Evaluation of stress transfer mechanism in single fiber pull-out test by numerical analysis
Nishiyabu Kazuaki; Yokoyama Atsushi; Zako Masaru
Abstract:The general aim of this study is to establish the modeling technique of interphase, which is the interfacial region between fiber and matrix, and to investigate the effects of interphase properties on the stress transfer mechanism and the fracture behavior in single fiber pull-out test. The finite element analytical model, which was divided independently with each element of fiber, matrix and interphase, has been applied. The interphase was assumed as orthotropy, because it can be dealt with the stress transfer and the stress bearing separately. The influence of interfacial shear stiffness on stress transmissibility was evaluated by the stress transferred from fiber to matrix by passing through the interphase. Also the effects of thermal stress which occurred at post curing of resin, and meniscus which formed at the edge between fiber and matrix surface were investigated by FEM. From the analytical results, the following points were obtained; (1) the interphase shearing modulus strongly affected the interfacial stress transmissibility, (2) the degree of stress concentration occurring at matrix surface was varied by interphase shear modulus, meniscus size and thermal stress, (3) the meniscus size largely affects both a success of pull-out testing and an appearance of the interfacial properties. Key Words:finite element method, composite interphase, pull-out test, stress transfer, meniscus, thermal stress