Effect of porosity on the hygrothermal behaviour of carbon fiber reinforced epoxy composite laminates

The effect of void content on the moisture absorption and interlaminar shear strength (ILSS) of (±45) ₄/(0,90) /(±45)_2S and (±45) /(0, 90)₂/(±45) _S carbon fiber reinforced epoxy composite laminates used in a aircraf twas studied. The carbon fiber/epoxy laminates with different void volume fractions were prepared by applying different curing pressures. The microstructure characteristics of voids were studied using optical image analysis.The results show that the voids mainly locate between the plies and grow with the increasing void content. The rate of water uptake and the maximum level of moisture absorption in the two carbon/epoxy composite laminates increase with the increasing void content. The ILSS of aged and unaged laminates decrease with the increasing void content.The ILSS of unaged and aged (±45) ₄/(0,90) /(±45)_2S laminates with the void volume fractions 0.6 %～6.3 % and 0.4 %～7.0 % decrease 6 % and 9 %, respectively. The ILSS of unaged and aged  (±45) /(0, 90)₂/(±45) _S laminates with the void volume fractions 0.4 %～6.9 % and 0.2 %～8.9 % decrease 14 % and 7 %, respectively.