https://cyberleninka.org/article/n/403409.pdf

A review of numerical analysis of friction stir welding

Friction stir welding (FSW), a highly efficient solid-state joining technique, has been termed as “green” technology due to its energy efficiency and environment friendliness. It is an enabling technology for joining metallic materials, in particular lightweight high-strength aluminum and magnesium alloys which were classified as unweldable by traditional fusion welding. It is thus considered to be the most significant development in the area of material joining over the past two decades. Friction stir processing (FSP) was later developed based on the basic principles of FSW. FSP has been proven to be an effective and versatile metal-working technique for modifying and fabricating metallic materials. FSW/FSP of aluminum alloys has prompted considerable scientific and technological interest since it has a potential for revolutionizing the manufacturing process in the aerospace, defense, marine, automotive, and railway industries. To promote widespread applications of FSW/FSP technology and ensure t...

Recent Advances in Friction Stir Welding/Processing of Aluminum Alloys: Microstructural Evolution and Mechanical Properties

Thermo-mechanical simulation of friction stir welding can predict the transient temperature field, active stresses developed, forces in all the three dimensions and may be extended to determine the residual stress. The thermal stresses constitute a major portion of the total stress developed during the process. Boundary conditions in the thermal modeling of process play a vital role in the final temperature profile. The heating and cooling rates with the peak temperature attained by the workpiece determine the thermal stress. Also, predicting realistic peak temperature becomes important as the operating temperature at the interface of tool-workpiece is very close to the solidus temperature of the aluminum workpiece. The convection heat-transfer coefficients of the surfaces exposed to air can be theoretically determined using Newton's law of cooling. Contact conductance depends on the pressure at the interface and has a non-uniform variation. The actual pressure distribution along the interface is dependent on the thermal stress from local temperature and non-linear stress–strain state. Therefore, applying an adaptive contact conductance can make the model more robust for process parameter variations. A finite element thermo-mechanical model with mechanical tool loading was developed considering a uniform value for contact conductance and used for predicting the stress at the workpiece and backplate interface. This pressure distribution contours are used for defining the non-uniform adaptive contact conductance used in the thermal model for predicting the thermal history in the workpiece. The thermo-mechanical model was then used in predict stress development in friction stir welding.

https://www.smu.edu/~/media/Site/Lyle/RCAM/Publications/Thermo-mechanical%20model%20with%20adaptive%20boundary%20conditions%20for%20friction%20stir%20welding%20of%20Al6061.ashx

Thermo-mechanical model with adaptive boundary conditions for friction stir welding of Al 6061

The objective of this work is to establish nominal friction stir [butt] welding process parameters for joining 4.76-mm-thick aluminum alloys 6061-T6 and 7075-T6 and to improve the joint quality via programmed tool offsets. In addition, dynamic tool–workpiece interface temperatures are measured during welding and used to explain the effects of alloy placement and weld tool offset from the joint. Weld tool offsets into the retreating side AA7075 increase the measured tensile strength of the dissimilar joint. The increased joint strength is facilitated by lower average weld temperatures with increasing amount of AA7075 stirred into the nugget.

Weld temperature effects during friction stir welding of dissimilar aluminum alloys 6061-t6 and 7075-t6

Role of welding parameters on interfacial bonding in dissimilar steel/aluminum friction stir welds

Friction stir welding (FSW), a new solid-state welding technology invited in the early 1990s, enables us weld aluminum alloys and titanium alloys etc. The processing of FSW, the microstructure in FSW alloys and the factors influencing weld quality are introduced. The complex factors affecting the properties are researched.

Friction stir welding of aluminum alloys

Micro-scale effect and wall slipping mechanism of polymer in micro-channels were studied and analyzed using on Polyflow software.The effect of viscosity and wall slipping on polymer flow in micro-channels was analyzed based on different boundary conditions.The effect of length of compressive section on deformation of the products was studied.It showed that with wall slipping,the resistances at flow of polymer melt decreased,velocity distribution became more uniform,and the deformation of the products reduced.

Fu Zhi-hong

Papers

Friction stir welding of aluminum alloys

Effect of Wall Slipping and Micro-scale Effect on Micro-extrusion