High-fidelity Aerostructural Optimization of Tow-steered Composite Wings
T. R. Brooks, J. R. R. A. Martins, and G. J. Kennedy
Journal of Fluids and Structures, 88122–147, 2019
Over the past several decades, composites have increasingly become the material of choice in modern aircraft structural design. This is primarily due to the high stiffness- and strength-to-weight ratios offered by conventional composites when compared to metals. Unconventional composite designs, such as tow-steered composites, have demonstrated potential for further expanding these advantages. Unlike their conventional composite counterparts, tow-steered composites feature layers with spatially varying fiber orientations. When applied to wing design, tow-steered composites offer an increase in design freedom at the cost of higher design complexity, making them ideal candidates for design optimization. We develop a methodology for the aerostructural design optimization of tow-steered composite wings using high-fidelity physics models. We also quantify the benefits of this new technology by performing a fuel burn minimization for both a tow-steered and a conventional composite wing design. This assessment is done for the undeflected Common Research Model, which is representative of a twin-aisle transport aircraft. We find improvements of up to 2.4% in fuel burn and 24% in wing weight relative to the optimized conventional composite design. We show that this improvement is due to a combination of improved passive aeroelastic tailoring and local strength tailoring in high-stress regions in the tow-steered structure. For a higher-aspect-ratio (13.5) wing design, we find improvements of up to 1.5% and 14% in fuel savings and wing weight, respectively. To better understand the effect of aspect ratio on tow-steered wing design, we perform an optimization study where the aspect ratio is varied between 7.5 and 13.5. We found that there are diminishing returns in the benefit of tow steering as the aspect ratio is increased because less passive load alleviation is possible.