scholarly journals Free and Forced Vibration Analysis of Airtight Cylindrical Vessels with Doubly Curved Shells of Revolution by Using Jacobi-Ritz Method

2017 ◽  
Vol 2017 ◽  
pp. 1-20 ◽  
Author(s):  
Fuzhen Pang ◽  
Haichao Li ◽  
Kwangnam Choe ◽  
Dongyan Shi ◽  
Kwanghun Kim
Keyword(s):  
Forced Vibration ◽  
Vibration Analysis ◽  
Jacobi Polynomials ◽  
Ritz Method ◽  
The Finite Element Method ◽  
Shells Of Revolution ◽  
Vessel Structure ◽  
Forced Vibration Analysis ◽  
Doubly Curved ◽  
Thin Shell Theory

This paper presents free and forced vibration analysis of airtight cylindrical vessels consisting of elliptical, paraboloidal, and cylindrical shells by using Jacobi-Ritz Method. In this research, the theoretical model for vibration analysis is formulated by Flügge’s thin shell theory and the solution is obtained by Rayleigh-Ritz method. The vessel structure is divided into shell components (i.e., ellipsoid, parabolic, and cylinder) and their segments, and each displacement field of shell segments is represented by the Jacobi polynomials and the standard Fourier series. The continuous conditions at the interface are modeled by using the spring stiffness technique. The reliability and the accuracy of the present method are verified by comparing the results of the proposed method with the results of the previous literature and the finite element method (FEM). Moreover, some numerical results for free and forced vibration of elliptical-cylindrical-elliptical vessel (ECE vessel) and paraboloidal-cylindrical-elliptical vessel (PCE vessel) are reported.

scholarly journals Forced Vibration Analysis of Composite Beams Reinforced by Carbon Nanotubes

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 571
Author(s):  
Ömer Civalek ◽  
Şeref D. Akbaş ◽  
Bekir Akgöz ◽  
Shahriar Dastjerdi
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Forced Vibration ◽  
Vibration Analysis ◽  
Volume Fraction ◽  
Ritz Method ◽  
Time History ◽  
Composite Beams ◽  
Reinforced Composite ◽  
Forced Vibration Analysis

This paper presents forced vibration analysis of a simply supported beam made of carbon nanotube-reinforced composite material subjected to a harmonic point load at the midpoint of beam. The composite beam is made of a polymeric matrix and reinforced the single-walled carbon nanotubes with their various distributions. In the beam kinematics, the first-order shear deformation beam theory was used. The governing equations of problem were derived by using the Lagrange procedure. In the solution of the problem, the Ritz method was used, and algebraic polynomials were employed with the trivial functions for the Ritz method. In the solution of the forced vibration problem, the Newmark average acceleration method was applied in the time history. In the numerical examples, the effects of carbon nanotube volume fraction, aspect ratio, and dynamic parameters on the forced vibration response of carbon nanotube-reinforced composite beams are investigated. In addition, some comparison studies were performed, with special results of published papers to validate the using formulations.

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.

scholarly journals Free and forced vibration analysis of T-shaped plates with general elastic boundary supports

2018 ◽  
Vol 37 (2) ◽  
pp. 355-372 ◽  
Author(s):  
Xianjie Shi ◽  
Dongyan Shi
Keyword(s):  
Series Expansion ◽  
Forced Vibration ◽  
Vibration Analysis ◽  
Present Method ◽  
Ritz Method ◽  
Boundary Edge ◽  
Coupling Conditions ◽  
Solution Algorithms ◽  
Present Solution ◽  
Forced Vibration Analysis

This investigation proposes a series solution method for free and forced vibration analysis of T-shaped plate structure with general elastic supports, arbitrary coupling angles and elastically coupled conditions. The present solution framework can be readily utilized for various boundary or coupling conditions without modifying the solution algorithms or procedures. The general boundary and coupling conditions are considered with artificial spring method and can be easily achieved with assigning the restraining springs with specified values. In the current approach, the displacement functions for in-plane and bending vibration are expressed as a new form of trigonometric series expansion. The sine terms are introduced to eliminate the discontinuity along the boundary edge or coupling edge. Rayleigh–Ritz method is employed to determine the series expansion coefficients, which are treated as the generalized coordinates. Numerous numerical examples are carried out to verify the accuracy and reliability of the present method. The present method can be directly extended to more complicated structures with any number of plates.

