Temperature Dependence of Accumulation of Fiber Breakages under Tensile Loading for Unidirectional CFRP Laminates

The temperature dependence of the tensile damage process as well as the tensile strength in unidirectional carbon fiber-reinforced plastic (CFRP) laminates is investigated experimentally and numerically. The constant strain rate (CSR) tensile tests for CFRP laminates are carried out at room temperature (RT) and 120°C. The damage process under tensile loading is recorded by using a digital microscope to comprehend the accumulation of fiber breakages observed with increasing strain. The fiber breakages observed under tensile loading increase strongly in the vicinity of ultimate failure load, and this behavior decreases with increasing temperature. The clusters of fiber breakages observed at RT cannot be observed at 120°C. These experimental results lead to the fact that the number of fiber breakages and the existence of cluster of fiber breakages are influenced by the temperature dependent stress-strain relation of matrix resin. Then, a new simulation based on finite element model considering the stress-strain relation of matrix resin is proposed. The damage process and strength predicted numerically by the proposed simulation agree well with experimental results. Therefore, the temperature dependent mechanism for the damage process, including the generation of clusters as well as the strength, is quantitatively shown.