Dynamic Performance of Shoe Centerless Grinding

2002 ◽  
Author(s):  
Hong Zhang ◽  
Junghsen Lieh ◽  
David Yen
Keyword(s):  
Numerical Simulations ◽  
Dynamic Performance ◽  
Critical Parameters ◽  
Grinding Process ◽  
Mass System ◽  
Frequency Domains ◽  
Single Mass ◽  
Centerless Grinding ◽  
The Stability ◽  
Time And Frequency Domains

In this paper, the dynamic performance of shoe centerless grinding is presented. The model is a single-mass system in time and frequency domains. Based on the model, the stability and the critical parameters of the grinding process were studied. Numerical simulations were conducted in order to evaluate key parameters for the grinding process. The model was verified by experiments from real grinding trials.

scholarly journals Vibration Induced by Subway Trains: Open-Trench Mitigation Analysis in the Time and Frequency Domains

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Wenbo Yang ◽  
Ran Yuan ◽  
Juan Wang
Keyword(s):  
Numerical Simulations ◽  
Frequency Domain ◽  
Frequency Domain Analysis ◽  
Soil Response ◽  
Physical Model Tests ◽  
Frequency Domains ◽  
Trench Isolation ◽  
Open Trench ◽  
Isolation Performance ◽  
Time And Frequency Domains

In this paper, we analyse the mitigation effects of open trenches on the vibrations induced by subway trains. The study is performed by using both physical model tests and numerical simulations. The effectiveness is evaluated by calculating the frequency response function (FRF) and the vibration acceleration peak (VAP) in both time and frequency domains. The experimental and numerical results demonstrate that the open trench has clear effects on the dynamic soil response. Both time and frequency domain results suggest that the dynamic response of the soils beyond the open trenches could be significantly affected, due to the existence of the open trench. According to the frequency domain analysis, the inclusion of open trenches could effectively reduce the soil response in a higher frequency range. Due to reflection effects at the boundaries of the trench, an amplification of the soil response in front of the open trench is observed. Parametric study by means of numerical simulations is also performed. The width of the open trench demonstrates negligible effects on the dynamic soil response, whilst the trench depth exhibits a large influence on the trench isolation performance. With an increase in the trench depth, the isolation performance is significantly improved. It is concluded that the open trenches perform well as an isolation barrier, in mitigating the vibration induced by subway trains.

A new perspective on the stability study of centerless grinding process

2010 ◽  
Vol 50 (2) ◽  
pp. 165-173 ◽  
Author(s):  
I. Garitaonandia ◽  
M.H. Fernandes ◽  
J. Albizuri ◽  
J.M. Hernández ◽  
D. Barrenetxea
Keyword(s):  
Stability Study ◽  
Grinding Process ◽  
Centerless Grinding ◽  
New Perspective ◽  
The Stability

Stability Analysis of a Transverse Cylindrical Grinding Process

2012 ◽  
Vol 479-481 ◽  
pp. 1190-1193
Author(s):  
Yao Yan ◽  
Jian Xu
Keyword(s):  
Stability Analysis ◽  
Grinding Wheel ◽  
Force Model ◽  
Grinding Process ◽  
Key Factors ◽  
Mass System ◽  
Cylindrical Grinding ◽  
Chatter Vibrations ◽  
The Stability ◽  
Euler Bernoulli Beam

The stability of a transverse cylindrical grinding process is investigated in this paper. The workpiece is considered as a rotating damped hinged-hinged Euler-Bernoulli beam and the grinding wheel a rotating damped spring mass system moving along the workpiece. Called regenerative force, the contact force between the workpiece and the wheel is a functional equation related to both the current and previous relative positions between the workpiece and the wheel since the regeneration exists on the surfaces of both the workpiece and the wheel. The two distinct time delays presented in the regenerative force model are inversely proportional to the rotation speeds of the workpiece and the wheel respectively. For grinding stability analysis, the regenerative effects are considered as the key factors in inducing chatter vibrations in the grinding process. The grinding stability is numerically analyzed since two distinct delays being involved in the model makes the analytical analysis extremely difficult. Finally, the grinding stability analysis is verified by numerical simulation.

