Modal Experiment Research on Fluid-Solid Coupling Vibration of Hydraulic Long-Straight Pipeline of Shield Machine

2011 ◽  
Vol 105-107 ◽  
pp. 286-293 ◽  
Author(s):  
Jing Hua Xie ◽  
Ke Tian ◽  
Li He ◽  
Tian Ren Yang ◽  
Xiang Heng Zhu
Keyword(s):  
Natural Frequency ◽  
Natural Frequencies ◽  
Vibration Mode ◽  
Vertical Plane ◽  
Low Frequency ◽  
Pipeline System ◽  
Experiment Research ◽  
Coupling Vibration ◽  
The Difference ◽  
Shield Machine

The hydraulic long-straight pipeline system of the shield machine is to be studied in this paper. Modal parameters of the hydraulic long-straight pipeline whose length is 8m under three kinds of spans (single span, double spans and four spans) were measured and analyzed. Considering the inherent vibration characteristics of the shield machine, we limited the natural frequency of the multi-span long straight pipeline studied within the range of 0~ 200Hz.What the experiment shows is as follows: Firstly, the natural frequency of the hydraulic long-straight pipeline is densely distributed mainly in the low frequency; Secondly, the natural frequencies of vibration in the horizontal plane are slightly higher than those of corresponding orders in the vertical plane, although the difference is little; In addition, by increasing the number of supports, pipeline span can be reduced and the natural frequencies of pipeline can be significantly increased, but this will make the vibration mode change irregularly.

1/2-Order Subharmonic Resonances in Horizontally Supported Jeffcott Rotor

2011 ◽  
Author(s):  
Nao Yoshida ◽  
Tomoyuki Takano ◽  
Hiroshi Yabuno ◽  
Tsuyoshi Inoue ◽  
Yukio Ishida
Keyword(s):  
Natural Frequency ◽  
Natural Frequencies ◽  
Equations Of Motion ◽  
Vertical Direction ◽  
Support Condition ◽  
Restoring Force ◽  
Rotary Machine ◽  
Jeffcott Rotor ◽  
The Difference ◽  
Subharmonic Resonances

A Rotary machine is a significant component of many mechanical systems. It is important to clarify the dynamic characteristics in several conditions. This study deals with nonlinear dynamics of a horizontally supported Jeffcott rotor. The equations of motion are derived by considering the effects of gravity and the cubic nonlinearity of restoring force by the support condition. These effects produce the difference between the linear natural frequencies in the vertical and horizontal directions and make the stiffness in the vertical direction unsymmetric. It is theoretically and experimentally shown that due to such effects, the 1/2-order subharmonic resonances are produced in the cases when the rotational speed is in the neighborhood of twice the natural frequencies in the horizontal and vertical directions, and the frequency response curve of the resonance near twice the horizontal natural frequency is hardening-type, while near twice the vertical natural frequency is softening-type.

The Experiments of Cantilever Piezoelectric Vibrator Power Generation

2012 ◽  
Vol 236-237 ◽  
pp. 1368-1372
Author(s):  
Su Xiang Qian ◽  
Hong Sheng Hu ◽  
Li Xia Ge ◽  
Jia You Song
Keyword(s):  
Power Generation ◽  
Natural Frequency ◽  
Low Frequency ◽  
Experiment Research ◽  
Piezoelectric Vibrator ◽  
Piezoelectric Resonators ◽  
Low Frequency Vibration ◽  
Proper Mass

Papers on cantilever piezoelectric resonators experiment research in the low frequency vibration environment. The study proved that, to choose a proper mass can effectively regulate the cantilever piezoelectric vibrators natural frequency The more close to the incentive frequency and the natural frequency of piezoelectric vibrators, the better the results of piezoelectric vibrators power generation.

Vibration and Stability of a Spinning Disk Under Stationary Distributed Edge Loads

1996 ◽  
Vol 63 (2) ◽  
pp. 439-444 ◽  
Author(s):  
Jen-San Chen
Keyword(s):  
Natural Frequency ◽  
Natural Frequencies ◽  
Modal Interaction ◽  
Reflected Waves ◽  
Reflected Wave ◽  
Nonzero Integer ◽  
Spinning Disk ◽  
The Difference

The vibration and stability of a spinning disk under conservative distributed edge tractions are studied both numerically and analytically. The edge traction is circumferentially stationary in the space. When the compressive traction is uniform, it is found that no modal interaction occurs and the natural frequencies of all nonreflected waves decrease, while the natural frequencies of the reflected waves increase. When the spinning disk is under distributed traction in the form of cos kθ, where k is a nonzero integer, it is found that the eigenvalue only changes slightly under the edge traction if the natural frequency of interest is well separated from others. When two modes are almost degenerate, however, modal interaction may or may not occur. It is observed that when the difference between the number of nodal diameters of these two modes is equal to ±k, frequency veering occurs when both modes are nonreflected, and merging occurs when one of these two modes is a reflected wave. In applying this rule, the number of nodal diameters of the forward and the reflected wave is considered as negative.

