1 Reply Latest reply on Mar 9, 2012 10:44 AM by Adrian Tayne

    sheetmetal/shell - contact sets - non penetration

    Peter Darby

      Hi,

      I am using sets of non penetration contacts to assess a sheetmetal spot welded locker type structure. I am having trouble getting this to work particularly in the top front corners where a vertical side panel and a vertical top panel intersect. At the corner the folded edges in U/Z/W type shapes intersect with edge/edge; edge/face and face/face - some of which I would like to constrain with non penetration contact sets to prevent them diving through eachother as the locker shell distorts. I don't seem to be able to get this to work, and there is insufficient documentation on a sound approach/methodology that gives some insight into how the underlying code 'thinks' and how to best work with it. (this is a huge drawback from SW and a detailed well indexed technical manual is really needed).

       

      To date its been an experimental/iterative approach which is time consuming with mesh/solve rebuilds as an overhead. In looking through the forum I came across one or two threads that provide some help (below), however I'm still looking for assistance or advice.

       

      Thanks in advance

       

       

      Brian Zias on 15/12/2011 6:01 AM Re: How to reduce penetration in solid works analysis

      and

      Bruce Shearer Re: Bonded Connections with Shell Elements

       

       

      Locker CornerPenetration from Simulation

      Locker Corner Detail.bmp

      red/white dots are contacts that I wish to constrain. Constraints have been applied but these do not seem to be having an effect. Probably contravening 'good practice' or breaking some rules but not sure what these may be. One difficulty is that sheetmetal parts do not seem to allow shell edge to face constraints. Is it possible/advisable to select a complete tangent surface and then constrain it against the adjacent parts touching edge loop (or other tangent surface ) in one non penetrating contact set. Does this create difficulty for simulation in generating the contacts and/or a huge overhead in processing/solution. There is a 0.25mm gap between some edges/faces to allow for final powder coating thickness.

      Deflection penetrating.bmp

       

        • Re: sheetmetal/shell - contact sets - non penetration
          Adrian Tayne

          This was mentioned in the other discussions you linked to but is worth asking.

           

          What is your deformation scale set to? I know, from speaking with my VAR, that even if parts are adhering to the no penetration contact condition, they can show up as penetrating if the deformation scale is set high enough. Imagine two parts that have a gap between them and deform in a way that brings them closer together, but still not in contact. If you increase the scale, SW will show that part deforming further without considering whether or not there is visual penetration. Check it with True 1:1 scale, if there is penetration, you have an issue with how it's restrained. If not, then it's behaving normally. You can also check this by increasing the load to a point where the parts would deform enough to penetrate at a 1:1 scale. This will tell you if you have a problem with restraints.

           

          -Adrian