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Semi-analytical approach for free vibration analysis of cracked beams resting on two-parameter elastic

null

《机械工程前沿（英文）》 2014年 第9卷 第2期   页码 191-202 doi: 10.1007/s11465-014-0293-y

摘要：

In present study, free vibration of cracked beams resting on two-parameter elastic foundation with elastically restrained ends is considered. Euler-Bernoulli beam hypothesis has been applied and translational and rotational elastic springs in each end considered as support. The crack is modeled as a mass-less rotational spring which divides beam into two segments. After governing the equations of motion, the differential transform method (DTM) has been served to determine dimensionless frequencies and normalized mode shapes. DTM is a semi-analytical approach based on Taylor expansion series that converts differential equations to recursive algebraic equations. The DTM results for the natural frequencies in special cases are in very good agreement with results reported by well-known references. Also, the DTM procedure yields rapid convergence beside high accuracy without any frequency missing. Comprehensive studies to analyze the effects of crack location, crack severity, parameters of elastic foundation and boundary conditions on dimensionless frequencies as well as effects of elastic boundary conditions on cracked beams mode shapes are carried out and some problems handled for first time in this paper. Since this paper deals with general problem, the derived formulation has capability for analyzing free vibration of cracked beam with every boundary condition.

关键词： free vibration     cracked beam     elastic foundation     restrained ends     differential transform method    

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Free vibration analysis of cracked thin plates by quasi-convex coupled isogeometric-meshfree method

Hanjie ZHANG,Junzhao WU,Dongdong WANG

《结构与土木工程前沿（英文）》 2015年 第9卷 第4期   页码 405-419 doi: 10.1007/s11709-015-0310-1

摘要： The free vibration analysis of cracked thin plates via a quasi-convex coupled isogeometric-meshfree method is presented. This formulation employs the consistently coupled isogeometric-meshfree strategy where a mixed basis vector of the convex B-splines is used to impose the consistency conditions throughout the whole problem domain. Meanwhile, the rigid body modes related to the mixed basis vector and reproducing conditions are also discussed. The mixed basis vector simultaneously offers the consistent isogeometric-meshfree coupling in the coupled region and the quasi-convex property for the meshfree shape functions in the meshfree region, which is particularly attractive for the vibration analysis. The quasi-convex meshfree shape functions mimic the isogeometric basis function as well as offer the meshfree nodal arrangement flexibility. Subsequently, this approach is exploited to study the free vibration analysis of cracked plates, in which the plate geometry is exactly represented by the isogeometric basis functions, while the cracks are discretized by meshfree nodes and highly smoothing approximation is invoked in the rest of the problem domain. The efficacy of the present method is illustrated through several numerical examples.

关键词： meshfree method     isogeometric analysis     quasi-convex isogeometric-meshfree method     free vibration     cracked thin plate    

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Free vibration analysis of laminated FG-CNT reinforced composite beams using finite element method

T. VO-DUY, V. HO-HUU, T. NGUYEN-THOI

《结构与土木工程前沿（英文）》 2019年 第13卷 第2期   页码 324-336 doi: 10.1007/s11709-018-0466-6

摘要： In the present study, the free vibration of laminated functionally graded carbon nanotube reinforced composite beams is analyzed. The laminated beam is made of perfectly bonded carbon nanotubes reinforced composite (CNTRC) layers. In each layer, single-walled carbon nanotubes are assumed to be uniformly distributed (UD) or functionally graded (FG) distributed along the thickness direction. Effective material properties of the two-phase composites, a mixture of carbon nanotubes (CNTs) and an isotropic polymer, are calculated using the extended rule of mixture. The first-order shear deformation theory is used to formulate a governing equation for predicting free vibration of laminated functionally graded carbon nanotubes reinforced composite (FG-CNTRC) beams. The governing equation is solved by the finite element method with various boundary conditions. Several numerical tests are performed to investigate the influence of the CNTs volume fractions, CNTs distributions, CNTs orientation angles, boundary conditions, length-to-thickness ratios and the numbers of layers on the frequencies of the laminated FG-CNTRC beams. Moreover, a laminated composite beam combined by various distribution types of CNTs is also studied.

