Study on Wear Dynamic Reliability of Gear System Based on Markov Diffusive Process

2021 ◽  
pp. 1-12
Author(s):  
Jia xing Pei ◽  
Xu Han ◽  
you rui Tao ◽  
Shizhe Feng
Keyword(s):  
Spectral Density ◽  
Normal Distribution ◽  
Transition Probability ◽  
Constant Load ◽  
Gear System ◽  
Wear Depth ◽  
Noise Spectral Density ◽  
Dynamic Reliability ◽  
Diffusive Process ◽  
Wear Life

Abstract Wear is one of the most common failure forms of gear transmission system. In this paper, a dynamic wear reliability evaluation method for gear system, which subjects to stochastic external load, is proposed on the basis of Markov diffusive process. The stochastic load is considered as the combination of constant load and random noise. The failure is defined as the wear depth of the maximum wear point of gear under the constant load exceeds a specific threshold. The maximum wear point and relative sliding velocity are obtained by deterministic wear analysis. The stochastic noise is assumed as Gaussian white noise; hence the wear depth can be described as Markov diffusive process, and the transition probability is governed by Fokker-Planck-Kolmogorov (FPK) equation. With the transition probability function, the wear life and dynamic reliability of gear system with different noise spectral density are predicted. The results revel that the wear depth obeys normal distribution and becomes more and more scattered with noise spectral density increases. The wear life does not obey normal distribution, the effect of noise spectral density on mean life is neglectable while on standard deviation of life is considerable.

Nonstationary Probabilistic Seismic Response Analysis of Nonlinear Soil Profile under Bidirectional Dynamic Loading

2012 ◽  
Vol 193-194 ◽  
pp. 949-953
Author(s):  
Xiao Dong Pan ◽  
Jia En Zhong ◽  
Chao Chao He
Keyword(s):  
Spectral Density ◽  
Seismic Response ◽  
Ground Motion ◽  
Power Spectral Density ◽  
Soil Profile ◽  
Response Analysis ◽  
Time Varying ◽  
Seismic Response Analysis ◽  
Dynamic Reliability ◽  
Power Spectral

In this paper, according to the characteristics of near-fault earthquakes, combined with the strong ground motion attenuation law in China, the nonstationary power spectrum of bidirectional ground motion input is obtained through random vibration analysis. By introducing the pseudo excitation algorithm, the evolutionary power spectral density (PSD) of acceleration at the engineering bedrock is handled as the nonstationary pseudo input, and the Hardin-Drnevich hyperbolic model is utilized to take into account the nonlinearity of soil layer. On this basis, finite element method in the time domain and frequency domain are used for seismic response analysis of soil profile. Values including various time-varying power spectral density of the dynamic response, time varying RMS and time-dependent reliability at different threshold can be obtained by calculating, which provides a basis for the analysis of the foundation dynamic reliability assessment.

A Numerical Simulation of Fretting Wear considering the Dynamic Evolution of Debris for the Coated Contact Surface

2021 ◽  
pp. 1-49
Author(s):  
Li Xiao ◽  
Yingqiang Xu ◽  
Zhiyong Chen
Keyword(s):  
Fretting Wear ◽  
Contact Pair ◽  
Dynamic Evolution ◽  
Wear Depth ◽  
Wear Coefficient ◽  
Wear Model ◽  
Wear Process ◽  
Dlc Coating ◽  
Wear Life ◽  
Wear Calculation

Abstract In this paper, a multi-layer body model in which material properties and wear coefficient change with node coordinates is proposed, so that the wear profile is not restricted by the singularity of the interface of the coated contact pairs. The conversion rate of the adhered particles was obtained to describe the growth and expansion of the debris at the fretting interface based on experiments, and the wear model of coated contact pair considering the dynamic evolution of the debris layer was established. By comparing the previous experimental and computational results, the wear calculation method proposed in this paper is more reasonable to predict the wear profile of the coated contact pair. In addition, the influence of the debris layer on the wear depth, friction width, and contact pressure in the fretting process is analyzed, indicating that the existence of the debris layer can delay the wear process. Finally, the fretting wear life of the SCMV steel contact pair deposited with the W-DLC coating is estimated.

Dynamic Model of a Spur Gear System With Backlash and Friction Consideration

1994 ◽  
Author(s):  
T. K. Shing ◽  
Lung-Wen Tsai ◽  
P. S. Krishnaprasad
Keyword(s):  
Free Oscillation ◽  
Equations Of Motion ◽  
Spur Gear ◽  
Constant Load ◽  
Friction Torque ◽  
Gear System ◽  
Real Time Control ◽  
Dynamical Equations ◽  
Gear Noise ◽  
Time Control

Abstract A new model which accounts for both backlash and friction effects is proposed for the dynamics of a spur gear system. The model estimates average friction torque and uses it to replace the instantaneous friction torque to simplify the dynamical equations of motion. Two simulations, free oscillation and constant load operation, are performed to illustrate the effects of backlash and friction on gear dynamics. The results are compared with that of a previously established model which does not account for the friction. Finally, the effect of adding a damper on the driving shaft is also studied. This model is judged to be more realistic for real time control of electronmechanical systems to reduce gear noise and to achieve high precision.

scholarly journals Thermal noise limit for ultra-high vacuum noncontact atomic force microscopy

2013 ◽  
Vol 4 ◽  
pp. 32-44 ◽  
Author(s):  
Jannis Lübbe ◽  
Matthias Temmen ◽  
Sebastian Rode ◽  
Philipp Rahe ◽  
Angelika Kühnle ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Signal Processing ◽  
Transfer Function ◽  
Spectral Density ◽  
Thermal Noise ◽  
Noise Spectral Density ◽  
Force Microscopy ◽  
Atomic Force ◽  
Noise Limit ◽  
Signal Processing Electronics

The noise of the frequency-shift signal Δf in noncontact atomic force microscopy (NC-AFM) consists of cantilever thermal noise, tip–surface-interaction noise and instrumental noise from the detection and signal processing systems. We investigate how the displacement-noise spectral density d z at the input of the frequency demodulator propagates to the frequency-shift-noise spectral density d Δ f at the demodulator output in dependence of cantilever properties and settings of the signal processing electronics in the limit of a negligible tip–surface interaction and a measurement under ultrahigh-vacuum conditions. For a quantification of the noise figures, we calibrate the cantilever displacement signal and determine the transfer function of the signal-processing electronics. From the transfer function and the measured d z , we predict d Δ f for specific filter settings, a given level of detection-system noise spectral density d z ds and the cantilever-thermal-noise spectral density d z th. We find an excellent agreement between the calculated and measured values for d Δ f . Furthermore, we demonstrate that thermal noise in d Δ f , defining the ultimate limit in NC-AFM signal detection, can be kept low by a proper choice of the cantilever whereby its Q-factor should be given most attention. A system with a low-noise signal detection and a suitable cantilever, operated with appropriate filter and feedback-loop settings allows room temperature NC-AFM measurements at a low thermal-noise limit with a significant bandwidth.

Measurements and analysis of the noise spectral density of YBCO films

2006 ◽  
Vol 203 (11) ◽  
pp. 2944-2949
Author(s):  
A. Taoufik ◽  
M. Bghour ◽  
A. Labrag ◽  
A. Bouaaddi ◽  
A. Abaragh ◽  
...  
Keyword(s):  
Spectral Density ◽  
Noise Spectral Density ◽  
Ybco Films
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