Effects of fiber type (CF and ALF) and temperature (RT and 77K) on interlaminar fracture properties of composite laminates with common epoxy matrix

摘要

Mode Ⅰ and Ⅱ interlaminar fracture toughness and delamination fatigue crack growth behavior were investigated with unidirectional carbon fiber (CF)/epoxy and alumina fiber (ALF)/epoxy laminates. Here, the same epoxy matrix was used to investigate the fiber effect only. The tests were carried out at room temperature (RT) and 77K. Though, the mode Ⅰ fracture toughness values of ALF/epoxy at 77K were 1.7 -1.8 times higher than those at RT, the mode Ⅰ fracture toughness values of CF/epoxy at 77K were only 1.2 -1.3 times higher. The mode Ⅱ fracture toughness values of both CF and ALF/epoxy laminates were insensitive to the test temperature. The mode Ⅰ fatigue threshold values of both CF and ALF/epoxy laminates at 77K were 3 to 4 times higher than those at RT. However, the mode Ⅱ fatigue threshold values were insensitive to the test temperature under the higher stress ratio. The ratios of the fracture toughness and fatigue threshold values of ALF/epoxy to those of CF/epoxy were about two for all experimental conditions. The mechanism of the fiber and temperature effects were discussed from the mesoscopic view points.