关键词： free vibration analysis     laminated FG-CNTRC beam     finite element method     first-order shear deformation theory     composite material    

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A frequency error estimation for isogeometric analysis of Kirchhoff–Love cylindrical shells

《结构与土木工程前沿（英文）》 doi: 10.1007/s11709-023-0006-x

摘要： A frequency error estimation is presented for the isogeometric free vibration analysis of Kirchhoff–Love cylindrical shells using both quadratic and cubic basis functions. By analyzing the discrete isogeometric equations with the aid of harmonic wave assumption, the frequency error measures are rationally derived for the quadratic and cubic formulations for Kirchhoff–Love cylindrical shells. In particular, the governing relationship of the continuum frequency for Kirchhoff–Love cylindrical shells is naturally embedded into the frequency error measures without the need of explicit frequency expressions, which usually are not trivial for the shell problems. In accordance with these theoretical findings, the 2nd and 4th orders of frequency accuracy are attained for the isogeometric schemes using quadratic and cubic basis functions, respectively. Numerical results not only thoroughly verify the theoretical convergence rates of frequency solutions, but also manifest an excellent magnitude match between numerical and theoretical frequency errors for the isogeometric free vibration analysis of Kirchhoff–Love cylindrical shells.

关键词： isogeometric analysis     Kirchhoff–Love cylindrical shell     free vibration     frequency error     convergence    

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Free vibration analysis of functionally graded porous curved nanobeams on elastic foundation in hygro–thermo–magnetic

《结构与土木工程前沿（英文）》 2023年 第17卷 第4期   页码 584-605 doi: 10.1007/s11709-023-0916-7

摘要： Herein, a two-node beam element enriched based on the Lagrange and Hermite interpolation function is proposed to solve the governing equation of a functionally graded porous (FGP) curved nanobeam on an elastic foundation in a hygro–thermo–magnetic environment. The material properties of curved nanobeams change continuously along the thickness via a power-law distribution, and the porosity distributions are described by an uneven porosity distribution. The effects of magnetic fields, temperature, and moisture on the curved nanobeam are assumed to result in axial loads and not affect the mechanical properties of the material. The equilibrium equations of the curved nanobeam are derived using Hamilton’s principle based on various beam theories, including the classical theory, first-order shear deformation theory, and higher-order shear deformation theory, and the nonlocal elasticity theory. The accuracy of the proposed method is verified by comparing the results obtained with those of previous reliable studies. Additionally, the effects of different parameters on the free vibration behavior of the FGP curved nanobeams are investigated comprehensively.

关键词： functionally graded porous material     curved nanobeam     hygro–thermo–magnetic     enriched finite element method    

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Simplified analytical solution for free vibration characteristics of Hardfill dam

XIAO Wei, HE Yunlong, ZHANG Yanfeng

《结构与土木工程前沿（英文）》 2008年 第2卷 第3期   页码 219-225 doi: 10.1007/s11709-008-0037-3

摘要： Formulas for computing natural frequencies and modes of Hardfill dams are derived based on one-dimensional shear wedge theory, in which the influences of the upstream concrete face and hydrodynamic pressure of water on the dams’ natural frequencies and modes are discussed. Furthermore, the seismic responses of Hardfill dams are calculated using response spectrum method. An example is analyzed to compare the differences of natural frequencies and modes between shear wedge method and FEM. Then the applicability and accuracy of shear wedge method to analyze free vibration characteristics of Hardfill dams are proven.

关键词： upstream concrete     hydrodynamic pressure     vibration     one-dimensional     applicability    

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An extended cell-based smoothed discrete shear gap method (XCS-FEM-DSG3) for free vibration analysis

M. H. NGUYEN-THOI,L. Le-ANH,V. Ho-HUU,H. Dang-TRUNG,T. NGUYEN-THOI

《结构与土木工程前沿（英文）》 2015年 第9卷 第4期   页码 341-358 doi: 10.1007/s11709-015-0302-1

摘要： A cell-based smoothed discrete shear gap method (CS-FEM-DSG3) was recently proposed and proven to be robust for free vibration analyses of Reissner-Mindlin shell. The method improves significantly the accuracy of the solution due to softening effect of the cell-based strain smoothing technique. In addition, due to using only three-node triangular elements generated automatically, the CS-FEM-DSG3 can be applied flexibly for arbitrary complicated geometric domains. However so far, the CS-FEM-DSG3 has been only developed for analyzing intact structures without possessing internal cracks. The paper hence tries to extend the CS-FEM-DSG3 for free vibration analysis of cracked Reissner-Mindlin shells by integrating the original CS-FEM-DSG3 with discontinuous and crack−tip singular enrichment functions of the extended finite element method (XFEM) to give a so-called extended cell-based smoothed discrete shear gap method (XCS-FEM-DSG3). The accuracy and reliability of the novel XCS-FEM-DSG3 for free vibration analysis of cracked Reissner-Mindlin shells are investigated through solving three numerical examples and comparing with commercial software ANSYS.

