On the effects of temperature on tensile behavior of carbon fiber reinforced epoxy laminates

As a highly promising lightweight material, carbon fiber reinforced plastics (CFRP) composites have been widely used in aerospace, marine and automotive industries, which could expose to low or high thermal environments with varying material properties. This study investigated the effects of temperature variation ranging from −30 °C to 160 °C on tensile properties of CFRP experimentally and theoretically. The specimens were prepared using thermo-forming technology; and the glass transition temperatures of epoxy resins were measured by dynamic mechanical analysis (DMA). Digital image correlation (DIC) technique was used to capture the variation in strain and damage fields. By means of scanning electron microscopy (SEM), the failure mechanisms, delamination and resin softening, were identified by scrutinizing the images of fracture areas subject to different temperatures. The two-parameter Weibull analysis was conducted to evaluate the theoretical tensile strengths from relatively discrete data. The obtained Weibull parameters are considered useful for the reliability analysis of CFRP structures. It is found that the tensile strength decreases with the increase of temperature in a nonlinear fashion, which can be modeled in terms of a tanh function by correlating with the temperature-dependent experimental data. The study is anticipated to provide fundamental understanding and a predictive tool for mechanical strength of composite structures operating under different thermal conditions