Failure Mode Analysis Of Carbon Fiber Reinforced Epoxy Resin Matrix Composites

The damage of carbon fiber reinforced epoxy resin matrix composites(CFRP)is different from that of metal and ceramic,and the failure mode of CFRP is more complicated due to the multiphase structure of fiber and resin.Any kind of damage,such as fiber fracture,resin matrix cracking and delamination,will lead to the failure of CFRP,so there are many factors affecting its failure mode.In addition,how to accurately obtain the effective failure mode of CFRP and achieve accurate evaluation of mechanical properties of composite materials is also an important research content,so it is necessary to conduct a comprehensive study on the failure mechanism of CFRP.In this paper,the effects of resin matrix properties,fiber types,test standards and sic whisker on failure modes of CFRP are studied.(1)Three kinds of epoxy resin systems,E306,E307 and E308,were prepared.The gel temperature,viscosity-temperature characteristics,curing process and basic mechanical properties of the three resin systems were studied.(2)Using T800S carbon fiber as reinforcement and using three resin systems(E306,E307,E308)as matrix resin,CFRP laminates were prepared by molding method.The mechanical properties and failure mechanism of three resin CFRP laminates under different loading conditions were investigated.The results show that proper fiber pull-out and delamination can improve the impact strength of CFRP,but large area delamination can significantly reduce the residual strength of laminates after low speed impact.Resin properties can affect the bending failure mode of CFRP,and improving the compressive strength and modulus of matrix can alleviate the local concentrated compressive stress and interfacial shear stress,and achieve cooperative fracture.(3)Three kinds of CFRP laminates were fabricated by molding method using Toray T700 S,T1100G and M55 J carbon fibers respectively.The flexural properties of three kinds of CFRP laminates were investigated,and the three-point bending failure modes of CFRP laminates under different test standards were studied.The results show that the bond degree of fiber and resin affects the bending strength and failure mode of CFRP,and the poor bond leads to the failure of the laminate due to delamination.The span thickness ratio of CFRP has significant influence on the bending failure mode of CFRP.The failure mode of the same CFRP under different span thickness ratio is different,and the failure mode of different CFRP under the same span thickness ratio is different.The failure mode determines whether the test results are valid or not(4)The effect of sic whisker on the mechanical behavior of E307 resin and E307/T1100 CFRP was investigated.The results show that the addition of sic whisker increases the bending modulus of resin casting,and decreases the bending strength and impact strength of E307 resin casting.The sic whisker did not significantly improve the bending strength and modulus of CFRP laminates...