Stability of Controlled Mechanical Systems With Ideal Coulomb Friction

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Soo Jeon ◽  
Masayoshi Tomizuka
Keyword(s):  
Coulomb Friction ◽  
Nonlinear Oscillations ◽  
Mechanical Systems ◽  
Feedback Systems ◽  
Relay Feedback ◽  
Mass System ◽  
Single Mass ◽  
Space Formulation ◽  
The Stability ◽  
Controlled Mechanical Systems

When a mechanical system with Coulomb friction is under feedback control, the closed-loop system may asymptotically converge to a point in the equilibrium set or generate nonlinear oscillations such as limit cycles depending on the control algorithm. Thus, it is important to know how to guarantee the stability in the presence of Coulomb friction. This paper presents the stability analysis of controlled mechanical systems with multiple ideal Coulomb friction sources. Common properties of controlled mechanical systems with multiple ideal Coulomb friction sources have been explored and generalized into the state space formulation leading to a class of ideal relay feedback systems. Various stability criteria are considered and a new sufficient condition for the pointwise global stability is suggested. Simulation results for a single mass system and experimental results for a single link flexible joint mechanism are presented to confirm the analysis and to illustrate various aspects of stability conditions for controlled mechanical systems with ideal Coulomb friction. The results given in this paper can be useful for the design of mechanical systems free from the limit cycle.

A Design of Comfortable Dental Treatment Sound Based on Chord-forming in Time and Frequency Domains

2015 ◽  
Vol 135 (12) ◽  
pp. 1565-1573
Author(s):  
Yoshitaka Ohshio ◽  
Daisuke Ikefuji ◽  
Yuko Suhara ◽  
Masato Nakayama ◽  
Takanobu Nishiura
Keyword(s):  
Dental Treatment ◽  
Frequency Domains ◽  
Time And Frequency Domains

Fuzzy Extreme Analysis in Time- and Frequency Domains

2011 ◽  
Vol 57 (4) ◽  
Author(s):  
Włodzimierz Pogribny ◽  
Marcin Drzycimski ◽  
Zdzisław Drzycimski
Keyword(s):  
Frequency Domains ◽  
Time And Frequency Domains

Influence of viscosity temperature dependence on the spectral characteristics of the thermoviscous liquids flow stability equation

2019 ◽  
Vol 14 (1) ◽  
pp. 52-58 ◽  
Author(s):  
A.D. Nizamova ◽  
V.N. Kireev ◽  
S.F. Urmancheev
Keyword(s):  
Reynolds Number ◽  
Spectral Characteristics ◽  
Wave Number ◽  
Critical Parameters ◽  
Fluid Viscosity ◽  
Flat Channel ◽  
Stability Equation ◽  
The Stability ◽  
Thermoviscous Fluid ◽  
Sommerfeld Equation

The flow of a viscous model fluid in a flat channel with a non-uniform temperature field is considered. The problem of the stability of a thermoviscous fluid is solved on the basis of the derived generalized Orr-Sommerfeld equation by the spectral decomposition method in Chebyshev polynomials. The effect of taking into account the linear and exponential dependences of the fluid viscosity on temperature on the spectral characteristics of the hydrodynamic stability equation for an incompressible fluid in a flat channel with given different wall temperatures is investigated. Analytically obtained profiles of the flow rate of a thermovisible fluid. The spectral pictures of the eigenvalues of the generalized Orr-Sommerfeld equation are constructed. It is shown that the structure of the spectra largely depends on the properties of the liquid, which are determined by the viscosity functional dependence index. It has been established that for small values of the thermoviscosity parameter the spectrum compares the spectrum for isothermal fluid flow, however, as it increases, the number of eigenvalues and their density increase, that is, there are more points at which the problem has a nontrivial solution. The stability of the flow of a thermoviscous fluid depends on the presence of an eigenvalue with a positive imaginary part among the entire set of eigenvalues found with fixed Reynolds number and wavenumber parameters. It is shown that with a fixed Reynolds number and a wave number with an increase in the thermoviscosity parameter, the flow becomes unstable. The spectral characteristics determine the structure of the eigenfunctions and the critical parameters of the flow of a thermally viscous fluid. The eigenfunctions constructed in the subsequent works show the behavior of transverse-velocity perturbations, their possible growth or decay over time.

