Finite element (FE) analysis of welding residual stress and deformation is one of the essential stages in the manufacturing process of mechanical structures and parts. It aids in reducing the production cost, minimizing errors, and optimizing the manufactured component. This paper presents a numerical prediction of residual stress and deformation induced by two-pass TIG welding of Al 2219 plates. The FE model was developed using ABAQUS and FORTRAN packages, Goldak’s heat source model was implemented by coding the nonuniform distributed flux (DFLUX) in user subroutine to represent the ellipsoidal moving weld torch, having front and rear power density distribution. Radiation and convection heat losses were taken into account. The mechanical boundary condition was applied to prevent the model from rotation and displacement in all directions while allowing material deformation. The FE model was experimentally validated and the compared results show good agreement with average variations of 18.8% and 17.4% in residual stresses and deformation, respectively.

Welding is one of the essential stages in the manufacturing process of mechanical structures. Friction stir welding structure of aluminum alloy has been used as a primary supporting member in aerospace equipment. However, friction stir welding inevitably generates residual stress that promotes the initiation and propagation of cracks, threatening the performance of the welded structure. Shot peening can effectively change the distribution of residual stress and improve the fatigue properties of materials. In this paper, friction stir welding and shot peening are performed on 2219 aluminum alloy plates. The residual stress fields induced by friction stir welding and shot peening are measured by using the X-ray diffraction method and incremental center hole drilling method, and the distribution characteristics of residual stress fields are analyzed. The effect of the pellet diameters and pellet materials used in shot peening on the redistribution of welding residual stress field are investigated. The pellet diameter used in the experiment is in the range of 0.6–1.2 mm, and the pellet material includes glass, steel, and corundum. This study provides guidance for the application of shot peening in friction stir welding structure of 2219 aluminum alloy.

In this paper, a dynamic welding model of tungsten inert gas welding is established to study the evolution of stress during welding and the distribution of residual stress. The residual stress of post-weld is measured by the hole-drilling method and compared with the simulation results to verify the validity of the calculation model.. The results show that there has a large instantaneous compressive stress existing in the front end and both sides of heat source during the welding process. After the heat source passes, the dynamic compressive stress at the back-end of heat source gradually transforms into tensile stress and the tensile stress region continuously expands to both sides of the weld. The residual stress of post-weld in the weld is mainly dominated by longitudinal tensile stress. The maximum tensile stress of post-weld is 165 MPa, which is about 47% of the yield strength of the base metal, and is located in the heat-affected zone. DOI: http://dx.doi.org/10.5755/j01.mech.25.1.21934

This study investigated the mechanical and sensing properties of ethylene-vinyl acetate (EVA)/carbon nanotubes (CNTs) composites in both film and fiber forms. The incorporation of aligned CNTs in the composite fibers possess improved mechanical properties and enhanced sensing performance compared to those of composite films with randomly dispersed CNTs. Thermogravimetric analysis revealed promising thermal stability, indicating potential applications for long-term usage. Cyclic tensile testing demonstrated that the fiber samples with better CNT alignment exhibit higher sensitivity, emphasizing the significance of CNT orientation in constructing an efficient conductive network for strain sensing. Considering the contribution of the CNTs orientation along the measuring direction, a model contains modification parameters was proposed, where a master curve was given, revealing the ideal potential of the EVA/CNTs composite fiber with perfectly aligned CNTs. This work provides valuable insights into the influence of CNT alignment on the mechanical and sensing properties of EVA/CNTs composites. The results underscore the importance of optimizing CNT orientation for enhanced sensing performance in various engineering applications.