Integrated Design and Numerical Simulation of Stiffened Panels Including Friction Stir Welding Effects

Abstract:

Stiffened panels are usually the basic structural building blocks of airplanes, vessels and other structures with high requirements of strength-to-weight ratio. They typically consist of a plate with equally spaced longitudinal stiffeners on one side, often with intermediate transverse stiffeners. Large aeronautical and naval parts are primarily designed based on their longitudinal compressive strength. The structural stability of such thin-walled structures, when subjected to compressive loads, is highly dependent on the buckling strength of the structure as a whole and of each structural member. In the present work, a number of modelling and numerical calculations, based on the Finite Element Method (FEM), is carried out in order to predict the ultimate load level when stiffened panels are subjected to compressive solicitations. The simulation models account not only for the elasto-plastic nonlinear behaviour, but also for the residual stresses, material properties modifications and geometrical distortions that arise from Friction Stir Welding (FSW) operations. To construct the model considering residual stresses, their distribution in FSW butt joints are obtained by means of a numerical-experimental procedure, namely the contour method, which allows for the evaluation of the normal residual stress distribution on a specimen section. FSW samples have been sectioned orthogonally to the welding line by wire electrical discharge machining (WEDM). Displacements of the relaxed surfaces are then recorded using a Coordinate Measuring Machine and processed in a MATLAB environment. Finally, the residual stress distribution is evaluated by means of an elastic FE model of the cut sample, using the measured and digitalized out-of-plane displacements as input nodal boundary conditions. With these considerations, the main goal of the present work will then be related to the evaluation of the effect of FSW operations, in the ultimate load of stiffened panels with complex cross-section shapes, by means of realist numerical simulation models.

• Periodical: Key Engineering Materials (Volumes 554-557)
• Pages: 2237-2242
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.554-557.2237
• Online since: June 2013
• Authors: Rui Miguel Ferreira Paulo, Pierpaolo Carlone, Robertt Valente, Filipe Teixeira-Dias, Gaetano S. Palazzo
• Keywords: Friction Stir Welding (FSW), Initial Geometrical Imperfections, Residual Stress, Stiffened Panels

References

[1] R.M.F. Paulo, F. Teixeira-Dias, R.A.F. Valente, Numerical simulation of aluminium stiffened panels subjected to axial compression: Sensitivity analyses to initial geometrical imperfections and material properties, Thin-Walled Structures, 62 (2013) 65-74.

DOI: 10.1016/j.tws.2012.07.024

[2] J.K. Paik, S. Veen, A. Duran, M. Collette, Ultimate compressive strength design methods of aluminum welded stiffened panel structures for aerospace, marine and land-based applications: A benchmark study, Thin-Walled Structures, 43 (2005) 1550-1566.

DOI: 10.1016/j.tws.2005.06.003

[3] M.R. Khedmati, A. Bayatfar, P. Rigo, Post-buckling behaviour and strenght of multi-stiffened aluminium panels under combined axial compression and lateral pressure, Thin-Walled Structures, 23 (2010) 39-66.

DOI: 10.1016/j.marstruc.2009.10.003

[4] A. Murphy, W. McCune, D. Quinn, M. Price, The characterisation of friction stir welding process effects on stiffened panel buckling performance, Thin-Walled Structures, 45 (2007) 339-351.

DOI: 10.1016/j.tws.2007.02.007

[5] P. Rigo, R. Sarghiuta, S. Estefen, E. Lehmann, S.C. Otelea, I. Pasqualino, B.C. Simonsen, Z. Wan, T. Yao, Sensitivity analysis on ultimate strength of aluminium stiffened panels, Marine Structures, 16 (2003) 437-468.

DOI: 10.1016/j.marstruc.2003.09.002

[6] J.W. Yoon, G.H. Bray, R.A.F. Valente, T.E.R. Childs, Buckling analysis for an integrally stiffened panel structure with a friction stir weld, Thin-Walled Structures, 47 (2009) 1608-1622.

DOI: 10.1016/j.tws.2009.05.003

[7] H.N.B. Schmidt, T.L. Dickerson, J.H. Hattel, Material flow in butt friction stir welds in AA2024-T3, Acta Materialia, 54 (2006) 1199–1209.

DOI: 10.1016/j.actamat.2005.10.052

[8] P. Carlone, R. Citarella, M. Lepore, G.S. Palazzo, Numerical Crack Growth Analysis in AA2024-T3 Friction Stir Welded Butt Joints, Proceedings of the Eighth International Conference on Engineering Computational Technology, (2012).

DOI: 10.4203/ccp.100.91

[9] M.B. Prime, Cross-sectional mapping of residual stresses by measuring the surface contour after a cut, Journal of Engineering Materials and Technology, 123 (2001) 162–168.

DOI: 10.1115/1.1345526

[10] H.F. Bueckner, The propagation of cracks and the energy of elastic deformations, Transaction of the ASME, 80 (1958) 1225-1230.

[11] P. Carlone, G.S. Palazzo, Experimental analysis of the influence of the process parameters on residual stress in AA2024-T3 friction stir welds, Key Engineering Materials, 504-506 (2012) 753-758.

DOI: 10.4028/www.scientific.net/kem.504-506.753

[12] O. Hatamleh, A. DeWald, An investigation of the peening effects on the residual stresses in friction stir welded 2195 and 7075 aluminum alloy joints, Journal of Materials Processing Technology, 209 (2009) 4822–4829.

DOI: 10.1016/j.jmatprotec.2008.12.010

[13] M.B. Prime, T. Gnäupel-Herold, J.A. Baumann, R.J. Lederich, D.M. Bowden, R.J. Sebring, Residual stress measurements in a thick, dissimilar aluminum alloy friction stir weld, Acta Materialia, 54 (2006) 4013–4021.

DOI: 10.1016/j.actamat.2006.04.034

[14] W. Woo, H. Choo, M.B. Prime, Z. Feng, B. Clausen, Microstructure, texture and residual stress in a friction-stir-processed AZ31B magnesium alloy, Acta Materialia, 56 (2008) 1701–1711.

DOI: 10.1016/j.actamat.2007.12.020

[15] A. Murphy, M. Price, R. Curran, Integration of strength and process modeling of friction-stir-welded fuselage panels, Journal of aerospace computing, information and communication, 3 (2006) 159-176.

DOI: 10.2514/1.17694