埋入式光纤传感器界面剪切强度实验

Test Attempt to Shear Strength of in Terface for Embedded Optical Fiber Sensors

采用实验方法对光纤与基体间界面性能进行研究。用临界断裂长度法直接测定界面的剪切强度,由于光纤拉伸强度高于树脂基的拉伸强度,出现试验时基体破坏而光纤完整地从树脂基中拔脱的现象。用单丝拔出法测量光纤与基体之间界面剪切强度,试验结果表明,光纤单丝拔出时,总是出现光纤涂层在锚入端断裂,而纤芯从涂层中拔脱的现象,说明当光纤埋入复合材料中,涂层和基体材料结合为一体,光纤涂层与纤芯之间界面剪切强度最低。承载时,若光纤所受正应力超过σmax,会出现光纤涂层与纤芯之间界面脱离,产生裂纹,降低整体结构力学性能。

In some occasions, optical sensors are embedded in structures for monitoring. When sensors are embedded, the interfaces which obviously affect the characters of the intelligent structures. Micro-experimental tests, such as fragmentation test and single fiber pull-out test, are conducted to investigate the interface shear strength between optical fiber and the whole structure, but the fragmentation test can not bring about useful interface information. The single fiber pull-out test reveals that the interface shear strength between the coating and the clad gets the weakest. For the embedded fiber into resin, the coating is usually broken near the end point, and the clad is pulled out from the coating. The shear strength is less than 0.8 MPa. The ultimate normal stress σmax acting on the optical fiber can be determined based on equilibrium concept. Once the fiber is overloaded, flaws appear between the coating and the clad of the optical fiber.