Failure modeling of friction stir welded joints in tensile tests

• Autorzy: Borino G. , Fratini L. , Parrinello F. , Burgarella A.

Warianty tytułu

PL

Modelowania pękania spoin otrzymanych z punktowego zgrzewania tarciowego ] z mieszaniem materiału zgrzeiny podczas testu rozciągania

• Języki publikacji: EN

Abstrakty

EN

The paper concerns with the mechanical modeling and the finite element simulation of the fracture failure in mode I of linear joints of aluminum friction stir weldings. The problem is analyzed employing a bulk finite strain-hardening plasticity model able to characterize the spatial diffuse plastic strains that initially develop in the neighboring extended zones of the welding line. Moreover, the decohesion process is described by a zero thickness interface model which is spatially inserted along the line of the welding. The interface is basically an elastic - cohesive fracture model which is rooted on the concept of Interface Damage Mechanics (IDM) and is able to properly describes a progressive elastic degradation of the internal ligaments of the friction stir welding up to local decohesion and eventually at the welding failure. The damage constitutive model of the zero thickness interface is derived following a thermodynamically consistent formulation in which the surface properties are derived projecting along a fictitious surface elastic and inelastic material properties and deformation mechanisms. Bulk and interface constitutive parameters identification problem is also addressed. To this aim laboratory direct traction experimental tests have been carried out on FSW butt joints and their results have been analyzed either, for local aspects related to the material properties and failure, or for the overall structural behavior of the specimens. Finally the finite element implementation of the bulk and interface models is discussed and the related numerical results are analyzed in details.

PL

Artykuł dotyczy mechanicznego modelowania i symi metodą elementów skończonych powstawania pęknięć w połączeniach spawanych aluminium uzyskanych metodą zgrzewania tarciowego z mieszaniem materiału zgrzeiny. Problem zostałprzeanalizowany za pomocą modelu odkształceń skończonych, który określa przestrzenną propagację odkształceń plastycznych zapoczątkowaną w sąsiedztwie wydłużonych stref linii spawu. Ponadto, w symulacji uwzględniono model rozwarstwiania materiału wzdłuż linii spawu.

Słowa kluczowe

EN

friction stir welding; finite elements; cohesive interface; failure analysis

• Wydawca: Wydawnictwa AGH
• Czasopismo: Computer Methods in Materials Science
• Rocznik: 2009
• Tom: Vol. 9, No. 1
• Strony: 37--42
• Opis fizyczny: Bibliogr. 12 poz., rys.

Twórcy

autor

Borino G.

autor

Fratini L.

autor

Parrinello F.

autor

Burgarella A.

• University of Palermo, Dipartimento di Ingegneria Strutturale e Geotecnica, Palermo, Italy,

Bibliografia

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• 2. Rhodes, C.G., Mahoney, M.W., Singel, W.H., Spurling, R.A., Bampton, C.C., Effects of Friction Stir Welding on Microstructure of 7075 Aluminum, Scripta Materialia,  36,1,1997,69-75.
• 3. Lee, W. B., Yeon, Y. M., Jung, S. B., The improvement of mechanical properties of friction-stir-welded A356 Al alloy, Mat. Science & Engineering, A355, 2003, 154-159.
• 4. Liu, S., Chao, Y.J., Determination of global mechanical response of friction stir welded plates using local constitutive properties, Modelling Simul. Mater. Sci. Eng.,  13, 2005, 1-15.
• 5. Fratini, L., Buffa, G., Hua, J., Shivpuri, R., Friction Stir Welding of Tailored Blanks: Investigation on Process Feasibility, Annals of CIRP, 55/1, 2006, 279-282.
• 6. Barcellona, A., Buffa, G., Fratini, L., Process parameters analysis in friction stir welding of AA6082-T6 sheets, Proc. 7th ESAFORM Conference, ed., Storen, S., Trondheim, 2004,371-374.
• 7. Ricciardi,  R.,  Montanari,  L.F.,  Moreschi,  A., Sili,S., Storai, Mechanical characterisation of fusion materials by indentation test, Fusion Engineering and Design, 58-59, 2001,755-759.
• 8. Scibetta, M., Lucon, E., Chaouadi, R., van Walie, E., Instrumented hardness testing using a flat punch, Int. J Pres. Ves. Piping, 80, 2003, 345-349.
• 9. Taljat, B., Zacharia, T., New analytical procedure to determine stress-strain curve from spherical indentation data, Int. J. Solids and Structures, 35, 1998, 4411-4426.
• 10. Zienkiewicz, O.C., The Finite Element Method, fourth ed., McGraw-Hill,UK,1991.
• 11. Polizzotto, C., Borino, G., A Thermodynamics-based forulation of gradient-dependendent plasticity,   Eur. J. Mech. A/Solids, 17, 1998,741-761.
• 12. Borino, G., Polizzotto, C., Thermodynamically consistent residual-based gradient plasticity theory and comparison, Modelling and Simulation in Material Science and Engineering, 15,2007,23-35.