SEDL / STP / STP791-EB / STP37071S

Analysis of Cracks at an Attachment Lug Having an Interference-Fit Bushing

Hsu, TM
Staff engineer and senior engineer, Lockheed-Georgia Co., Marietta, Ga.

Kathiresan, K
Staff engineer and senior engineer, Lockheed-Georgia Co., Marietta, Ga.

Pages: 22    Published: Jan 1983

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Abstract

An analytical procedure was presented for computing the stress-intensity factors for a crack emanating from an attachment lug having an interference-fit bushing. The procedure consists of two major steps. First, the effective unflawed stress distribution on the prospective crack surface was obtained by superimposing the residual hoop stresses due to the installation of an interference-fit bushing on the tangential stresses obtained due to the application of pin loading. Next, a crack was introduced in this stress field by removing the tractions on the crack faces and computing the corresponding effective stress-intensity factor using the developed Green's function. It was found that the installation of an interference-fit bushing caused an increase in the effective stress-intensity factor ratio (R^eff = K^min/K^max), and a significant decrease in the effective stress intensity factor range (ΔK^eff = K^max − K^min). This would result in reduction of the fatigue crack growth rate. The effects of the rigidity and the thickness of the bushing on the stresses and the effective stress-intensity factors also were presented.