International Journal of Automotive Technology

The Korean Society of Automotive Engineers (한국자동차공학회)
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ESTIMATION OF FATIGUE LIFE BY LETHARGY COEFFICIENT USING MOLECULAR DYNAMIC SIMULATION

  • Song, J.H. (Department of Mechanical ＆ Aerospace System Engineering, Chonbuk National University) ;
  • Noh, H.G. (Department of Mechanical ＆ Aerospace System Engineering, Chonbuk National University) ;
  • Yu, H.S. (Department of Mechanical ＆ Aerospace System Engineering, Chonbuk National University) ;
  • Kang, H.Y. (Department of Mechanical ＆ Aerospace System Engineering, Chonbuk National University) ;
  • Yang, S.M. (Department of Mechanical ＆ Aerospace System Engineering, Chonbuk National University)
  • Published : 2004.09.01
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Abstract

A vehicle structure needs to be more precisely analyzed because of complexities and varieties. Structural fatigue which is generated by fluctuations of stresses during the service life of a mechanical system is the primary concern in the structural design for safety. A fatigue life is difficult to obtain in structural components during the service life of mechanical systems since the fluctuating stress contributes to fatigue. This study introduces new procedures to measure the lethargy coefficient and to predict the fatigue life of a mechanical structure by using molecular dynamic simulation. A lethargy coefficient is the total defect-estimating coefficient, which was obtained by using the results of a simple tensile test in this study. With this lethargy coefficient, fatigue life was estimated. The proposed method will be useful in predicting the fatigue life of a structurally-modified vehicle design. The effectiveness of the proposed method using lethargy coefficient measurement to predict the fatigue life of a structure was examined by applying this method to predict the fatigue life of SS41 steel, used extensively as material of vehicle structures. Two types of specimen such as pre-cracked plate and simple plate is discussed. equation of fatigue life using the lethargy coefficient and failure time, both obtained from a simple tensile test, will be useful in engineering. This measurement and prediction technology will be extended for use in analysis of any geometric shapes of modified automotive structures.

Keywords

References

  1. Baginski, M., Resat, H. and Borowski, E. (2002). Comparative molecular dynamics simulations of amphotericin Bcholesterol/ergosterol membrane channels. Biochimica et Biophysica Acta (BBA) - Biomembranes 1567, 63-78 https://doi.org/10.1016/S0005-2736(02)00581-3
  2. Chu, S. J., Chu, Y. W., Yum, Y. J., You, H. and Choi, B. G. (1999). Analysis of fatigue life of spot-welded specimens. Transactions of KSAE 7, 6, 279-286
  3. Fatigue strength data (1996). Japanes Society ofMaterial Engineers I, CODE-SERIES 135-010
  4. Hong, S. H., Joo, W S., Lee, D. W, Lee, S. B. and Cho S. S. (2001). A study on failure analysis of turbine blade using surface roughness and FEM. Transactions of KSAE 9, 6, 170-177
  5. Kim, Y. I., Lee, H. J., Koh, S. K., Kim, W. D. and Lee, S. R. (1996). Fatigue life evaluation of notched shaft using local strain approach. Transactions of KSAE 4, 2, 80-89
  6. Lee, B. D. (1982). A General theory on fatigue creep life, Lec. at Univ. Tokyo
  7. Paik, W. and Ralph, I. S. (1990). Computational life prediction methodology for mechanical systems using dynamic simulation, finite element analysis, and fatigue life prediction methods. Ph.D. Dissertation, Univ. of Iowa
  8. Pusztai, L., Dominguez, H. and Pizio, O. A. (2002). Reverse Monte Carlo simulation of the microscopic structure for chemically associating fluids by using experimental data. Physica A: Statistical Mechanics and its Applications 316, 1-4, 65-76 https://doi.org/10.1016/S0378-4371(02)01209-8
  9. Song, J. H., Yang, S. M., Kang, H. Y., Kim, H. S. and Park, J. M. (1998). Prediction of Life of SAPH45 Steel with Measured Fracture Time and Strength. Proceeding of the Korean Society of Machine Tool Engineers 269-273
  10. Ward, D. J. and Arnell, R. D. (2002). Finite element modelling of stress development during deposition of ion assisted coatings. Thin Solid Films 420-421, 269-274 https://doi.org/10.1016/S0040-6090(02)00934-3
  11. Yang, S. M., Song, J. H., Kang, H. Y. and Kwon, S. J. (1997). Failure life prediction by simple tensile test under dynamic load. ICF 407-413
  12. Zhurkov, S. N. (1965). Kinetic concept of the strength of solids. International Journal of Fracture Mechanics 1, 311-323