en Research Paper Research Paper <div style="text-align: justify;">One of the interesting state-of-the-art approaches to welding is the process of friction stir welding (FSW). In comparison with the fusion processes, FSW is an advantageous method as it is suitable for the non-fusion weldable alloys and polymeric materials joining. Regarding the materials pure solid state joining, it also provides joints with less distortion and enhanced mechanical properties. In the present work, a three-dimensional (3D) model based on finite element analysis was applied to study the thermal history and thermomechanical procedure in friction stir welding of high density polyethylene plate. The technique includes the tool mechanical reaction and the weld material thermomechanical procedure. The considered heat source in the model, includes the friction among three items: the material, the probe and the shoulder. Finally, the model was validated by measuring actual temperatures near the weld nugget using thermocouples, and good agreement was obtained for studied materials and conditions.</div> Polyethylene (PE), Friction stir welding (FSW), Finite element method (FEM), Temperature distribution, Thermomechanical model. 40 52 http://ijmse.iust.ac.ir/browse.php?a_code=A-10-1583-1&slc_lang=en&sid=1 M. Naseri m-naseri@phdstu.scu.ac.ir 180031947532846009636 180031947532846009636 No Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran M. Alipour alipourmo@ut.ac.ir 180031947532846009637 180031947532846009637 No Department of Materials Science and Engineering, University of Tabriz, Tabriz, Iran A. Ghasemi a.ghasemi@iau-tnb.ac.ir 180031947532846009638 180031947532846009638 Yes Department of Mechanical Engineering, Faculty of Engineering, North Tehran Branch, Islamic Azad University, Tehran, Iran E. Davari m.seyyed.ali1@gmail.com 180031947532846009639 180031947532846009639 No Department of Chemistry, Tarbiat Modares University, Tehran, Iran