These slides were presented at the NAFEMS World Congress 2025, held in Salzburg, Austria from May 19–22, 2025.

Abstract

The aim of the presented work is to extend the building block approach as currently used in certification of aircraft structures and apply and combine it with aerodynamic aspects. The goal of this work is to reduce physical test effort and shorten development time while increasing the required degree of confidence into the performance of the aircraft. Aeroelastic effects are considered to enhance the predictive level of loads by using full fluid structure interaction. Fluid-structure-interaction is considered on certification grade structural finite element models to include the changes of loads with the changes in displacement. In the development of new aircrafts, the structural building block approach and structural test pyramid is commonly employed and part of the acceptable means of compliance with the regulators on the structural side. The same approach is used here to derive more accurate values for the aerodynamic loads applied to the aircraft. To that extend the verification and validation procedures are executed along the levels of the aerodynamic test pyramid. At the bottom, coupon level simulations on 2D profiles are done that serve as verification cases. Simple closed form solutions are compared with numerical results to establish correct implementation of the mathematical equations into the computer code. These are flat plate and simple profiles solutions for laminar and turbulent flow. Also, aeroelastic closed form solutions are used. Stretching the profile in spanwise direction will be used for the validation in the element level. This closes the non-specific simulation on the aerodynamic side. The next levels serve for validation with increasing complexity based on real geometries for later application. Here the simulation results are compared to the experimental results of a 3D wing geometry under turbulent flow as well as fluid flow around high lift devices (detail level). Also, fluid-structure-interaction of vortex shedding around a cylinder and elastic member is considered. Finally, the aeroelastic deformations are presented at the component level of the test pyramid. Here a composite wing structure is deforming under aerodynamic loads and thus altering the flow characteristics. Considering the interaction between fluid and structure and evaluating loads based on the deformed structure is expected to improve the quality of the numerical predictions. Numerical and experimental results are compared with each other to complete the validation process. By consistently applying verification and validation from the bottom to the top of the structure and aerodynamic test pyramid, confidence can be placed in the predictive capability of the models and ultimately a reduction in test efforts can be attempted. In comparison to other fluid-structure-interaction investigations, the present analysis is focused on large deformation and deflection. The methodology is presented at the example of the outer wing of a glider aircraft which shows a tip deflection of 1.5 meters over a 5 m wing span. Secondly, no simplification of the structural model is performed and the structural model with the resulting load can be used as is for structural certification. The implications of large deformation analysis and no structural simplification on the analysis effort will be highlighted and resulting complications and solution presented.