Prediction on residual stresses of carbon/epoxy composite at cryogenic temperature

Abstract

In this article, the elastic modulus and coefficient of thermal expansion of bisphenol F epoxy resin from room temperature to cryogenic temperature (−180°C) were tested through a cryogenic environment test system. The elastic modulus of carbon/epoxy composite at room and cryogenic temperature was also tested. The measured temperature‐dependent material parameters are used as the input of a 3D micromechanical finite element model of fiber‐reinforced polymer matrix composite, considering random fiber distribution. The longitudinal and transversal elastic modulus of the carbon/epoxy composite is predicted by the present model, with good agreements between the predicted and experimental results. Then the residual stresses of carbon/epoxy composite due to cryogenic temperature are predicted by this model. It is found that high residual stress occurs in the matrix between two adjacent fibers. The longitudinal residual stress is compressive in fibers but tensile in matrix. The transversal stress in fibers is mainly compressive, and there is comparable transversal tensile and compressive stress in matrix. The maximum residual stress in the composite is the longitudinal tensile stress in matrix. This work can lay a foundation for the design and application of polymer–matrix composites in cryogenic environment. POLYM. COMPOS., 40:3412–3420, 2019. © 2019 Society of Plastics Engineers