A Numerical Investigation of Bolt Underhead Temperature Evolution Under Various Fastening Conditions

Abstract

The temperature rise that occurs due to frictional heating under a turning fastener head during the tightening process of bolted joints can have a significant effect on surface and thread wear and galling. In the present study, the spatial and temporal temperature rise in a bolt during the tightening process is numerically investigated for a variety of sliding and loading conditions. The effect of tightening speed, angle of turn, and frictional energy input is numerically investigated. Tightening speeds were varied between 1 rpm and 3000 rpm and the angle of turn was varied between 15 and 720 degrees past free spinning. Significant temperature rises of the bolt underhead were observed computationally for higher tightening speeds and angles of turn and the potential for localized melting or near-melting temperatures was shown. In the case of lower tightening speeds, the temperature rise was not as dramatic, but temperature increases are then observed along the length of the shank, showing the possibility of contributing to thermally induced galling between the threads. Due to the temperature variations observed in most cases in the underhead and along the bolt shank, this study indicates that such thermal effects should be considered when modeling the wear of bolted joints, particularly in cases involving larger tightening speeds or softer (lower stiffness) joints.

KEY WORDS:

• Heat Transfer Analysis
• Frictional Heating
• Fasteners
• Wear

Acknowledgments

Review led by Thierry Blanchet