Effect of loading and lamination parameters on the optimum design of laminated plates (original) (raw)
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Optimum design of laminated composite plates using lamination parameters
AIAA/ASME/ASCE/AHS/ASC Structures, Structural …, 1991
A new and unified optimal design method is established. When laminated composite plates are symmetric and orthotropic, their in-plane and flexural stiffnesses become functions of lamination parameters which are functions of their stacking sequences. The lamination ...
Optimization of laminated composite plates subjected to nonuniform thermal loads
Polymers and Polymer Composites, 2019
Fiber-reinforced laminated composite structures are extensively used in aircraft and aerospace industries for their high specific strength and stiffness. In such applications, they are generally subjected to nonuniform thermal loads due to change in thermal conditions. Therefore, the composite structures used in the applications in which they are subjected to nonuniform thermal loads must also be designed to withstand thermal loads. As mechanical and thermal properties of fiber-reinforced laminated composites are greatly influenced by the direction of fibers and stacking sequences, they are optimally varied in this article to maximize the critical buckling temperature of the composite plate. The ply angle and stacking sequence of the laminated composite plate are optimized using genetic algorithm to maximize the thermal buckling temperature. As the plate is subjected to different kinds of nonuniform thermal load cases, finite element technique is used to analyze the plate during the optimization process. As geometry and supporting conditions of the plate also have great influence on its thermal buckling strength, the investigation is further widened by carrying out the optimization process for the plate model constructed with various types of support conditions, aspect ratio, and nonuniform load cases. The numerical results clearly show the necessities that the optimum ply angle and stacking sequences are greatly varying based on the aspect ratio, support conditions, and nonuniform loading cases.
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
Aided Design in Case of the Laminated Composite Materials
2015
The work firstly shows the analytical calculus model used to compute the distribution of the strains and stresses over the thickness in case of the laminated composite plates subjected to bending. Then, it is briefly described the main steps (calculus procedures) of the Matlab program that is used in design of the laminated composite plate in order to compute the stresses and to draw the distributions of the both strains and stresses. Therefore, rectangular plates subjected to the uniformly distributed force, with different boundary conditions (all sides simply supported, two sides simple supported while the others sides are free end) may be designed by using this program. The program also reports: the stiffness matrix corresponding to the plate element of the laminated composite plate that is computed; the safety coefficients are also computed by using one of the failure theories (maximum stress criterion; Tsai-Hill’s criterion, Tsai-Wu’s criterion).
Finite element analysis of laminated composite plates
International Journal for Numerical …, 1979
A general finite element formulation with the eight-noded isoparametric curved quadratic element applicable for the analysis of doubly curved laminated composite shell structures has been reported in another paper. The bending behaviour of composite shells having the form of paraboloid of revolution has been investigated. In the present paper the finite element fo~u~tion is extended to analyse the conoidal shells. Numerical results are obtained for two isotropic conoidal shell problems and one laminated composite shell problem with eight different ply lay-ups and layers. The authors' results of the two isotropic problems compare well with those available in published literature. The numerical results of deflection and stress resultants of eight different types of the third problem are discussed in order to estimate their relative performance for the uniformly distributed loading. The authors further propose a comparative performance matrix to study the relative performance of two laminated composite materials which will be of great help in design.
Design Optimization of Composite Plate under Transverse Loading using Ritz Method
Materials Today: Proceedings, 2020
MATLAB program is developed using classical laminate theory, along with Ritz solution, for especially orthotropic laminates. The minimization of deflection of the symmetrical composite plate with transverse loading for clamped edge boundary conditions is the main motive of the present study for different design parameters. In order to observe the effects of various design parameters like fiber orientation, aspect ratio and thickness ratio of the plate on maximum deflection, two different plates of four layered and ten layered symmetrical composite plates are used. For optimization study, developed MATLAB program calculates the optimum fiber orientation and thickness of plies for the different parameters. This developed MATLAB program is further used to analyze hybrid laminates. The developed MATLAB programs can check all the combination possible and effectively minimize the maximum deflection of plate with optimum fibers of different material, ply thickness, fiber angles. For present study around eighteen thousand combinations were checked to give optimized composite plate.
Discrete Optimization for Vibration Design of Composite Plates by Using Lamination Parameters
Advanced Composite Materials, 2009
A design method is proposed to optimize the stacking sequence of laminated composite plates for desired vibration characteristics. The objective functions are the natural frequencies of the laminated plates, and three types of optimization problems are studied where the fundamental frequency and the difference of two adjacent frequencies are maximized, and the difference between the target and actual frequencies is minimized. The design variables are a set of discrete values of fiber orientation angles with prescribed increment in the layers of the plates. The four lamination parameters are used to describe the bending property of a symmetrically laminated plate, and are optimized by a gradient method in the first stage. A new technique is introduced in the second stage to convert from the optimum four lamination parameters into the stacking sequence that is composed of the optimum fiber orientation angles of all the layers. Plates are divided into sub-domains composed of the small number of layers and designed sequentially from outer domains. For each domain, the optimum angles are determined by minimizing the errors between the optimum lamination parameters obtained in the first step and the parameters for all possible discrete stacking sequence designs. It is shown in numerical examples that this design method can provide with accurate optimum solutions for the stacking sequence of vibrating composite plates with various boundary conditions.
WIT transactions on engineering sciences, 1970
Optimal buckling designs of symmetrically laminated rectangular plates are presented, taking the effect of in-plane restraints along the unloaded edges into account. Restraints give rise to Poisson's effect which leads to lower buckling loads, and may cause premature instability. Moreover, the laminate behavior with respect to fiber orientations changes significantly in the presence of Poisson's effect as compared to that of a laminate with this effect neglected. This change in behavior has significant implications for design optimisation as the optimal values of design variables with or without restraints differ substantially. In the present study, the design objective is the maximisation of the uniaxial buckling load by optimally determining the fiber orientations. The finite element method, coupled with an optimisation routine, is employed in analysing and optimising the designs. Numerical results are given for five different combinations of free, simply supported and clamped boundary conditions.
Multi-objective optimization of composite plates using lamination parameters
Materials & Design, 2019
• Multi-objective optimization of composite plates is performed using lamination parameters. • Fundamental frequency, buckling load and effective stiffness metrics are maximized. • Pareto-optimal solutions are determined considering various problem cases. • A valuable insight has been provided on conformity/conflict of multiple objectives. • Presented methodology can be utilized for the optimal design of laminated plates.
Buckling Load Maximization of Laminated Composite Plates
2017
In the present study, buckling load carrying capacity of laminated plates having midplane symmetry is maximized for a given total thickness. The ply angle in discrete form is considered as design variables with constant ply thickness. Buckling analysis is carried out using the finite element method for uniaxial as well as biaxial loadings. It is observed that for any given ply thickness, buckling load carrying capacity can be improved by optimizing ply angle stacking sequence. The optimum results obtained using finite elements analysis for uniaxial load cases are verified by experimental results and the FEA model is validated. The validated FEA model is then utilized for Bi-axial load conditions and maximum buckling load carrying capacities obtained for various load conditions are compared with already published results. In the current study, unconstrained optimization is carried out using genetic algorithm available in Hyperstudy. It is observed that the removal of constraint like ...