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논문 기본 정보

자료유형
학위논문
저자정보

김동엽 (부산대학교, 부산대학교 대학원)

지도교수
김명현
발행연도
2020
저작권
부산대학교 논문은 저작권에 의해 보호받습니다.

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이 논문의 연구 히스토리 (2)

초록· 키워드

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HFMI (High-Frequency Mechanical Impact) post-treatment is a proven method to significantly improve fatigue life of welded structures. Positive effects of the HFMI treatment to improve fatigue life of material are influenced by the weld toe geometry and compressive residual stress. This study investigates the effect of geometric and mechanical improvements by HFMI treatment on fatigue strength with an explicit consideration of weld toe magnification factor. The conventional fatigue life estimation method to assess the effect of HFMI treatment by experiment and analysis involves excessive cost and time. In this regard, this study suggests a more efficient method by considering weld toe magnification factor and the stress ratio for assessing the effect of HFMI post treatment. First step of this method is to calculate weld magnification factor in HFMI treated condition to consider the geometrical effect of HFMI treatment at weld toe region. Second, the stress ratio model is introduced to consider the compressive residual stress by HFMI treatment based on Paris equation. The result is obtained by Paris-Erdogan equation for S355 material. The result from this study is calculated as fatigue life of butt-welded structure. As a result, calculated fatigue strength is validated by comparison with previous experiment data about fatigue strength of HFMI treated welded specimen.

목차

Chapter. 1 INTRODUCTION 1
Chapter. 2 Objective 2
Chapter. 3 Theoretical Background 3
3.1 Weld toe magnification factor considering HFMI treatment 4
3.2 Calculation of residual stress by welding and HFMI treatment 7
3.3 Calculation of stress intensity factor range ΔK considering residual stress 10
3.4 Numerical method for fatigue life estimation 12
Chapter. 4 Result and discussion 12
4.1 Weld toe magnification factor for the consideration of geometrical effect 13
4.2 Effective stress ratio considering residual stress distribution 15
4.3 Fatigue life estimation considering HFMI treatment effect 17
Chapter. 5 Conclusion 20

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