关键词： cracked Reissner-Mindlin shell     free vibration analysis     cell-based smoothed discrete shear gap method (CS-FEM-DSG3)     extended cell-based smoothed discrete shear gap method (XCS-FEM-DSG3)     smoothed finite element methods (SFEM)    

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Vibration suppression of speed-controlled robots with nonlinear control

Paolo BOSCARIOL,Alessandro GASPARETTO

《机械工程前沿（英文）》 2016年 第11卷 第2期   页码 204-212 doi: 10.1007/s11465-016-0380-3

摘要：

In this paper, a simple nonlinear control strategy for the simultaneous position tracking and vibration damping of robots is presented. The control is developed for devices actuated by speed-controlled servo drives. The conditions for the asymptotic stability of the closed-loop system are derived by ensuring its passivity. The capability of achieving improved trajectory tracking and vibration suppression is shown through experimental tests conducted on a three-axis Cartesian robot. The control is aimed to be compatible with most industrial applications given the simplicity of implementation, the reduced computational requirements, and the use of joint position as the only measured signal.

关键词： industrial robot     nonlinear control     vibration damping     model-free control     motion control    

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Flow, thermal, and vibration analysis using three dimensional finite element analysis for a flux reversal

B. VIDHYA,K. N. SRINIVAS

《能源前沿（英文）》 2016年 第10卷 第4期   页码 424-440 doi: 10.1007/s11708-016-0423-9

摘要： This paper presents the simulation of major mechanical properties of a flux reversal generator (FRG) viz., computational fluid dynamic (CFD), thermal, and vibration. A three-dimensional finite element analysis (FEA) based CFD technique for finding the spread of pressure and air velocity in air regions of the FRG is described. The results of CFD are mainly obtained to fine tune the thermal analysis. Thus, in this focus, a flow analysis assisted thermal analysis is presented to predict the steady state temperature distribution inside FRG. The heat transfer coefficient of all the heat producing inner walls of the machine are evaluated from CFD analysis, which forms the main factor for the prediction of accurate heat distribution. The vibration analysis is illustrated. Major vibration sources such as mechanical, magnetic and applied loads are covered elaborately which consists of a 3D modal analysis to find the natural frequency of FRG, a 3D static stress analysis to predict the deformation of the stator, rotor and shaft for different speeds, and an unbalanced rotor harmonic analysis to find eccentricity of rotor to make sure that the vibration of the rotor is within the acceptable limits. Harmonic analysis such as sine sweep analysis to identify the range of speeds causing high vibrations and steady state vibration at a mode frequency of 1500 Hz is presented. The vibration analysis investigates the vibration of the FRG as a whole, which forms the contribution of this paper in the FRG literature.

关键词： flux reversal generator     air velocity     computation fluid dynamics     thermal analysis     vibration analysis     finite element analysis    

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Conformal analysis of fundamental frequency of vibration of elastic clamped plates

QI Hongyuan, ZHU Hengjun

《机械工程前沿（英文）》 2007年 第2卷 第4期   页码 429-432 doi: 10.1007/s11465-007-0073-z

摘要： To calculate the fundamental frequency of vibration of special-shaped and elastic clamped plates, the conformal mapping theory is adopted to separate the interpolating points of a complicated boundary into odd and even sequences, both of which can be mutually iterated, so that the conformal mapping function between the complicated region and the unit dish region is established. Trigonometric interpolation and convergence along the normal direction methods are provided, and the complex coefficients of the conformal mapping function are calculated. Galerkin method is used to obtain the solution of fundamental frequency in the vibrating differential function of the complicated vibrating region. Finally, taking ellipse elastic clamped plates as an example, the effects on fundamental frequency coefficient caused by eccentric ratio and area size are analyzed.

