Dynamic analysis of prestressed variable stiffness composite shell structures

The design space for high-performance lightweight composite structures has grown considerably since the advent of the variable stiffness concept. In fact, variable stiffness composites have been found to improve buckling performance and dynamic stability, and to tune the structure’s dynamic response by tailoring structural stiffness. Thus, in order to exploit this wider design space, efficient linear analysis tools have an important role in preliminary design of variable stiffness structures, enabling designers to find more effective solutions when considering prestressed dynamically excited aerospace components. Considering this, a multi-domain Ritz method for eigenfrequency, transient and dynamic instability analysis of prestressed variable stiffness laminated doubly-curved shell structures is presented. Working within the first-order shear deformation theory, Sanders–Koiter shell kinematics allow general orthogonal surfaces to be modelled without further assumptions on the shallowness or on the thinness of the structure. The efficiency of the proposed Ritz method is granted by using Legendre orthogonal polynomials as displacement trial functions, while flexibility in modelling and design is given by penalty techniques that allow stiffened variable angle tow shell structures to be modelled as an assembly of shell-like domains. The proposed approach is verified by comparison with published benchmark results and finite element solutions. Original solutions are presented for a prestressed stiffened variable angle tow shell structure, which show great accuracy with an order of magnitude fewer variables when compared to standard finite element procedures, proving the reliability and efficiency of the present method in dealing with the dynamic analysis of multi-part aerospace structures.