Experimental characterization of fracture of glass fiber reinforced composites laminates subjected to freeze‐thaw cycles

The simultaneous effect of moisture and freeze‐thaw cycle on the mechanical behavior of glass/epoxy composites laminates is experimentally investigated. The study is planned in order to simulate the detrimental presence of humidity due to rainfall in surface damage of composite structures operating in cold weather. Different mechanisms governing the monotonic response of specimens subjected to freeze‐thaw cycles are pointed out by taking advantages of SEM images. Comparing SEM images taken from dry and wet specimens shows that the failure mechanisms such as matrix cracking and delamination are vastly activated around the notched region when the material is exposed to humidity and freeze‐thaw cycle. The load‐displacement response of examined specimens, namely the linear response, is remarkably altered under these conditions. A reduction of approximately 40% in ultimate load and 30% in slope of tangent line of load‐displacement curves is identified after 100 cycles of freeze‐thaw as well as more than 20% decrease of strain energy release rate.