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A Structural Damage Detection Method Using XGBoost Algorithm on natural frequencies

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系统仿真技术 2021年第3期17卷 210-215页

作者： DONG Zhenyuan ZHANG Peng Technology and Engineering Center for Space Utilization Chinese Academy of SciencesBeijing 100094China University of Chinese Academy of Sciences Beijing 100049China

Structural damage detection and monitoring are vital in product lifecycle management of aeronautic system in space *** this paper,a method based on vibration characteristics and ensemble learning algorithm is proposed to achieve damage *** on the small volume of modal frequency data for intact and damage structures,the extreme gradient boosting algorithm enables robust damage localization under noise condition of wing-like structures on numerical *** method shows satisfactory performance on localizing damage with random geometrical profiles in most cases.

关键词： structural damage detection ensemble learning XGBoost natural frequencies

Determination of natural frequencies of Multilayered Plates by Mixed Finite Elements

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Journal of Mechanics Engineering and Automation 2014年第10期4卷 820-827页

作者： Roberto S. Carnicer Braian A. Desia Rodolfo A. Schwarz Faculty of Engineering University of Belgrano Autonomous City of Buenos Aires C1426BMJ Argentina

natural frequencies for multilayer plates are calculated by mixed finite element method. The main object of this paper is to use the mixed model for multilayer plates, analyzing each layer as an isolated plate, where the continuity of displacements is achieved by Lagrange multipliers （representing static variables）. This procedure allows us to work with any model for single plate （so as to ensure the proper behavior of each layer）, and the complexity of the multilayer system is avoided by ensuring the condition of displacements by the Lagrange multipliers （static variables）. The plate is discretized by finite element modeling based on a primary hybrid model, where the domain is divided by quadrilateral, both for the displacement field and static variables. This mixed element for plates was implemented and several examples of vibrations have been verified successfully by the results obtained by other methods in the literature.

关键词： Mixed finite element multilayer plate Lagrange multipliers natural frequencies free vibrations.

FEA-based Geometrical Modification of Switched Reluctance Motor for Radial Force Reduction

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Chinese Journal of Electrical Engineering 2024年第1期10卷 124-135页

作者： Rani S Jayapragash R School of Electrical Engineering Vellore Institute of TechnologyChennai 600127India

Switched reluctance motors(SRMs)are becoming increasingly popular in the automotive sector owing to their robust ***,SRMs are preferred particularly for EV applications owing to their fault tolerance,magnet-free structure,and high power/torque *** main concerns of SRM compared to other machines include torque ripple and *** primary cause of vibration is the radial force created by the SRM.A geometry-based modification of the SRM to reduce the radial force without significantly changing the average torque produced is *** primary goal is to design a 4-phase,8/6 SRM with a lower radial *** possible geometrical alterations are proposed:one with square windows and the other with circular holes on the rotor *** windows are sized and positioned to avoid flux *** criteria are developed for the optimal window size and *** element analysis(FEA)modelling of the SRM is used to validate its *** FEA results are compared with the performance parameters obtained using the analytical *** the multiphysics design tool ANSYS to obtain the natural frequencies and associated deformations through modal *** to the conventional geometry,the radial force is significantly reduced by providing windows.

关键词： 8/6 SRM radial force modal analysis FEA analysis natural frequencies SRM with windows

Revisited dynamic modeling and eigenvalue analysis of the cable-stayed beam

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Acta Mechanica Sinica 2020年第4期36卷 950-963页

作者： Lianhua Wang Xiaoyu Zhang Kai He Jian Peng College of Civil Engineering Hunan UniversityChangsha 410082China Key Laboratory for Wind and Bridge Engineering of Hunan Province Hunan UniversityChangsha 410082China Guangxi Communications Design Group Co. LtdNanning 530022China Hunan Provincial Key Laboratory of Structures for Wind Resistance and Vibration Control Hunan University of Science and TechnologyXiangtan 411201China

In this study,the Hamilton’s principle is applied to revisit the dynamic modeling of the cable-stayed beam,and the motion equations governing the nonlinear response of the cable-stayed beam are *** corresponding boundary terms are transformed to the dynamic equilibrium conditions through the continuity of the displacement at the anchoring *** the standard condensation procedure,the condensed model of the cable-stayed beam is *** eigenvalue analysis is performed to determine the closed-form eigenvalue solution of the linear problems,and two types of eigenvalue solution are *** is shown that the frequency spectrum of the cable-stayed beam exhibits the curve veering and crossover *** to these phenomena,the mode shapes of the cable-stayed beam may exhibit the coupling ***,the discrete model of the cable-stayed beam is determined,and the possible nonlinear interactions are discussed.

关键词： Cable-stayed beam Dynamic modeling natural frequencies Mode shapes Curve veering

INVESTIGATION OF THE THICKNESS VARIABILITY AND MATERIAL HETEROGENEITY EFFECTS ON FREE VIBRATION OF THE VISCOELASTIC CIRCULAR PLATES

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Acta Mechanica Solida Sinica 2013年第1期26卷 83-98页

作者： M.Shariyat A.A.Jafari M.M.Alipour Faculty of Mechanical Engineering K.N.Toosi University of Technology

The present study deals with free vibration analysis of variable thickness viscoelastic circular plates made of heterogeneous materials and resting on two-parameter elastic foundations in addition to their edge conditions. It is assumed that the viscoelastic material properties vary in the transverse and radial directions simultaneously. The complex modulus approach is employed in conjunction with the elastic-viscoelastic correspondence principle to obtain the solution. The governing equations are solved by means of a power series solution. Finally, a sensitivity analysis including evaluation of effects of various edge conditions, thickness variations, coefficients of the elastic foundation, and material loss factor and heterogeneity on the natural frequencies and modal loss factors is accomplished.

