{"title":"Investigation on Fatigue Crack Propagation Behaviour of U-Notched 316 L Specimen Under Strain-Controlled Mode","authors":"X. Chen, W. Zhang, Q. Yang, P. Yin, C. Zhou","doi":"10.1007/s40799-025-00778-5","DOIUrl":null,"url":null,"abstract":"<div><p>During the practical service condition, the strain-controlled fatigue is an important reason for component failure, which cannot be demonstrated by the traditional fatigue crack growth test under stress-controlled mode in accordance to ASTM E647. Therefore, this study is devoted to investigating the fatigue crack propagation behaviour of U-notched specimen under strain-controlled mode. The numerical study is firstly performed to clarify the stress/strain concentration effect and crack tip mechanical behaviour, which is then validated by strain-controlled fatigue tests. The compliance method is also adopted to calibrate the crack length obtained by optical measurement. A modified geometry factor for stress intensity factor (SIF) <i>K</i> considering short crack is proposed for comparison with a <i>J</i>-integral solution based on Electric Power Research Institute (EPRI) method. Digital image correlation (DIC) technology is also adopted to capture the strain field at crack tip to validate the numerical strain distribution. Moreover, different fracture parameters, including Δ<i>K</i> and Δ<i>J</i>, are applied to characterize the crack driving force. It is shown that the strain concentration phenomenon at the notch root can reflect the accumulation of fatigue damage. The Δ<i>K</i> under small scale yielding (SSY) situation is not applicable due to the large plastic deformation occurring at the crack tip. Whereas, agreement is found between crack propagation rate and the fracture parameter Δ<i>J</i> based on the elastic-plastic fracture mechanics (EPFM).</p></div>","PeriodicalId":553,"journal":{"name":"Experimental Techniques","volume":"49 4","pages":"743 - 761"},"PeriodicalIF":1.9000,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Experimental Techniques","FirstCategoryId":"5","ListUrlMain":"https://link.springer.com/article/10.1007/s40799-025-00778-5","RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"ENGINEERING, MECHANICAL","Score":null,"Total":0}
引用次数: 0
Abstract
During the practical service condition, the strain-controlled fatigue is an important reason for component failure, which cannot be demonstrated by the traditional fatigue crack growth test under stress-controlled mode in accordance to ASTM E647. Therefore, this study is devoted to investigating the fatigue crack propagation behaviour of U-notched specimen under strain-controlled mode. The numerical study is firstly performed to clarify the stress/strain concentration effect and crack tip mechanical behaviour, which is then validated by strain-controlled fatigue tests. The compliance method is also adopted to calibrate the crack length obtained by optical measurement. A modified geometry factor for stress intensity factor (SIF) K considering short crack is proposed for comparison with a J-integral solution based on Electric Power Research Institute (EPRI) method. Digital image correlation (DIC) technology is also adopted to capture the strain field at crack tip to validate the numerical strain distribution. Moreover, different fracture parameters, including ΔK and ΔJ, are applied to characterize the crack driving force. It is shown that the strain concentration phenomenon at the notch root can reflect the accumulation of fatigue damage. The ΔK under small scale yielding (SSY) situation is not applicable due to the large plastic deformation occurring at the crack tip. Whereas, agreement is found between crack propagation rate and the fracture parameter ΔJ based on the elastic-plastic fracture mechanics (EPFM).
期刊介绍:
Experimental Techniques is a bimonthly interdisciplinary publication of the Society for Experimental Mechanics focusing on the development, application and tutorial of experimental mechanics techniques.
The purpose for Experimental Techniques is to promote pedagogical, technical and practical advancements in experimental mechanics while supporting the Society''s mission and commitment to interdisciplinary application, research and development, education, and active promotion of experimental methods to:
- Increase the knowledge of physical phenomena
- Further the understanding of the behavior of materials, structures, and systems
- Provide the necessary physical observations necessary to improve and assess new analytical and computational approaches.