Numerical Investigation on Optimizing Fatigue Life in a Lap Joint Structure

Riveting process is one of the important ways to keep fastening the lap joints in aircraft structures. Failure of aircraft lap joints directly depends on the stress field in the joint. An important application of riveting process is in the construction of aircraft fuselage structures. In this paper, a 3D finite element method is carried out in order to optimize residual stress field in a riveted lap joint and also to estimate its fatigue life. In continue, a number of experiments are designed and analyzed using design of experiments (DOE). Then, Taguchi method is used to select an optimized case between different levels of each factor. Besides that, the factor which affects the most on residual stress field is investigated. Such optimized case provides the maximum residual stress field. Fatigue life of the optimized joint is estimated by Paris-Erdogan law. Stress intensity factors (SIFs) are calculated using both finite element analysis and experimental formula. In addition, the effect of residual stress field, geometry and secondary bending are considered in SIF calculation. A good agreement is found between results of such methods. Comparison between optimized fatigue life and fatigue life of other joints has shown an improvement in the joint’s life.

Authors:

• P. Zamani
• S. Mohajerzadeh
• R. Masoudinejad
• Kh. Farhangdoost

Keywords:

• Fatigue life
• Residual stress
• Riveting process
• Stress intensity factor
• Taguchi method.

References:

[1] S.H. Cheraghi, Effect of variations in the riveting process on the quality
of riveted joints. Int J Adv Manuf Technol 2008: 39: 1144-1155.
[2] R.P.G. Muller. An experimental and analytical investigation on the
fatigue behavior of fuselage riveted lap joints. PhD thesis, Delft
University of Technology, Delft, The Netherlands: 1995.
[3] N.E. Frost, K.J. Marsh, L.P. Pook, Metal fatigue. Oxford University
Press, London, 1974.
[4] A. Trego, D. Cope, Evaluation of damage tolerance analysis tools for lap
joints. AIAA Journal 2001: 39(12): 2250-2254.
[5] C. Ranse, P.V. Straznicky, Riveting process induced residual stresses
around solid rivets in mechanical joints. Journal of Aicraft 2007: 44(1):
323-329.
[6] K. Iyer, C.A. Rubin, G.T. Hahn, Three-dimensional analysis of single
rivet row lap joints-part I: Elastic-Plastic response. Recent Adv Solids
Struct 1999: 398: 41-57.
[7] Z. Kaifu, C. Hui, L. Yuan, Riveting process modeling and simulating for
deformation analysis for aircraft’s thin-walled sheet-metal parts. Chinese
Journal of Aeronautics 2011: 24: 369-377.
[8] M.R. Urban, Analysis of the fatigue life of riveted sheet metal helicopter
airframe joints. International Journal of Fatigue 2003: 25: 1013-1026.
[9] C.P. Fung, Smart J., Riveted single lap joints. Part 1: Fatigue life
prediction. Proceedings of the institution of mechanical engineers, part
G (Journal of Aerospace Engineering) 1997: 211(1): 13-27.
[10] C.P. Fung, Smart J., Riveted single lap joints. Part 2: A numerical
parametric study. Proceedings of the institution of mechanical engineers,
part G (Journal of Aerospace Engineering) 1997: 211(2): 123-128.
[11] X. Deng, J.W. Hutchinson, The clamping stress in a cold driven rivet.
International Journal of Mechanical Sciences 1998: 40(7): 683-694.
[12] M.P. Szolwinski, T.N. Farris, Linking riveting process parameters to the
fatigue performance of riveted aircraft structures. Journal of Aircraft
2000: 37(1): 130-137.
[13] P.M.G.P. Moreira, P.F.P. de Matos,S.T. Pinho, D. Pastrama, P.P.
Camanho, P.M.S.T. de Castro, The residual stress intensity factors for
cold-worked cracked holes: A technical note. Fatigue and Fracture of
Engineering Materials and Structures 2004: 27(9): 879-886.
[14] J.J.M Rijck, J.J. Homan, J. Schijve, R. Benedictus, The driven rivet head
dimensions as an indication of the fatigue performance of aircraft lap
joints. International Journal of Fatigue 2007: 29: 2208-2218.
[15] H.K. Yoon, S.P. Lee, B.H. Min, S.W. Kim, Y. Katoh, A. Kohyama.
Fatigue life and fatigue crack propagation behavior of JLF-1 steel.
Fusion Engineering and Design 2002: 61: 677-682.
[16] P.C. Paris, F. Erdogan, A critical analysis of crack propagation laws.
Transactions ASME Journal of Basic Engineering 1963: 85: 528-534. [17] J.L Beuth, J.W. Hutchinson, Fracture analysis of multi-site cracking in
fuselage lap joints, Computational Mechanics 1994:13: 315-331.
[18] J.J.M. Rijck, S.A. Fawaz, Schijve J., Benedictus R., Homan J.J., Stress
analyses of mechanically fastened joints in aircraft fuselages, 24th ICAF
Symposium, Naples, 2007.