Transverse elastic moduli of unidirectional fiber composites with interfacial debonding

Abstract

A mathematical model is developed to predict the transverse elastic moduli of unidirectional fiber composites. Two cases of fiber/matrix interfacial bondings are investigated: perfect bonding and complete debonding,i.e., no transferring of tensile stress on surfaces where the fiber and matrix materials are separated. Fibers are assumed to exhibit transverse isotropy, and the elastic interactions among fibers are also considered. In the analysis of the completely debonded case, the cavity formation model is adopted and the original fiber and surrounding cavities are replaced by an imaginary anisotropic inclusion. Closed form solutions of effective elastic moduli are obtained for transverse tensile and compressive moduli, and transverse shear moduli. The limiting case of fiber-like voids is also studied. Numerical results are presented for two metal matrix composites, where the optimal wetting between the fiber and matrix is difficult to be obtained and hence the interfacial bonding and transverse property have been major concerns.