Tack Welds

Steel Frame Structure

VrWeld Guide
Given CAD files for the parts to be welded, the set of weld procedures to be used, and material properties for the materials being welded, VrWeld enables a designer to simulate the transient 3D temperature field, the evolution of microstructure in low alloy steel welds, transient 3D displacement, stress and strain in the structure as it is being welded.

In our experience, a rough estimate of the number of hours to set up an analysis is the number of parts plus the number of weld joints divided by five or ten. For example, a welded structure with fifty parts and fifty weld joints might require ten to twenty hours to set up. Most of the time is spent specifying the weld paths, weld passes and weld procedures.

We believe that VrWeld is the best weld analysis simulation software available.

We study a weld joint with a part that is stiffer at one end and more compliant or flexible at the other end. We show that welding from the flexible toward to the stiffer end, reduces distortion due to welding. We show that adding two additional tack welds at the one-third and two-thirds distance along the weld path further reduces the distortion due to welding. The following four videos demonstrate this.
The following three videos show one connection in a structure with 88 parts and 250 weld joints. The tubes are roughly 7 cm in diameter. This connection has seven weld joints; three tube-to-tube and four bracket-to-tube welds. A MIG welding process is used. The color shows the transient temperature. The deformation is due to the thermal expansion and contraction from the heat of the arc. The deformation is magnified 10x to make it easier to see the distortion. The three views shown (right, front, and left) allow you to follow the welding process as the arc travels along the weld joints.