纤维方位角对玻纤复合材料破坏机理的影响研究

利用扫描电子显微镜（SEM）对不同纤维方位角的玻纤增强树脂复合材料（GFRP）在单拉载荷下的破坏过程进行了实时观测．在桥联模型基础上，将纤维剪应力和基体正应力定义为界面的应力状态，对概化的GFRP材料单元进行了定量分析，得到了单拉载荷下纤维体积分数为27．5％的单元起裂时的应力状态，并通过最大应力强度准则确定了导致起裂的应力分量．综合SEM图片中裂纹形态和断口形貌，分析了不同纤维方位角的GFRP材料裂纹萌生和裂纹扩展的机理．分析结果表明，随着纤维方位角增大，导致GFRP材料裂纹萌生的应力分量由基体最大主应力演化为界面剪应力；裂纹扩展路径由最大主应力控制的基体开裂演化为最大剪应力控制的界面开裂．

Influence of fibers＇ orientation angle on failure mechanism of glass fiber reinforced polymer composites

A scanning electron microscope （SEM） is employed to carry out an in-situ investigation of crack growth in unidirectional glass fiber-reinforced polymer （GFRP） composites under the different orientation angle of fibers. Defining the shear stress on fiber and the normal stress on matrix as a stress state of interface between matrix and fibers, the failure-induced stress components of generalized elements with 27.5% fibers in volume fraction are estimated analytically on the basis of the bridging model. Moreover, combining the crack propagation path with the fracture morphology in SEM photos, the mechanism of crack generation and crack propagation of GFRP material with different orientations of fibers are analyzed comprehensively. The results of analysis show that, with increasing of fiber orientation, the stress components caused crack generation of material develop from the maximum normal stress of matrix into the shear stress of interface. The propagation path of crack evolves from cracking of matrix controlled by the maximum normal stress of matrix into cracking of interface controlled by the shear stress of interface.