微拉曼光谱研究M55JB碳纤维/微滴的拉伸变形行为

使用评价纤维/基体界面力学性能的新方法纤维微滴拉伸测试,来研究M55JB碳纤维/环氧树脂基体之间的界面应力传递性能。使用自制的微加载装置对碳纤维/环氧树脂微滴试样进行对称式拉伸测试,用微拉曼光谱仪记录下不同应变下的嵌入微滴内纤维上的拉曼频移信号,经过应力/频移关系转换成纤维轴向应力。实验结果显示,微滴内纤维轴向应力随载荷而明显增加。根据界面力平衡模型得到相应的界面剪切应力呈反对称式分布,在纤维嵌入端存在剪应力集中。新测试方法能保证嵌入微滴内纤维上的应力呈对称式分布,而且能降低纤维嵌入端附近的应力奇异性。

On the Tensile Deformation Behavior of M55JB Carbon Fiber/Microdroplet Based on Micro-Raman Spectroscopy

A new method for evaluating mechanical properties of interface between fiber and matrix -fiber/microdroplet tensile test-was adopted to study interfacial stress transfer behavior of M55JB carbon fiber/epoxy matrix. Symmetric tensile tests for M55JB carbon fiber/epoxy microdroplet specimen were performed by using a home-made micro-loading device. Raman frequency shift signal from the microdroplet embedded in fiber were recorded by micro-Raman spectroscopy under different strain levels. Then, fiber axial stress can be obtained by a relationship between the stress or strain and G' Raman peak shift of carbon fiber. Experimental results reveal that the fiber axial stress increases significantly with the load increase. The interfacial shear stress was obtained from a force balance model, which presents an antisymmetric distribution. Shear stress concentration occurs at the fiber end where the microdroplet is embbeded. The new testing method ensures a symmetric stress distribution of microdroplet embedded fiber and reduces the stress singularity often occurred at the embedded end of fiber.