Factors controlling the transverse tensile properties of unidirectional SiC/Ti-6AI-4V

A parametric study is carried out to investigate various factors that influence the transverse properties of unidirectional SiC/Ti. Interface debonding is the beginning of material failure. It is important because a composite with debonded interfaces is no longer integral and it will be weakened. An interface failure criterion is developed. Selected models are analysed to investigate possible effects on interface failure initiation. The main considerations are the interfacial residual stresses and the stress concentration factors for the applied transverse load. Residual stresses are beneficial for transverse loading because they tend to delay interface debonding. The residual stress distribution is discussed. Increasing the interface strength improves the transverse properties. Decreasing fibre volume fraction by keeping the same fibre spacing and increasing the ply thickness yields higher stress and strain to interface failure. When the volume fraction is kept constant, the closer the fibres are placed, the higher the interface failure stress and strain. With the same model geometry, the interface debonds slightly earlier with rectangular fibre packing than with staggered packing. In most cases, the matrix material is elastic before interface failure initiates. The non-linear stress-strain behaviour is mainly due to interface debonding.