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Size-dependent thermomechanical vibration characteristics of rotating pre-twisted functionally graded shear deformable microbeams
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作者 Songye JIN Bo ZHANG +4 位作者 Wuyuan ZHANG Yuxing WANG Huoming SHEN Jing WANG Juan LIU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2024年第6期1015-1032,共18页
A three-dimensional(3D)thermomechanical vibration model is developed for rotating pre-twisted functionally graded(FG)microbeams according to the refined shear deformation theory(RSDT)and the modified couple stress the... A three-dimensional(3D)thermomechanical vibration model is developed for rotating pre-twisted functionally graded(FG)microbeams according to the refined shear deformation theory(RSDT)and the modified couple stress theory(MCST).The material properties are assumed to follow a power-law distribution along the chordwise direction.The model introduces one axial stretching variable and four transverse deflection variables including two pure bending components and two pure shear ones.The complex modal analysis and assumed mode methods are used to solve the governing equations of motion under different boundary conditions(BCs).Several examples are presented to verify the effectiveness of the developed model.By coupling the slenderness ratio,gradient index,rotation speed,and size effect with the pre-twisted angle,the effects of these factors on the thermomechanical vibration of the microbeam with different BCs are investigated.It is found that with the increase in the pre-twisted angle,the critical slenderness ratio and gradient index corresponding to the thermal instability of the microbeam increase,while the critical material length scale parameter(MLSP)and rotation speed decrease.The sensitivity of the fundamental frequency to temperature increases with the increasing slenderness ratio and gradient index,and decreases with the other increasing parameters.Moreover,the size effect can suppress the dynamic stiffening effect and enhance the Coriolis effect.Finally,the mode transition is quantitatively demonstrated by a modal assurance criterion(MAC). 展开更多
关键词 thermomechanical vibration rotating pre-twisted functionally graded(FG)microbeam refined shear deformation theory(RSDT) modified couple stress theory(MCST) modal assurance criterion(MAC)
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ODS & Modal Testing Using a Transmissibility Chain 被引量:1
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作者 Brian Schwarz Patrick McHargue Mark Richardson 《Sound & Vibration》 2018年第2期2-7,共6页
In this paper, we show how Operating Deflection Shapes (ODS’s) andmode shapes can be obtained experimentally from measurements thatare made using only two sensors and two short wires to connect them to amulti-channel... In this paper, we show how Operating Deflection Shapes (ODS’s) andmode shapes can be obtained experimentally from measurements thatare made using only two sensors and two short wires to connect them to amulti-channel acquisition system. This new test procedure is depicted inFigure 1. Not only is the equipment required to do a test much more costeffective, but this method can be used to test any sized test article, especiallylarge ones. 展开更多
关键词 Fourier spectrum (DFT) Auto power spectrum (APS) Crosspower spectrum (XPS) Frequency Response Function (FRF) OperatingDeflection Shape (ODS) Experimental Mode Shape (EMA Mode) OperationalMode Shape (OMA Mode) Modal assurance criterion (MAC) ShapeDifference Indicator (SDI)
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Optimal sensor placement in health monitoring of suspension bridge 被引量:9
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作者 LI BinBin LI DongSheng +1 位作者 ZHAO XueFeng OU JinPing 《Science China(Technological Sciences)》 SCIE EI CAS 2012年第7期2039-2047,共9页
Structural health monitoring(SHM) provides an effective approach to ensure the safety of structures.However,with the restriction of the cost of sensor system and data processing,only a small number of sensors could be... Structural health monitoring(SHM) provides an effective approach to ensure the safety of structures.However,with the restriction of the cost of sensor system and data processing,only a small number of sensors could be available in the health monitoring system(HMS).In order to obtain the best identification of structural characteristics,optimal sensor placement(OSP) becomes an inevitable task in the design of HMS.This paper introduces the process for determining the OSP in HMS of a suspension bridge,in which four different OSP methods have been investigated,including the effective independence(EI) method,the effective independence driving-point residue(EFI-DPR) method,the minimized modal assurance criterion(minMAC) method and the principal subset selection-based extended EI(PSS-EI) method.Then,three criteria,which are modal assurance matrix(MAC),condition number(CN) of mode shape matrix and determinant of Fisher information matrix(FIM),were employed to evaluate the effect of the OSP methods respectively.The result showed that the PSS-EI method developed has the ability to guarantee the highest determinant of FIM,a relatively small off-diagonal term of MAC and agreeable CN,as well as the deployment of sensors in a uniform and symmetric fashion for the studied bridge.Finally,the scheme obtained by PSS-EI was adopted in the HMS. 展开更多
关键词 structural health monitoring optimal sensor placement fisher information matrix modal assurance criterion
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Mode shape description of an aero-engine casing structure using Zernike moment descriptors 被引量:6
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作者 LIU Ying-chao ZANG Chao-ping 《航空动力学报》 EI CAS CSCD 北大核心 2011年第4期760-770,共11页
