Study of Stresses and Loads on Double Shear
Lug Joint By Varying Material Combinations

B.Vijaya Kumar; F.An; Raju; S.Sunil Kumar Reddy

Study of Stresses and Loads on Double Shear Lug Joint By Varying Material Combinations

B.Vijaya Kumar¹, F.Anand Raju², S.Sunil Kumar Reddy³

PG Student, Department of Mechanical Engineering, SITEK, Puttur, Andhra Pradesh, India
Professor, Department of Mechanical Engineering, SITEK, Puttur, Andhra Pradesh,India
Head of Department, Department of Mechanical Engineering, SITEK, Puttur, Andhra Pradesh, India

Related article at Pubmed, Scholar Google

Visit for more related articles at International Journal of Innovative Research in Science, Engineering and Technology

Abstract

Attachment lug joints are commonly used in aerospace and mechanical structures. Lug joints are generally used to connect major structure components for transfer of loads and they often subjected to repeated load spectra. Lug and pin joints have been designed based on theoretical strength of materials models. In this study, geometry was determined and analysed using theoretical Strength of material calculations. The ultimate loads and allowable stresses by using different materials (Inconel718, Waspaloy, Stellite6, 2024T351 plate, 7075T651 plate, Mg Bronze, 4130 steel) in the current lug joint geometry are caliculated by strength of material calculations. From calculations we determined the allowable limiting loads for those different materials in the double shear lug joint. It is suggested the highest allowable limiting load of a double shear lug joint by using different materials in the geometry under allowable stresses.

Keywords

Lug joint, limiting load, Inconel718, Waspaloy, Stellite6, 2024T351 plate, 7075T651 plate, Mg Bronze, 4130 steel.

I. INTRODUCTION

Lugs are connector type elements used as structural supports for pin connections. Prior to the 1950’s, lugs were overdesigned as weight and space were not design driving factors. With the tightening of weight, cost, and space requirements in the aerospace industry, a more precise method of lug analysis was required. Early aerospace lug analysis, developed in the 1950’s at Lockheed Aircraft Corporation by F.P. Cozzone, M.A... Melcon, and F.M Hoblit and summarized in Reference 2 and 3, addressed prior anticonservative assumptions, such as incomplete evaluation of the effect of stress concentration and pin adequacy with respect to bending. This work provided to analyse axial and transverse components for various material combinations of Inconel718, Waspaloy, Stellite6, 2024T351 plate, 7075T651 plate, Mg Bronze, 4130 steel in lug-link-bush-pin geometry to determined bearing stress &bearing load of lug joints ,bush bearing stress and bush bearing load ,shear stress , bending stress and bending load of pin .By considering all allowable loads in the lug-link-bush-pin geometry, hence predicted the allowable limiting of lug-linkbush- pin for different material combinations. From the predicted allowable limiting loads for different material combinations in lug-link-bush-pin geometry, choosing the maximum allowable limiting load combination to bear the loads without failure in the geometry

II. RELATED WORK

From [6] ] Christina A. Stenman caliculated the margin of safty for both stresses and loads in double shear lug joint for a single material combination .In present work here caliculated the limiting loads in double shear lug joint for different material combinations

III. CALCULATION OF ULTIMATE LOADS AND ULTIMATE STRESS FOR A UNIFORMLY LOADED LUG-LINK-BUSH-PIN (INCONEL718-WASPALOY-STELLITE6-INCONEL718)

The design Procedure and calculations are performed from the reference [5]

1) Lug Bushing Under Axial Load

a) Lug Bearing Strength

IV. RESULTS &DISCUSSIONS

From the calculations the following results are obtained and tabulated below.

From the above table the bearing stress for inconel718 is maximum and 2024T351 is minimum .For net section tensile Stress also inconel 718 having maximum and 2024T351is minimum. For bush bearing stress also inconel718 is maximum and 2024T351 is minimum. So here for lug 2024T351 is preferable.

From the above table the bearing stress for Waspaloy is maximum and 7075T651plate is minimum .For net section tensile Stress also Waspaloy having maximum and 7075T651plate is minimum for bush bearing stress also Waspaloy is maximum and Mg bronze is minimum so here for link 7075T651plate is preferable

From the above table the bearing stress for inconel718 is maximum and 2024T351 is minimum For net section tensile Stress also inconel 718 having maximum and 2024T351is minimum for bush bearing stress also inconel718 is maximum and 2024T351 is minimum so here for lug 2024T351 is preferable.

From the above table the bearing stress for Waspaloy is maximum and 7075T651plate is minimum for net section tensile Stress also Waspaloy having maximum and 7075T651plate is minimum for bush bearing stress also Waspaloy is maximum and Mg bronze is minimum so here for link 7075T651plate is preferable.

From the above table it is observed that shear load is maximum in Inconel718 and minimum in 4130Steel Bending load is maximum in Inconel718 and minimum in 4130Steel. It is preferred that 4130 is best material to pin.

From the above table it is observed that Allowable limiting load of the Double shear Lug joint is 37900 lbs. and all the values for the different combinations are almost nearer values except one combination .i.e. (2024T351 plate- 2024T351plate-Mg bronze-4130 steel).It is observed that the values for the three combinations are same even though changing of material in lug and link happened also that is just because of not changing material combination of bush and pin.

V. CONCLUSIONS

1) From the results it is observed that the limiting load is same even though changing of material in lug and link happened also that is just because of not changing material combination of bush and pin, by changing the material combinations of pin and bush the limiting load varying depends on the material properties .So choosing more strength material for pin and bush than lug and link.

2)The allowable limiting load for three combinations is maximum i.e. (2024T351 plate-7075T651plate-Mg bronze- 4130 steel),( 2024T351 plate-7075T651plate-Mg bronze- Inconel718),( 2024T351 plate-2024T351plate-Mg bronze- 4130 steel) is 37900lbs.On cost basis Inconel718 and 7075T651 is high than 2024T351,So this combination is better suit for 2024T351 plate-2024T351plate-Mg bronze-4130 steel is better suit for the geometry in strength wise as well as cost wise.

NOMENCLATURE

Fbeu = Lug Ultimate Bearing Stress (psi)

Fbey = Lug Yield Bearing Stress (psi)

Ftu = Ultimate Tensile Strength (psi)

ACKNOWLEDGMENT

The authors are thankful to Sri G.Mariya Das, Sr.Lecturer, S.V.Govt.Polytechinic, Friends and Family members who support, guide and encouraged us for completion of work.

References

Maddux, G.E., Leon A. Vorst, F. Joseph Giessler, and Terence Moritz. Stress Analysis Manual. Dayton: Technology Incorporated, 1969.
Cozzone, F.P, Melcon, Hoblit. "Analysis of Lugs and Shear Pins Made of Aluminum or Steel Alloys." Product Engineering 21(May 1950): 113- 117.
Melcon, M.A., Hoblit. "Developments in the Analysis of Lugs and Shear Pins." Product Engineering 24(May 1953): 160-170.
Military Handbook 5H – Metallic Materials and Elements for Aerospace Vehicle Structures, Columbus: Battelle Memorial Institute, 1998.
Lug Analysis.- Air Force Flight Dynamics Laboratory by JE Williams,1979.
Christina A. Stenman, A Comparison of the Predicted Mechanical Behavior of Lug Joints using Strength of Materials Models and Finite Element Analysis,2008.