Plastic collapse of pipe bends with attached straight pipes under combined internal pressure and in-plane closing moment is investigated by elastic–plastic finite element analysis. Three load histories are investigated, proportional loading, sequential pressure–moment loading and sequential moment–pressure loading. Three categories of ductile failure load are defined: limit load, plastic load (with associated criteria of collapse) and instability loads. The results show that theoretical limit analysis is not conservative for all the load combinations considered. The calculated plastic load is dependent on the plastic collapse criteria used. The plastic instability load gives an objective measure of failure and accounts for the effects of large deformations. The proportional and pressure–moment load cases exhibit significant geometric strengthening, whereas the moment–pressure load case exhibits significant geometric weakening

Article information:To cite this document: Robert Hamilton, Donald MacKenzie, Hongjun Li, (2010),"Multi-physics simulation of friction stir welding process", Engineering Computations, Vol. 27 Iss: 8 pp. 967 -985 Permanent link to this document: http://dx.Access to this document was granted through an Emerald subscription provided by University of Calgary For Authors:If you would like to write for this, or any other Emerald publication, then please use our Emerald for Authors service. Information about how to choose which publication to write for and submission guidelines are available for all. Please visit www.emeraldinsight.com/authors for more information. About Emerald www.emeraldinsight.comWith over forty years' experience, Emerald Group Publishing is a leading independent publisher of global research with impact in business, society, public policy and education. In total, Emerald publishes over 275 journals and more than 130 book series, as well as an extensive range of online products and services. Emerald is both COUNTER 3 and TRANSFER compliant. The organization is a partner of the Committee on Publication Ethics (COPE) and also works with Portico and the LOCKSS initiative for digital archive preservation. AbstractPurpose -The friction stir welding (FSW) process comprises several highly coupled (and non-linear) physical phenomena: large plastic deformation, material flow transportation, mechanical stirring of the tool, tool-workpiece surface interaction, dynamic structural evolution, heat generation from friction and plastic deformation. This paper aims to present an advanced finite element (FE) model encapsulating this complex behaviour and various aspects associated with the FE model such as contact modelling, material model and meshing techniques are to be discussed in detail. Design/methodology/approach -The numerical model is continuum solid mechanics-based, fully thermo-mechanically coupled and has successfully simulated the FSW process including plunging, dwelling and welding stages. Findings -The development of several field variables are quantified by the model: temperature, stress, strain. Material movement is visualized by defining tracer particles at the locations of interest. The numerically computed material flow patterns are in very good agreement with the general findings from experiments. Originality/value -The model is, to the best of the authors' knowledge, the most advanced simulation of FSW published in the literature.

The significant development in welding technology for the last decade is the emergence of Friction Stir Welding (FSW). This paper investigates the thermo-mechanical phenomena involved in the FSW welded plates by Finite Element Analysis. The numerical models are fully thermo-mechanically coupled in that heat generated by material plastic deformation and temperature dependent mechanical material properties are taken into account. The whole FSW process is divided into three distinct stages: plunge, dwell and transverse. The transient temperature, stress and velocity of material particles around the tool are reported from the numerical models. It is found that temperature plays an important role in obtaining a sound weld, and only when a proper temperature field is established can the FSW process proceed to next stage. It is also found that it is not possible to fully simulate the FSW process using the ALE formulation without full remeshing during the travel stage of the process due to excessive element distortion.

This version is available at https://strathprints.strath.ac.uk/27456/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the AbstractThe success of the Friction Stir Welding (FSW) process, and the weld quality produced, depends significantly on the design of the welding tool. In this paper the effect of variation in various tool geometry parameters on FSW process outcomes, during the plunge stage, were investigated. Specifically the tool shoulder surface angle and the ratio of the shoulder radius to pin radius on tool reaction force, tool torque, heat generation, temperature distribution and size of the weld zone were investigated. The studies were carried out numerically using the finite element method. The welding process used AA2024 aluminium alloy plates with a thickness of 3 mm. It was found that, in plunge stage, the larger the pin radius the higher force and torque the tool experiences and the greater heat generated. It is also found that the shoulder angle has very little effect on energy dissipation as well as little effect on temperature distribution. Tables Table 1 Typical List of Figures

Background. The allowable plastic load in pressure vessel Design by Analysis is determined by applying a