关键词： viscoelastic variable thickness circular plate natural frequencies elastic foundation material heterogeneity power series solution

Numerical study of the natural frequency and mode shape of prototype Francis turbine runner

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Journal of Hydrodynamics 2022年第1期34卷 125-134页

作者： Wei Wang Ling-jiu Zhou Xiang Xia Xi-jie Song Zheng-wei Wang Department of Energy and Power Engineering Tsinghua UniversityBeijing100084China College of Water Resources and Civil Engineering China Agricultural UniversityBeijing100083China

The prediction of the dynamic behavior of the structure is a key to ensure the safe and stable operation of the *** this paper,the acoustic fluid-structure coupling method is used to study the natural frequency and the mode shape of the prototype Francis turbine *** an added mass,the natural frequency of the runner in the water is *** added mass force mc is reduced under the cavitation,resulting in an increase of the natural frequency,but it is still much lower than the frequency in the *** the order number of the runner mode increases,the added mass force increases,and the frequency reduction rate *** 0ND to 4ND,the nodal lines on the upper crown of the runner gradually disappear,and the mode shape becomes more *** modal displacement D*in the circumferential direction of the runner and the outlet edge of the blade are selected to compare the structural mode shapes under different operating *** results show that the amplitude of D*in the circumferential direction of the runner gradually increases from the upper crown to the lower band of the runner,and the curve assumes a symmetrical distribution of sinusoidal waves,whose number is twice of that of the nodal lines of the *** D*value changes are caused by the added mass in the water,and it will further change under the cavitation *** means that the vibration form of the structure has *** will cause damages to the runner under the resonance conditions at different positions and in different degrees.

关键词： Runner natural frequencies mode shapes modal displacements acoustic fluid-structure coupling method

Flapwise Bending Vibration Analysis of Rotating Tapered Rayleigh Beams for the Application of Offshore Wind Turbine Blades

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China Ocean Engineering 2021年第4期35卷 544-553页

作者： CHEN Yan-fei ZANG Zhi-peng DONG Shao-hua AO Chuan LIU Hao MA Shang HOU Fu-heng FENG Wei School of Mechanical and Transportation Engineering China University of PetroleumBeijing 102249China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian 116024China State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China CIMC Offshore Co.Ltd Shenzhen 518000China

The flapwise bending vibrational equations of tapered Rayleigh beam are derived based on Hamilton’s *** corresponding vibrational characteristics of rotating tapered Rayleigh beams are investigated via variational iteration method(VIM).natural frequencies and corresponding mode shapes are examined under various rotation speed,taper ratio and slenderness ratio focusing on two types of tapered *** convergence of VIM is examined as part of the *** of VIM solution is made by referring to results available in other literature and corresponding results show that VIM is capable of yielding precise results in a very efficient way.

关键词： tapered Rayleigh beam flapwise bending vibration variational iteration natural frequencies convergence

Multi-wavelength pulse generation using flattop optical frequency comb and arrayed waveguide grating

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Chinese Optics Letters 2012年第12期10卷 82-83页

作者：窦玉杰张洪明姚敏玉 State Key Laboratory on Integrated Optoelectronics Tsinghua National Laboratory for Information Science and TechnologyDepartment of Electronic EngineeringTsinghua University

A scheme of multi-wavelength pulse generator using optical frequency comb and arrayed waveguide grating （AWG） is proposed and experimentally demonstrated. A flattop optical frequency comb is shaped into multiple narrowband Gaussian spectra by using an AWG which contains a number of Gaussian channels, and then multi-wavelength optical pulses are achieved. In the experiment, six wavelength pulses with full width at half-maximum （FWHM） of 14.6 ps at I0 GHz are obtained, and two wavelength-interleaved pulse trains at 20 GHz and four wavelength-interleaved multi-wavelength optical pulses. This scheme has and time-interval can be readily controlled. pulse trains at 40 GHz are demonstrated by using the flexibility because the pulse width, the repetition rate,

关键词： natural frequencies Optical materials Pulse generators Telecommunication Wavelength

Flextensional fiber Bragg grating-based accelerometer for low frequency vibration measurement

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Chinese Optics Letters 2011年第9期9卷 25-28页

作者：张敬花乔学光忽满利冯忠耀高宏杨扬周锐 Department of Physics Northwest University of China

The intelligent structural health monitoring method, which uses a fiber Bragg grating （FBG） sensor, is a new approach in the field of civil engineering. However, it lacks a reliable FBG-based accelerometer for taking structural low frequency vibration measurements. In this letter, a fiextensional FBG-based accelerometer is proposed and demonstrated. The experimental results indicate that the natural frequency of the developed accelerometer is 16.7 Hz, with a high sensitivity of 410.7 pm/g. In addition, it has a broad and flat response over low frequencies ranging from 1 to 10 Hz. The natural frequency and sensitivity of the accelerometer can be tuned by adding mass to tailor the sensor performance to specific applications. Experimental results are presented to demonstrate the good performance of the proposed FBG-based accelerometer. These results show that the proposed accelerometer is satisfactory for low frequency vibration measurements.

关键词： Accelerometers Civil engineering Frequency response natural frequencies Sensors Structural health monitoring Vibration measurement

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