Optimal design of variable stiffness laminated composite truncated cones under lateral external pressure (original) (raw)
Related papers
Composite Structures, 2004
The problem of minimizing the dynamic response of laminated truncated conical shells with minimum control force is presented. The total elastic energy of the shell is taken as a measure of the dynamic response which is formulated based on shear deformation theory. The ply thickness and fiber orientation angles are taken as optimization design variables. The Liapunov-Bellman theory is used to obtain explicit solutions for controlled deflections and closed loop control force. The present design and control optimization procedure is examined numerically for angle-ply, three-layer symmetric truncated conical shells with supported-supported, clamped-supported and clamped-clamped edges. The influences of the edges conditions, geometric and material parameters on the minimization process are illustrated.
2011
In this study, the buckling behavior of optimum laminated composite cylindrical shells subjected to axial compression and external pressure are studied. The cylindrical shells are composed of multi orthotropic layers that the principal axis gets along with the shell axis (x). The number of layers and the fiber orientation of layers are selected as optimization design variables with the aim to find the optimal laminated composite cylindrical shells. The optimization procedure was formulated with the objective of finding the highest buckling pressure. The Genetic Algorithm (GA) and Imperialist Competitive Algorithm (ICA) are two optimization algorithms that are used in this optimization procedure and the results were compared. Also, the effect of materials properties on buckling behavior was analyzed and studied.
Optimization of laminated composites considering different failure criteria
Composites Part B: Engineering, 2009
The purpose of the present work is to analyse the influence of the failure criterion on the minimum weight and cost of laminated plates subjected to in-plane loads. Three different failure criteria are tested independently: maximum stress, Tsai-Wu and the Puck failure criterion. The optimisation problem is solved by a genetic algorithm.
2017
An optimal design of internal pressurized stiffened conical shell is investigated using the genetic algorithm (GA) to minimize the structural weight and to prevent various types of stress and buckling failures. Axial compressive load is applied to the shell. Five stress and buckling failures as constraints are taken into account. Using the discrete elements method as well as the energy method, global buckling load and stress field in the stiffened shell are obtained. The stiffeners include rings and stringers. Seven design variables including shell thickness, number of rings and stringers, stiffeners width and height are considered. In addition, the upper and lower practical bounds are applied for the design variables. Finally, a graphical software package named as Optimal Sizer is developed to help the designers.
Optimum Design of Laminated Composite Structures
1992
Because of their superior mechanical properties compared to single phase materials, laminated fibrous composite materials are finding a wide range of applications in structural design, especially for lightweight strnctures that have stringent stiffness and strength requirements. Designing with laminated composites, on the other hand, has become a challenge for the designer because of a wide range of parameters that can be varied, and because the complex behavior and multiple failure modes of these structures require sophisticated analysis techniques. Finding an efficient composite structural design that meets the requirements of a certain application can be achieved not only by sizing the cross-sectional areas and member thicknesses, but also by global or local tailoring of the material properties through selective use of orientation, number, and stacking sequence of laminae that make up the composite laminate. The increased number of design variables is both a blessing and a curse for the designer, in that he has more control to fine-tune his strllctme to l1H'et design requirements, but only if he can figme out how to select those dpsign variables. The possibility of achieving an efficient design that is safe against multiple failure mechanisms, coupled with the difficulty in selecting the values of a large set of design variables makes structural optimization an obvious tool for the design of laminated composite structures. Because of the need for sophisticated analysis tools for most realistic applications, designing with laminated composites largely relied on procpclmes that simply coupled those analyses with black-box optimizers. However a better understanding of the peculiarities associated with optimization of composites can best be illustrated through simple examples. In this chapter we emphasize examples that focus on hasic concepts. 11.1 Mechanical Response of a Laminate \Vhile laminated composite materials are attractive replacements for metallic materials for many structural applications that require high stiffness-to-weight and high strength-to-weight ratios, the analysis and design of these materials are considerably
Optimal design of filament wound truncated cones under axial compression
Composite Structures, 2017
In this study, filament wound truncated cones under axial compression are optimized with the objectives of minimizing the total weight and maximizing the failure load, which is defined as the minimum of the buckling and the first-ply failure (FPF) loads. The numerical results are obtained using an axisymmetric degenerated shell element based on a refined first-order shear deformable shell theory and a 2D degenerated shell element is used for verification purposes. It is shown that, FPF is more critical than buckling for thicker cones with lower cone angles. Optimal designs, where FPF and buckling are imposed as design constraints, are presented for filament wound cones using Micro-Genetic Algorithms. The results show that, using more layers having different winding angles has negligible influence on the failure load and the optimal design is not FPF critical for moderate levels of axial compression. The influence of the rotational boundary conditions on the optimal failure load is also demonstrated.
Surrogate models for optimum design of stiffened composite shells
Composite Structures, 2004
An optimization procedure is developed for the design of composite stiffened shells subjected to buckling and post-buckling constraints. The optimization method is based on building surrogate models employing the experimental design and response surface methodology. A combined data set consisting of test results of stiffened shells and numerical data obtained by finite element simulation is used for building the surrogate models. These models are used for sensitivity analysis, evaluation of the weight saving parameters and for design optimization of stiffened composite panels under axial compression loading. It was shown that employing the surrogate models satisfactory accuracy can be achieved to describe the post-buckling behavior of the stiffened panels and to use these models in design optimization.
Concurrent Lamination and Tapering Optimization of Cantilever Composite Plates under Shear
Materials, 2021
The operational performance of cantilever composite structures can benefit from both stiffness tailoring and geometric design, yet, this potential has not been fully utilized in existing studies. The present study addresses this problem by simultaneously optimizing layer and taper angles of cantilever laminates. The design objective is selected as minimizing the average deflection of the tip edge subjected to shear loads while keeping the length and total volume constant. The plate stiffness properties are described by lamination parameters to eliminate the possible solution dependency on the initial assumptions regarding laminate configuration. The responses are computed via finite element analyses, while optimal design variables are determined using genetic algorithms. The results demonstrate that the plate aspect ratio significantly influences the effectiveness of stiffness tailoring and tapering as well as the optimal layer and taper angles. In addition, concurrent exploitation of the lamination characteristics and plate geometry is shown to be essential for achieving maximum performance. Moreover, individual and simultaneous optimization of layer and taper angles produce different optimal results, indicating the possible drawback of using sequential approaches in similar composite design problems.