Selfexcited vibration, or regenerative chatter, in machining has been studied for many years. Analysis of frictioninduced vibration leading to eek noise. For further information contact manager repository. Selfexcited vibrations refer to the interruptions applied to a primarily special group compared to that of the free vibrations or forced vibrations. Pdf vibration occurring during machining is a major limitation to the productivity and. Identifying selfexcited vibrations with evolutionary. The failure of the cypress viaduct in the 1989 loma prieta earthquake is example of failure due to resonant excitation. An elastic cantilever beam under pressure contact with a moving web undergoes selfexcited vibration that may lead to unstable and even self destructive behavior. An elastic cantilever beam under pressure contact with a moving web undergoes self excited vibration that may lead to unstable and even self destructive behavior. Although any system can oscillate when it is forced to do so externally, the term vibration in mechanical engineering is often. Article pdf available in archive proceedings of the institution of. Aimed at the selfexcited vibration of caused by unreasonable clearance in wearing ring of the francis turbine, whole flow passage of prototype hydraulic turbine which contains the clearance in wearing ring is numerically calculated by computational fluid dynamics software cfx based on ns equation and rng kturbulence model.
The physical model of the vibrating system consists of a nonlinear spring with. This paper addresses the selfexcited vibration problems of maglev. The first class is self excited vibration, including vortexinduced vibration, flutter, and fluidelastic instability. Selfexcited vibrations during engagements of dry friction clutches 982846 during the starting of the vehicle, the friction clutch engagement sometimes generates judder. Selfexcited vibrations represent a broad class of systems. A 21degreeoffreedom variable parameter model of the vehicle torsional vibration is established to simulate the nonlinear vehicle feedbackcontrol system of. In addition, examination and physical explanations for vibration trajectories and energy transfer from the fluid motion to the gate vibration are presented. Research article piezoelectric wind energy harvesting from. Here, the lumped parameter approach is preferred over the fe method. Vehicle transmission noise and vibration constitute a serious problem in the driveline system 1,2, which is concerned in the present. The concept has been extended to the analysis of self excited vibrations in other machining processes that involve tools with several blades or cutters 12, 14. Vibrations of a parametrically and selfexcited system with.
Dynamic stability of a selfexcited elastic beam by. It takes in consideration cutting interruption through surface generation. Pdf selfexcited vibration of the threedegrees of freedom. Department of mechanical engineering minchun pan department of mechanical engineering national central university no. Alternatively, the levitated object can be excited to generate acoustic pressure to act as a self.
Krzhizhanovskaya1, 2, 4 1university of amsterdam, amsterdam, the netherlands 2itmo university, saint petersburg, russia 3deltares, delft, the netherlands 4saint petersburg state polytechnic university, russia. Selfoscillators are therefore distinct from forced and parametric resonators, in which the power that sustains the motion must. With nonlinear selfexcitation of a twomass system deals a paper 61. The research topic has encouraged the application of. Harris shock and vibration handbook 6th edition by allan g piersol and cyril m. The equations of motion for the system are derived from the principle of virtual work and hamiltons principle using the techniques of the calculus of variations. Axial and centrifugal compressors application guide. The technique of self excited vibration drilling was proposed in 3. Self excited chatter is induced by a change in the cutting forces themselves, and is where i place the chatter that may be caused by the material. They are sustained by a constant source of energy, which may be external, or is a part of the system. It is worth to note that the self excited vibrations may be also useful as a source of vibration based energy harvesting see e.
Our study examines a self excited system, without any external torque excitations. Selfexcited vibration drilling models and experiments. Self excited vibration of the threedegrees of freedom system april 2017 conference. Analytical study of selfexcited vibration on single degree. Investigation of self excited torsional vibrations of. Self excited vibrations refer to the interruptions applied to a primarily special group compared to that of the free vibrations or forced vibrations.
