Supersonic Flutter and Buckling Optimization of Tow-Steered Composite Plates

Abstract

The supersonic aeroelastic stability of tow steered carbon reinforced composite panels, in each layer of which the fibers follow curvilinear paths, is assessed. A structural model based on the Rayleigh-Ritz method, combined with the aerodynamic piston theory, is derived to represent the aeroelastic behavior of rectangular plates under different boundary conditions. In this model, the Classical Lamination Theory, considering symmetric stacking sequence and fiber trajectories described by Lagrange polynomials of different orders, is used. In addition, manufacturing constraints, which impose limitations to the feasible fiber trajectories, and the effect of in-plane loads, are also considered in the model. Using a multi-criteria Differential Evolution algorithm, numerical optimization is performed for a variety of scenarios, aiming at increasing the flutter and linear buckling stability margins of tow-steered plates, considering the geometrical parameters defining the fiber trajectories on the layers as design variables. Results obtained for the different optimization scenarios are compared, having a composite plate with unidirectional fibers as the baseline, aiming at evaluating the benefits achieved by the optimum tow-steered plates. Results enable to quantify the stability improvements by exploring fiber steering, which has been shown to be beneficial, even in situations where manufacturing constraints are accounted for.

Optimal Design of Plated/Shell Structures under Flutter Constraints—A Literature Review

“…Tow-steered composites were used to tailor the aeroelastic behavior, and they showed a good performance over traditional unidirectional composite laminates. The identical conclusion to the above was formulated later in References [92][93][94][95][96][97][98][99][100][101]. Stodieck et al [94] assessed the potential wing weight savings of a full-size aeroelastically tailored wing.…”

“…Steering and control fiber orientations in finite elements ( Figure 4b) combined with topology optimization is discussed by Muc et al [89,90] It has been noticed that the flutter maximal speed can be increased or decreased depending on the variable fiber spacing-Shih-Yao Kuo [91]. The identical conclusion to the above was formulated later in References [93][94][95][96][97][98][99][100][101]. Stodieck et al [92,93] studied the aeroelastic behavior of rectangular composite wing.…”

“…Stanford et al [96] studied the aeroelastic tailoring of a cantilevered flat plate in low-speed flow, locating the Pareto front between static aeroelastic stresses and dynamic flutter boundaries using a genetic algorithm. Guimaraes et al [97] investigated the flutter behavior of tow-steered composite panels using the Ritz method combined with supersonic aerodynamic piston theory. The flutter stability boundaries for constant stiffness laminates and variable stiffness laminates were compared.…”

Modelling of fibre steered plates with coupled thickness variation from overlapping continuous tows

“…However, the nonlinear thickness variation due to overlaps is only a function of the manufacturing angle , as discussed in Section 2.3 and 2.4, resulting in different thickness profiles for Case 1 and Case 2. Until now, the literature only assumed uniform thickness at any location, such that the ply rotation angle could simply be added afterwards [19,20,26,30,41,44]. By means of this example, it is clear that when overlaps are considered, the rotation angle must be judged concurrently with the manufacturing angles .…”

“…Since, the benefits of VAT have been used and researched numerically into increasing mechanical properties, such as stiffness [19], buckling [10,18,20,44] and post-buckling [43,42,35] capabilities for laminates alone, or along the interac- tion of stiffeners in a bay design [15,32] and linear buckling of VAT filament-wound cylinders [38]. These benefits have been proven in experiments to increase properties in different applications, such as bending [37] and buckling for cylinders [24,25] and plates [27,29].…”