Experimental investigation and numerical simulation of laser beam welding induced residual stressed and distorsions in AA 6056-T4 sheets for aeronautic application

par Muhammad Zain-ul-abdein

Thèse de doctorat en Mécanique

Sous la direction de Daniel Nélias et de Jean-François Jullien.

Soutenue en 2009

à Lyon, INSA .


  • Résumé

    The effort is made in this work to experimentally measure and numerically simulate the residual stresses and distortions induced by laser beam welding with industrially used thermal and mechanical boundary conditions on the thin sheets of an aluminium alloy AA 6056-T4. Several small scale experiments were carried out with various instrumentations like thermocouples and LVDT sensors, which were used to record the temperatures and displacements during welding, respectively. Infra-red camera was also used to qualify the evolution of weld pool temperature as a function of time. Measurements of in-plane and out-of-plane displacements were achieved by stereo image correlation technique. Micrography was carried out to measure the dimensions of fusion zone. The database so prepared served as benchmark for the validation of numerical simulation results. Thermo-mechanical characterisation of 6056-T4 was also performed in order to identify the material properties to be used during numerical simulation. Finite element (FE) simulations are performed with the commercial FE software Abaqus and the volumetric heat source models with Gaussian distribution of flux are programmed in Fortran. The industrially used thermal and mechanical boundary conditions are integrated in the numerical models. Heat transfer analyses are performed first in order to achieve the required weld pool geometries and temperature fields. Mechanical analyses are performed next so as to predict the distortion and the residual stress state. The material is assumed to follow elasto-plastic and/or elasto-viscoplastic law with isotropic hardening (von Mises plasticity model). The comparative analyses between the experimental and simulation results have shown good agreements. Finally, the residual stress and strain states are evaluated through simulations


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Informations

  • Détails : 1 vol. (IX-251 p.)
  • Annexes : Bibliogr. p. 211-219

Où se trouve cette thèse ?

  • Bibliothèque : Institut national des sciences appliquées (Villeurbanne, Rhône). Service Commun de la Documentation Doc'INSA.
  • Disponible pour le PEB
  • Cote : C.83(3485)
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