Effect of Thermal Deformation and Chemical Shrinkage on the Process Induced Distortion of Carbon/Epoxy Curved Laminates

Abstract

Effect of anisotropy of the thermal expansion and the chemical shrinkage of epoxy on the process induced distortion of carbon/epoxy composite stiffener structures was investigated and analyzed. The coefficients of thermal expansion (CTE) and elastic properties in the material principal directions were characterized for temperature variation. By applying the characterized properties to the classical lamination theory, the change of CTE of general laminates was calculated for the temperature variation. A computational method to predict the distortion of curved laminate due to the difference of CTE and the chemical shrinkage of epoxy resin was proposed. The spring-forward angles of L-section laminates of various angle plies were measured and compared with those predicted. The predicted values from the thermal and the chemical shrinkage analysis show that the difference of CTE and the chemical shrinkage strain are the major sources of the process induced deformation of curved section laminates.