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Vibration response and Stress Analysis of Planar Elastic Tube Bundle Induced by Fluid Flow

Chinese Journal of Mechanical Engineering 2018年第2期31卷 89-96页

作者： De-Rong Duan Pei-Qi Ge Wen-Bo Bi Yan-Ying Dong School of Mechanical Engineering Shandong University Key Laboratory of High Efficiency and Clean Mechanical Manufacture of Ministry of Education Shandong University

Flow?induced vibration plays a positive role on heat transfer enhancement. Meanwhile, it is also a negative factor for fatigue strength. Satisfying the fatigue strength is the primary prerequisite for heat transfer enhancement. This paper numerically studied the flow?induced vibration of planar elastic tube bundle based on a two?way fluid–structure interaction(FSI) calculation. The numerical calculation involved the unsteady, three?dimensional incompressible governing equations solved with finite volume approach and the dynamic balance equation of planar elastic tube bundle solved with finite element method combined with dynamic mesh scheme. The numerical approach was verified by comparing with the published experimental results. Then the vibration trajectory, deformation and stress contour of planar elastic tube bundle were all studied. Results show that the combined movement of planar elastic tube bundle represents the agitation from inside to outside. The vibration of out?of?plane is the main vibration form with the typically sinusoidal behavior because the magnitude of displacement along the out?of?plane direction is the 100 times than the value of in?plane direction. The dangerous point locates in the innermost tube where the equivalent stress can be utilized to study the multiaxial fatigue of planar elastic tube bundle due to the alternating stress concentration. In the velocity range of 0.2-3 m/s, it is inferred that the vibration amplitude plays a role on the stress response and the stress amplitude is susceptible to the fluid velocity. This research paves a way for studying the fatigue strength of planar elastic tube bundle by flow?induced vibration.

关键词： Flow?induced vibration Planar elastic tube bundle Vibration response Stress analysis

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Nonlinear Vibration response characteristics of a dual-rotor-bearing system with squeeze film damper

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Chinese Journal of Aeronautics 2021年第10期34卷 128-147页

作者： Xinxing MA Hui MA Haiqin QIN Xumin GUO Chenguang ZHAO Mingyue YU School of Mechanical Engineering and Automation Northeastern UniversityShenyang J10819China Institute of vibration Shock and NoiseShanghai Jiao Tong UniversityShanghai 200240China Key Laboratory of vibration and Control of Aero-Propulsion System Ministry of Education Northeastern UniversityShenyang 110819China Department of Aeronautical Mechanics Naval Aeronautical and Astronautical University Qingdao CampusQingdao 266041China

Rolling bearing and Squeeze Film Damper(SFD)are used in rotor support structures,and most researches on the nonlinear rotor-bearing system are focused on the simple rotor-bearing systems.This work emphasizes the comparative analysis of the influence of SFD on the nonlinear dynamic behavior of the dual-rotor system supported by rolling bearings.Firstly,a reduced dynamic model is established by combining the Finite Element(FE)method and the freeinterface method of component mode synthesis.The proposed model is verified by comparing the natural characteristics obtained from an FE model with those from the experiment.Then,the steady-state Vibration responses of the system with or without SFD are solved by the numerical integration method.The influences of the ball bearing clearance,unbalance,centralizing spring stiffness and oil film clearance of SFD on the nonlinear steady-state Vibration responses of the dual-rotor system are analyzed.Results show that SFD can effectively suppress the amplitude jump of the dual rotor system sustaining two rotors unbalance excitations.As the ball bearing clearance or unbalance increases,the amplitude jump phenomenon becomes more obvious,the resonance hysteresis phenomenon strengthens or weakens,the resonant peaks shift to the left or the right,respectively.SFD with unreasonable parameters will aggravate the system vibration,the smaller the oil film clearance,the better the damping performance of the SFD,the larger the centralizing spring stiffness is,the larger resonance amplitudes are.

