Fatigue delamination growth in woven glass/epoxy composite laminates under mixed-mode II/III loading conditions at cryogenic temperatures

• We studied the cryogenic mixed-mode II/III fatigue delamination growth in woven laminates.
• The resistance to fatigue delamination growth at cryogenic temperatures is higher than that at room temperature.
• The fracture surfaces show the presence of matrix hackles.
• The inclined hackles are identified with the mixed-mode II/III delamination growth.

We investigate the cryogenic delamination growth behavior in woven glass fiber reinforced polymer (GFRP) composite laminates under mixed-mode II/III fatigue loading. Fatigue delamination tests were conducted with six-point bending plate (6PBP) specimens at room temperature, liquid nitrogen temperature (77 K) and liquid helium temperature (4 K), and the delamination growth rate data for various mixed-mode ratios of Modes II and III were obtained. The energy release rate was evaluated using the three-dimensional finite element method. In addition, the fatigue delamination growth mechanisms were characterized by scanning electron microscopic observations of the specimen fracture surfaces.