Interlaminar fracture characterization of woven glass/epoxy composites under mixed-mode II/III loading conditions at cryogenic temperatures

This paper presents a study of the delamination fracture behavior of woven glass fiber reinforced polymer (GFRP) composite laminates under combined Modes II and III loading at cryogenic temperatures. Mixed-mode II/III delamination fracture tests were carried out with six-point bending plate (6PBP) specimens at room temperature, liquid nitrogen temperature (77 K) and liquid helium temperature (4 K). A three-dimensional finite element analysis was also performed to determine the critical energy release rate at the onset of delamination growth, i.e., fracture toughness, and the dependence of the fracture toughness on the temperature and the mixed-mode II/III ratio was discussed. In addition, scanning electron microscopic observations of the fracture surfaces were conducted to examine the cryogenic fracture mechanisms in the woven GFRP laminates under mixed-mode II/III conditions.

► We studied the cryogenic mixed-mode II/III delamination fracture of woven laminates.
► The fracture toughnesses at 77 K and 4 K are higher than that at room temperature.
► The fracture toughness increases with an increasing component of Mode III loading.
► The fracture surfaces are characterized by the presence of fiber/matrix debonding.
► The inclined hackles are signs of the mixed-mode II/III delamination fracture.