scholarly journals ANALYTICAL MODELING OF PLANETARY GEAR AND SENSITIVITY OF NATURAL FREQUENCIES

2013 ◽  
pp. 35-40
Author(s):  
MAJID MEHRABI ◽  
DR. V.P. SINGH
Keyword(s):  
Natural Frequency ◽  
Degrees Of Freedom ◽  
Analytical Modeling ◽  
Natural Frequencies ◽  
Vibration Mode ◽  
Planetary Gear ◽  
Vibration Modes ◽  
Planetary Gears ◽  
System Parameters ◽  
Inertia Parameters

This work develops an analytical model of planetary gears and uses it to investigate their natural frequencies and vibration modes. The model admits three planar degrees of freedom for each of the sun, ring, carrier and planets. Vibration modes are classified into rotational, translational and planet modes. The natural frequency sensitivities to system parameters are investigated for tuned (cyclically symmetric) planetary gears. Parameters under consideration include support and mesh stiffnesses, component masses, and moments of inertia. Using the well-defined vibration mode properties of tuned planetary gears, the eigen sensitivities are calculated and expressed in simple exact formulae. These formulae connect natural frequency sensitivity with the modal strain or kinetic energy and provide efficient means to determine the sensitivity to all stiffness and inertia parameters by inspection of the modal energy distribution.

scholarly journals Mechanism Analysis of a Low-Frequency Disc Brake Squeal Based on an Energy Feed-In Method for a Dual Coupling Subsystem

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yidong Wu
Keyword(s):  
Vibration Mode ◽  
Low Frequency ◽  
Element Model ◽  
Disc Brake ◽  
Mechanism Analysis ◽  
Brake Squeal ◽  
Complex Mode ◽  
Vehicle Noise ◽  
Complex Modal Analysis ◽  
The Difference

Brake squeal is a major component of vehicle noise. To explore the mechanism of the low-frequency brake squeal, a finite element model of an automobile disc brake was established, and a complex mode numerical simulation was performed. According to the unstable modes stemming from the complex modal analysis results, the low-frequency range brake squeal can be determined. Based on an energy feed-in method, the coupling subsystems of the piston-caliper and the disc-pad were established, and a calculation formula for the feed-in energy of the dual coupling subsystem was derived. The results showed that when the feed-in energy of the dual coupling subsystem is close to zero, the complex mode cannot be excited at the corresponding frequency. In addition, the difference in feed-in energy between the two coupling subsystems is positively correlated with the probability of the brake squeal, which can be used to determine the complex mode under which the brake squeal may occur. The greater the feed-in energy of a coupling subsystem is, the more likely it is that the maximum brake vibration mode will appear at this subsystem or its adjacent parts. The increase in brake oil pressure will eliminate some lower-frequency sounds but will not change the frequency of the original low-frequency brake squeals.

scholarly journals The Influence of Shaft’s Bending on the Coupling Vibration of a Flexible Blade-Rotor System

2017 ◽  
Vol 2017 ◽  
pp. 1-19 ◽  
Author(s):  
Chao-feng Li ◽  
Hou-xin She ◽  
Wen Liu ◽  
Bang-chun Wen
Keyword(s):  
Natural Frequency ◽  
Critical Speed ◽  
Vibration Mode ◽  
Rotor System ◽  
Rotor Blades ◽  
Mode Shapes ◽  
Coupling Vibration ◽  
Mode Function ◽  
Coupling Mode ◽  
Supporting Condition

The influence of shaft bending on the coupling vibration of rotor-blades system is nonignorable. Therefore, this paper analyzed the influence of shaft bending on the coupling vibration of rotor-blades system. The vibration mode function of shaft under elastic supporting condition was also derived to ensure accuracy of the model as well. The influence of the number of blades, the position of disk, and the support stiffness of shaft on critical speed of system was analyzed. The numerical results show that there were two categories of coupling mode shapes which belong to a set where the blade’s first two modes predominate in the system: shaft-blade (SB) mode and interblade (BB) mode due to the coupling between blade and shaft. The BB mode was of repeated frequencies of (Nb-2) multiplicity for number blades, and the SB mode was of repeated frequencies of (2) multiplicity for number blades. What is more, with the increase of the number of blades, natural frequency of rotor was decreasing linearly, that of BB mode was constant, and that of SB mode was increasing linearly. Natural frequency of BB mode was not affected while that of rotor and SB mode was affected (changed symmetrically with the center of shaft) by the position of disk. In the end, vibration characteristics of coupling mode shapes were analyzed.

