A study of the stress distribution in threads of bolts with cracks

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:205413

Pacey, M N; Burguete, R L; Patterson, E A ^[1]

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1. Univ. of Sheffield (United Kingdom). Dept. of Mechanical and Process Engineering

Three dimensional photoelastic models were used to make an assessment of the effect of cracks in bolts on the distribution of stress along the bolt thread. Only cracks in the first thread root above the loaded face of the nut were considered in the photoelastic tests. The stress intensity factors of the cracks were found from the models and compared well with those predicted by the empirical formula derived by James and Mills (1988). The existence of a crack in a bolt was shown to cause a shift in the stress concentration factor away from the loaded face by an amount that was proportional to the depth of the crack. Tests were also performed to determine the changes that occur in the shape of fatigue cracks in bolts and to investigate the possibility of secondary cracking occurring. It was concluded that the shape of fatigue cracks depends upon the mean stress at which the bolt is tested. High mean stresses caused crescent shaped cracks to develop, the crescent shape becoming less marked at lower mean stresses, almost to the extent of becoming straight-edged. Secondary cracking was found to occur although not necessarily at the second thread root.

• OSTI ID: 205413
• Report Number(s): CONF-950695--; ISBN 0-7918-1309-6
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
CALCULATION METHODS
CRACK PROPAGATION
FRACTURE MECHANICS
OFFSHORE PLATFORMS
STRESS ANALYSIS
THREADED JOINTS