Free and Forced Vibration Analysis of an Idealized Compliant Tower With Superstructure, due to Current Loads, Wave Excitation, and Earthquake Impulses

2014 ◽  
Author(s):  
Ankit ◽  
N. Datta
Keyword(s):  
Forced Vibration ◽  
Vibration Analysis ◽  
Natural Frequencies ◽  
Ritz Method ◽  
Mode Shapes ◽  
Wave Excitation ◽  
Uniform Beam ◽  
Compliant Tower ◽  
Forced Vibration Analysis ◽  
Beam Mode

A compliant tower (CT) is modeled as a partially dry, partially tapered, damped Timoshenko beam with the superstructure modeled as an eccentric tip mass, and a non-classical damped boundary at the base. The foundation is modeled as a combination of a linear spring and a torsional spring, along with linear and torsional dampers. The mean empty space factor due to the truss type structure of the tower is included. The effect of shear deformation and rotary inertia are included in the vibration analysis; with the non-uniform beam mode-shapes being a weighted sum of the uniform beam mode-shapes. The weights are evaluated by the Rayleigh-Ritz method, using the first ten modes and verified using Finite Element Method (FEM). The superstructure adds to the kinetic energy without affecting the stiffness of the beam, thereby reducing the natural frequencies. The weight of the superstructure acts as an axial compressive load on the beam, reducing its frequencies further. Kelvin-Voigt model of structural damping is included. A part of the structure being underwater, the virtual added inertia is included to calculate the wet natural frequencies. The CT is first subjected to steady current loads of a given velocity profile. The static deflection and overturning moment is estimated for current loads. The CT is then studied for wave excitation at various seas states. Morrison’s equation and Pierson-Moskowitz Spectrum are used to derive the forces for different sea states. The forced vibration analysis of the structure is done via Rayleigh-Ritz method and verified using FEM. The maximum horizontal deflection and shear stress of the base of the superstructure, and the normal/shear stresses at the foundation are analyzed. Finally, the CT is subjected to earthquake excitation, modeled as an arbitrary horizontal impact excitation at the base. The above forced vibration analysis is repeated.

scholarly journals Hull girder: Forced vibration analysis by propeller

2016 ◽  
Vol 9 (18) ◽  
pp. 35
Author(s):  
Franklin Domínguez
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Forced Vibration ◽  
Vibration Analysis ◽  
Element Model ◽  
Added Mass ◽  
Forced Vibrations ◽  
Hull Girder ◽  
Vessel Structure ◽  
Forced Vibration Analysis

The non-uniform wake around the propeller generates fluctuating forces on the propulsion shaft. This article presents a methodology used for the forced vibrations analysis of hull girder due to this propeller excitation. This approach is applied to a research boat considering the propeller working in the operating range using a finite element model including all ship structures, rudder, and propulsion lines with their respective supports. Added mass and damping in all submerged elements were also considered. Vibration levels acting in the vessel structure are compared with the limits proposed by ISO 6954 (2000). 

scholarly journals Forced Vibration Analysis of Laminated Composite Shells Reinforced with Graphene Nanoplatelets Using Finite Element Method

2020 ◽  
Vol 2020 ◽  
pp. 1-17 ◽  
Author(s):  
Trung Thanh Tran ◽  
Van Ke Tran ◽  
Pham Binh Le ◽  
Van Minh Phung ◽  
Van Thom Do ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Forced Vibration ◽  
Vibration Analysis ◽  
Shear Deformation Theory ◽  
Laminated Composite ◽  
Thermal Environments ◽  
Forced Vibration Analysis ◽  
Laminated Composite Shells ◽  
Element Method

This paper carries out forced vibration analysis of graphene nanoplatelet-reinforced composite laminated shells in thermal environments by employing the finite element method (FEM). Material properties including elastic modulus, specific gravity, and Poisson’s ratio are determined according to the Halpin–Tsai model. The first-order shear deformation theory (FSDT), which is based on the 8-node isoparametric element to establish the oscillation equation of shell structure, is employed in this work. We then code the computing program in the MATLAB application and examine the verification of convergence rate and reliability of the program by comparing the data of present work with those of other exact solutions. The effects of both geometric parameters and mechanical properties of materials on the forced vibration of the structure are investigated.

Forced vibration analysis of blade after selective laser shock processing based on Timoshenko’s beam theory

2020 ◽  
Vol 243 ◽  
pp. 112249 ◽  
Author(s):  
Peilin Fu ◽  
Jianghong Yuan ◽  
Xu Zhang ◽  
Guozheng Kang ◽  
Ping Wang ◽  
...  
Keyword(s):  
Forced Vibration ◽  
Vibration Analysis ◽  
Beam Theory ◽  
Laser Shock ◽  
Laser Shock Processing ◽  
Forced Vibration Analysis ◽  
Shock Processing
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