Design and Validation of Lightweight Composite Load-Bearing Structures for Aircraft Using Topology Optimization and Multiscale Verification

Composite materials have become widespread for use in aircraft load bearing structures due to their ability of reducing structural mass without compromising the required stiffness, strength and safety requirements in the face of aerodynamic, inertial and thermal service loads. This work has addressed with success the development and validation of such an integrated lightweight-design framework applied to a representative composite aircraft load-carrying structure. The workflow exploits SIMP topology optimization and parametric modelling as well as Kriging and support vector regression surrogate models, Latin hypercube sampling and a multi-island genetic algorithm, to screen the low mass design space subject to stress, deformation, buckling and manufacture ability constraints. The optimized FE model contained 2.15M elements. It predicts a max prinicpal stress of 263.4MPa,a stress margin of 4.18, and a tip deflection of 1.24 mm under the 2.0 mm limit, and the minimum buckling factor was 3.47. The prototype test recorded maximum stress at 257.6 MPa, and thermal deflection of 1.27 mm while deviation between simulations and testing remained below 6%. In general, the above results indicate that the surrogate model based optimization coupled by the manufacturing feedback will be able to relate the aircraft composite structure design, fabrication and validation, and can be used as a realistic benchmark for digital engineering analysis of light-weight aircraft structures.