scholarly journals Finite Element Model for Hysteretic Friction Damping of Traveling Wave Vibration in Axisymmetric Structures

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
X. W. Tangpong ◽  
J. A. Wickert ◽  
A. Akay
Keyword(s):  
Finite Element ◽  
Natural Frequency ◽  
Traveling Wave ◽  
Degrees Of Freedom ◽  
Propagation Constant ◽  
Excitation Frequency ◽  
Friction Damping ◽  
Bending Vibration ◽  
Axisymmetric Structures ◽  
Hysteretic Friction

A finite element method is developed to treat the steady-state vibration of two axisymmetric structures—a base substructure and an attached damper substructure—that are driven by traveling wave excitation and that couple through a spatially distributed hysteretic friction interface. The base substructure is representative of a rotating brake rotor or gear, and the damper is a ring affixed to the base under preload and intended to control vibration through friction along the interface. In the axisymmetric approximation, the equation of motion of each substructure is reduced in order to the number of nodal degrees of freedom through the use of a propagation constant phase shift. Despite nonlinearity and with contact occurring at an arbitrarily large number of nodal points, the response during sticking, or during a combination of sticking and slipping motions, can be determined from a low-order set of computationally tractable nonlinear algebraic equations. The method is applicable to element types for longitudinal and bending vibration, and to an arbitrary number of nodal degrees of freedom in each substructure. In two examples, friction damping of the coupled base and damper is examined in the context of in-plane circumferential vibration (in which case the system is modeled as two unwrapped rods), and of out-of-plane vibration (alternatively, two unwrapped beams). The damper performs most effectively when its natural frequency is well below the base’s natural frequency (in the absence of contact), and also when its natural frequency is well separated from the excitation frequency.

scholarly journals Finite Element Model for Hysteretic Friction Damping of Traveling Wave Vibration in Axisymmetric Structures

2007 ◽  
Author(s):  
X. W. Tangpong ◽  
J. A. Wickert ◽  
A. Akay
Keyword(s):  
Finite Element ◽  
Natural Frequency ◽  
Traveling Wave ◽  
Degrees Of Freedom ◽  
Propagation Constant ◽  
Excitation Frequency ◽  
Friction Damping ◽  
Bending Vibration ◽  
Axisymmetric Structures ◽  
Hysteretic Friction

A finite element method is developed to treat the steady-state vibration of two axisymmetric structures—a base substructure and an attached damper substructure—that are driven by traveling wave excitation, and that couple through a spatially-distributed hysteretic friction interface. The base substructure is representative of a rotating brake rotor or gear, and the damper is a ring affixed to the base under preload and intended to control vibration through friction along the interface. In the axisymmetric approximation, the equation of motion of each substructure is reduced in order to the number of nodal degrees of freedom through the use of a propagation constant phase shift. Despite nonlinearity and with contact occurring at an arbitrarily large number of nodal points, the response during sticking, or during a combination of sticking and slipping motions, can be determined from a low-order set of computationally tractable nonlinear algebraic equations. The method is applicable to element types for longitudinal and bending vibration, and to an arbitrary number of nodal degrees of freedom in each substructure. In two examples, friction damping of the coupled base and damper is examined in the context of in-plane circumferential vibration (in which case the system is modeled as two unwrapped rods), and of out-of-plane vibration (alternatively, two unwrapped beams). The damper performs most effectively when its natural frequency is well below the base’s natural frequency (in the absence of contact), and also when its natural frequency is well-separated from the excitation frequency.

