Aeroelasticity of Plates with Nonuniform Boundary Conditions Ranging from Pinned to Clamped

The aeroelastic stability and dynamic response of thin panels are important considerations in aerospace structures design. Traditional nonlinear Rayleigh-Ritz (RR) analysis struggles when applied to panels with nonuniform boundary conditions (BCs) or local constraints. Generating the necessary global basis functions is difficult, often leading to slow convergence and requiring many modes.
This study combines the Finite Element Method (FEM) for modeling arbitrary BCs with the computational efficiency of the RR method for incorporating geometric nonlinearity. First, an eigenvalue problem is solved in FEM with arbitrary BCs. The resulting eigenmodes are used as basis functions to compute structural tensors in the RR scheme, with an appropriate modification to the potential energy terms. This hybrid FEM-RR approach is validated against a commercial solver.
We apply this to explore how locally stiffened edges, representing rivet patterns, affect supersonic aeroelastic response. Eigenvalue analysis shows that specific nonuniform BCs can significantly delay flutter onset, opening the way for design optimization. However, time-marching the nonlinear structural equations reveals a trade-off: stress analyses indicate that while flutter onset is delayed, edge stress concentrations might lead to earlier structural failure in the post-flutter regime than without restraints.

This work is towards an M.Sc. degree under the supervision of Assistant Prof. Maxim Freydin, The Stephen B. Klein Faculty of Aerospace Engineering, Technion.