Study on uniaxial tensile strength of unidirectional ceramic matrix composites

A study on uniaxial tensile strength of the unidirectional ceramic matrix composites was presented in this paper using micromechanical approach.The shear lag model was used to obtain the micro stress field of the damaged composites.The statistical matrix cracking model and fracture mechanics interface debonding criterion were used to determine matrix crack spacing and interface debonding length.After the saturation of matrix cracking,the fiber failure probabilities and fracture locations during tensile loading were determined by fiber statistical failure model based on the assumption that fiber strength is subject to Weibull distribution,and the loads carried by the broken and intact fibers meet the global load shearing criterion.The composites can no longer support the applied load when the total force supported by broken and intact fibers reaches its maximum.The effects of matrix Weibull modulus and characteristic strength,fiber/matrix interface shear stress and interface debonding energy,fiber Weibull modulus and characteristic strength on fiber failure and the tensile strength of ceramic matrix composites were discussed.The predicted results agree well with experimental data,proving the efficiency of the present model.