The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The modal truncation problem of non-classically damped systems is constantly encountered in the dynamic analysis of engineering. The present study is designed to calculate the frequency response functions of the non-classically damping systems accurately on account of the Neumann expansion theory and the frequency shifting technique. Considering the first and the second term influence of the Neumann...
This paper presents a method for controlling torsional vibrations in rotating machines with nonlinear dynamics. The work is motivated by rotating machines with cam or crankshaft mechanisms that generate harmonic signal components in the angular speed with respect to the rotation angle. In the system description, the torsional vibrations are modeled as disturbances acting upon a linear plant. Thus,...
The mathematical model of the experimental stand for vibration damping is described in the article. A vibration table is used as a source of vibration of different frequencies. Asynchronous motors are attached to the vibrating table from below. These motors are frequency-controlled and have eccentric disks on the shafts. Due to imbalance, the motors create a vibration that is transmitted to the upper...
Flow of a fluid through pipe can impose pressure on the walls of the pipe causing it to deflect under certain flow conditions. The deflection of the pipe may lead to structural instability in the pipe system which affects its efficiency. The present study deals with the effect of various parameters such as pipe diameter, pipe wall thickness, and volumetric flow rate (discharge) on the amplitude of...
The dynamic hydroelasticity problem of annular channel outer wall, surrounded by elastic medium and interacting with highly viscous incompressible liquid, filling the channel, is considered. The inner wall, being an absolutely rigid cylinder of finite sizes, performs harmonic oscillations according to the assigned law. The second outer channel wall is formed by elastic cylinder shell, surrounded by...
The mathematical model and exact analytical solution of the forced axisymmetric vibrations of semiin-finite cylindrical shell partially submerged into the liquid is constructed. The protruding part of the shell is infinite. The source of the vibrations in the system shell-liquid is incident wave propagating from the infinite side of the shell. The joint oscillations of the shell and ideal compressible...
This paper presents a method for generating stator currents supplying a surface permanent magnets synchronous motor with lack of turns in one of its winding. The currents are calculated in order to minimize the torque ripple generated by the dissymmetry. The analytical model used is based on the role of the space harmonics of the stator and rotor flux density on generation of torque harmonics. This...
In this paper the isolation of a single equipment by means of a semi active control device item is investigated. The configuration of ground-mounted equipment, that is an equipment directly mounted on the ground, is studied, and a single horizontal component of ground acceleration is assumed as base excitation, having considered the sliding response of the equipment among the possible response modes...
Nonlinear dynamics can be a means to improve the properties of energy harvesting devices. Mathematical analysis of these systems as a tool for design or interpretation of experiments requires the solution of nonlinear differential equations. Most works use the third-order polynomial force (Duffing model) in order to qualitatively model mechanically nonlinear features. However, under large vibrations,...
It has been shown that the complicated nonlinear vibration phenomena in mechanical workpieces under excitations of intense ultrasonic pulses increase greatly the detectability of defects (cracks). To study the nonlinear vibration phenomena of plates induced by the ultrasonic pulses, an electrical circuit model is proposed to simulate the mechanical vibro-impact motions between the transducer horn...
This paper presents an inexpensive, portable experimental platform that, when coupled with student-owned data acquisition boards, can be used in a variety of lecture-based courses including signals and systems, circuits, electronics, electromagnetics, system dynamics, and vibrations. This paper presents the model, simulation results, and experimental results obtained from a data acquisition board.
The nonlinear vibration of a circular curved carbon nanotube using Euler-Bernoulli beam theory is investigated. The governing equation of motion of the system is developed and the Galerkin method is utilized to obtain the nonlinear ordinary differential equation of the curved carbon nanotube. A quarter-circular curvature is considered for the nanotube and it is assumed to have a single wall with simply-supported...
Fractional-slot windings is widely used in synchronous machine due to give us more flexibility on selection of the number of slot at design stage. It is also known that fractional-slot windings produces additional harmonics compare to integral-slot windings. These harmonics may cause increasing of stray losses and stator core vibration This paper describes the result of space flux harmonics caused...
Vibration isolation systems with nonlinear stiffness under sinusoidal excitation exhibit unwanted jump phenomena and superharmonics when they are lightly damped. These characteristics can be suppressed by linear viscous damping but the force transmissibility over the high frequency range increases as a result. In this study, nonlinear viscous damping will be chosen to solve this problem with the aid...
The scanning and tracking accuracy of piezoelectric mechanisms over broadband frequencies are limited due to inherent dynamic hysteresis. This phenomenon has been a key bottleneck in the use of piezoelectric mechanisms in fast precision scanning applications. This paper presents a systemic model identification and composite control strategy without hysteresis measurement for such applications. First,...
Design of multi-level packages for better reliability life under drop impact is often conducted through board-level drop testing. Among many failure modes associated with the board-level drop impact test, PCB pad cratering and solder joint disconnection are of particular interests. Because of the complexity and rigor in modeling and simulations, most of the present work is completed through design...
In this paper, theoretical analysis and numerical simulation of a vertical vibrating system with an impact damper is presented. Different impacting forms are occurred in system under simple harmonic excitation. Phase diagram of periodic motion and temporal changes of velocity and displacement in time domain are given. Two important parameters of mass ratio and restitution coefficient are discussed...
In this paper, we analytically investigate the dynamic modeling of a nonlinear microrobot based on the “friction drive principle”. The superposition of a horizontal vibration at the interface between the robot and work floor and an active variation of friction force, obtained by the vertical vibration of the base, makes the robot to move on the substrate. Periodic solutions obtained from the harmonic...
Angular-misaligned shafts connected by gear coupling is the main study object. First introduced a model that consists of two angular-misaligned rigid shafts mounted on bearings. The non-dimensional lateral vibration differential equation of angular-misaligned shaft during startup process is derived, the equation is investigated by numerical integral method. The result reveals that the vibration peaks...
In this paper, we investigate nonlinear dynamic behaviors of a piezoelectric plate. By the methods of boundary integration and modal truncation, the partial differential equation governing the vibration of piezoelectric plates has been derived. The piezoelectric resonator is described as a parametrically excited nonlinear vibration system. The calculations based on the coupled-mode equations based...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.