On a self-developed circular-translation polishing machine,the influence of different electric potentials on the friction coefficient and wear properties of SiC/HT200 friction pair,which contacted as one electrode,wer...On a self-developed circular-translation polishing machine,the influence of different electric potentials on the friction coefficient and wear properties of SiC/HT200 friction pair,which contacted as one electrode,were studied in NaOH solutions.The results show that the friction coefficient of SiC/HT200 pair is 0.25 under no externally applied potential;but it decreases to 0.23 while applying +3 V polarization potential on the pair;in contrast,it increases to 0.30 when applying-3 V polarization potential on the pair.And the polished SiC surface under + 3 V potential is much smoother,while there are clear ploughing marks and adhesive region on the polished SiC surface under zero and-3 V potential,respectively.The mixed triboelectrochemical friction model has been proposed and the mechanisms of the electric effects on the tribological properties of SiC/HT200 friction pair in NaOH electrolyte are addressed.Results and discussion show that the anodic passivation technique may be used for hastening the running-in process of SiC/Fe friction pairs,as well as for polishing SiC to increase its materials removal efficiency while maintaining good surface quality.展开更多
In the diagnosis of rotor crack based on wavelet analysis, it is a painful task to find out an adaptive mother wavelet as many of them can be chosen and the analytic results of different mother wavelets are yet not th...In the diagnosis of rotor crack based on wavelet analysis, it is a painful task to find out an adaptive mother wavelet as many of them can be chosen and the analytic results of different mother wavelets are yet not the same. For this limitation of wavelet analysis, a novel diagnostic approach of rotor crack based on multi-scale singular-spectrum analysis （MS-SSA） is proposed. Firstly, a Jeffcott model of a cracked rotor is developed and the forth-order Runge-Kutta method is used to solve the motion equations of this rotor to obtain its time response （signals）. Secondly, a comparatively simple approach of MS-SSA is presented and the empirical orthogonal functions of different orders in various scales are regarded as analyzing functions. At last, the signals of the cracked rotor and an uncracked rotor are analyzed using the proposed approach of MS-SSA, and the simulative results are compared. The results show that, the data-adaptive analyzing functions can capture many features of signals and the rotor crack can be identified and diagnosed effectively by comparing the analytic results of signals of the cracked rotor with those of the uncracked rotor using the analyzing functions of different orders.展开更多
基金Sponsored by the National Natural Science Foundation of China(Grant No.51475119)the National Program on Key Basic Research Project of China(Grant No.2011CB013202)
文摘On a self-developed circular-translation polishing machine,the influence of different electric potentials on the friction coefficient and wear properties of SiC/HT200 friction pair,which contacted as one electrode,were studied in NaOH solutions.The results show that the friction coefficient of SiC/HT200 pair is 0.25 under no externally applied potential;but it decreases to 0.23 while applying +3 V polarization potential on the pair;in contrast,it increases to 0.30 when applying-3 V polarization potential on the pair.And the polished SiC surface under + 3 V potential is much smoother,while there are clear ploughing marks and adhesive region on the polished SiC surface under zero and-3 V potential,respectively.The mixed triboelectrochemical friction model has been proposed and the mechanisms of the electric effects on the tribological properties of SiC/HT200 friction pair in NaOH electrolyte are addressed.Results and discussion show that the anodic passivation technique may be used for hastening the running-in process of SiC/Fe friction pairs,as well as for polishing SiC to increase its materials removal efficiency while maintaining good surface quality.
基金This project is supported by National Fundamental Research and Development Project Foundation of China(No.G1998020321).
文摘In the diagnosis of rotor crack based on wavelet analysis, it is a painful task to find out an adaptive mother wavelet as many of them can be chosen and the analytic results of different mother wavelets are yet not the same. For this limitation of wavelet analysis, a novel diagnostic approach of rotor crack based on multi-scale singular-spectrum analysis （MS-SSA） is proposed. Firstly, a Jeffcott model of a cracked rotor is developed and the forth-order Runge-Kutta method is used to solve the motion equations of this rotor to obtain its time response （signals）. Secondly, a comparatively simple approach of MS-SSA is presented and the empirical orthogonal functions of different orders in various scales are regarded as analyzing functions. At last, the signals of the cracked rotor and an uncracked rotor are analyzed using the proposed approach of MS-SSA, and the simulative results are compared. The results show that, the data-adaptive analyzing functions can capture many features of signals and the rotor crack can be identified and diagnosed effectively by comparing the analytic results of signals of the cracked rotor with those of the uncracked rotor using the analyzing functions of different orders.