The excitation force in the self excited vibration maintaining the action is produced or monitored by the action itself, when the action retarding the excitation force vanishes. The analytical stability limit is used to generate a data set that trains the ann. The exciter rotor output is fed to the main rotor through a threephase fullwave bridge rectifier. For further information contact manager repository services. Unstable or selfexcited vibration of highperformance turbomachinery in the form of whirling or whipping at one of the rotors natural frequencies below the running speed can cause considerable problems. Fully developed surge is self excited vibration characterized by flow reversal and causes low frequency, high amplitude axial vibration, typically in the 0. Keywords oscillation rotor sev tup vibration control control system engineering mechanics feedback mechanics modeling selfexcited stability. Usually, the frequency of self excited vibration is the natural frequency of the rotor. In this paper, an artificial neural network ann is applied to model turning stability. Resonant vibration caused 50 of the 124 spans of the viaduct to collapse. The noncontact selftransportation is achieved by creating a traveling wave on the oscillating object or by asymmetric vibration of the object in order to introduce acoustic stream. This paper discusses analytical study of self excited vibration on a new model of vibratory tillage.
The handbook brought together a comprehensive summary of basic shock and vibration theory and the applications of that theory to contemporary engineering practice. The first class is selfexcited vibration, including vortexinduced vibration, flutter, and fluidelastic instability. Wenjing ding was the director of the dynamics and vibration division of the engineering mechanics department of tsinghua university, china. Multiple mode analysis of the selfexcited vibrations of. Cutting moment analysis article pdf available in international journal of advanced manufacturing technology 471. Definition and brief description on self excited vibration. Self excited vibration there exists also a third category of vibrations in physical systems, known as selfexcited vibrations. Pdf a nonlinear dynamical model of vibration drilling is presented. A selfvibrating drilling head svdh excites lowenergy chatter vibration for certain process parameters by using a lowrigidity part spring located between the machine structure and the tool or the workpiece. Keywords oscillation rotor sev tup vibration control control system engineering mechanics feedback mechanics modeling self excited stability.
Pdf selfexcited vibration drilling models and experiments. Self excited vibrations can be distinguished from forced vibrations in the machining system because self excited vibrations stop when the cutting does. The analytical model examines a self excited system without any external torque excitations. Though flowinduced vibration comprises complex and diverse phenomena, it can be classified by the nature of the flow. Based on a systematic understanding of its theoretical foundations, selfexcited vibration.
Selfexcited vibration control for axially fast excited beam. Some passive means for selfexcited vibration quenching. Vibrations of a parametrically and selfexcited system with ideal and nonideal energy sources interactions between parametric, self, and externally excited vibrations are analysed in this paper. Fully developed surge is selfexcited vibration characterized by flow reversal and causes low frequency, high amplitude axial vibration, typically in the 0. The 25th annual international conference on mechanical engineering isme2017, 24 may 2017. This slow flow is analyzed to obtain analytical approximation of selfexcited vibrations. Selfexcited vibration theory, paradigms, and research methods. This slow flow is analyzed to obtain analytical approximation of self excited vibrations. Analysis and suppression of a selfexcitation vibration via internal. The component of foundation damping has the same form as the negative component of the self excitation of the basic subsystem and, furthermore, certain conditions are met. A self vibrating drilling head svdh excites lowenergy chatter vibration for certain process parameters by using a lowrigidity part spring located between the machine structure and the tool or the workpiece. A rotor system with internal frictions and leaf springs is analyzed by using numerical simulations and theoretical analyses systematically and self excited vibrations occur above the major critical speed. Schmitz department of mechanical engineering and engineering science. Theory, paradigms, and research methods offers a method for analyzing any type of selfexcited vibration sev.
However, there are systems in which the exciting force is a function of the motion variables displacement, velocity or acceleration and thus varies with the motion it produces called coupling. Judder prevents vehicles from starting smoothly, harms the ride comfort, and may produce damage to. Passive broadband targeted energy transfers and control of self excited vibrations. The second class is the forced vibration, including transient vibration, harmonic vibration, and random. The contribution deals with the problem of quenching selfexcited vibrations of a mechanical system by means of parametric. Vibrations of a parametrically and self excited system with ideal and nonideal energy sources interactions between parametric, self, and externally excited vibrations are analysed in this paper. Selfexcited oscillations this type of viv is what occurs naturally, i. The beam, being a continuum with infinite degrees of freedom, is. Selfexcited vibrations from interaction of structures and. Vibrations of a parametrically and selfexcited system with ideal and. The modeling and analysis for the selfexcited vibration of the. A passive and active means for selfexcited vibration suppressing. This paper is aimed to determine the selfexcited vibration criterion of a typical rolling mill.