关键词： dual-rotor rolling bearing squeeze film damper finite element method Vibration response

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Modal analysis of subway tunnel in soft soil during operation

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Underground Space 2023年第1期8卷 181-195页

作者： Ling Wan Xiongyao Xie Lujun Wang Pan Li Qiang Huang College of Civil Engineering and Architecture Nanchang Hangkong UniversityNanchang 330063China Jiangxi Transportation Institute Co LtdNanchang 330200China Key Laboratory of Geotechnical and Underground Engineering Ministry of EducationTongji UniversityShanghai 20092China Center for Hypergravity Experimental and Interdisciplinary Research MOE Key Laboratory of Soft Soils and Geoenvironmental EngineeringCollege of Civil Engineering and ArchitectureZhejiang UniversityHangzhou 310058China Institute of Geotechnical Engineering Ningbo UniversityNingbo 315211China

Modal parameters are of great significance in civil engineering because they can characterize the properties of structures and be used for vibration control and structural health monitoring.Subway tunnels are long linear truss structures combined with the mutual cou-pling of the surrounding soil.Therefore,the operational modal analysis of a mutual coupling tunnel is complicate,as is the modal iden-tification of shield tunnels in a time–frequency domain,and these are hot civil engineering topics.Using the shield tunnel of Shanghai metro line No.12 project as a case study,we carried out the Vibration response monitoring of a subway tunnel during operation and presented methods to identify structural modal parameters.The modal parameters of lower vibration modes were estimated using response measurements.Modal frequencies and shapes were identified with high precision and accuracy using the orthogonal polynomial clustering algorithm under hammer excitation conditions and the autoregressive-moving-average model under ambient excitation con-ditions.The dynamic behavior of a mutual coupling tunnel presented obvious low frequency characteristics,and the first 9th order mode frequencies were less than 100 Hz.The diagonal values of the modal assurance criteria were all greater than 0.85.The modal parameters can be used for the health monitoring of operational subway tunnels.

关键词： Monitoring method Modal identification Vibration response Operational subway tunnel

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Modal analysis strategy and nonlinear dynamic characteristics of complicated aero-engine dual-rotor system with rub-impact

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Chinese Journal of Aeronautics 2022年第1期35卷 184-203页

作者： Pingchao YU Guo CHEN Lunxu LI College of Civil Aviation Nanjing University of Aeronautics and AstronauticsNanjing 211106China

This paper aims to gain insight into the nonlinear modal characteristics and the possible influence of the modes on the responses for the practical dual-rotor system with rub-impact in aero-engine.The finite solid element method combined with a constraint stiffness model produced by rub-impact is introduced to build the governing equation of the complicated nonlinear dual-rotor system.In order to deal with the efficiency and numerical divergence in the process of solving the nonlinear modes of this large-scale nonlinear system,an analysis strategy is proposed by integrating a two-layer reduction technique into the harmonic balance method.The effectiveness of the analysis strategy is validated by applying to a simple rotor system,which can easily obtain the theoretical result.Based on the modeling method and analysis strategy,the modal characteristics of an aero-engine dual-rotor system with rub-impact are revealed.The results show that the modal frequency of the dual-rotor system increases when rub-impact occurs and has the feature of interval,which allows us to obtain the critical speeds of the rubbing system by traditional Campbell diagram.The rotation direction is an important factor since it can not only affect the gyroscopic effect but also change the friction effect of the rub-impact.It is found that the modal frequencies of the counter-rotation dual-rotor are less than those of co-rotation condition.More importantly,the forward modes of the counter-rotation dual-rotor may be instable when rub-impact occurs at a certain rotor,while the corresponding modes under the co-rotation condition are always stable.Furthermore,by analyzing the rubbing response of the dual-rotor,it is found that the modal characteristics have an important influence on rotor’s response.The instable forward modes existing in the counter-rotation dual-rotor may lead to the divergence of the response when passing the corresponding critical speed.

