Effect of hygrothermal conditioning on compressive strength after impact in carbon fiber/epoxy composites

Carbon fiber-reinforced polymers have been widely applied in structural parts and components in several sectors, in addition to being constantly used in environments with the presence of humidity and high temperatures, which can affect their density, hardness, and rigidity. In this work, the influence of hydrothermal conditioning on carbon fiber (CF)/epoxy composites was investigated using three types of epoxy resin and two different CF fabric reinforcements, that is, plain weave and eight harness satin (8HS) arrangements. The CF/epoxy composites were subjected to compression after impact (CAI) test by 28 and 40 J energy and then exposed to hydrothermal conditioning for 8 weeks. After the CAI tests, the visual analysis of all composites presented microbuckling mechanisms. The composites tested with 40 J energy absorbed only 2% more moisture compared with the other composites, nonimpacted, and tested with 28 J, indicating that the impact damage did not cause delamination between the layers of the composites, which could facilitate the absorption of water. All composites analyzed showed resistance to CAI even after exposure to humidity, with decreases ranging from 2.8% to 23.8% about the unconditioned specimens. The decrease in CAI also shows the influence of the type of epoxy matrix and the arrangement of the CF in fabrics.