Qualitative separation of the effect of voids on the static mechanical properties of hygrothermally conditioned carbon/epoxy composites

The paper investigates the effect of voids and hygrothermal conditions on bending, compressive, and interlaminar shear strength (ILSS) of T300/914 composite laminates. By adopting different autoclave pressures during a cure cycle, specimens with three different void contents ranging from 0.33% to 1.50% were obtained. Experimental results reveal that compressive, bending strength, and ILSS decrease with increasing void contents and immersion time. The most significant decrease in strength of aged specimens is in the ILSS and compressive strength, followed by the bending strength. The effect of voids on the absorption/desorption behavior is also discussed. For a similar porosity, the compressive strength and ILSS of dried specimens are higher than that of the aged specimens, while they are lower than that of the unaged specimens. The bending strength of the dried specimens is higher than that of the unaged specimens. The experimental results are explained by the supportive micrographs that illustrate different types of voids and their morphology before and after moisture absorption/desorption.