单向陶瓷基复合材料单轴拉伸强度研究

采用细观力学方法对单向纤维增强陶瓷基复合材料单轴拉伸强度进行研究.采用剪滞模型描述复合材料出现损伤后的细观应力场,结合基体随机开裂模型、断裂力学界面脱黏准则确定基体裂纹间距及界面脱黏长度.当基体裂纹达到饱和后,假设纤维强度服从威布尔分布,完好纤维和断裂纤维承载满足总体载荷承担法则,采用纤维随机失效模型确定继续加载过程中纤维断裂概率及断裂位置,当纤维承载达到最大时,复合材料失效.讨论了基体威布尔模量和特征强度、纤维/基体界面剪应力和界面脱黏能、纤维威布尔模量和特征强度对纤维失效,进而对复合材料拉伸失效强度的影响.与试验数据对比表明:提出的模型是有效的. 

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.