光纤布拉格光栅监测复合材料固化

复合材料层合板在固化成型过程中形成的残余应变和应力是影响材料质量的重要因素,它与预浸料铺层在固化工艺过程中产生的应变密切相关。在研究和测试了光纤布拉格光栅应变和温度传感器传感特性的基础上,将二者埋入复合材料预浸料铺层,在热压釜成型工艺过程中监测了材料内部的温度和应变发展历程,由此获得对称正交层合板的宏观残余应变。监测结果表明,单向和对称正交层合板在固化结束后都将产生收缩,对称正交层合板铺层内的残余应变平行于纤维方向为压应变,垂直于纤维方向为拉应变。光纤光栅传感器为复合材料固化监测及层合板残余应力分析提供了一种新的工具,为实现复合材料从制造到服役的全寿命、一体化监测提供了可能。 

CURE MONITORING OF COMPOSITES USING FIBER BRAGG GRATING SENSORS

Residual strain and residual stress formed in cure process are two key factors that affect the quality of composite products, and both of them correlate closely with the process induced strain of pre-preg. In this paper,the fiber Bragg grating (FBG) sensors were calibrated and embedded in pre-preg to in-situ monitor the strain and temperature evolution of laminates during the cure process. Based on the strain measured with the FBG sensors, the macro residual strain of the cross-ply laminate was studied. The results show that both of unidirectional and cross-ply laminates will shrink in the course of cure. There is a negative residual strain in the longitudinal direction and a positive residual strain in the transverse direction of any ply of a cross-ply laminate. The FBG sensor can be used as a new tool to monitor the cure process and analyze the residual stress of composites, and makes it possible to monitor composite structures from manufacture stage to service stage continuously.