A Car Exhaust System Hook Position Optimization Analysis

2015 ◽  
Vol 778 ◽  
pp. 3-9 ◽  
Author(s):  
Shu Hua Liao ◽  
Wei Zhang ◽  
Li Liu ◽  
Guo Bing Liu
Keyword(s):  
Finite Element ◽  
Natural Frequency ◽  
Degrees Of Freedom ◽  
Excitation Frequency ◽  
Exhaust System ◽  
Fem Analysis ◽  
Optimization Analysis ◽  
Finite Element Software ◽  
Car Exhaust ◽  
System Use

Based on the study of a car exhaust system, use HyperMesh Software and its build-in finite element software to build FEM , Analysis the free modal of exhaust system, Calculate its natural frequency, Then optimize the position of hook based on the ways of average degrees of freedom (ADDOFD), Makes its modal frequencies avoiding engine idling frequency. Finally, through the calculated constraint mode, Verify whether coupling with the excitation frequency of engine, and further verify the reasonableness of the position of the hook.

Modal Analysis of the 1.5MW Wind Turbine Tower

2013 ◽  
Vol 712-715 ◽  
pp. 1494-1500
Author(s):  
Bi Feng Cao ◽  
Hui Yu
Keyword(s):  
Finite Element ◽  
Wind Turbine ◽  
Modal Analysis ◽  
Natural Frequency ◽  
Excitation Frequency ◽  
Horizontal Axis ◽  
Horizontal Axis Wind Turbine ◽  
Finite Element Software ◽  
Wind Turbine Tower ◽  
Tower Model

The paper uses the finite element software ANSYS to establish a 1.5 MW horizontal-axis wind turbine tower model as an example and works on the modal analysis. The modal analysis takes into account the totalmass of wind rotor and nacelle and assumes the bottom of the wind turbine tower is fully constrained. The result shows that the natural frequency of the 1.5MW wind turbine tower is not coincident with the excitation frequency of the wind turbine, and the wind turbine can operate stably at the design condition.

scholarly journals Analysis and Research on Longitudinal Vibration Characteristics of Deep Sea Mining Pipe Based on Finite Element Method

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Qiang Liu ◽  
Linjing Xiao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Natural Frequency ◽  
Vibration Amplitude ◽  
Longitudinal Vibration ◽  
Excitation Frequency ◽  
Vibration Characteristics ◽  
Wind Condition ◽  
Vibration Intensity ◽  
Element Method

This paper aimed to study the longitudinal vibration characteristics of the 5000 m mining pipe in the ocean under different working wind conditions, offset angle, damping, and ore bin weight. Based on the finite element method, the mining pipe is simplified into beam element and discretized, and the physical and mathematical models of the mining pipe system are established. The Wilson-θ direct integral method is adopted for numerical calculation. The results show that the longitudinal vibration of the mining pipe is irregular, which presents the phenomenon of oscillation. The vibration amplitude decreases first and then increases from top to bottom, the minimum vibration amplitude appears at 1000 m, and the maximum vibration amplitude appears at the top of the mining pipe. Under the same working wind condition, the overall longitudinal vibration amplitude of the mining pipe can be increased by increasing the ore bin weight and the offset angle, but neither of them can change the frequency of the longitudinal vibration. The closer the excitation frequency generated by different working wind conditions is to the natural frequency, the larger the mining pipe longitudinal vibration amplitude is. The closer the vibration frequency generated by the same excitation frequency is to the natural frequency, the stronger the vibration intensity is, and when damping is added, the vibration intensity decreases faster.

Development of Nonlinear Building Block Approach

1988 ◽  
Vol 110 (1) ◽  
pp. 36-41 ◽  
Author(s):  
K. Watanabe ◽  
H. Sato
Keyword(s):  
Natural Frequency ◽  
Building Block ◽  
Degrees Of Freedom ◽  
Dynamic Performance ◽  
Excitation Frequency ◽  
Historical Analysis ◽  
Computation Time ◽  
Algebraic Equations ◽  
Response Characteristics ◽  
Block Approach

