A Study of Fatigue Life Prediction for Automotive Spot Weldment Using Local Strain Approach

국부변형률근사법을 이용한 차체 점용접부의 피로수명 예측에 관한 연구

  • Lee, Song-In (Automotive New Technology Research Center, Dept.of Mechanical Engineering, Chonbuk National University) ;
  • Gwon, Il-Hyeon (Automotive New Technology Research Center, Dept.of Mechanical Engineering, Chonbuk National University) ;
  • Lee, Beom-Jun (Dept.of Mechanical Engineering, Chonbuk National University) ;
  • Yu, Hyo-Seon
  • 이송인 (전북대학교 기계공학부, 자동차신기술연구소) ;
  • 권일현 (전북대학교 기계공학부, 자동차신기술연구소) ;
  • 이범준 (전북대학교 대학원 기계공학부) ;
  • 유효선
  • Published : 2001.02.01


The fatigue crack initiation life is studied on automotive tensile-shear spot weldment made from cold rolled carbon steel(SPC) sheet by using DCPDM and local strain approach. It can be found that the fatigue crack initiation behavior in spot weldment can be definitely detected by DCPDM system. To predict the fatigue life of spot weldment, the local stresses and strains at the potential critical region are estimated by approximate method based on Neubers rule and elastic-plastic FEM analysis. A satisfactory correlation between the predicted life obtained from Local strain approach based on Neubers rule and experimental life can be found in spot weldment within a factor of 2.


Spot Welding;Fatigue Crack Initiation Life;Local Strain Approach;DC Potential Drop Method


  1. Morrow, J., 1968, Fatique Design Handbook, Advance in Engineering, Vol. 4, Society of Automotive Engineers Warendale, Pa, Sec. 3.2, pp. 21-29
  2. Smith, K. N., Waston, P. and Topper, T. M., 1970, 'A Stress-Strain Function for the Fatigue of metals,' Journal of Material, Vol. 5, No. 4, pp. 767-778
  3. Neuber, H., 1961, 'Theory of Stress Concentration for Shear-Strained Prismatic Bodies with Arbitrary Nonlinear Stress- Strain Law,' Journal of Applied Mechanics, pp. 544-550
  4. Topper, T. H., wetzel, R.and Morrow, J., 1968, 'Neuber's Rule Applied to Fatigue of Notched Specimens,' J. Materials, Vol. 4, No. 2, pp. 200-209
  5. Koknke, P. E., 1997, ANSYS Theoritical Manual, Swanson Analysis System Inc., Houston, Pennsylvania
  6. Lawrence, F. V., 1983, 'An Empirical Method for Estimating the Fatigue Resistance of Tensile-shear Spot-welds,' SAE Paper 830035
  7. 高橋, 伊藤, 失崎, 1971, 鐵 と 鋼, Vol. 57, No. 9
  8. 河在宣, 宋智浩. 李時中, 1988, '變動荷重下의 疲勞壽命 豫測,' 大韓機械學會論文集, 第 12券, 第 4號, pp. 747-754
  9. Mitchell, M. R., 1954, Fundamentals of Modern Fatigue Analysis for Design, Fatigue and Microstructure, ASM, pp. 385-437
  10. Kikugawa, M., Jono, M., Kamata, T., Song, J. and Himuro, H., 1977, 'Low-Cycle Fatique under Varying Strain Conditions(Effects of the Mean Plastic Strain and the Stress Factor),' Bulletin of the JSME, Vol. 20, No. 140, pp. 145-152
  11. Manson, S. S., 1965, 'Fatique : A Complex Subject-Some Simple Approximations,' Experimental Mechanics, Vol. 5, No. 7, pp. 193-226
  12. Bannatine, J. A., Comer, J. J and Handdrpck, J. J., 1990, Fundamentals of Metal Fatigue Analysis, Prentice Hall, Englewood Cliffs, New Jersey 07632, pp. 59-64
  13. Hyo Sun, Yu, 1999, 'A Study on Ultrasonic Test for Evaluation of Spot Weldability in Automotive Materials,' KSME International Journal, Vol. 13, No. 11, pp. 775-782
  14. 서창민, 강성수, 1988, '고장력 강판과 아연도금 강판간의 점용접 피로특성,' 대한기계학회논문집, 제12권, 제4호, pp. 747-754
  15. 이형일, 이태수, 김남호, 2000, '점용접 시편의 극한하중과 피로특성에 관한 실험적 고찰,' 대한기계학회논문집 A, 제24권, 제1호, pp. 38-51
  16. 박장원, 이태수, 채수원, 2000, '점용접부 최적설계를 위한 적응적 유한요소망의 구성,' 대한기계학회논문집 A, 제24권, 제7호, pp. 1763-1770
  17. 손일선, 이범노, 배동호, 홍정균, 2000, '잔류응력을 고려한 점용접 이음재의 피로설계,' 대한기계학회논문집 A, 제24권, 제3호, pp. 743-751
  18. Barsom, J. M. and Rolfe, S. T., 1983, Fracture and Fatigue Control in Structures, Prentice-Hall, Englewood Cliffs, pp. 223-249
  19. Pollard, B., 1982, Fatigue Strength of Spot Welds in Titanium-bearing HSLA Steels, SAE Paper 820284