关键词： direction     theory     vibration     odd     complicated boundary    

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Application of python-based Abaqus preprocess and postprocess technique in analysis of gearbox vibration

Guilian YI, Yunkang SUI, Jiazheng DU

《机械工程前沿（英文）》 2011年 第6卷 第2期   页码 229-234 doi: 10.1007/s11465-011-0128-z

摘要：

To reduce vibration and noise, a damping layer and constraint layer are usually pasted on the inner surface of a gearbox thin shell, and their thicknesses are the main parameters in the vibration and noise reduction design. The normal acceleration of the point on the gearbox surface is the main index that can reflect the vibration and noise of that point, and the normal accelerations of different points can reflect the degree of the vibration and noise of the whole structure. The K-S function is adopted to process many points’ normal accelerations as the comprehensive index of the vibration characteristics of the whole structure, and the vibration acceleration level is adopted to measure the degree of the vibration and noise. Secondary development of the Abaqus preprocess and postprocess on the basis of the Python scripting programming automatically modifies the model parameters, submits the job, and restarts the analysis totally, which avoids the tedious work of returning to the Abaqus/CAE for modifying and resubmitting and improves the speed of the preprocess and postprocess and the computational efficiency.

关键词： Abaqus secondary development     Python language     vibration and noise reduction     K-S function     vibration acceleration level    

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Numerical analysis of vehicle-bridge coupling vibration concerning nonlinear stress-dependent damping

Pengfei LI; Jinquan ZHANG; Shengqi MEI; Zhenhua DONG; Yan MAO

《结构与土木工程前沿（英文）》 2022年 第16卷 第2期   页码 239-249 doi: 10.1007/s11709-021-0804-y

摘要： Damping is known to have a considerable influence on the dynamic behavior of bridges. The fixed damping ratios recommended in design codes do not necessarily represent the complicated damping characteristics of bridge structures. This study investigated the application of stress-dependent damping associated with vehicle-bridge coupling vibration and based on that investigation proposed the stress-dependent damping ratio. The results of the investigation show that the stress-dependent damping ratio is significantly different from the constant damping ratio (5%) defined in the standard specification. When vehicles travel at speeds of 30, 60, and 90, the damping ratios of the bridge model are 3.656%, 3.658%, and 3.671%, respectively. The peak accelerations using the regular damping ratio are 18.9%, 21.3%, and 14.5% of the stress-dependent damping ratio, respectively. When the vehicle load on the bridge is doubled, the peak acceleration of the mid-span node increases by 5.4 times, and the stress-related damping ratio increases by 2.1%. A corrugated steel-web bridge is being used as a case study, and the vibration response of the bridge is compared with the measured results. The acceleration response of the bridge which was calculated using the stress-dependent damping ratio is significantly closer to the measured acceleration response than that using the regular damping ratio.

关键词： vehicle-bridge vibration system     dynamic analysis     stress-dependent damping     energy dissipation    

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Vibration analysis of medium and small span bridges subjected to mixed marshalling freight trains

LI Qi, WU Dingjun, HUANG Xiaobin

《结构与土木工程前沿（英文）》 2008年 第2卷 第2期   页码 133-138 doi: 10.1007/s11709-008-0019-5

摘要： It has been reported several times that train derailment occurs when mixed marshalling freight trains traverse bridges at high speeds in China. This study aims to explain this phenomenon numerically based on the train-bridge coupling vibration theory and its associated computer program. The train-bridge vibration characteristic is analyzed by a computer program when mixed marshalling freight trains traverse 32-meter-span prestressed concrete simple beam bridges. The mechanism that dynamic responses of the bridges are prominent and that empty trains are inclined to derail are derived from the dynamic responses analysis. The analysis indicates that the significant differences of axle loads between heavy vehicles and empty vehicles produce periodic forced loadings of large amplitudes. These periodic loadings cause severe vibration of bridges. In turn, severe vibration of the bridges produces intensive counteraction to empty vehicles.

