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International Journal of Automotive Technology 2004;5(3): 215-219. |
| ESTIMATION OF FATIGUE LIFE BY LETHARGY COEFFICIENT USING MOLECULAR DYNAMIC SIMULATION |
| S. M. YANG, J. H. SONG, H. G. NOH, H. S. YU, H. Y. KANG |
| Chonbuk National University |
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| ABSTRACT |
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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. {{br}}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. |
| Key Words:
Lethargy coefficient, Molecular dynamic simulation, Fatigue life, Probability, Tensile test |
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