Isogeometric blended shells for dynamic analysis: simulating aircraft takeoff and the resulting fatigue damage on the horizontal stabilizer

Aircraft horizontal stabilizers are prone to fatigue damage induced by the flow separation from aircraft wings and the subsequent impingement on the stabilizer structure in its wake, which is known as a buffet event. In this work, the previously developed isogeometric blended shell approach is reformulated in a dynamic analysis setting for the simulation of aircraft takeoff using varying pitch angles. The proposed Kirchhoff–Love (KL) and continuum shell blending allows the critical structural components of the aircraft horizontal stabilizer to be modeled using continuum shells to obtain high-fidelity 3D stresses, whereas the less critical components are modeled using computationally efficient KL thin shells. The imposed aerodynamic loads are generated from a hybrid immersogeometric and boundary-fitted computational fluid dynamics (CFD) analysis to accurately record the dynamic excitation on the stabilizer external surface. Specifically, the entire aircraft except for the wings and stabilizers is immersed into a non-boundary-fitted fluid domain based on the immersogeometric analysis (IMGA) concept for computational savings, whereas the mesh surrounding the aircraft wing and stabilizers is boundary-fitted to accurately compute the aerodynamic loads on the stabilizer. The obtained time histories of the loads are then applied to dynamic blended shell analysis of the horizontal stabilizer, and the high-fidelity stress response is evaluated for subsequent fatigue assessment. A simple frequency-domain fatigue analysis is then carried out to evaluate the buffet-induced fatigue damage of the stabilizer. The results from both the steady-state and dynamic nonlinear blended shell analyses of a representative horizontal stabilizer demonstrate the numerical accuracy and computational efficiency of the proposed approach.