Study On The Interface Property Of The Fiber/epoxy Composites

As one of the critical and competing materials in national economy and defense, fiber reinforced polymer composite has been most developed and widely used. Based on the investigation of the effects of the formation process, the characteristic, adhesion and stress transfer of interface on its macroscopical mechanical properties and accurate characterization of the adhering conditions between the reinforcement and matrix, it is possible to achieve effective control of interface, which is the key to obtain high quality composite. In this paper, single fiber composite fragment (SFC) method, which is one of the most widespread and effective experimental methods for determining the mechanical properties of interface, was adopted to study the load transfer mechanism and to evaluate the adhesion performance of composite with surface-treated fibers. This is helpful for optimization design of interface.First, the one-dimension load transfer model presented by Cox was studied in details. Based on the ideal interface bonding load transfer model, a fibre fracture criterion and an interface debonding criterion were established in terms of fracture mechanics, which bettered the interphase load transfer model. This model could also describe the process of single-fiber composites fragmentation.In addition, a new analytical method was used to solve the shear strength of the fiber/epoxy interface. The result showed good agreement with that from the Kelly-Tyson equation. Meanwhile, according to the SFC tests of the single fiber reinforced epoxy matrix composites treated by four types of surface treatments, the interfacial adhesion conditions were estimated by critical fiber length, interfacial shear strength and single fiber microdamge mode.As a bridge to composites, the study on interface including the establishment of load transfer model, shearing strength and breakage pattern provides theoretic foundation for the interface optimization design and enhancement of composites properties. Moreover, it also plays an important role in promoting the wide application of composites.