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인장-전단하중을 받는 IB형 일점 Spot 용접이음재의 파괴역학적 피로강도 평가
손일선(I.S. Sohn),정원석(W.S. Jung),배동호(D.H.Bae) 한국자동차공학회 1997 한국자동차공학회 학술강연초록집 Vol.1997 No.4
According as the member of the automobile body structure have been thinned their thickness and have become high strength. each part of the body structure has been put more severe stress condition. And. because fatigue strength of the spot welded lap joint is influenced by its geometrical and mechanical factors, welding condition and etc, there needs a quantitative and systematic evaluation method for them. In this study, by considering nugget edge of the spot weld part of the IE-type spot welded lap joint under tension-shear load to the ligament crack. fatigue strength of various IE-type spot welded lap joints was estimated with the stress intensity factor (S.I.F.) Km which is fracture mechanical parameter. We could find that fatigue strength evaluation of the IE-type spot welded lap joints by Km is more effective than the maximum principal stress (??_ 1max) at edge of the spot weld part obtained from FEM analysis.
잔류응력을 고려한 IB형 spot 용접이음재의 피로강도 평가
손일선(I.S.Sohn),배동호(D.H.Bae) 한국자동차공학회 1997 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1997 No.6_2
In systematic and orderly estimation of fatigue strength of the spot welded lap joints, because the influence of residual stress on fatigue crack initation and growth is not negligible, there need to estimate fatigue strength considered residual stress at near spot weld part of the lap joints. Therefore, in this thesis, performed stress distribution and residual stress analysis at near the spot weld part by F.E.M and X-ray diffraction method, and obtained the maximum principal stress considered residual stress at nugget edge by superposing their results. From the results obtained above, we could find that fatigue strength of the IB-type spot welded lap joints was rearranged by the maximum principal stress considered residual stress at nugget cdge and was cntircly low about 13percents compare with that neglected residual stress.<br/>
도로하중조건을 고려한 상용차 Leaf Spring의 피로강도 평가
손일선(I.S. Sohn),배동호(B.H. Bae),정원석(W.S. Jung),정원욱(W.W. Jung),박순철(S.C. Park) 한국자동차공학회 2002 한국자동차공학회 Symposium Vol.2002 No.11
Suspension system of vehicle is directly influenced to ride and handling. Therefore, suspension part<br/> should have enough endurance during its lifetime to protect passenger. Spring is one of major<br/> suspension part of vehicle. Thus, in this paper, a fatigue design method for leaf spring based on road<br/> load response is proposed. At first, strain and acceleration of leaf spring is measured on the proving<br/> ground. And next, the maximum load of leaf spring under driving condition was defined from the<br/> road load response. And leaf spring fatigue test and 3 point bending specimen tests were carried out.<br/> From the above, the maximum load-fatigue life relation of leaf spring was defined, and test results<br/> have good agreement between 3 point bending test result and leaf spring fatigue test. It is expect that<br/> 3 point bending test can verify leaf spring fatigue endurance as well as saving time and cost.
[구조강도부문] 점용접부의 용접잔류응력 해석과 피로강도 평가
손일선(I.S.Sohn),배동호(D.H.Bae) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Because welding residual stress is formidable result in electric resistance spot welding process, and it detrimentally affect to fatigue crack initiation and growth at nugget edge of spot welded lap joints, it should be considered in fatigue analysis.<br/> Thus, accurate prediction of residual stress is very important. In this study, nonlinear finite element analysis on welding residual stress generated in process of the spot welding was conducted, and their results were compared with experimental data measured by X-ray diffraction method. By using their results, the maximum principal sucess . considered welding residual stress at nugget edge of the spot welded lap joint subjected to tension-shear load was calculated by superposition method. And, the ΔP-Nf relations obtained through fatigue tests on the IB-type spot welded lap joint was systematically rearranged with the maximum principal stress considered welding residual stress. From the results, it was found that fatigue strength of the IB-type spot welded lap joints could be systematically and more reasonably reasonably rearranged by the maximum principal stress (σ1max-res) considered welding residual stress at nugget edge of the spot welding point.<br/> <br/>
잔류응력을 고려한 IB형 spot 용접이음재의 피로강도 평가
손일선(I.S.Sohn),고광성(C.S.Koh),배동호(D.H.Bae) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.11_2
In systematic and orderly estimation of fatigue strength of the spot welded lap joints for establishing 'long-life' design criterion of the automobiles, the influence of residual stresses must be considered. Therefore, the stress distribution and residual stress analysis at near the spot welded part were calculated by FEM and X-ray diffraction method. Using their results, superposing the maximum principal stress calculated by FEM analysis and measured residual stress at nugget edge, the fatigue strength of the IB type spot welded lap joints were re-evaluated. From the results, it was found that fatigue strength of the IB type spot welded lap joints could be systematically and more reasonably re-arranged by the maximum principal stress considered residual stress at nugget edge.<br/>
변형에너지밀도에 의한 스테인레스 박강판 IB형 Spot 용접이음재의 피로강도 평가
오세빈(S.B.Oh),손일선(I.S.Sohn),배동호(D.H.Bae) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.11_2
Stainless steel plates have been used for vehicles such as the bus and train. Because stainless steels have good mechanical properties, weldbility, resistance of corrosion, and fine appearance.<br/> By the way. to estabilish long life design criteria of spot welded structures using these materials, evaluate of fatigue strength their spot welded joints and systemetic arrangement of them.<br/> In this report, numerical analysis on the spot welded lap joint of SUS 304 sheet subjected to in-plane bending (IB signed) force by tension-shear load was performed using 3-dimensional finite element model. And fatigue strength of the IB-type spot welded lap joints having various thickness, joint angle, lapped length, and width were evaluated. Using their results, we tried systematic rearrangement to estabilish long life design criteria of spot welded IB type joints of SUS 304 sheet by strain energy density. It was found that fatigue strength of the IB-type spot welded lap joints could be effectively and systematically rearranged by strain energy density at the edge of nugget.<br/>