Effect of Friction

International Journal of Research and Scientific Innovation (IJRSI) | Volume IV, Issue XII, December 2017 | ISSN 2321–2705 

Effect of Friction during Load Transfer in Lug Joints

P. Neelima & B. Dattaguru

Department of Aerospace Engineering, Jain University, Jakkasandra Post, Kanakapura Road, Bangalore, India 562112

Abstract: Pin joints are structural elements which are extensively used in mechanical and structural design. Friction plays a significant role in fastener joints in redistributing the stress and there by affecting fatigue life. In the current paper lug joint with rigid push fit is considered. It is well known that as the load is increased on the interface, localized relative slip is initiated between the pin and the lug. This initiated slip is due to the shear forces on parts of interface overcoming the local frictional forces. Therefore the region of slip spreads non- linearly with the applied load. Slip amplitude for push fit with smooth and rough interface is determined by inverse technique. Slip region leads to high stress concentration at the edge of the hole influence difficulties in fretting damage, crack initiation crack growth life.

Keywords: fastener joints push fit, proportional interference, slip region.

I. INTRODUCTION

Fatigue causes structural damage, This occurs when material undergoes cyclic loading and fretting damage .Due to fretting crack can initiate in fretting zone ,Hence crack propagates into the material .Lug joints primarily to transfer load from one structural components to other like wing root fitting , under carriage connections ,Pylon attachment etc. are the locations of fretting damage occurrence. At surface interface of lug-pin, Fretting happens and roughness of the surface considered as major factor. Interference fit with infinite friction coefficient for various increments in load reduces the radial stresses and increases the shear stresses at the critical location and after reaching critical load, shear stress increases but slip initiate at the interface. With assistance of known slip region of infinite friction, the actual slip region for defined friction coefficient of interference fit has to be determined. This actual slip region is more than the known slip region of finite friction lug with interference fit. This amplitude of slip develops fretting damage and reduces the life of joints.

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