Rapid high temperature loads on dry and moist carbon fibre epoxy composite materials

Carbon-fibre epoxy panels have been subjected to rapid high temperature loads. The effects of temperature, exposure time and moisture content of the panels have been studied. It could be demonstrated that the combination of high moisture content and rapid heating can lead to excessive damage, such as sudden formation of delaminations up to the development of large bubbles on the panel. While it is well known that matrix and fibre–matrix interface strength generally decrease both with water uptake and temperature increase, a more severe damage mechanism has been observed here. The combination of high moisture content and rapid high temperature loads leads to an internal vapour pressure overload that can cause extensive cracks and delaminations. Subsequently, this permanent damage leads to serious changes in mechanical properties. Whereas heating dry panels to 350℃ for 1 h and testing them at room temperature reduced interlaminar shear strength less than 25%, many of the moist panels were fully destroyed within the first minute of heating.