Forced Motions of Composite Conoidal Shell Roofs with Complicated Boundary Conditions

2010 ◽  
Vol 123-125 ◽  
pp. 89-92
Author(s):  
Kaustav Bakshi ◽  
Hari Sadhan Das ◽  
Dipankar Chakravorty
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Forced Vibration ◽  
Vibration Characteristics ◽  
Finite Element Code ◽  
Isoparametric Finite Element

An eight noded isoparametric finite element code is applied to study static bending, free and forced vibration characteristics of composite conoidal shell roofs with complicated boundary conditions which are often encountered in the industry.

Investigation of the incremental and deformation theories of plasticity on the elastoplastic postbuckling of plates

2020 ◽  
Vol 234 (7) ◽  
pp. 1017-1031
Author(s):  
HM Soltani ◽  
M Kharazi
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Deformation Theory ◽  
Finite Element Code ◽  
Postbuckling Behavior ◽  
Incremental Theory ◽  
Aspect Ratios ◽  
Theory Of Plasticity ◽  
The Difference

This article investigates the elastoplastic response of buckling and postbuckling behavior of plates under uniaxial and biaxial end-shortening considering incremental theory and deformation theory of plasticity. According to elastoplastic buckling and postbuckling behavior of plates, the finite element code considering geometrically and material nonlinearities is developed based on incremental theory and deformation theory of plasticity. The results show that boundary conditions, loading ratios, and aspect ratios of a plate have a significant effect on the discrepancy between incremental theory and deformation theory. Moreover, differences in estimating the buckling point using incremental theory and deformation theory are less than 10%, while in a number of plates at the last loading steps, postbuckling paths determined by incremental theory and deformation theory are diverted from each other. Also the difference between these two theories in the postbuckling region is more noticeable by increasing the thickness of plates.

scholarly journals Design and Analysis of a Ceramic Stator Vane

1975 ◽  
Author(s):  
S. C. Sanday ◽  
T. L. Lam ◽  
T. J. Rahaim
Keyword(s):  
Finite Element ◽  
Thermal Stress ◽  
High Temperature ◽  
Three Dimensional ◽  
Finite Element Code ◽  
Isoparametric Finite Element ◽  
Stator Vane ◽  
Transient Thermal ◽  
Industrial Gas Turbine ◽  
Temperature Time

The development of a ceramic stator vane for the first stage of a high temperature industrial gas turbine is presented. The elastic transient thermal stress analysis of the latest design, using a three-dimensional isoparametric finite element code is outlined. Results for a vane assembly made of silicon nitride and exposed to several temperature-time conditions are discussed.

Thermo-mechanical induced vibration characteristics of shear deformable functionally graded ceramic—metal plates using finite element method

2010 ◽  
Vol 225 (1) ◽  
pp. 50-65 ◽  
Author(s):  
M Talha ◽  
B N Singh
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Temperature Field ◽  
Boundary Conditions ◽  
Vibration Characteristics ◽  
Functionally Graded ◽  
Thickness Direction ◽  
Aspect Ratios ◽  
Shear Deformable ◽  
Element Method

This paper deals with the thermomechanical-induced vibration characteristics of shear deformable functionally graded material (FGM) plates. Theoretical formulations are based on higher-order shear deformation theory with a significant improvement in the transverse displacement using finite-element method. The mechanical properties of the plate are assumed to be temperature-dependent and graded in the thickness direction according to a power-law distribution in terms of the volume fractions of the constituents. The temperature field is ascertained to be a uniform distribution over the plate surface and varied in the thickness direction only. The fundamental equations for FGM plates are derived using variational approach by considering traction-free boundary conditions on the top and bottom faces of the plate. A C0 continuous isoparametric Lagrangian finite-element with 13 degrees of freedom (DOF) per node have been used to accomplish the results. Convergence and comparison studies have been performed for square plates to demonstrate the efficiency of the present model. The numerical results are obtained for different thickness ratios, aspect ratios, volume fraction index, and temperature rise with different boundary conditions. The results reveal that the temperature field and the gradient in the material properties have significant effect on the vibration characteristics of the FGM plates.

Stiffness Characteristics of Membrane Space Structures Supported by Booms

2012 ◽  
Author(s):  
H. Tamaru ◽  
T. Akita ◽  
M. C. Natori ◽  
H. Yamakawa
Keyword(s):  
Finite Element ◽  
Parametric Study ◽  
Vibration Characteristics ◽  
Space Structures ◽  
Finite Element Code ◽  
Membrane Structures ◽  
Square Planar ◽  
Applied Tension ◽  
Planar Membrane ◽  
Stiffness Characteristics

A systematic parametric study on the stiffness characteristics of compound space structures consisted of membranes and booms is presented. Using a tension field finite element code including membrane wrinkle effects, basic vibration characteristics of a square planar membrane structures are shown, and the effects of various conditions of applied tension between membrane and boom elements are discussed.

scholarly journals A Semianalytic Method for Vibration Analysis of a Sandwich FGP Doubly Curved Shell with Arbitrary Boundary Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Zhongyu Zhang ◽  
Jiayang Gu ◽  
Jianjun Ding ◽  
Yanwu Tao
Keyword(s):  
Boundary Conditions ◽  
Forced Vibration ◽  
Vibration Analysis ◽  
Shear Deformation Theory ◽  
Vibration Characteristics ◽  
Functionally Graded ◽  
Arbitrary Boundary ◽  
Forced Vibration Analysis ◽  
Doubly Curved ◽  
Curved Structure

