A parametric study of the elastic stress distribution in pin-loaded tubes

Abstract

This paper describes a numerical study of the stress distribution in pin-loaded tubes. The effects of (a) the distance from the pin to the open end, (b) the variation in pin diameter, (c) the variation of tube thickness and (d) the variation in pin fit on the radial and circumferential stresses around the pin hole have been found and discussed. It is found that there are considerable differences between the stresses at the inner and outer surfaces of the tube which arise because the region around the pin and towards the open end of the tube ovalizes. This ovalization is more pronounced for a small head distance, a smaller diameter pin, a thinner tube and a clearance fit. The results for the pin-loaded tube are compared with those for a pin-loaded lug and it is shown that there are many similarities in the stress patterns.

Parametric study of the elastic stress distribution in pin-loaded lugs modelled in two and three dimensions and loaded in tension

“…These effects and the general trend are echoed in photoelastic work by Heywood [4], in photoelastic work on tubes by Ahmad and Stanley [7], and in numerical work, again on tubes, by Grant and Smart [2]. When changing from a snug-to an interference-fitting pin, large variations in the position and the magnitude of the circumferential stresses are documented [1,2]. For a joint subject to fatigue loading, the beneficial effects of an interference fit are commented upon; here, it is reported that this leads to a reduction in the alternating circumferential stresses around the pin hole.…”

“…6 Two-dimensional variation in s r around the lug hole for an interference fit by loading increments of 20 per cent of P the hole and causes distinct changes in the position of the maximum circumferential stress, although, away from a snug fit, the stresses are not sensitive to the value of the clearance. These effects and the general trend are echoed in photoelastic work by Heywood [4], in photoelastic work on tubes by Ahmad and Stanley [7], and in numerical work, again on tubes, by Grant and Smart [2]. When changing from a snug-to an interference-fitting pin, large variations in the position and the magnitude of the circumferential stresses are documented [1,2].…”

“…Photoelastic work on pin-loaded tubes by Ahmad and Stanley [7] and finite element work on tubes by Grant and Smart [2] both show that the stress concentration factor is reduced when the wall thickness is increased. In his work on lug and riveted joints, Schijve [8], agreeing with the previous authors, comments that there is a considerable difference between the tangential stress values found around the outside edges of the hole bore and those obtained in the middle of the section of the material: maximum circumferential stress was obtained at the outside of the section.…”

“…For a joint subject to fatigue loading, the beneficial effects of an interference fit are commented upon; here, it is reported that this leads to a reduction in the alternating circumferential stresses around the pin hole. In comparison, a clearance-fitting pin would produce very large alternating stresses, with a detrimental effect on fatigue life [2].…”

“…Past papers by Grant et al [1] and Grant and Smart [2] have examined the effects of pin loading on structural connections for lugs and tubes. In reference [1] this involved a two-dimensional (2D) parametric study of a lug, while reference [2] considered a three-dimensional (3D) analysis of a pin-loaded tube. For the tube it was apparent that there were significant through-thickness effects present in this type of joint; such effects were obviously not evident from the 2D study.…”