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. This 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 paper 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 gages 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 experimental validation tests, the 
coefficients of thermal expansion (CET) of each of the layers 
can be calculated. This tests showed that the proposed model is 
reliable and consistent.