碳纤维三维编织复合材料横向变形损伤声发射监测

ACOUSTIC EMISSION MONITORING OF TRANSVERSE DEFORMATION AND DAMAGE OF CARBON FIBER 3D BRAIDED COMPOSITES

利用声发射(Acoustic Emission,简称"AE")技术和数字图像相关(Digital Image Correlation,简称"DIC")方法,结合破坏断口形貌,研究三维五向编织复合材料横向拉伸状态下的变形与损伤规律,分析横向拉伸力学响应、表层变形场及声发射信号特征。结果表明:三维五向编织复合材料的横向拉伸极限载荷较小,力学曲线分线性和非线性两个阶段,破坏曲线为非线性,与横向拉伸破坏机理有关。撞击累计数的递增趋势能较好地反映材料的损伤演化过程。三维编织复合材料横向拉伸破坏断口沿纤维编织方向呈非平齐状,失效模式主要为基体开裂和纤维脱粘以及少量的纤维断裂。表面全场信息很好地反映了材料横向拉伸损伤演化特征,为三维编织复合材料结构健康监测提供了依据。

Combine with the fracture morphology,Acoustic Emission(AE)technology and Digital Image Correlation(DIC)method were used to study the law of deformation and damage of three-dimensional(3 D)five-directional braided composites under transverse tensile condition.Transverse tensile mechanical response,AE characteristic parameters and deformation field information were analyzed.The results show that the limit load for 3 D five-directional braided composites under transverse tensile condition is relatively low and the mechanical curve is divided into two phases including linear and nonlinear phases.The failure curve is nonlinear and related to the failure mechanism of transverse tension.The increasing trend of the cumulative counts can reflect the damage evolution process of transverse tension better.The transverse tensile fracture of 3 D braided composites is not flush along the direction of fiber braiding and the failure modes are mainly matrix cracking,fiber deboning and few fiber fracture.The surface full-field information in the process of transverse tension reflects the damage evolution characteristics of the materials and provides basis for the structural health monitoring of 3 D braided composites.