Fatigue research of metro car body based on operational loads
Purpose – The principle of infinite life design currently directs fatigue resistance strategies for metro car bodies. However, this principle might not fully account for the dynamic influence of operational loads and the inevitable presence of defects. This study aims to integrate methods of service...
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| Format: | Article |
| Language: | English |
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Emerald Publishing
2024-10-01
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| Series: | Railway Sciences |
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| Online Access: | https://www.emerald.com/insight/content/doi/10.1108/RS-06-2024-0023/full/pdf |
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| _version_ | 1850207385436553216 |
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| author | Xihong Jin Feng Guo |
| author_facet | Xihong Jin Feng Guo |
| author_sort | Xihong Jin |
| collection | DOAJ |
| description | Purpose – The principle of infinite life design currently directs fatigue resistance strategies for metro car bodies. However, this principle might not fully account for the dynamic influence of operational loads and the inevitable presence of defects. This study aims to integrate methods of service life estimation and residual life assessment, which are based on operational loads, into the existing infinite life verification framework to further ensure the operational safety of subway trains. Design/methodology/approach – Operational loads and fatigue loading spectra were determined through the field test. The material test was conducted to investigate characteristics of the fracture toughness and the crack growth rate. The fatigue strength of the metro car body was first verified using the finite element method and Moore–Kommers–Japer diagrams. The service life was then estimated by applying the Miner rule and high-cycle fatigue curves in a modified form of the Basquin equation. Finally, the residual life was assessed utilizing a fracture assessment diagram and a fitted curve of crack growth rate adhered to the Paris formula. Findings – Neither the maximum utilization factor nor the cumulative damage exceeds the threshold value of 1.0, the metro car body could meet the design life requirement of 30 years or 6.6 million km. However, three out of five fatigue key points were significantly influenced by the operational loads, which indicates that a single fatigue strength verification cannot achieve the infinite life design objective of the metro car body. For a projected design life of 30 years, the tolerance depth is 12.2 mm, which can underscore a relatively robust damage tolerance capability. Originality/value – The influence of operational loads on fatigue life was presented by the discrepancy analysis between fatigue strength verification results and service life estimation results. The fracture properties of butt-welded joints were tested and used for the damage tolerance assessment. The damage tolerance life can be effectively related by a newly developed equation in this study. It can be a valuable tool to provide the theoretical guidance and technical support for the structural improvements and maintenance decisions of the metro car body. |
| format | Article |
| id | doaj-art-882170cef50545778dc09bc8ee92e072 |
| institution | OA Journals |
| issn | 2755-0907 2755-0915 |
| language | English |
| publishDate | 2024-10-01 |
| publisher | Emerald Publishing |
| record_format | Article |
| series | Railway Sciences |
| spelling | doaj-art-882170cef50545778dc09bc8ee92e0722025-08-20T02:10:32ZengEmerald PublishingRailway Sciences2755-09072755-09152024-10-013555857410.1108/RS-06-2024-0023Fatigue research of metro car body based on operational loadsXihong Jin0Feng Guo1State Key Laboratory of Heavy-Duty and Express High-Power Electric Locomotive, Product Research and Development Center, CRRC Zhuzhou Locomotive Co., Ltd., Zhuzhou, ChinaState Key Laboratory of Heavy-Duty and Express High-Power Electric Locomotive, Product Research and Development Center, CRRC Zhuzhou Locomotive Co., Ltd., Zhuzhou, ChinaPurpose – The principle of infinite life design currently directs fatigue resistance strategies for metro car bodies. However, this principle might not fully account for the dynamic influence of operational loads and the inevitable presence of defects. This study aims to integrate methods of service life estimation and residual life assessment, which are based on operational loads, into the existing infinite life verification framework to further ensure the operational safety of subway trains. Design/methodology/approach – Operational loads and fatigue loading spectra were determined through the field test. The material test was conducted to investigate characteristics of the fracture toughness and the crack growth rate. The fatigue strength of the metro car body was first verified using the finite element method and Moore–Kommers–Japer diagrams. The service life was then estimated by applying the Miner rule and high-cycle fatigue curves in a modified form of the Basquin equation. Finally, the residual life was assessed utilizing a fracture assessment diagram and a fitted curve of crack growth rate adhered to the Paris formula. Findings – Neither the maximum utilization factor nor the cumulative damage exceeds the threshold value of 1.0, the metro car body could meet the design life requirement of 30 years or 6.6 million km. However, three out of five fatigue key points were significantly influenced by the operational loads, which indicates that a single fatigue strength verification cannot achieve the infinite life design objective of the metro car body. For a projected design life of 30 years, the tolerance depth is 12.2 mm, which can underscore a relatively robust damage tolerance capability. Originality/value – The influence of operational loads on fatigue life was presented by the discrepancy analysis between fatigue strength verification results and service life estimation results. The fracture properties of butt-welded joints were tested and used for the damage tolerance assessment. The damage tolerance life can be effectively related by a newly developed equation in this study. It can be a valuable tool to provide the theoretical guidance and technical support for the structural improvements and maintenance decisions of the metro car body.https://www.emerald.com/insight/content/doi/10.1108/RS-06-2024-0023/full/pdfMetro car bodyField testStructural integrityDamage accumulationDamage tolerance |
| spellingShingle | Xihong Jin Feng Guo Fatigue research of metro car body based on operational loads Railway Sciences Metro car body Field test Structural integrity Damage accumulation Damage tolerance |
| title | Fatigue research of metro car body based on operational loads |
| title_full | Fatigue research of metro car body based on operational loads |
| title_fullStr | Fatigue research of metro car body based on operational loads |
| title_full_unstemmed | Fatigue research of metro car body based on operational loads |
| title_short | Fatigue research of metro car body based on operational loads |
| title_sort | fatigue research of metro car body based on operational loads |
| topic | Metro car body Field test Structural integrity Damage accumulation Damage tolerance |
| url | https://www.emerald.com/insight/content/doi/10.1108/RS-06-2024-0023/full/pdf |
| work_keys_str_mv | AT xihongjin fatigueresearchofmetrocarbodybasedonoperationalloads AT fengguo fatigueresearchofmetrocarbodybasedonoperationalloads |