On the Tensile Deformation Behavior of M55JB Carbon Fiber/Microdroplet Based on Micro-Raman Spectroscopy
微拉曼光谱研究M55JB碳纤维/微滴的拉伸变形行为

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.