| LU Chun,YIN Jia-bao,ZHANG Qing-he,FU Qiang.Wear Degradation of Railway Vehicle Brake Pad Friction Block in Running-in Stage[J],51(12):63-71 |
| Wear Degradation of Railway Vehicle Brake Pad Friction Block in Running-in Stage |
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| DOI：10.16490/j.cnki.issn.1001-3660.2022.12.005 |
| KeyWord:running-in stage tribological behavior railway vehicle friction and wear brake pad friction block |
| Author | Institution |
| LU Chun |
School of Mechanical Engineering, Southwest Jiaotong University, Chengdu , China;Technology and Equipment of Rail Transit Operation and Maintenance Key Laboratory of Sichuan Province, Chengdu , China |
| YIN Jia-bao |
School of Mechanical Engineering, Southwest Jiaotong University, Chengdu , China;Technology and Equipment of Rail Transit Operation and Maintenance Key Laboratory of Sichuan Province, Chengdu , China |
| ZHANG Qing-he |
School of Mechanical Engineering, Southwest Jiaotong University, Chengdu , China;Technology and Equipment of Rail Transit Operation and Maintenance Key Laboratory of Sichuan Province, Chengdu , China |
| FU Qiang |
School of Mechanical Engineering, Southwest Jiaotong University, Chengdu , China;Technology and Equipment of Rail Transit Operation and Maintenance Key Laboratory of Sichuan Province, Chengdu , China |
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| Abstract: |
| In the using of railway vehicle brake pad friction block, 85% contact area is assumed to be an indication of the accomplishment of the running-in process without theoretical support. Only few studies mention tribological behavior and interface damage analysis for the running-in phase. Through the comprehensive analysis of the tribological behavior in running-in stage, the characteristics of tribological behaviors at the end of the running-in process are determined, which provides a theoretical criterion for determining whether the running-in stage is complete or not and gives theoretical support for running-in period shortening and wear life increasing. With the help of self-designed brake performance test bench, the changes of the tribological behaviors such as contact pressure, contact area, wear and interface damage in running-in stage are recorded to study the braking performance of the friction block in running-in stage. Using UMESHMOTION subroutine, ALE technology and Archard wear model, the tribological behavior of the friction block considering wear degradation accumulation is analyzed. Inaddition, the correctness of simulation results is verified by the experimental data.Finally, based on the results from experiments and simulation, the evolving tribological behavior of the friction block during the running-in process is thoroughly evaluated in terms of contact pressure, contact area, wear volume, damage characteristics, etc. And the tribological behavior features and determination method at the end of the running-in process are provided. It is found that the uneven contact pressure at the beginning of the running-in stage results in a rapid wear on the friction block cut-in side. The increase of the macroscopic contact area leads to a rapid decrease of the average contact stress. In the middle of the running-in stage, the secondary contact plateaus are gradually established by the accumulation and compaction of the generated wear debris. The increase of the macroscopic contact area gradually slows down, as well as the decrease rate of the average contact stress. At the end of the running-in stage, the increase rate in macro contact area further slows down. There is a dynamic balance between the formation and collapse of the secondary contact plateaus, the average contact stress reaches a stable value. According to the variation characteristics of the average contact stress in running-in stage, i.e., first quickly reduces, then slowly reduces and finally remains stable, the running-in stage can be divided into rapid running-in phase, transitional running-in phase and stable running-in phase. Thus, the indication of the accomplishment of the running-in process is that the average contact stress remains unchanged, that is, the stable running-in phase is entered. Under the test conditions in this work, it is found that the running-in process is completed when the contact area of the friction block reaches 90% of the nominal contact area of the friction block. According to these findings, it is possible to keep the average contact stress stable by fine-tuning the preset wear, adjusting the friction block mounting structure and interface contact state during the manufacturing process of the brake friction block.Thesecould help to shorten the running-in time and extend the service life of the brake pad friction block. |
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