{"title":"Fatigue life of elbow pipe for in-plane loading (Part II: carbon steel)","authors":"Masayuki Kamaya","doi":"10.1016/j.ijpvp.2025.105491","DOIUrl":null,"url":null,"abstract":"<div><div>It has been pointed out that the fatigue life of elbow pipes made of carbon steel subjected to cyclic in-plane bending was shorter than that predicted for uniaxial cyclic loading. This study aimed to investigate the fatigue life of elbow pipes and to quantify the reduction in fatigue life for component design. The fatigue test was conducted at room temperature using eight elbow specimens made of carbon steel. To suppress the ratcheting strain, only slight internal pressure was applied to detect crack penetration. Uniaxial and plate bending fatigue tests were also conducted using specimens taken from an elbow pipe of the same heat. The equivalent strain range at the crack initiation point, which was the inner surface of the crown, was successfully estimated from the measured strain using finite element analysis results. It was shown that the fatigue life obtained by the elbow test was shorter than that obtained by the axial and plate bending fatigue tests for the same equivalent strain range, and the reduction in fatigue life became more significant as the strain range increased. It was deduced that the ratcheting strain was not a major factor that caused the fatigue life reduction of elbow pipes. Then, the degree of the fatigue life reduction of the elbow specimens was quantified. The ratio of the fatigue life of the elbow specimen to that for uniaxial fatigue loading did not exceed 4 when the fatigue life of the elbow pipe was more than 120 cycles.</div></div>","PeriodicalId":54946,"journal":{"name":"International Journal of Pressure Vessels and Piping","volume":"216 ","pages":"Article 105491"},"PeriodicalIF":3.0000,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"International Journal of Pressure Vessels and Piping","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0308016125000614","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENGINEERING, MECHANICAL","Score":null,"Total":0}
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Abstract
It has been pointed out that the fatigue life of elbow pipes made of carbon steel subjected to cyclic in-plane bending was shorter than that predicted for uniaxial cyclic loading. This study aimed to investigate the fatigue life of elbow pipes and to quantify the reduction in fatigue life for component design. The fatigue test was conducted at room temperature using eight elbow specimens made of carbon steel. To suppress the ratcheting strain, only slight internal pressure was applied to detect crack penetration. Uniaxial and plate bending fatigue tests were also conducted using specimens taken from an elbow pipe of the same heat. The equivalent strain range at the crack initiation point, which was the inner surface of the crown, was successfully estimated from the measured strain using finite element analysis results. It was shown that the fatigue life obtained by the elbow test was shorter than that obtained by the axial and plate bending fatigue tests for the same equivalent strain range, and the reduction in fatigue life became more significant as the strain range increased. It was deduced that the ratcheting strain was not a major factor that caused the fatigue life reduction of elbow pipes. Then, the degree of the fatigue life reduction of the elbow specimens was quantified. The ratio of the fatigue life of the elbow specimen to that for uniaxial fatigue loading did not exceed 4 when the fatigue life of the elbow pipe was more than 120 cycles.
期刊介绍：
Pressure vessel engineering technology is of importance in many branches of industry. This journal publishes the latest research results and related information on all its associated aspects, with particular emphasis on the structural integrity assessment, maintenance and life extension of pressurised process engineering plants.
The anticipated coverage of the International Journal of Pressure Vessels and Piping ranges from simple mass-produced pressure vessels to large custom-built vessels and tanks. Pressure vessels technology is a developing field, and contributions on the following topics will therefore be welcome:
• Pressure vessel engineering
• Structural integrity assessment
• Design methods
• Codes and standards
• Fabrication and welding
• Materials properties requirements
• Inspection and quality management
• Maintenance and life extension
• Ageing and environmental effects
• Life management
Of particular importance are papers covering aspects of significant practical application which could lead to major improvements in economy, reliability and useful life. While most accepted papers represent the results of original applied research, critical reviews of topical interest by world-leading experts will also appear from time to time.
International Journal of Pressure Vessels and Piping is indispensable reading for engineering professionals involved in the energy, petrochemicals, process plant, transport, aerospace and related industries; for manufacturers of pressure vessels and ancillary equipment; and for academics pursuing research in these areas.
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