Title: Increasing abutment friction at bolted joint interfaces through particle enhanced sealants

Authors: Anthony F. Luscher, Si C. Lee, Clint Frysinger

Addresses: Department of Mechanical Engineering, 206 West 18th Avenue, The Ohio State University, Columbus, OH 43210-1107, USA. Department of Mechanical Engineering, 206 West 18th Avenue, The Ohio State University, Columbus, OH 43210-1107, USA. Product Design Center, Westerville, OH 43081, USA

Abstract: In large bolted joints, the shear strength of the joint is limited by the friction present in the joint. In the case of joints found in large axles, the joint is considered to have failed if any slipping at all has occurred. It is therefore desirable to increase the coefficient of static friction in these joints as much as possible. This paper considers one possible method of increasing the static coefficient of friction of a joint. This concept consists of adding grit into the anaerobic sealant currently used in bolt joints. Two types of grit, abrasive brown aluminium oxide, and stainless steel shot were investigated. The goal was to allow the grit to embed into both sides of the joint and effectively lock them together. By testing several different grit sizes, concentrations and normal loads, an optimum combinations of these variables was found. Using a pin-on-ring friction test, it was found that the coefficient of friction could be increased from 0.08 to over 0.27 using abrasive grits. Normal load in the joint was by far the greatest factor in determining the coefficient of friction. One results of this study was that the brown aluminium oxide was not able to withstand all of the loads present in the joint. Micrographs of the failed surface showed that the grits shattered and failed before ploughing through the cast iron test coupons. Stainless steel shot did not fracture but flattened limiting the increase in friction. This limited the increase in coefficient of friction to 0.252.

Keywords: abutment friction; bolted joint interfaces; particle enhanced sealants; coefficient of static friction.

DOI: 10.1504/IJVD.2002.002014

International Journal of Vehicle Design, 2002 Vol.29 No.3, pp.288-306

Published online: 15 Aug 2003 *

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