Due to the excellent mechanical properties of doubly curved structure and functionally graded porous (FGP) material, the study of their vibration characteristics has attracted wide attention. The main aim of this research is to establish a formulation for free and forced vibration analysis of a new Sandwich FGP doubly curved structure. Four models of Sandwich materials are considered. The potential energy and kinetic energy functions are obtained on the foundation of the first-order shear deformation theory (FSDT). The idea of domain energy decomposition is applied to the theoretical modeling, where the structure is segmented along the generatrix direction. The continuity conditions for the interfaces between adjacent segments are balanced by the weighted parameters. For each segment, the displacement functions are selected as the Jacobi orthogonal polynomials and trigonometric series. The boundary conditions of the structure are obtained by the boundary spring simulation technique. The solution is obtained by the variational operation of the structural functional. The convergence performance and correctness of the theoretical model are examined by several numerical examples. Finally, some novel results are given, where free and forced vibration characteristics of Sandwich FGP doubly curved structures are examined in detail.

The Effect of Graded Strength on Damage Propagation in Continuously Nonhomogeneous Materials

2003 ◽  
Vol 125 (4) ◽  
pp. 412-417 ◽  
Author(s):  
Priya Thamburaj ◽  
Michael H. Santare ◽  
George A. Gazonas
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Damage Model ◽  
Numerical Results ◽  
Finite Element Code ◽  
Different Boundary Conditions ◽  
One Dimensional ◽  
Damage Propagation ◽  
Dynamic Finite Element ◽  
Nonhomogeneous Materials

A damage model developed by Johnson and Holmquist is implemented into a dynamic finite element code. This is then used to study the effect of grading of the phenomenological damage parameters on the propagation of damage through the material. The numerical results for two one-dimensional example problems with different boundary conditions are presented, wherein the effect of a gradient in the intact strength of the material on damage propagation is studied. The results show that introducing different strength gradients can alter the location of the site of maximum damage. This may have important implications in the design of impact resistant materials and structures.

Dynamic Analysis of Sandwich Plates with Isotropic Skins and Viscoelastic Core

2019 ◽  
Vol 19 (03) ◽  
pp. 1950033 ◽  
Author(s):  
R. K. Ojha ◽  
S. K. Dwivedy
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Forced Vibration ◽  
Sandwich Plate ◽  
Vibration Suppression ◽  
Loss Modulus ◽  
Harmonic Excitation ◽  
Sandwich Plates ◽  
Isotropic Layer ◽  
Lagrange Principle

The free and forced vibration characteristics of three-layered sandwich plates with thin isotropic faces and Leptadenia pyrotechnica rheological elastomer (LPRE) core are studied in this investigation. The LPRE core is fabricated and experimented to determine its shear storage modulus and loss modulus. It is observed that the stiffness and damping characteristics of the LPRE core is significantly higher than those of the room-temperature vulcanized silicone rubber elastomer (RTVE) core. The governing equation of motion for the sandwich plate is derived by the Lagrange principle and given in finite element form. The natural frequencies and loss factors of the three-layered sandwich plate are studied by varying the thicknesses of the core and the constraining isotropic layer, and material of the constraining layer with different boundary conditions. The results are compared with those of similar structures with different core materials and boundary conditions. In addition, a LPRE-based sandwich plate is fabricated and its fundamental frequency is determined experimentally and compared with the finite element result. The forced vibration response of the three-layered sandwich plate is also explored under a harmonic excitation force. This study provides supports for the application of the LPRE-based sandwich plates potentially to the passive vibration suppression of structures.

Vibration Modes of Centrifugally Stiffened Beams

1982 ◽  
Vol 49 (1) ◽  
pp. 197-202 ◽  
Author(s):  
A. D. Wright ◽  
C. E. Smith ◽  
R. W. Thresher ◽  
J. L. C. Wang
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Cantilever Beam ◽  
Mass Distribution ◽  
Flexural Rigidity ◽  
Mode Shapes ◽  
Vibration Modes ◽  
Finite Element Code ◽  
Rotating Beams ◽  
Tip Mass

The method of Frobenius is used to solve for the exact frequencies and mode shapes for rotating beams in which both the flexural rigidity and the mass distribution vary linearly. Results are tabulated for a variety of situations including uniform and tapered beams, with root offset and tip mass, and for both hinged root and fixed root boundary conditions. The results obtained for the case of the uniform cantilever beam are compared with other solutions, and the results of a conventional finite-element code.

Aeolian vibration of a single conductor with a Stockbridge damper

2012 ◽  
Vol 227 (5) ◽  
pp. 935-945 ◽  
Author(s):  
Oumar Barry ◽  
Donatus CD Oguamanam ◽  
Der Chyan Lin
Keyword(s):  
Mathematical Model ◽  
Finite Element ◽  
Forced Vibration ◽  
Flexural Rigidity ◽  
Excitation Frequency ◽  
Finite Element Code ◽  
Vibrational Response ◽  
Aeolian Vibration ◽  
The Mathematical Model ◽  
Stockbridge Damper

The planar vibrational response of a single conductor with an attached Stockbridge damper is investigated. The mathematical model accounts for the two-way coupling between the conductor and the damper, the flexural rigidity of both the damper and the conductor, and the mass of the two counterweights of the damper. Hence, the dynamic behaviors of the damper and conductor are simultaneously assessed. Both free and forced vibration analyses are implemented via the use of a finite element code developed in MATLAB. The results of the force vibration analyses show that the effectiveness of Stockbridge dampers depends on their location, mass, and excitation frequency.

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