A Parametric Study of Laminated Composite Shells with Environmental Effects, Using a Higher-Order FE Model

In this study a higher-order shear deformable, analytical model is developed to analyze composite shells with parametric modeling capabilities. The material and geometric properties and loading conditions can be varied as parameters which satisfy a set of constraints to allow the designer to achieve a sensible and computationally feasible FE model. The formulation is derived with equal emphasis on all the six strain as well as stress components at a generic point in the shell laminate. Unlike many other available models which violates the equilibrium conditions at lamina interfaces, this model satisfies the equilibrium conditions at the lamina interfaces for a certain class (angle-ply and unidirectional orthotropic) of laminates. This model also can calculate the through-thickness stress distribution very accurately, thereby allowing the design or material processing engineer to have a better understanding about all the components of residual stresses at surface and within the shell laminate. An existing micromechanics model is integrated into the present model to determine the material degradation due to environmental effects such as high moisture absorption and heat conduction. The residual stresses caused by the changes in environment are also included in the analysis. A parametric study is conducted to study the structural response due to changes in geometry, ply set-up and environmental effects.