3 Replies Latest reply on Jul 6, 2017 10:18 PM by David Hooper

# Simulation edge weld results vs. Throat Shear Method

Hi all,

This is longer than it needs to be, so bear with me

I am trying to model some welds and wanted to do a check of the SW edge weld connector results with the throat shear method before I continued on.

I used the throat shear method outlined in this presentation: http://www.eng.uwo.ca/designcentre/FEA%20resources/116_Welds.pdf

Here is the help page describing the formulas Solidworks uses: 2015 SOLIDWORKS Help - Weld Size Calculations (American Standard)

I performed a simulation of two flat plates welded together with a double sided fillet weld. I did one simulation where the flat plate was joined using the double sided fillet weld connector, and another simply bonding the two plates and using splitlines to align the nodes. My fillet weld connector is a custom steel with a shear allowable of 40000 psi and a safety factor of 1. Both models were shell meshed with draft quality, and one to one node correspondence at the joint. Equal loading conditions and fixtures were applied to both models.

With the throat shear method, I am getting a maximum weld size of about 1.60e-5 in, and using the Edge Weld connector I get a maximum weld size of about 1.65e-5 in. So this looks good!

Now the problem is...

When I do the throat shear method, I am basically extracting the loads at each node, dividing that by the "nodal length" (the total length of element acting on the node) to get the load per unit length. When I divide by the nodal length, I get a force per unit length unit (for Normal, Shear, and Bending), which is dependent obviously on element size.

The total normal load going through the weld joint is 1.25 lbs

The throat shear method, in the normal direction, gives me an average force per unit length of .25 lbf/in. The weld joint is 5 in long, so 5 in x .25 lbf/in is 1.25. So that makes sense.

The solidworks weld, in the normal direction, gives me an average force per unit length of 11 lbf/in. 11 lbf/in x 5 in = 55 lbf, which to me doesn't make any sense.

So, how exactly is the solidworks weld loading calculated? It must be correct, because I am getting the same weld size for both methods, just different loading.

Attached are screenshots of my results

• ###### Re: Simulation edge weld results vs. Throat Shear Method

In other words, can anyone tell me exactly how Solidworks calculates the weld loading? Because I am doing it manually and not getting the same results.

• ###### Re: Simulation edge weld results vs. Throat Shear Method

Well, people...

Turns out there is a bug in SW 2015, 2016, and any other Solidworks that uses the Edge Weld Connector. There is a unit conversion error in the loading output for English units only. If you output the results in Metric units and convert, you get the correct loading output.

• ###### Re: Simulation edge weld results vs. Throat Shear Method

Could one extract the: joint normal force, shear weld axis force, shear surface force, and bending moment for a given weld size from the weld connector output dialogue box and determine the stress at that point (namely the only two points provided maximum weld fillet and minimum weld fillet)?

I would expect using this output from Solidworks when taking into account Factor of Safety, ultimate shear stress of electrode to get a corresponding stress (Ultimate Shear/ FoS).

When I use this information with the shear throat calculations I get a much lower stress then I would have expected and the two values are not identical as I assumed.  Any help would be appreciated.