Composite Ply Orientation Research Articles

Performance analysis of composite ply orientation in aeronautical application of unmanned aerial vehicle (UAV) NACA4415 wing

The advancement in today's material science has driven composite materials to globally use in aircraft design with its superiority in high structural stiffness and significant weight reduction. Composite structures ordinarily comprise of laminates with various fiber orientation angles offers unique outcome, hence lead to optimized design for composite structure. The paper deals with the layerwise finite element model for static structural analysis of a CFRP laminated composite of unmanned aerial vehicle (UAV) wing. The objective of this study is to compare the results for different orientation of ply combinations which contributed to the high performance of composite materials that exhibit both orthotropic strength and stiffness properties. Both properties present unique challenges for analysis and design. The study is further up to determine the optimum design for selected ply combination on a wing with a tubercle design at the leading edge of the wing. Tubercles mimicking the protuberances on the leading edge of a Humpback whale pectoral flipper, offering great performance from an aerodynamic perspective. Hence, optimum design of composite is found from the tabulated stress and displacement for each ply combination, where the tubercles design at the leading edge of UAV wing showed better performance with a reduction in 38.75% of deformation and 46.83% of stress, compared to normal leading edge of NACA4415 airfoil.

Exploring how optimal composite design is influenced by model fidelity and multiple objectives

This paper explores how optimal configuration of a composite panel is influenced by the choice of analysis model – analytic or computational – and the consideration of multiple objectives. While past research has explored aspects of this problem separately – composite ply orientation, multiple load scenarios, and multiple performance objectives – there has been limited work addressing the interactions between these factors. Three loading scenarios are considered in this work, and it is demonstrated that for certain scenarios an analytical model likely over-predicts composite performance. Further, for complex loading scenarios it is impossible to develop an analytical model. However, this work also demonstrates that the use of analytical models can be advantageous. Analytical models can provide similar estimates to computational models for some loading cases at significantly reduced computational expense. More importantly, it is also shown how solutions from the analytical model, which can be relatively cheap to find computationally, can be used to seed the initial designs of a Finite Element-based optimization. Run time reductions as large as 80% are demonstrated when these informed seeded designs are used, even when the designs were created for a different set of loading scenarios.

Trim Optimizations of an Adaptive Tailless Aircraft with Composite Wing

This paper investigates aeroelastic tailoring and optimal trailing edge control surface deflection to minimize induced drag for a HALE UAV flying wing configuration. The analysis process is conducted on the Finite Element(FE) model of a composite slender wing. Genetic Algorithm(GA) is employed to aeroelastically tailor the wing by setting the composite ply orientation. The study examined conformal and traditional flaps and explored two optimization formulations to minimize drag. The impacts of the conformal control surface are recognized as required deflection saving which can be translated to drag reduction. The results also show that the control demands for the optimal trim can be further reduced if the wing is properly tailored.

An aeroelastic model for composite rotor blades with straight and swept tips. Part I: Aeroelastic stability in hover

An analytical model for predicting the aeroelastic behavior of composite rotor blades with straight and swept tips is presented. The blade is modeled by beam type finite elements along the elastic axis. A single finite element is used to model the swept tip. The non-linear equations of motion for the finite element model are derived using Hamilton's principle and based on a moderate deflection theory and accounts for: arbitrary cross-sectional shape, pretwist, generally anisotropic material behavior, transverse shears and out-of-plane warping. Numerical results illustrating the effects of tip sweep, anhedral and composite ply orientation on blade aeroelastic behavior are presented. It is shown that composite ply orientation has a substantial effect on blade stability. At low thrust conditions, certain ply orientations can cause instability in the lag mode. The flap-torsion coupling associated with tip sweep can also induce aeroelastic instability in the blade. This instability can be removed by appropriate ply orientation in the composite construction.

MULTIDISCIPLINARY OPTIMIZATION OF COMPOSITE WINGS USING REFINED STRUCTURAL AND AEROELASTIC ANALYSIS METHODOLOGIES

An integrated multidisciplinary procedure has been developed for structural and aeroelastic optimization of composite wings based on refined analysis techniques. A refined higher-order theory is used to analyze a composite box beam, which represents the load carrying member of the wing. Unsteady aerodynamic computations are performed using a panel code based on the constant-pressure lifting surface method. Flutter/ divergence dynamic pressure is obtained by the Laplace domain method through rational function approximation of unsteady aerodynamic loads. The objective of the optimization procedure is to minimize wing structural weight with constraints on flutter/ divergence speed and stresses at the root due to the static load. Composite ply orientations and laminate thicknesses are used as design variables. The Kreisselmeier-Stcinhauscr function approach is used to efficiently integrate the objective function and constraints into a single envelope function. The resulting unconstrained optimization problem is solved using the Davidon-Fletcher-Powell algorithm. Numerical results are presented showing significant improvements, after optimization, compared to a reference design.