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Simulation of the Local Strain Effect on Deformation of a Steel Part

Ebrahimi, Hossein | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48154 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Karimi Taheri, Ali
  7. Abstract:
  8. One of the methods of forming the metal parts is to apply a localized strain field to the workpiece. This field can be generated by creating a deformation in an actuator connected to the workpiece, or directly by a localized imposing heat (thermal localized strain) to the workpiece. For example in laser forming process, the workpieces in the forms of sheet and tube can be deformed by creating localized strain field induced from thermal field caused by laser irradiation. The main mechanisms in laser forming are temperature gradient mechanism, upsetting mechanism and buckling mechanism. It is worth mentioning that until now, the localized strain field induced by laser irrediation is considerably studied for temperature gradient mechanism but researchs on upsetting and buckling mechanisms has been very limited. Therefore, in this thesis, in addition to development of an analytical model for assessing the effects of localized strain field on the deformation of a workpiece in the form of sheet, tube and rod, the laser forming process for upsetting and buckling mechanisms are analyzed. In this regard, the effect of parameters such as laser beam diameter, workpiece geometry, laser scanning velocity, laser power and the number of laser beams on the localized stran field and the deformation of the workpiece caused from that field, are studied and the results are compared with the results of the finite element method. It was found that the critical temperature needed for starting the buckling in the sheet, is affected by sheet dimensions so that with increasing the thickness and/or decreasing the sheet width, the critical temperature is increased. Moreover, increasing the laser power, decreasing the scanning velocity, and increasing the number of laser beams postpone the occurrence of buckling in the laser forming process. Further, it was shown that the analytical model results are in a good agreement with finite element model results indicating that the assumptions made in developing the analytical model are logic
  9. Keywords:
  10. Finite Element Method ; Buckling ; Simulation ; Metals Forming ; Strain Field ; Local Strain ; Laser Forming

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