AEROELASTIC TAILORING OPTIMISATION OF A COMBAT AIRCRAFT WING WITH TOW-STEERED COMPOSITES

This paper investigates the possibility of employing tailored unidirectional and fibre steered aeroelastically tailored composite lay-up techniques for a combat aircraft wing to meet performance requirements (maximise lift/drag) at more than one design condition whilst still satisfying aeroelastic and structural constraints, with particular emphasis on desired camber / twist schedules. A finite element model of the combat aircraft wing is presented and then, static aeroelastic analysis and modal analysis are carried out to understand the underlying structural and aeroelastic behaviour. Following the definition of a baseline “black metal” (BM) results, a design case exploration for unidirectional (UD) rotated composite layers is performed. After these initial studies, an in-house passive aeroelastic tailoring optimisation code has been developed in MATLAB 2020a incorporating Nastran 2018 gradient-based algorithms to minimise the wing weight, subject to a range of aeroelastic and structural constraints, through the optimisation of thickness distribution and ply angle orientation. Unidirectional, 1D Variable Angle Tow (VAT) and 2D Variable Angle Tow design strategies are considered, and the results compared to the baseline BM case. It is found that weight reduction could be achieved using the UD, 1D VAT and 2D VAT design approaches with up to 35% achieved in the latter case compared to the baseline. This study demonstrates the potential of using passive aeroelastic tailoring for wing structural design and suggests a pathway toward practical passive aeroelastic wing designs.