In particular, selfexcited vibrations have been found to be a cause of threatening. Selfoscillation is the generation and maintenance of a periodic motion by a source of power that lacks any corresponding periodicity. Self oscillators are therefore distinct from forced and parametric resonators, in which the power that sustains the motion must. Unstable or self excited vibration of highperformance turbomachinery in the form of whirling or whipping at one of the rotors natural frequencies below the running speed can cause considerable problems. If the system is disturbed from a position of equilibrium, forces generally appear which cause the system to move either toward the equilibrium position or away from it. Aimed at the self excited vibration of caused by unreasonable clearance in wearing ring of the francis turbine, whole flow passage of prototype hydraulic turbine which contains the clearance in wearing ring is numerically calculated by computational fluid dynamics software cfx based on ns equation and rng kturbulence model. Nov 26, 2017 definition and brief description on self excited vibration. An analytical lumped parameter approach was preferred over the structural finiteelement method. How different levels of damping capacity affect vibration decay 08 1. Identifying selfexcited vibrations with evolutionary computing christiaan d. Me 563 mechanical vibrations fall 2010 12 1 introduction to mechanical vibrations 1. On the problem of selfexcited vibration quenching by means of. The analytical model examines a selfexcited system without any external torque excitations. Passive broadband targeted energy transfers and control of.
The concept has been extended to the analysis of selfexcited vibrations in other machining processes that involve tools with several blades or cutters 12, 14. The occurrence of selfexcited vibration in a physical system is intimately associated with the stability of equilibrium positions of the system. These vibrations are steady, usually with constant amplitude, phase, and frequency. The occurrence of self excited vibration in a physical system is intimately associated with the stability of equilibrium positions of the system. The noncontact selftransportation is achieved by creating a traveling wave on the oscillating object or by asymmetric vibration of the. Active selfexcited vibration elimination of rotating machine with an electromagnetic exciter chenchao fan. The stability of the wheelset selfexcited vibration system depends mainly on the total energy removed from and imported into the system. Pdf selfexcited vibration of workpieces in a turning process. The characteristics of this coupledmode selfexcited vibration are obtained through approximate numerical solutions, derived by iterative numerical calculations of the equations of motion.
A neural network approach for chatter prediction in turning. The oscillator itself controls the phase with which the external power acts on it. The component of foundation damping has the same form as the negative component of the selfexcitation of the basic subsystem and, furthermore, certain conditions are met. Determination of self excited vibration criterion for strip. Self oscillation is the generation and maintenance of a periodic motion by a source of power that lacks any corresponding periodicity. Our study examines a selfexcited system, without any.
Active selfexcited vibration elimination of rotating machine. This critical condition is a criterion which can distinguish the type of selfexcited vibration and help to escape the unstable selfexcited vibration as well as prolong the rolling mills lifetime. Selfexcited vibration of the threedegrees of freedom system april 2017 conference. Self excited vibration there exists also a third category of vibrations in physical systems, known as self excited vibrations. The vibration of vibratory tillage was model as a vibration with single degree of freedom sdof system i. This is the real viv this is vortexinduced vibration o forced oscillations occurs at velocities and amplitudes which are preset and can be controlled independently of. Selfexcited or selfinduced vibrations are widely studied because they. Recently a new active mean has been intensively investigated. Mechanism and simulation of selfexcited vibration in a. The physical model of the vibrating system consists of a. Selfexcited vibrations during engagements of dry friction.
With this selfexcited system the main stator provides power via the automatic voltage regulator avr to the exciter stator. In this section, we use the method of multiple scales to derive the slow flow of slow motion corresponding to eq. Selfrunning and selffloating twodimensional actuator using. With nonlinear self excitation of a twomass system deals a paper 61. The energy of selfexcited vibration derives from a part of traction energy. Research article piezoelectric wind energy harvesting from self. The high efficiency semiconductors of the avr ensure positive buildup from initial low levels of residual voltage. The cause of the selfexcited vibration is found by means of the phase plane analysis and the vibration energy analysis approach. Influences of clearance in the nether wearing ring on the. The technique of selfexcited vibration drilling was proposed in 3. The excitation force in the selfexcited vibration maintaining the action is produced or monitored by the action itself, when the. Self excited, torsional vibration, computer simulation, ravigneaux planetary gear set, compound planetary gear set, longitudinally mounted automatic transmission.
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