A nonlinear building block approach (NLBBA) is proposed to evaluate frequency response characteristics of nonlinear structure systems including springs with nonlinear stiffness and clearances at slide or bearing as occur in actual systems. The advantage of the building block approach (BBA) was that dynamic performance of the total linear system can be evaluated by analyzing and synthesizing the performance of subsystems. In this paper the method was extensively developed to investigate systems with nonlinearities. The describing function was adopted to represent nonlinearity in the system equations. The compliance could be obtained by solving nonlinear simultaneous algebraic equations for multi-degrees-of-freedom system with multinonlinearities. The method was applied to a beam supported by nonlinear springs and a spindle of a machine tool. The evaluated compliance could quantitatively show effects of the nonlinearity such as transfer of the natural frequency, variance of the compliance at the natural frequency, and jump phenomena for sweep of the excitation frequency. The results of the application agreed well with those obtained by step-by-step integration in the time domain (time historical analysis) which is generally used, and also agreed well with the empirical phenomenon of the stability to the self-excited chatter. The computation time could be significantly shortened by the proposed method.

Finite Element Modal Analysis of a Semi-Trailer Frame

2014 ◽  
Vol 685 ◽  
pp. 199-203
Author(s):  
Pei Ming Zhang ◽  
Wei Wang ◽  
Wei Chun Zhang
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Natural Frequency ◽  
Vibration Mode ◽  
Excitation Frequency ◽  
Modal Parameters ◽  
Frequency Effect ◽  
Frame Design ◽  
The Road

The paper carries out the finite modal analysis of a Semi-trailer frame and obtains the modal parameters such as frame natural frequency and vibration mode. It also compares the modal analysis results with the excitation frequency effect caused by the road on the frame, the conclusion supports a reference to improve the frame design.

The Model Analysis of Mobile Emergency Platform Car Frame Based on ANSYS

2012 ◽  
Vol 490-495 ◽  
pp. 2961-2965 ◽  
Author(s):  
Bo Gao ◽  
Zi Ming Kou ◽  
Juan Wu
Keyword(s):  
Modal Analysis ◽  
Natural Frequency ◽  
Optimization Design ◽  
Degrees Of Freedom ◽  
Excitation Frequency ◽  
Electrical Equipment ◽  
Elastic Vibration ◽  
Equipment Failure ◽  
Vibration System ◽  
Treatment Equipment

Mobile emergency platform is the carrier of mechanical and electrical equipment. The car frame vibration would make mechanical and electrical equipment failure even damaged. Mobile emergency platform car frame can be considered as the elastic vibration system with many degrees of freedom. Modal analysis is used to analyze the car frame. It is shown that the first natural frequency is 15.153 Hz and the second natural frequency is 19.579 Hz, which is close to20 Hz that is generated by the excitation frequency . Resonance is ocuuered. Optimization design is used to design car frame.After optimization design the natural frequency of car frame avoid the excitation frequency. Emergency mobile platform is environmental emergencies emergency treatment equipment, which video and audio monitoring equipment, wireless communications equipment , sophisticated electronic equipment and instrumentation need are carried in. When transportation or work process, these equipments, especially data-receiving treatment equipment, communications data transmission control equipment, image processing service and other equipment, will be affected inevitably even be failure for the mechanical vibration of the engine and the uneven road. If the equipment is damaged, the entire mobile platform of paralysis will be occurred. Car frame of mobile emergency platform can be considered as the elastic vibration system with many degrees of freedom and vibration led directly to the equipment failure. It is necessary to make modal analysis for the car frame.

Experimental Study on Vibration Characteristics of Acoustic System in Ultrasonic Vibration Lapping

2010 ◽  
Vol 455 ◽  
pp. 313-319 ◽  
Author(s):  
Chang Juan Zhang ◽  
Chuan Shao Liu ◽  
Bo Zhao
Keyword(s):  
Experimental Study ◽  
Natural Frequency ◽  
Ultrasonic Vibration ◽  
Degrees Of Freedom ◽  
Vibration Mode ◽  
Excitation Frequency ◽  
Acoustic System ◽  
Resonant Condition ◽  
Vibration Effect ◽  
Displacement Equation

