Static and dynamic aeroelastic tailoring with composite blending and manoeuvre load alleviation

Abstract

In aircraft design, proper tailoring of composite anisotropic characteristics allows to achieve weight saving while maintaining good aeroelastic performance. To further improve the design, dynamic loads and manufacturing constraints should be integrated in the design process. The objective of this paper is to evaluate how the introduction of continuous blending constraints affects the optimum design and the retrieval of the final stacking sequence for a regional aircraft wing. The effect of the blending constraints on the optimum design (1) focuses on static and dynamic loading conditions and identifies the ones driving the optimization and (2) explores the potential weight saving due to the implementation of a manoeuvre load alleviation (MLA) strategy. Results show that while dynamic gust loads can be critical for wing design, in the case of a regional aircraft, their influence is minimal. Nevertheless, MLA strategies can reduce the impact of static loads on the final design in favour of gust loads, underlining the importance of considering such load-cases in the optimisation. In both cases, blending does not strongly affect the load criticality and retrieve a slightly heavier design. Finally, blending constraints confirmed their significant influence on the final discrete design and their capability to produce more manufacturable structures.

Multi-scale deterministic optimisation of blended composite structures: case study of a box-wing

“…In recent years, many works focusing on the development of design methodologies for composite structures have been carried out. However, an efficient use of composite materials to build large optimised structures remains one of the main challenges of aircraft industry [1]. In fact, if compared to isotropic metallic structures, the design of composite laminates introduces a higher level of complexity due to the increased number of design variables, the mathematical formulation of anisotropy, and the manufacturing and feasibility constraints formulation and modelling.…”

“…A sound alternative for describing the anisotropic behaviour of composite materials is represented by the polar formalism introduced in [7] by Verchery, and generalised to the case of higher-order equivalent single layer theories in [8][9][10] by Montemurro. Thanks to the polar formalism it is possible to represent any plane tensor by means of tensor invariants, referred to as polar parameters (PPs), which are directly related to the symmetries of the tensor. Some interesting works using LPs can be found in the literature [1,11,12]. The multi-scale two-level optimisation strategy (MS2LOS) based on the polar formalism has been originally introduced in [13,14] and has been later generalised, expanded and used in several works, such as [15][16][17][18][19][20][21].…”

Multi-Fidelity Optimization of a Composite Airliner Wing Subject to Structural and Aeroelastic Constraints

“…where n an integer-valued variable allowed to range between its upper and lower bounds, and i an internal variable counter, ranging from 1 to the number of variables of the optimization problem. This formulation was deemed advantageous due to a straightforward and less complex implementation than advanced lamination parameters techniques, such as References [3,4,11]. The results, expressed as the required integer number of plies to achieve an optimized percentage of different ply orientations up to the required thickness is deemed satisfactory for the purpose of this study.…”

“…In later works, efforts were directed towards closure of the up-to-then incomplete feasible design space of the lamination parameters [6], and the aeroelastic tailoring of regular and variable stiffness composite materials wings [7,8], as well as the stiffness optimization subject to aeroelastic constraints [9]. Macquart et al [10], as well as Bordogna et al [11], extended the capabilities of the state-of-the art lamination parameters optimization algorithms, introducing blending constraints in order to guarantee a certain degree of ply continuity inside a variable stiffness composite wing.…”

Buckling optimization of blended composite structures using lamination parameters

“…In the work of Liu et al [25], the first order optimization method available in the ANSYS finite element analysis (FEA) software was employed in the first stage to conduct a weight optimization where the bending lamination parameters and the number of plies of each angle were used as design variables. Then in the second stage, the blended stacking sequences of the whole structure were obtained based on the optimized lamination parameters using the shared layer blending (SLB) approach with a permutation GA. Macquart et al [26] studied the blending constraint in lamination parameters space for the first stage of the optimization, which was then imposed in later works [27][28][29] where a gradient-based optimizer was employed to optimize lamination parameters and laminate thicknesses, and a guide-based GA was then utilized to search the corresponding stacking sequences. In the work of Meddaikar et al [30], a multipoint structural approximation was used in the two-stage optimization, with the mass of a composite structure being minimized by optimizing lamination parameters and laminate thicknesses in the first stage and blended stacking sequences obtained using GAs incorporated with SST in the second stage.…”