Optimization of Joined Conical Shells Based on Free Vibration

2016 ◽  
Author(s):  
Rayehe Karimi Mahabadi ◽  
Firooz Bakhtiari-Nejad
Keyword(s):  
Genetic Algorithm ◽  
Free Vibration ◽  
Natural Frequency ◽  
Conical Shell ◽  
Fibre Orientation ◽  
Laminated Composite ◽  
Conical Shells ◽  
Design Variables

This work aims at utilizing genetic algorithm (GA) to pursue the optimization of joined conical shells based on free vibration. Semi-vertex angles of cones and fibre orientation of the laminated composite are considered as design variables. First, the model is simulated in ABAQUS, the model is validated by comparing its results to other obtained from the literature. Then the first non-zero natural frequency of isotropic joined conical shell is maximized by changing the two semi-vertex angles of cones. Last the fibre orientation of laminated joined shells are optimized to achieve the maximum natural frequency.

Stability and vibration analysis of an axially moving thin walled conical shell

2021 ◽  
pp. 107754632199760
Author(s):  
Hossein Abolhassanpour ◽  
Faramarz Ashenai Ghasemi ◽  
Majid Shahgholi ◽  
Arash Mohamadi
Keyword(s):  
Natural Frequency ◽  
Conical Shell ◽  
Shell Theory ◽  
Cone Angle ◽  
Theory Of Elasticity ◽  
Lower Velocity ◽  
Motion Equations ◽  
Conical Shells ◽  
Divergence Instability ◽  
Axially Moving

This article deals with the analysis of free vibration of an axially moving truncated conical shell. Based on the classical linear theory of elasticity, Donnell shell theory assumptions, Hamilton principle, and Galerkin method, the motion equations of axially moving truncated conical shells are derived. Then, the perturbation method is used to obtain the natural frequency of the system. One of the most important and controversial results in studies of axially moving structures is the velocity detection of critical points. Therefore, the effect of velocity on the creation of divergence instability is investigated. The other important goal in this study is to investigate the effect of the cone angle. As a novelty, our study found that increasing or decreasing the cone angle also affects the critical velocity of the structure in addition to changing the natural frequency, meaning that with increasing the cone angle, the instability occurs at a lower velocity. Also, the effect of other parameters such as aspect ratio and mechanical properties on the frequency and instability points is investigated.

Free vibration analysis of laminated composite conical, cylindrical shell and annular plate with variable thickness and general boundary conditions

2021 ◽  
Author(s):  
Kwang Hun Kim ◽  
Songhun Kwak ◽  
Kwangil An ◽  
Kyongjin Pang ◽  
Pyol Kim
Keyword(s):  
Cylindrical Shell ◽  
Free Vibration ◽  
Boundary Conditions ◽  
Variable Thickness ◽  
Conical Shell ◽  
Annular Plate ◽  
Laminated Composite ◽  
Haar Wavelet ◽  
Algebraic Equations ◽  
Arbitrary Boundary

Abstract This paper presents a unified solution method to investigate the free vibration behaviors of laminated composite conical shell, cylindrical shell and annular plate with variable thickness and arbitrary boundary conditions using the Haar wavelet discretization method (HWDM). Theoretical formulation is established based on the first order shear deformation theory(FSDT) and displacement components are extended Haar wavelet series in the axis direction and trigonometric series in the circumferential direction. The constants generating by the integrating process are disposed by boundary conditions, and thus the equations of motion of total system including the boundary condition are transformed into an algebraic equations. Then natural frequencies of the laminated composite structures are directly obtained by solving these algebraic equations. Stability and accuracy of the present method are verified through convergence and validation studies. Effects of some material properties and geometric parameters on the free vibration of laminated composite shells are discussed and some related mode shapes are given. Some new results for laminated composite conical shell, cylindrical shell and annular plate with variable thickness and arbitrary boundary conditions are presented, which may serve as benchmark solutions.

scholarly journals Mode frequency analysis of antisymmetric angle-ply laminated composite stiffened hypar shell with cutout

2019 ◽  
Vol 23 (1) ◽  
pp. 162-171
Author(s):  
Puja Basu Chaudhuri ◽  
Anirban Mitra ◽  
Sarmila Sahoo
Keyword(s):  
Free Vibration ◽  
Natural Frequency ◽  
Frequency Analysis ◽  
Fiber Orientation ◽  
Orientation Angle ◽  
Shear Deformation Theory ◽  
Laminated Composite ◽  
Mode Frequency ◽  
Thickness Ratio ◽  
Fiber Orientation Angle

