MODEL FOR THE ANALYSIS OF INTRALAMINAR THERMAL STRESSES IN LAMINATED COMPOSITES MATERIALS

Abstract

When a structural element is manufactured with a laminated composite material (MCL) and this is subjected to temperature changes, intralaminar thermal stresses are generated. The intralaminar thermal stresses occur due to the differences among the coefficients of thermal expansion and the elastic properties of the layers that make up the MCL. It is possible that a combination of intralaminar stresses and mechanical stresses will produce faults by separation in the MCL layers (delamination). In this article we presents an analytical model with which global and intralaminar thermal stresses produced by temperature changes induced in symmetric metallic MLCs are calculated, without restrictions at the borders. The model is fed by deformation data obtained by strain gauges placed at the border of the MLC. The model can be used in the determination of intralaminar and global stresses considering restrictions or loads at the border, only if the problem is of flat stresses. The model was developed by making an analogy to the analytical model developed in [1], which consists of calculating intralaminar and global stresses that are generated by the difference between the elastic constants of the materials that make up an MCL subjected to simple tension. The proposed model is based on the theory of linear elasticity, the classical theory of plates and the principle of superposition. With the model and through an array of experimental tests, the coefficients of thermal expansion (CET) of each of the layers can be calculated. Finally, experimental validation tests were carried out which showed that the proposed model is reliable and consistent. Keywords: Thermal stress, intralaminar stress, Thermal Expansion Coefficient, Composite Materials.