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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.
쇼트피닝 잔류응력이 Leaf Spring의 피로강도에 미치는 영향
배동호(B. H. Bae),손일선(I. S. Sohn),정원석(W. S. Jung),김낙수(N. S. Kim),정원욱(W. W. Jung),박순철(S. C. Park) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Spring is one of major suspension pan of vehicle. Thus, in the process of manufacturing, it is shot-peened to improve its fatigue strength. In this paper, residual stresses by shot peening were calculated through finite element analysis, and the effects of these residual stresses on fatigue strength of leaf spring were evaluated. Fatigue tests were performed with two kinds of specimens, one is actual leaf spring assembly, and another is 3-point bending specimen simply simulated. And all fatigue tests were also performed under the loading condition that was measured on the proving ground. From the results, the maximum load-fatigue life relation of leaf spring was defined, and test results have good agreement between 3 point bending specimen and leaf spring assembly. The effects of residual stresses by shot peening on fatigue strength of leaf spring is not large in the high load range, however, in the low load range, its effects were revealed a little.<br/> <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.
인장-전단하중을 받는 IB형 일점 Spot용접 이음재의 응력분포와 피로강도평가
정원석(W.S.Jung),구재민(J.M.Koo),손일선(L.S.Sohn),배동호(D.H.Bae) 한국자동차공학회 1996 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1996 No.11_1
Stress distribution on the IB-type single spot welded lap joint under tension-shear load were investigated by finite element method. And using the maximum principal stress at nugget edge obtained by FEM analysis, evaluated the fatigue strength of the IB-type spot welded lap joints having various dimensions. From the results, it was found that △P- N_f curves of specimens could be systematically rearranged by the maximum principal stress (?? lmax) at the edge of the nugget.
AT 형 Spot 용접 이음재의 응력해석 및 피로강도 평가
허정범(J. B. Heo),배동호(D. H. Bae),정원석(W. S. Jung),손일선(I. S. Sohn) 한국자동차공학회 2002 한국자동차공학회 Symposium Vol.2002 No.11
Stress distribution and deformation on AT-type spot welded lap joint subjected to out of plane tensile load were<br/> analyzed by finite element method, and its geometrical factors on the stress concentration at the nugget edge of spot<br/> weld were also evaluated. Using the fatigue database of AT-type spot welded lap joint, evaluated its fatigue strength<br/> with the maximum principal stress.<br/> Obtained results are as follows;<br/> (1) Maximum principal stresses at the nugget edge of AT-type spot welded lap joints subjected to out of plane<br/> tensile load are influenced by the nugget diameter, the plate thickness, and the width of plate.<br/> (2) It was found that the fatigue strength of AT-type spot welded lap joints having various dimensions and<br/> materials could be systematically rearranged by the maximum principal stress at the nugget edge of the spot<br/> weld.