关键词： Dual-rotor system Instability Modal characteristics Rub-impact Vibration response

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Parametric Stability Analysis of Marine Risers with Multiphase Internal Flows Considering Hydrate Phase Transitions

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Journal of Ocean University of China 2021年第1期20卷 23-34页

作者： LIANG Weixing LOU Min College of Petroleum Engineering China University of Petroleum(East China)Qingdao 266580China

This study investigates the effects of multiphase internal flows that consider hydrate phase transitions on the parametric stability of marine risers.A numerical model of the multiphase internal flow that considers a hydrate phase transition is established.The model first solves the flow parameters and subsequently obtains the natural frequencies of risers with different gas intake ratios.The stability charts of marine risers with different gas intake ratios are plotted by applying Floquet theory,and the effects of the gas intake ratio on the instability and Vibration response of the risers are identified.The natural frequency increases with an increase in the gas intake ratio;thus,instability zones move to higher frequency ranges in the stability charts.As the increasing gas intake ratio reduces the damping effect of the Coriolis force,the critical amplitude of the heave in the unstable region decreases,especially when hydrodynamic damping is not considered.As a result,higher-order unstable regions are excited.When in an unstable region,the Vibration response curve of a riser with a high gas intake ratio excited by parametric resonance diverges quickly due to parametric resonance.

关键词： hydrate phase transition marine risers multiphase internal flow parametric stability Vibration response

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Numerical and test study on vertical vibration characteristics of pile group in slope soil topography

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Earthquake Engineering and Engineering vibration 2021年第2期20卷 377-390页

作者： Qu Liming Ding Xuanming Zheng Changjie Wu Chongrong Cao Guangwei College of Civil Engineering Chongqing UniversityChongqing 400045China Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing UniversityChongqing 400045China School of Civil Engineering Fujian University of TechnologyFuzhou 350118China Fujian Provincial Key Laboratory of Advanced Technology and Informatization in Civil Engineering Fuzhou 350118China

Topography effects on the vertical Vibration responses of pile group are revealed though numerical analysis and model tests.First,a series of model tests with different topography of ground and bedrock are conducted.The results indicate that displacement amplitude of the pile head in sloping ground topography is larger than in horizontal ground.Differential displacement at various positions of the pile cap is observed in non-horizontal topography.Afterwards,a numerical algorithm is employed to further explore the essential response characteristics in group piles of different topography configurations,which has been verified by the test results.The lengths of the exposed and frictional segment,together with the thickness of the subsoil layer,are the dominant factors which cause non-axisymmetric vibration at the pile cap.

关键词： topography effects pile group Vibration response model test numerical method

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vibration and sound radiation of a rotating train wheel subject to a vertical harmonic wheel–rail force

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Journal of Modern Transportation 2018年第2期26卷 81-95页

作者： Tingsheng Zhong Gong Chen Xiaozhen Sheng Xueyan Zhan Liqun Zhou Jian Kai State Key Laboratory of Traction Power Southwest Jiaotong University Chengdu 610031 China Faculty of Geosciences and Environmental Engineering Southwest Jiaotong University Chengdu 610031 China

The rapid development of high-speed railway networks requires advanced methods for analysing vibration and sound radiation characteristics of a fast rotating train wheel subject to a vertical harmonic wheel-rail force. In order to consider the rotation of the wheel and at the same time increase the computational efficiency, a procedure is adapted in this paper taking advantage of the axial symmetry of the wheel. In this procedure, a recently developed 2.5D finite element method, which can consider wheel rotation but only requires a 2D mesh over a cross section containing the wheel axis, is used to calculate the Vibration response of the wheel. Then, the Vibration response of the wheel is taken as acoustic boundary condition and the 2.5D acoustic boundary element method, which only requires a 1D mesh over the boundary of the above cross section, is utilised to calculate the sound radiation of the wheel. These 2.5D methods and relevant programs are validated by comparing results from this procedure with those from conventional 3D analyses using commercial software. The comparison also demonstrates that these 2.5D methods have a much higher computational efficiency. Using the 2.5D methods, we study the wheel rotation speed influences on the factors including the vertical receptance of the wheel at wheel-rail contact point, sound pressure level at a pre-defined standard measurement point, radiated sound power level, directivity of the radia- tion, and contribution of each part of the wheel. It can be concluded that the wheel rotation speed splits most peaks of the vertical receptance at the wheel-rail contact point, sound pressure levels at the field, and the sound power level of the wheel into two peaks. The directivity and power contribution of the wheel are also significantly changed by the wheel rotation speed. Therefore, the rotation of a train wheel should be taken into account when calculating its vibration and sound radiation.

