3 Replies Latest reply on Feb 17, 2011 7:01 PM by Matthew Blight

    Simulating a Welded Frame

    Matthew Blight

      I'm trying to do some analysis on a Trailer Chassis, which is generally a fairly basic frame made up of lengths of RHS.

       

      My issue is that i'm not sure how i should treat the joins between the tubing etc.  Currently the model is made primarily from weldments, with the addition of some webs and brackets etc.  It's a little complex to run as just Beams, as i don't get proper "nodes" in some areas due to the design.  So i'm running it as all solids.

       

      The thing is, that i've just got bits of tube cut off square butted up to other bits of tube, and normally there would be a nice fillet weld around the whole join.  But simulation doesn't seem to recognise "welds" and hence i've just "bonded" the faces using contact sets.  This seems to work OK, but is this the best option?  It doesn't seem quite equivalent to me, as you get areas where part of the square cut tube would be welded to the radiused corner of the mating tube, but in simulation these faces aren't contacting.  On part of the suspension for the same trailer, there is a section of rectangular tube that joins up with a round tube, which creates a gap that would normally be filled by weld, but there doesn't seem to be a way of "welding" across the gap.  Should i be converting the model into a single solid body and filleting the joins where all the welds would be??

       

      This is kind of a critical project, so no time to go and do a Solidworks Simulation course...

        • Re: Simulating a Welded Frame
          Paul Mihala

          You can use the trim/extend command in the weldments toolbar to butt up to any surface.

           

          Or you can convert entities of your profile at both ends of the RHS to do an extrude up to body whilst editing the part in the assembly.

           

          You want to have no gaps in the face contacts to act as a welded part.

          • Re: Simulating a Welded Frame
            Kevin De Smet

            This is kind of a tough thing, and it's equally so common a thing to want to simulate. I don't have the answer but you might want to read this: http://www.eng.uwo.ca/designcentre/FEA%20resources/116_Welds.pdf

             

            It's a couple years old now, but it's a really good read to get some insight and it's like 20 short pages so you can go through it in an evening.

            • Re: Simulating a Welded Frame
              Matthew Blight

              Thanks guys for your help.

               

              I've ended up using a combination of things.  For some joints I've combined the bodies and added fillets etc to create the appropriate amounts of metal, but in most cases i've just relied on the "bonding" in simulation, as this seems to give quite valid results.  Obviously this isn't going to be 100% representative, but it seems it's not really possible when dealing with something like a weld, which doesn't have consistent properties, but it provides a reasonable indication of what the weak points are etc.

               

              Cheers!