风电叶片复合材料拉伸损伤破坏声发射行为

Acoustic emission behavior on tensile failure of composite for wind turbine blades

通过风电叶片单向和多向复合材料拉伸力学性能实验,结合声发射技术,研究复合材料损伤演化特性及纤维预断缺陷对复合材料力学性能的影响。复合材料单向和加卸载拉伸实验时,采用声发射实时监测整个损伤破坏过程,获取复合材料试件的拉伸力学性能、损伤破坏特征及相应的声发射响应特征。结果表明:由于纤维预断缺陷的存在,单向复合材料加载到约30%破坏载荷时,缺陷位置及相邻区域的基体和界面开始出现明显损伤;加载到约60%破坏载荷时,含缺陷层和相邻的层出现明显的层间剪切破坏,导致刚度的急剧缩减,声发射撞击累积数明显高于无缺陷试件。含纤维预断多向复合材料加载到约60%破坏载荷时,纤维预断处树脂基体出现明显损伤;随相对应力水平的提高,多向复合材料的Felicity比下降较为平缓。

For the study of the damage evolution and the effect of fiber pre-broken on the mechanical properties of composites for wind turbine blades,unidirectional and loading-unloading tensile tests of unidirectional and multi-axial composite were conducted.In this experiment,real-time acoustic emission monitoring was used,and tensile mechanical properties,damage failure characteristics and the corresponding acoustic emission response characteristics were obtained.The results show that because of the presence of fiber pre-broken,the damage of matrix and interface in the defect location and the adjacent region of unidirectional composites appears obviously when the load reaches to about 30% of the failure load.As the load increases to about 60%,interlaminar shear failure between defects layer and adjacent layers are induced,leading to a sharp reduction in stiffness,the acoustic emission cumulative hits are significantly higher than that of the defect-free ones.As the load reaches to about 60% of the failure load,the obvious damage of matrix resin in fiber pre-broken region occurs in the case of multi-axial composite with fiber pre-broken.As the relative stress level increases,the Felicity ratio of multi-axial composite gradually decreases.