Vibration mode shape description of an aero-engine casing structure using Zernike moment descriptor(ZMD) was introduced in this paper.The mode shapes of the aero-engine casing structure can be decomposed as a linear c... Vibration mode shape description of an aero-engine casing structure using Zernike moment descriptor(ZMD) was introduced in this paper.The mode shapes of the aero-engine casing structure can be decomposed as a linear combination of a series of Zernike polynomials,with the feature of each Zernike polynomial reflecting a part of characteristic of mode shapes,based on Zernike moment transformation.Meanwhile,the reconstruction of mode shapes with ZMD was explored and its ability to filtering the noise contaminated in the mode shapes was studied.Simulation of the aero-engine casing structure indicated the advantage of this method to depict the mode shapes of a symmetric structure.Results demonstrate that the Zernike moment description of the mode shapes can effectively describe the double modes in the symmetric structure and also has the ability to remove or significantly reduce the influence of noise in the mode shapes.Such feature shows great practical value for further research on the correlation,model updating and model validation of the symmetric structure's finite element model. 展开更多
关键词 ZERNIKE mode shape modal assurance criterion(MAC) RECONSTRUCTION noise filtering
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A combination of damage locating vector method (DLV) and differential evolution algorithm (DE) for structural damage assessment 被引量:2
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作者 T. NGUYEN-THOI A. TRAN-VIET +2 位作者 N. NGUYEN-MINH T. VO-DUY V. HO-HUU 《Frontiers of Structural and Civil Engineering》 SCIE EI CSCD 2018年第1期92-108,共17页
In this study, a two-stage method is presented for identifying multiple damage scenarios. In the first stage, the damage locating vector (DLV) method using normalized cumulative energy (nce) is employed for damage... In this study, a two-stage method is presented for identifying multiple damage scenarios. In the first stage, the damage locating vector (DLV) method using normalized cumulative energy (nce) is employed for damage localization in structures. In the second stage, the differential evolution algorithm (DE) is used for damage severity of the structures. In addition, in the second stage, a modification of an available objective function is made for handing the issue of symmetric structures. To verify the effectiveness of the present technique, numerical examples of a 72-bar space truss and a one-span steel portal frame are considered. In addition, the effect of noise on the performance of the identification results is also investigated. The numerical results show that the proposed combination gives good assessment of damage location and extent for multiple structural damage cases. 展开更多
关键词 damage assessment damage locating vector method (DLV) differential evolution (DE) multiple damagelocation assurance criterion (MDLAC) mode shape error function
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Mode Tracking Scheme Among Remeshed Models for Structural Optimization
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作者 LIU Jun DING Ziqi +1 位作者 LU Qi HAN Xianhong 《Journal of Shanghai Jiaotong university(Science)》 EI 2019年第6期706-715,共10页
Mode tracking is required in the structural optimization when the frequencies of certain specified modes must be maintained within a suitable range.A simple tracking method employing the mode number is invalid or misl... Mode tracking is required in the structural optimization when the frequencies of certain specified modes must be maintained within a suitable range.A simple tracking method employing the mode number is invalid or misleading when local modes appear or disappear during mesh updating.In this work,a mode tracking scheme combining the nearest neighbor method(NNM)with the modal assurance criterion(MAC)is proposed.Several NNM algorithms are compared,and the k-dimensional tree(kd-tree)NNM is used to transform eigenvectors(mode shapes)from different scales to identical one.A threshold determination method is implemented for the MAC to assess the similarities in all the calculated modes.On the basis of the mode tracking scheme,specified modes can be tracked between different finite element method(FEM)models which have different meshes and optimized shapes.The effectiveness is verified through an example of shape optimization using an electric motor structure. 展开更多
关键词 mode tracking scheme remeshed models optimization process nearest neighbor method(NNM) modal assurance criterion(MAC)
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Topology optimization of piezocomposite resonator for maximizing excitation strength and synthesizing desired eigenmodes
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作者 Xuansheng Wang Zheqi Lin Yiru Ren 《Acta Mechanica Solida Sinica》 SCIE EI CSCD 2017年第5期531-539,共9页
A topology optimization method is proposed for the design of piezocomposite resonator with the aim of maximizing excitation strength and synthesizing desired eigenmodes. The objective function consists of maximizing t... A topology optimization method is proposed for the design of piezocomposite resonator with the aim of maximizing excitation strength and synthesizing desired eigenmodes. The objective function consists of maximizing the electromechanical coupling strength at the mode of interest. The topology layout of a structure with desired eigenmodes is obtained by adding the modal assurance criterion as additional constraint in the topology optimiza- tion model. Numerical examples are presented and the results illustrate that aside from maximizing the electromechanical coupling strength, the existing eigenmode of the piezo- composite resonator can be modified to be the desired one at the mode of interest. 展开更多
关键词 Topology optimizationPiezocomposite resonatorFinite element methodElectromechanical couplingcoefficientModal assurance criterion
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