Research of Frame Optimization Technology Based on SIMP

2012 ◽  
Vol 468-471 ◽  
pp. 2802-2805
Author(s):  
Xue Tao Huang ◽  
Liang Gu ◽  
Wei Wei Lv
Keyword(s):  
Natural Frequency ◽  
Natural Frequencies ◽  
Ride Comfort ◽  
Low Frequency ◽  
Frame Structure ◽  
Resonance Phenomenon ◽  
Impact Factors ◽  
First Order ◽  
Low Frequency Vibration ◽  
External Motivation

The low frequency vibration of vehicle is very popular. The vibration can reduce ride comfort and cause early damage of part, so we must do something to reduce it. But the vibration has more complex impact factors, so it is very difficult to solve it. This paper has studied a new method to reduce it. It has studied the natural frequencies of the frame on the platform of OptiStruct software. Through the research, we find that the first order mode natural frequency of the frame is close to the external motivation, which is caused by moving unbalance of wheels. It leads to the resonance phenomenon, which is the main reason for vehicle low frequency vibration. In order to improve the vibration, this paper has researched the principle of SIMP topology optimization technology, and searched for the topology frame structure, whose first mode natural frequency is far away from the external motivation. Finally, this paper shows a new design for the frame, which reduces the low frequency vibration of vehicle greatly.

scholarly journals Natural Frequencies and Stability of a Spinning Disk Under Follower Edge Tractions

1997 ◽  
Vol 119 (3) ◽  
pp. 404-409 ◽  
Author(s):  
Jen-San Chen
Keyword(s):  
Analytical Methods ◽  
Natural Frequencies ◽  
Low Frequency ◽  
Circular Disk ◽  
Interaction Frequency ◽  
Modal Interaction ◽  
Frequency Range ◽  
Reflected Waves ◽  
Spinning Disk ◽  
The Difference

The vibration and stability of a spinning disk under follower edge tractions are studied both numerically and analytically. The edge traction is circumferentially stationary in the space. When the compressive traction is uniform, natural frequencies of most of the non-reflected waves decrease, except some of the zero-nodal-circle modes with small number of nodal diameters in the low frequency range. When the spinning disk is under nonuniform traction in the form of cos kθ, where k is a nonzero integer, it is found that the eigenvalue only changes slightly under the edge traction if the natural frequency of interest is well separated from others. When two modes are almost degenerate, however, modal interaction (frequency loci veering or merging) occurs when the difference between the number of nodal diameters of these two modes is equal to ±k. Types of modal interaction vary as the radius ratio of the circular disk changes. Analytical methods for predicting how the eigenvalue changes and what type of modal interaction will occur are proposed and verified.

The Results of Experiment Analysis on Body-in-White Research

2014 ◽  
Vol 556-562 ◽  
pp. 6358-6361 ◽  
Author(s):  
Hua Xin Zhang ◽  
Min Yong Tong
Keyword(s):  
Natural Frequency ◽  
Model Test ◽  
Vibration Mode ◽  
Low Frequency ◽  
The Body ◽  
Modal Parameters ◽  
Modal Characteristic ◽  
Modal Properties ◽  
Body In White ◽  
Experiment Analysis

This paper through the body-in-white model test got each order modal natural frequency, vibration mode, damping about this body-in-white. At the same time, on the basis of the test, analyzing the influence about windshield condition of each order modal parameters. Study shows that the low-frequency dynamic characters of the body-in-white is better, to improve local modal properties, increase the windshield on the body-in-white modal characteristic has certain strengthen.

Vibration Mode Analysis of Frames by the Method of Reverberation Ray Matrix

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
F. X. Miao ◽  
Guojun Sun ◽  
Y. H. Pao
Keyword(s):  
Wave Propagation ◽  
Natural Frequencies ◽  
Vibration Mode ◽  
Coefficient Matrix ◽  
Mode Analysis ◽  
System Matrix ◽  
Governing Equations ◽  
Unit Impulse ◽  
Impulse Load ◽  
The Difference

The method of reverberation ray matrix (MRRM) has been developed by (Pao et al. 1999, “Dynamic Response and Wave Propagation in Plane Trusses and Frames,” AIAA J., 37(5), pp. 594–603) recently based on the theory of wave propagation for transient analysis of truss or frame structures. In this study, the MRRM is employed to obtain the frequency response function (FRF) of displacement of a frame under the action of a unit impulse load. The natural frequencies of the frame are determined from the FRF, since the curve of FRF has peak when a resonant frequency is approached. The vibration mode is retrieved from the adjoint matrix of the coefficient matrix of the governing equations of MRRM. The MRRM has advantage over numerical methods, such as finite element method (FEM), since in MRRM the frame is treated as an assembly of multiconnected beams, and exact solutions to the beam differential equations are employed to yield the system matrix of the frame. The vibration mode obtained is therefore exact. A planar frame made of 17 aluminum bars is analyzed. The vibration modes, as well as natural frequencies obtained from MRRM, coincide accurately with those obtained from FEM of ANSYS for the first a few modes; however, the difference of the frequencies between the two methods becomes a bit obvious when high order modes are examined.

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