EP composites is 65.2 MPa and the in-plane shear strength is 68.6 MPa; The PI/EP composites possess excellent mechanical properties because of good interface bonding integration condition, the longitudinal tensile strength is up to 1 835 MPa and the flexural strength is 834 MPa. The longitudinal tensile failure form of the PI/EP composites is explosion damage of filament. The high strength and high modulus PI fiber has excellent toughness and high elongation, so the time of failure becomes longer when the PI/EP composites are subjected to great tensile stress. The longitudinal compression failure form is 45° kinking band. The high strength and high modulus PI/EP composites provides a new material selection scheme for advanced aerospace composites.