In this paper, the natural frequency and the vibration mode of the lapping tool in ultrasonic vibration lapping are analyzed, the resonance mechanism of the lapping tool is researched by establishing its mechanical model and displacement equation, and the experimental study is carried out in ultrasonic vibration lapping of engineer ceramics. The conclusions include: 1) The natural frequency of the designed lapping tool is ; 2) The acoustic system in ultrasonic vibration lapping is simplified to equivalent many-degrees of freedom system, while the damp is ignored, the lapping tool is resonant with itself-natural frequency, the joint of the horn and the lapping tool is a displacement node, and the whole system is in resonant condition. 3）While the experimental condition is no-load and ultrasonic, the vibration frequency of the lapping tool is 21.3125 , which is further closed to the calculated natural frequency, at that time the amplitude of the lapping tool is maximal and the system is in resonant condition. Moreover, while the resonance frequency of the horn and the lapping tool is different, the good vibration effect of the lapping tool can be obtained by adjusting the excitation frequency of generator.

Influence of Lumped Mass on the Natural Frequency of Cylindrical Pipe

2012 ◽  
Vol 532-533 ◽  
pp. 403-407
Author(s):  
Bing Li ◽  
Yu Lan Wei ◽  
Dan Zhang ◽  
Qing Huang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Natural Frequency ◽  
Natural Frequencies ◽  
Vibration Modes ◽  
Lumped Mass ◽  
Cylindrical Pipe ◽  
Bending Vibration ◽  
Element Analysis ◽  
Lumped Masses

The lumped mass on the cylindrical pipe affects the natural frequency of the cylindrical pipe. The first-three order natural frequencies and vibration modes of the cylindrical pipe with different lumped masses are analyzed by the bending vibration theory and finite element analysis, respectively. The results with different lumped masses are obtained by experiments. As shown in the results, the natural frequencies of the cylindrical pipe with lumped mass are lower than those without lumped mass. The greater the lumped mass is, the smaller the natural frequencies of the pipe are.

scholarly journals Presentation of an Approach on Determination of the Natural Frequency of Human Lumbar Spine Using Dynamic Finite Element Analysis

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Fan Ruoxun ◽  
Liu Jie ◽  
Liu Jun ◽  
Wang Weijun
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Natural Frequency ◽  
Excitation Frequency ◽  
Element Model ◽  
Mechanical Parameters ◽  
Element Analysis ◽  
Dynamic Finite Element ◽  
Dynamic Finite Element Analysis ◽  
Human Lumbar Spine

Occurring resonance may negatively affect the health of the human lumbar spine. Hence, vibration generated in working and living environments should be optimized to avoid resonance when identifying the natural frequency of the human lumbar spine. The range of the natural frequency of the human lumbar spine has been investigated, but its specific numerical value has not been determined yet. This study aimed at presenting an approach based on resonance for predicting the specific numerical value of the natural frequency of the human lumbar spine. The changes in the numerical fluctuation amplitudes and the cycles of lumbar mechanical parameters during resonance are greater than those during nonresonant vibration. Given that the range of the natural frequency has been identified, vibrations at different excitation frequencies within this range can be applied in a human lumbar finite element model for dynamic finite element analysis. When the excitation frequency is close to the natural frequency, resonance occurs, causing great changes in the numerical fluctuation amplitudes and the cycles of lumbar mechanical parameters. Therefore, the natural frequency of the lumbar finite element model could be back-calculated. Results showed that the natural frequency of the established model was 3.5 Hz. Meanwhile, the closer the excitation frequency was to the natural frequency, the greater the changes in the numerical fluctuation amplitudes and cycles in the parameters would be. This study presented an approach for predicting the specific numerical value of the natural frequency of the human lumbar spine. Identifying the natural frequency assists in finding preventive measures for lumbar injury caused by vibration and in designing the vibration source in working and living environments to avoid approximating to the natural frequency of the human lumbar spine.

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