Developing of a New Eigen-strain Based Method for Estimation of Macro Residual Stresses of Laminated Polymeric Composites under Curing Cycles

The major source of residual stresses in laminated polymeric composites is the mismatch of mechanical and thermal properties of different layers. This kind of stresses is known as macro-stresses. In the present study, a new method for calculation of macro residual stresses has been proposed by using the eigen-strain concept. The new proposed method depends on technical implementations of the incremental hole drilling and slitting methods. In the first step, a relation between the eigen-strain distribution and released elastic strains was introduced. Then, experimental hole drilling and slitting tests of a specified glass/epoxy cross-ply by a stacking sequence of [04/904]s were performed. After that, the eigen-strain based (ESB) method is applied and the thermal strain field was obtained by utilizing of finite element (FE) simulations. Finally, the predicted residual stress field has been compared with the stresses estimated by the classical laminated plate theory (CLPT). The results showed a good agreement of the present method and the CLPT.