Dynamic Performance of High-Speed Electric Multiple Unit within Multi-Body System Simulation

2019 ◽  
Vol 12 (4) ◽  
pp. 339-349
Author(s):  
Junguo Wang ◽  
Daoping Gong ◽  
Rui Sun ◽  
Yongxiang Zhao
Keyword(s):  
High Speed ◽  
Rapid Development ◽  
Dynamic Performance ◽  
Body System ◽  
High Speed Railway ◽  
Evaluation Indexes ◽  
Actual Operation ◽  
Multiple Unit ◽  
The Stability ◽  
Multi Body

Background: With the rapid development of the high-speed railway, the dynamic performance such as running stability and safety of the high-speed train is increasingly important. This paper focuses on the dynamic performance of high-speed Electric Multiple Unit (EMU), especially the dynamic characteristics of the bogie frame and car body. Various patents have been discussed in this article. Objective: To develop the Multi-Body System (MBS) model of EMU, verify whether the dynamic performance meets the actual operation requirements, and provide some useful information for dynamics and structural design of the proposed EMU. Methods: According to the technical characteristics of a typical EMU, a MBS model is established via SIMPACK, and the measured data of China high-speed railway is taken as the excitation of track random irregularity. To test the dynamic performance of the EMU, including the stability and safety, some evaluation indexes such as wheel-axle lateral forces, wheel-axle lateral vertical forces, derailment coefficients and wheel unloading rates are also calculated and analyzed in detail. Results: The MBS model of EMU has better dynamic performance especially curving performance, and some evaluation indexes of the stability and safety have also reached China’s high-speed railway standards. Conclusion: The effectiveness of the proposed MBS model is verified, and the dynamic performance of the MBS model can meet the design requirements of high-speed EMU.

Systems with Condensates and Pairing

2018 ◽  
Author(s):  
Klaus Morawetz
Keyword(s):  
Critical Parameters ◽  
Einstein Condensation ◽  
Cooper Pairs ◽  
Pair Breaking ◽  
Systematic Theory ◽  
Bose Einstein Condensation ◽  
T Matrix ◽  
The Stability ◽  
Bose Einstein

The Bose–Einstein condensation and appearance of superfluidity and superconductivity are introduced from basic phenomena. A systematic theory based on the asymmetric expansion of chapter 11 is shown to correct the T-matrix from unphysical multiple-scattering events. The resulting generalised Soven scheme provides the Beliaev equations for Boson’s and the Nambu–Gorkov equations for fermions without the usage of anomalous and non-conserving propagators. This systematic theory allows calculating the fluctuations above and below the critical parameters. Gap equations and Bogoliubov–DeGennes equations are derived from this theory. Interacting Bose systems with finite temperatures are discussed with successively better approximations ranging from Bogoliubov and Popov up to corrected T-matrices. For superconductivity, the asymmetric theory leading to the corrected T-matrix allows for establishing the stability of the condensate and decides correctly about the pair-breaking mechanisms in contrast to conventional approaches. The relation between the correlated density from nonlocal kinetic theory and the density of Cooper pairs is shown.

scholarly journals Fast-Scale Instability and Stabilization by Adaptive Slope Compensation of a PV-Fed Differential Boost Inverter

2021 ◽  
Vol 11 (5) ◽  
pp. 2106
Author(s):  
Abdelali El Aroudi ◽  
Mohamed Debbat ◽  
Mohammed Al-Numay ◽  
Abdelmajid Abouloiafa
Keyword(s):  
Numerical Simulations ◽  
Full Range ◽  
Weather Conditions ◽  
Current Loop ◽  
Point Tracking ◽  
Bifurcation Phenomena ◽  
Slope Compensation ◽  
Power Point ◽  
The Stability ◽  
Detailed Circuit

Numerical simulations reveal that a single-stage differential boost AC module supplied from a PV module under an Maximum Power Point Tracking (MPPT) control at the input DC port and with current synchronization at the AC grid port might exhibit bifurcation phenomena under some weather conditions leading to subharmonic oscillation at the fast-switching scale. This paper will use discrete-time approach to characterize such behavior and to identify the onset of fast-scale instability. Slope compensation is used in the inner current loop to improve the stability of the system. The compensation slope values needed to guarantee stability for the full range of operating duty cycle and leading to an optimal deadbeat response are determined. The validity of the followed procedures is finally validated by a numerical simulations performed on a detailed circuit-level switched model of the AC module.

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