Research of Composite Fracture Mechanism Based on Acoustic Emission and Representative Volume Element Model

In this paper, acoustic emission (AE) technology is applied to monitor the damage of carbon/epoxy composite during its tensile experiment. To understand the experiment result, representative volume element is taken to form the micromechanics model for the composite. With the analysis of experiment result and micromechanics model, the composite fracture mechanism is discussed. The results show that the damage course of carbon/epoxy composite can be divided into three stages: elastic deformation stage, damage developing and accumulating stage, the stage of critical fracture nearing. During the first stage, there is little damage accruing. In the second stage, the damage come form the fracture of epoxy and interface, with the tendency of increasing at first, then decreasing quickly after it reaches the peak value. During the last stage, the damage seems to be somewhat calm but in fact at this time the carbon fibers begin to damage and fracture. This damage predicts the critical fracture would come, because final fracture occur short time after that damage.