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RISS 인기검색어
- 검색키워드
- 저자 : Houjun Qi (검색결과 3 건)
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Dynamics responses analysis in frequency domain of helical gear pair under multi-fault conditions
Lin Han,Houjun Qi 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.11
This work aims to investigate dynamic characteristics of a helical gear pair under multiple faults condition, through model-based dynamic analysis. Two kinds of faults, tooth spalling and local breakages are considered. Firstly, influences of each kind of fault on meshing stiffness of gear pair with one or more faulted teeth were revealed. Then an 8 degree of freedom lumped-parameter model was developed to obtain dynamic responses. Furthermore, frequency spectrum analysis of the responses was conducted and compared with those under healthy condition. Results indicate that spalling or local breakage introduce different affects into mesh stiffness, and consequently displacement & velocity amplitudes of pinion appear with different waveforms, especially for the case only tooth breakages happen. This work could provide useful instructions for fault detection diagnosis of geared transmissions under multiple fault conditions.
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Influences of friction and mesh misalignment on time-varying mesh stiffness of helical gears
Lin Han,Lixin Xu,Houjun Qi 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.7
As one of the most important excitation sources of vibration, time-varying mesh stiffness of helical gear pairs need accurately calculated. Compared with spur gears, friction in helical gears is significant. This work for the first time presents an improved calculation method for the mesh stiffness of helical gears with effect of friction incorporated. Firstly, helical gear is sliced into number of pieces along its axis direction and each piece could be regarded as spur gear. Then forces applied to each piece including friction force are analyzed. Potential energy method is employed to develop time-varying mesh stiffness of each piece pair of both kinds of helical gears with different transverse and axial contact ratios. Furthermore, influences of various working conditions and misalignment on mesh stiffness are also investigated. Results indicate that effect brought by friction on total mesh stiffness should be not neglected. The reduction amount of stiffness increases with lower speed, heavier load and rougher surface. The stiffness difference between cases with and without friction is affected by gear geometry and mounting parameters like module, helix angle and mounting misalignment. This work provides an essential tool for comprehensive dynamics analysis with consideration of the relationship between stiffness and working conditions.
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Yanhui Liu,Ke Xu,Xiaochen Zhang,Chunhua Qi,Qingchun Lv,Houjun Feng 한국물리학회 2016 Current Applied Physics Vol.16 No.5
A simple electrochemical codeposition technique has been introduced to fabricate graphene oxide/ polypyrrole (GO/PPy) composites. To increase the adsorption of colloidal GOs at the liquideliquid interface, the organic supporting electrolyte like benzenesulfonate sodium (BS) is added in GO/pyrrole micelle solution, which does not induce the flocculation sedimentation of GO at elevated ionic strength. The narrow size distribution of GO/pyrrole/BS micelles is benefit for uniform codeposition of GO/PPy on the carbon fiber surface. Moreover, the GO nanosheets and benzensulfonate have been incorporated into composites as mixture dopants, which increased the growth orientation of PPy in electropolymerization process and result in more loose structure for ionic transportation. The composites electrodes exhibit high specific capacitance, good cyclic stability after electrochemical reduction of graphene oxide (RGO). The specific capacitance of composite electrode with low mass density still reaches 358 F/g at scan rate of 10 mV/s within an electrochemical windows of 1.0 V. The strong interaction effect between two components resists the mechanical deformation effect and exhibits only 7.1% decay at a charge/discharge current of 3 A/g after 1000 cycles. At increasing the mass density of composites to 8.4 mg/cm2, the areal capacitance of electrode almost grow linearly to 1.286 F/cm2, which is more than triple that of BS-doped PPy with the same mass density. The high capacity of the composite electrode exerts the potential applications in capacitive deionization, microbial fuel cell or even capacitive energy storage.
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