拉伸载荷下碳纤维复合材料T型接头脱粘特性与FBG监测分析

Debonding characteristics and FBG monitoring analysis of CFRP T-joints under tensile load

研究了拉伸载荷下碳纤维复合材料(CFRP)T型接头的界面脱粘与裂纹扩展过程。对拉伸载荷下T型接头破坏过程进行数值模拟;在模拟敏感区域布置光纤布拉格光栅(FBG),实时监测界面脱粘的产生及扩展应变特征;使用高速摄像机,捕捉脱粘及裂纹扩展的图像数据。结果表明:T型接头的三角填料区首先出现损伤,裂纹向两个方向扩展。水平方向:向L型层与一型层之间的胶层扩展;竖直方向:向两个L型层之间的胶层扩展。裂纹扩展最终引起结构失效。光纤布拉格光栅中心波长的变化能够在非视觉条件下记录损伤的出现、积累与扩展,可正确预警结构内部损伤的产生,还原裂纹扩展路径。

This article studies the debond and crack propagation of carbon fiber reinforced plastic （CFRP） T-joints under tensile load. The numerical model for the T-joints provided the sensitive areas on which fiber Bragg grating （FBG） sensors could be fixed. FBG sensors along with a high speed camera were used to monitor the appearance and propagation of debond. The results show that the damage initiates at the T-joints filling area. The cracks propagate along two directions： the horizontal direction, i. e. , the glue layers between the L prepreg and the skin and the vertical direction, i. e. , the glue layers between two L prepregs. The propagation of cracks ultimately causes the struc- ture failure. The changes of the FBG central wavelengths succeed in recording the appearance, accumulation and propagation of damage under non-visual conditions, which can help alarm the inner damage of the structure and indicate the crack propagation paths.