Papers by Keyword: Vibration Response

Abstract: The method using Born-Jordan transformation has been developed for the evaluation of response signals obtained by rail fastening analysis. In the paper the laboratory measurements and dynamic parameters analyses of flexible fastening of Vossloh SKL14 type have been descripted. This method can also be used for designing new fastening systems and their parts, for comparison of various rail fastening types and so on.

Abstract: Vibration characteristic of a structure is unique due to mainly its material and geometrical properties. Hence, a variation imposed on either one or both the parameters can cause a different vibration response. This fact can be used to develop an alternative approach in testing the purity of gold particularly when the gold bar (Au) is no longer isotropic material due to the presence of other metals. A fake gold bar is commonly made by filling inside of the bar with other material for example Tungsten or Wolfram (W) which has density nearly the same as gold but its price is cheaper. This can not be identified easily without performing a testing as it has the same appearance as the pure gold bar. The purpose of this research is to develop gold bar purity testing method by observing natural frequencies and Frequency Response Function (FRF) of vibration response. For early development, the vibration response of gold bar and fake one are investigated. For this, numerical calculations are used rather than measurements. The results show that the natural frequencies and frequency response function (FRF) are useful information to detect whether a metal bar is pure gold bar or containing other metals. Higher natural frequency orders are required when the volume of tungsten in the bar reduces as the gap of lower order natural frequencies of pure gold bar and the fake become small. Moreover, the excitation point at corner and central of area of gold bar are suggested to be chosen during purity testing

Abstract: Based on comprehensive considerations the influences of stiffness excitation, deviation excitation, meshing impact excitation, friction of tooth surface, and other kinds of nonlinear factors, it established a nonlinear coupled vibration model of bending-torsion-axial-swing coupled helical gear transmission system by applying the Lumped Mass Method. After transformed the model to dimensionless form, it used Runge-Kutta method to solve the nonlinear vibration model of the system, and then the time domain chart, spectrum chart, phase chart, Poincare chart, and FFT chart were obtained; it discussed the influence of system parameters on its dynamic characteristics.

Abstract: It has been well known that bone has piezoelectric properties and these properties have been considered to be caused by the shift of the center of symmetry of the positive and negative electrical charge due to the strain of the collagen fibers included in the bone. Thus, it has long been considered that there were no piezoelectric effects in the hexagonal hydroxyapatite (HAp) which has center of symmetry of crystal. However, in recent years, the piezoelectric property of artificially synthesized HAp was reported. In the authors’ previous report, a new result which showed the piezoelectricity of the hydroxyapatite (HAp) films fabricated by the pulsed laser deposition (PLD) method was reported. In this study, the effect of poling treatment on piezoelectric constant of pulsed laser deposited HAp films was investigated.

Abstract: Constrained damping layer (CDL) treatment has been an effective way to suppress vibration level of various structures. by introducing this method into the vibration control system of electronic equipments, this paper firstly discussed the dominant mechanism difference between free damping layer treatment and constrained damping layer treatment, Then base on the constrained layer damping layout optimization method in the vibration system of a rectangle thin board like PCB, a series of experimental investigations were presented on the vibration response of printed circuit boards treated with partial constrained damping layers. as a result, it proves the CDL treatment having good effect on vibration response control of PCBs.

Abstract: The fracture pump will vibrate remarkably in the operating process due to the complex combined loads. It is necessary to study the dynamic performance of its whole structure so as to ensure its safety and operating efficiency. Therefore, the ANSYS was applied to conduct harmonic response of a certain three-cylinder fracture pump and study vibration response by mechanical excitations of a crank-connecting rod-piston system. It was shown that the acceleration amplitude of fracture pump is very large in some frequency and easy to resonate, such as 77.35Hz, 126.7Hz, 744.6Hz and 792.2Hz. Some tests were implemented to validate the feasibility of the FEM method in the dynamic response analysis of the fracture pump, on their basis the optimal design became possible for the fracture pump.

Abstract: The vibration characteristics and vibration response under different load cases in the underground powerhouse structure of Yixing pumped-storage power station were studied by establishing three-dimensional finite element model. The harmonic and transient analysis methods were proposed to study the vibration response of the powerhouse structure under various generating unit dynamic loads and in transient process. The numerical results were evaluated according to the related rules and regulations. The result shows that the vibration response of the power house structure is in the limit of the rules and regulations and there was little chance of resonance.

Abstract: This paper is concerned with the milling instability of spindle-ball bearing milling system. The finite-element analyzes is adopted. It is verified that there existed close relationships between the vibration response and the milling instability contributed by the same spindle mode. The spindle mode, which excites the maximum peak spectrum value, will produce the milling instability most likely. The front bearing preload has much more remarkable influences on spindle modes and milling stability than the rear one. It is therefore very important to adjust the front bearing preload according to the actual processing situations and stability demands in the spindle system design stage.

Abstract: The take-up winder is an important equipment of chemical fiber textile machinery. Vibration performance is the key to decide quality and service life of product. The modal of winder is analyzed. It is shown that the rotation speed cannot be kept away from fifth and sixth resonance frequency. The Maximum stress response is calculated by harmonic analysis. According to results of high-cycle fatigue tests, the service life of winder is evaluated. The results show that there is the risk of fatigue damage for small damp ratio. Unlimited fatigue life can be obtained by creasing damp ratio. It can be concluded that creasing damp is an effective way to improve the service life.

Abstract: A dynamic finite element model of a coupled gear-rotor-bearing-housing gear system is developed by combining the gearbox transmission model with the housing structure model of spiral bevel gearbox used in ship lift synchronization system with taking stiffness excitation, error exaction and meshing impact exaction as the dynamic excitation. The intrinsic modes and vibration response are calculated, and then the modal frequency, mode shape, vibration displacement, velocity and acceleration of the gearbox are obtained to achieve the goal of prediction on vibration severity. In fact, the proposed approach not only provides a more comprehensive understanding of spiral bevel gearbox, but also can serve as the basis for vibration control of gear system used in ship lift synchronization system.