Abstract This article deals with finite element method for the analysis of antisymmetric angle-ply laminated composite hypar shells (hyperbolic paraboloid bounded by straight edges) that applies an eight-noded isoparametric shell element and a three-noded beam element to study the mode-frequency analysis of stiffened shell with cutout. Two-, 4-, and 10-layered antisymmetric angle-ply laminations with different lamination angles are considered. Among these, 10-layer antisymmetric angle-ply shells are considered for elaborate study. The shells have different boundary conditions along its four edges. The formulation is based on the first-order shear deformation theory. The reduced method of eigen value solution is chosen for the undamped free vibration analysis. The first five modes of natural frequency are presented. The numerical studies are conducted to determine the effects of width-to-thickness ratio (b/h), degree of orthotropy (E11/E22), and fiber orientation angle (θ) on the nondimensional natural frequency. The results reveal that free vibration behavior mainly depends on the number of boundary constraints rather than other parametric variations such as change in fiber orientation angle and increase in degree of orthotropy and width-to-thickness ratio.

scholarly journals Free Vibration Analysis of Laminated Composite Plates with General Boundary Elastic Supports Under Initial Thermal Load

2019 ◽  
Vol 15 (4) ◽  
pp. 23-32
Author(s):  
Mohammed B. Hammed ◽  
Widad I. Majeed
Keyword(s):  
Aspect Ratio ◽  
Free Vibration ◽  
Natural Frequency ◽  
Thermal Load ◽  
Ritz Method ◽  
Laminated Composite ◽  
Free Vibration Analysis ◽  
Composite Plates ◽  
Design Parameters ◽  
Laminated Plate

Free vibration behavior was developed under the ratio of critical buckling temperature of laminated composite thin plates with the general elastic boundary condition. The equations of motion were found based on classical laminated plate theory (CLPT) while the solution functions consists of trigonometric function and a continuous function that is added to guarantee the sufficient smoother of the so-named remaining displacement function at the boundaries, in this research, a modified Fourier series were used, a generalized procedure solution was developed using Ritz method combined with the imaginary spring technique. The influences of many design parameters such as angles of layers, aspect ratio, thickness ratio, and ratio of initial in- plane thermal load in addition to different boundary conditions on the natural frequencies of laminated plate is analyzed. In general, the changes of fundamental natural frequency is inversely proportional with the ratio of thermal buckling load, also most parameters aspect ratio effect on the natural frequency about 35 – 40%. The present results were compared with those obtained by other researchers, and show good agreement.

Genetic Algorithm Approach for Optimization of FRP Laminated Cylindrical Shells Under Constraint

1999 ◽  
Author(s):  
Yoshiki Ohta
Keyword(s):  
Genetic Algorithm ◽  
Cylindrical Shells ◽  
Laminated Composite ◽  
Frequency Equation ◽  
Genetic Operators ◽  
Fundamental Frequencies ◽  
Design Variables ◽  
Structural Applications ◽  
Genetic Algorithm Approach ◽  
Laminated Cylindrical Shells

Abstract Fiber Reinforced Plastic (FRP) materials have been increasingly used in many structural applications of space shuttles, airplanes and automobiles, and the structural optimization of FRP laminated composite shells has been studied for stiffer structural design by many researchers. This paper studies the maximization of fundamental frequencies of FRP laminated cylindrical shells under stiffness constraint by using Genetic Algorithm (GA). For this purpose, the frequency equation for simply-supported shells with symmetrically balanced stacking sequence is derived analytically based on Classical Lamination Theory. In optimization the fiber angles and the thickness ratio of each FRP ply, which have continuous real values, are taken as design variables, and fundamental frequency of the shell is maximized under in-plane stiffness constraints. In numerical experiments, extensive numerical calculations are carried out to determine better genetic operators that would be suitable for FRP laminates design, and genetic parameters are tuned for better reliabilities and lower computational costs in the present GA. Optimal design solutions for various laminated cylindrical shells are obtained and then the applicability of the GA to the maximization of frequencies of the shells is studied from numerical results obtained.

Fiber Orientation Angles Optimization for Maximum Fundamental Frequency of Laminated Composite Plates by the Genetic Algorithm and Meshless Method

2014 ◽  
Vol 709 ◽  
pp. 130-134
Author(s):  
Feng Wang ◽  
Wei Ping Zhao ◽  
Song Xiang
Keyword(s):  
Genetic Algorithm ◽  
Fundamental Frequency ◽  
Fiber Orientation ◽  
Meshless Method ◽  
Laminated Composite ◽  
Composite Plates ◽  
Laminated Plates ◽  
Laminated Composite Plates ◽  
Fundamental Frequencies ◽  
Design Variables

Fiber orientation angles optimization is carried out for maximum fundamental frequency of clamped laminated composite plates using the genetic algorithm. The meshless method is utilized to calculate the fundamental frequency of clamped laminated composite plates. In the present paper, the maximum fundamental frequency is an objective function; design variables are a set of fiber orientation angles in the layers. The examples of square laminated plates are considered. The results for the optimal fiber orientation angles and the maximum fundamental frequencies of the 2-layer plates are presented.

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