Void content and interfacial properties of composite laminates under different autoclave cure pressure

With an identical temperature profile, various cure pressures were applied to determine the effect of cure pressure on void distribution and interlaminar shear strength (ILSS) of [0]10 T800/X850 composite laminate. Void shape, distribution, and void content within the composite laminates were characterized using optical microscope. The ILSS was evaluated using short-beam three-point bending tests and their interface debonding failure and fracture surfaces were determined using scanning electron microscope. The experimental results indicated that long strips voids are generated in the low-pressure curing stage. The voids mainly exist in the two forms of rod-like shape and spherical shape, and their number and size decrease as the cure pressure increases. The influence of cure pressure on the void content and ILSS shows a different trend in two stages: when the cure pressure is lower than 0.4 MPa, the ILSS decrease by 5.21% with 1% increase in void content, and their relationship is inversely linear. However, when the cure pressure is higher than 0.4 MPa, the void content is less than 1% and ILSS increase slightly by 1.69% when the cure pressure goes from 0.4 to 0.6 MPa, the influence of cure pressure on void content and ILSS is clearly presented.