Journal of Engineering and Architecture

Minimizing Bending Stresses in Disconnect Pins
Steven M. Tipton, Ph.D., P.E., FASME, FASM

Abstract
Disconnect features on web slings consist of interlocking eye straps through which a round pin is inserted such that the sling may be connected/disconnected at its midsection. These are common features on marine slings, since they make it easier to install basket hitches around large boat hulls. On most slings the width of each finger of the disconnect is uniform on each side. This paper offers guidance on varying the width of the fingers in order to optimize the connection in terms of the bending strength of the pin. Slight changes to the width of the fingers can significantly reduce the maximum bending moment in the pin relative to those caused by uniform finger widths, by a factor of 2.6 for a 2x3 disconnect and by a factor of 4.8 for a 3x4 disconnect. This corresponds to a reduction of the overall weight (cost) of the required pin by 47% and 65%, respectively. A set of equations is also presented to compute ideal finger widths for disconnects of any order, i x (i+1), which minimize bending stress in the pin. It is demonstrated (somewhat surprisingly) that the higher the order of the disconnect, the greater the reduction in maximum bending moment, relative to the moment with uniform finger widths.

Full Text: PDF     DOI: 10.15640/jea.v12n1a1