Title: Fatigue life prediction of bolted joints in vehicle structures by the lethargy coefficient

Authors: S.M. Yang, H.Y. Kang, J.H. Song, H.G. Kim

Addresses: Automobile Hi-Technology Research Institute, Department of Mechanical Engineering, Chonbuk National University, Chonju, 561-756, Korea. Automobile Hi-Technology Research Institute, Department of Mechanical Engineering, Chonbuk National University, Chonju, 561-756, Korea. Automobile Hi-Technology Research Institute, Department of Mechanical Engineering, Chonbuk National University, Chonju, 561-756, Korea. Department of Mechanical and Industrial Engineering, Jeonju University, Chonju 560-759, Korea.

Abstract: Mechanical fastened joints are widely used for joining structural parts. In estimating the reliability of a bolted joint in vehicle structures, the prediction of failure life is the most important failure mode to be considered. This paper presents a method for determining the fatigue life of bolted SAPH45 steel structures used extensively in truck vehicle frames. First, the fastening torque on bolted joints in the structure is determined by a vibration test. Under such torque, the fatigue life of the bolted joint can be estimated using the lethargy coefficient as the total defect estimation coefficient and the stress distribution factor. The lethargy coefficient is based upon previous applications of molecular dynamics in materials research field. In this paper, it is obtained from a simple tensile test and is measured by complete fracture time and ultimate stresses.

Keywords: bolted joint; fatigue life; lethargy coefficient; molecular dynamics.

DOI: 10.1504/IJVD.2002.002030

International Journal of Vehicle Design, 2002 Vol.30 No.1/2, pp.155-164

Published online: 15 Aug 2003 *

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