关键词： train-bridge vibration     vibration characteristic     associated computer     train-bridge     phenomenon    

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Vibration analysis of blade-disc coupled structure of compressor

WANG Chunjie, SONG Shunguang, ZONG Xiao

《能源前沿（英文）》 2008年 第2卷 第3期   页码 302-305 doi: 10.1007/s11708-008-0064-8

摘要： While a 3D assembly model of blade-disc structure was established, a finite element model for calculating the vibration characteristics during blade-disc coupling was built by taking into consideration the coupling action of contact stress between the blade and the disc. The vibration characteristics of the blade-disc coupling structure was calculated and analyzed using cycle analysis method with the aid of ANSYS software. The modeling experiment shows that this method is feasible for analyzing the rabbet assembly structure.

关键词： blade-disc coupling     assembly     experiment     vibration     blade-disc structure    

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Kinetic energy based model assessment and sensitivity analysis of vortex induced vibration of segmental

Nazim Abdul NARIMAN

《结构与土木工程前沿（英文）》 2017年 第11卷 第4期   页码 480-501 doi: 10.1007/s11709-017-0435-5

摘要： In this paper, semi 3D models for segmental Bridge decks are created in ABAQUS CFD program with the support of MATLAB codes to simulate and analyze vortex shedding generated due to wind excitation through considering the stationary position of the deck. Three parameters (wind speed, deck streamlined length and dynamic viscosity of the air) are dedicated to study their effects on the kinetic energy of the system in addition to the shapes and patterns of the vortices. Two benchmarks from the literature Von Karman and Dyrbye and Hansen are considered to validate the vortex shedding aspects for the CFD models. Good agreement between the results of the benchmarks and the semi 3D models has been detected. Latin hypercube experimental method is dedicated to generate the surrogate models for the kinetic energy of the system and the lift forces. Variance based sensitivity analysis is utilized to calculate the main sensitivity indices and the interaction orders for all the three parameters. The kinetic energy approach performed very well in revealing the rational effects and the roles of each parameter in the generation of vortex shedding and predicting vortex induced vibration of the deck.

关键词： vortex induced vibration     reynolds number     kinetic energy     vorticity     latin hypercube sampling    

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标题 作者 时间 类型 操作

Semi-analytical approach for free vibration analysis of cracked beams resting on two-parameter elastic

null

期刊论文

Free vibration analysis of cracked thin plates by quasi-convex coupled isogeometric-meshfree method

Hanjie ZHANG,Junzhao WU,Dongdong WANG

期刊论文

Free vibration analysis of laminated FG-CNT reinforced composite beams using finite element method

T. VO-DUY, V. HO-HUU, T. NGUYEN-THOI

期刊论文

A frequency error estimation for isogeometric analysis of Kirchhoff–Love cylindrical shells

期刊论文

Free vibration analysis of functionally graded porous curved nanobeams on elastic foundation in hygro–thermo–magnetic

期刊论文

Simplified analytical solution for free vibration characteristics of Hardfill dam

XIAO Wei, HE Yunlong, ZHANG Yanfeng

期刊论文

An extended cell-based smoothed discrete shear gap method (XCS-FEM-DSG3) for free vibration analysis

M. H. NGUYEN-THOI,L. Le-ANH,V. Ho-HUU,H. Dang-TRUNG,T. NGUYEN-THOI

期刊论文

Vibration suppression of speed-controlled robots with nonlinear control

Paolo BOSCARIOL,Alessandro GASPARETTO

期刊论文

Flow, thermal, and vibration analysis using three dimensional finite element analysis for a flux reversal

B. VIDHYA,K. N. SRINIVAS

期刊论文

Conformal analysis of fundamental frequency of vibration of elastic clamped plates

QI Hongyuan, ZHU Hengjun

期刊论文

Application of python-based Abaqus preprocess and postprocess technique in analysis of gearbox vibration

Guilian YI, Yunkang SUI, Jiazheng DU

期刊论文

Numerical analysis of vehicle-bridge coupling vibration concerning nonlinear stress-dependent damping

Pengfei LI; Jinquan ZHANG; Shengqi MEI; Zhenhua DONG; Yan MAO

期刊论文

Vibration analysis of medium and small span bridges subjected to mixed marshalling freight trains

LI Qi, WU Dingjun, HUANG Xiaobin

期刊论文

Vibration analysis of blade-disc coupled structure of compressor

WANG Chunjie, SONG Shunguang, ZONG Xiao

期刊论文

Kinetic energy based model assessment and sensitivity analysis of vortex induced vibration of segmental

Nazim Abdul NARIMAN

期刊论文