A. Arrese

Analysis of Thermal Stresses in Unsymmetric Cross-ply Composite Strips

An approach based on the hypotheses of the classical beam theory for determining thermal stresses in unsymmetric cross-ply strips has been developed. The material behavior is considered linear elastic, and viscoelastic effects are not considered. By supposing linear strain distribution in the cross-sections, the position of the neutral axis, the radius of curvature and the distribution of thermal stresses have been determined. The analysis is valid in the case of large displacements, since the curvature is constant and the deformed shape is an arc of circumference. Five different lay-up configurations of strip geometry specimens have been used for experimental verification. Mid-point deflections have been measured and compared with theoretical values, applying both the proposed approach and the classical laminated plates theory.

Analysis of In-plane and Out-of-plane Thermo-mechanical Stresses in Un-symmetric Cross-ply Curved Laminated Strips

A new approach for determining in-plane and out-of-plane stresses due to thermal and mechanical loading, in un-symmetric [0n/90 m] cross-ply curved laminated strips is presented in this work. This approach can also be applicable to bi-modulus curved laminated strips. Predictions of curvatures, displacements, and stresses based on the superposition principle are carried out. In-plane stresses are calculated considering classical beam theory. In addition, out-of-plane stresses are predicted by using the Airy’s stress function in polar coordinates. The new approach satisfies the continuity conditions at the interface between 0° and 90° layers. Results show that in-plane and out-of-plane stresses are particularly sensitive to the thickness ratio and to geometric conditions. Finally, thermo-mechanical predictions have revealed that out-of-plane stresses are much lesser than in-plane stresses for initially flat laminates. For laminates with high imposed curvatures out-of-plane stresses are high, leading to delamination failure.