关键词： Train wheel Vibration response Soundradiation 2.5D FEM. 2.5D BEM Rotation effect

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A vertical coupling dynamic analysis method and engineering application of vehicle–track–substructure based on forced vibration

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Railway Sciences 2022年第2期1卷 224-240页

作者： Guolong Li Mangmang Gao Jingjing Yang Yunlu Wang Xueming Cao Infrastructure Inspection Research Institute China Academy of Railway Sciences Corporation LimitedBeijingChina Standards and Metrology Research Institute China Academy of Railway Sciences Corporation LimitedBeijingChina

Purpose–This study aims to propose a vertical coupling dynamic analysis method of vehicle–track–substructure based on forced vibration and use this method to analyze the influence on the dynamic response of track and vehicle caused by local fastener failure.Design/methodology/approach–The track and substructure are decomposed into the rail subsystem and substructure subsystem,in which the rail subsystem is composed of two layers of nodes corresponding to the upper rail and the lower fastener.The rail is treated as a continuous beam with elastic discrete point supports,and spring-damping elements are used to simulate the constraints between rail and fastener.Forced displacement and forced velocity are used to deal with the effect of the substructure on the rail system,while the external load is used to deal with the reverse effect.The fastener failure is simulated with the methods that cancel the forced vibration transmission,namely take no account of the substructure–rail interaction at that position.Findings–The dynamic characteristics of the infrastructure with local diseases can be accurately calculated by using the proposed method.Local fastener failure will slightly affect the vibration of substructure and carbody,but it will significantly intensify the Vibration response between wheel and rail.The maximum vertical displacement and the maximum vertical vibration acceleration of rail is 2.94 times and 2.97 times the normal value,respectively,under the train speed of 350 km$h1.At the same time,the maximum wheel–rail force and wheel load reduction rate increase by 22.0 and 50.2%,respectively,from the normal value.Originality/value–This method can better reveal the local vibration conditions of the rail and easily simulate the influence of various defects on the dynamic response of the coupling system.

关键词： Vehicle–track–substructure Coupling dynamic analysis Forced vibration Vibration response Fastener Failure

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Instability Assessment of Deep-Sea Risers Under Parametric Excitation

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China Ocean Engineering 2009年第4期23卷 603-612页

作者：杨和振李华军 State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University College of Engineering Ocean University of China

This study deals with the nonlinear dynamic response of deep-sea risers subjected to parametric excitation at the top of a platform. As offshore oil and gas exploration is pushed into deep waters, difficulties encountered in deep-sea riser design may be attributed to the existence of parametric instability regarding platform heave motions. Parametric resonance in risers can cause serious damage which might bring disastrous accidents such as environment pollution, property losses and even fatalities. Therefore, the paranletric instability analysis should attract more attention during the design process of deep-sea risers. In this work, an equation of motion for a deep-sea riser is derived firstly. The motion equation is analyzed by the Floquet theory which allows the determination of both system response and stability properties. The unstable regions in which parametric resonance easily occurs can be determined. The effects of damping on parametric instability are also investigated, and the stability maps are presented. The results demonstrate that the available damping is vital in suppressing the instability regions. The suggestions for reduction of instability regions are proposed in deep-sea riser design.

关键词： deep-sea riser parametric excitation instability Vibration response

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Fault Identification of Rotor Machine Based on Optimized Method

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Tsinghua Science and Technology 2004年第3期9卷 249-253页

作者：郭丹卢文秀陈真勇褚福磊 State Key Laboratory of Tribology Department of Precision Instruments and Mechanology Tsinghua University Beijing 100084 China

The size and complexity of modern equipment require more advanced fault diagnosis techniques. Different from signal analysis based methods, a dynamic model based diagnosis technique can further diagnose the location and severity of the fault, and detect multiple faults at one time. A model based fault diagnosis method was developed to identify typical faults of rotating machinery. This method can identify mass unbalances, crack locations and sizes, and oil film parameters in rotating machinery by optimization methods and dynamics simulation technique. Numerical and experimental results demonstrate that the method is useful for detecting faults of rotating systems.

关键词： rotor system fault identification Vibration response optimized method

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