17 Replies Latest reply on Jun 27, 2013 8:56 PM by Jared Conway

    Unable to sew surfaces together

    Scott Chabineau

      OK, have tried just about everything I can think of for this one and frankly want to scrap Solidworks Simulation for Ansys or Comsol at this point. This should be basic no brainer!

       

      I have a simple two tine fork model that I just can not get the deformed shape to generate. fork shape.jpg

      I have simplifed it as far as I can - even took out the radius on the bottom - cranked the element size way down, tried tried mesh control, shell, non-linear, static, etc... Why will this not generate the deformed shape?

        • Re: Unable to sew surfaces together
          Anna Wood

          Can you post your part for the Simulatiom experts to look at?

           

          You can use the Advanced Editor link in the upper right of the dialog box.

           

          Cheers,

           

          Anna

          • Re: Unable to sew surfaces together
            Bill McEachern

            Your post is not clear on what you are trying to do. What kind of analysis procedure did you use, what output are you trying to get. What does it hae to do with surfaces not sewing together. Further to the best of my knowledge neither ofht eprogram you mentioned with generate a deformed shape as a solid model - you can get maybe get a deformed mesh but eventhat I think is non-trivial. you could post the model and may be some kind heart might fix it for you.

              • Re: Unable to sew surfaces together
                Scott Chabineau

                Bill -

                I am attempting to create a solid body from the deformed shape. I am not new to this type of problem, but this is the first time I could not work around it. What should have taken an hour is now going on the second day, so I am frustrated (and lashing out a bit)

                 

                After sleeping on it, I am going to try the following:

                 

                1. Change the restraints

                2. Use additional bodies to restrain and apply loads to better simulate reality.

                3. Use Plasticity for the model type (the simulation does exceed the yield strength of the material)

              • Re: Unable to sew surfaces together
                Scott Chabineau

                Sorry for such a lousy first post!

                 

                I kept saying deformed shape, when clearly the shape is deformed! What I should have said:

                 

                I can not get the solid body to generate from the deformed shape.

                 

                Hope this clears things up.

                  • Re: Unable to sew surfaces together
                    Bill McEachern

                    Scott,

                    first off this function is not relieable in its ability to generate shapes - in my expereince it is hit or miss. I would suspect that uniform elements will help  - I don't think it likes little sliver faces. To get an accurate deformed shape you do not need a lot of elements. Try less. Also try generating the shape a lower displacements - it is hard to tell what the scale of things are. I know for a fact that the other code you mention can not do what you are seeking - I think hyper mesh can do it but that is the only one I know of.

                      • Re: Unable to sew surfaces together
                        Scott Chabineau

                        Thanks Bill - I will try these suggestions as well. So far this morning I was able to get one attempt to create a solid body, but it was just a sliver and was nothing like the actual deformed shape.

                         

                        Based on your comments regarding the other programs I must be missing something. FEA packages generate a 3D image, so obviously somewhere in the code the the x,y,z visualization data exists. Why is it so difficult to use this data to create a surface? Intuitively, this should be straight forward.

                          • Re: Unable to sew surfaces together
                            Bill McEachern

                            because you have to map a surface to each exterior element face and then sew all those surface together so they hold water to make a solid body - the lower the number of surfaces (element faces)  the easier it is to pull this off I suspect. Oh and I forgot - those company's you mentioned are not cad companies - they are analysis companies.

                          • Re: Unable to sew surfaces together
                            Scott Chabineau

                            Bill, using the suggestion to back off on the deformation amount, I am able to 'see' what is happening - thanks for the suggestion.

                             

                            Here is what starts to happen to the solid body as I increase the deflection distance. Obviously, the further I go - the worse this becomes until the surface can not be created. I am going to play with the mesh settings and see if I can get better the surfaces to improve.

                            6-27-2013 10-08-59 AM.jpg

                              • Re: Unable to sew surfaces together
                                Bill McEachern

                                I have no clue what the loading is but you might want to consider puttinght heload in withthe remote load rigid option and maybe splitting hte surface - it may reduce the local deformations but leave the overall displacements. sorry for the typo's but I just suck at it.

                                  • Re: Unable to sew surfaces together
                                    Scott Chabineau

                                    I have fixed the top face of the 'short' leg, and I am applying a rotational distance to the top face of the 'long' leg about an axis placed just above the inside face of  the 'U' shape.

                                     

                                    I am going to work on placing this in a more 'realistic' environment next. However, I dont think this is going to help. The solid body faces are not generating correctly, so unless I can fingure out how to control that - I don't think I will be able to find a solution. This is an obvious BUG in the software.

                                      • Re: Unable to sew surfaces together
                                        Bill McEachern

                                        always easy to blame the software but not always justified.

                                          • Re: Unable to sew surfaces together
                                            Scott Chabineau

                                            In this case, I don't see any other explanation. FEA simulation generates a 3D representation of the deformed shape. I can zoom, twist, rotate, and otherwise see a visual representation of effects of the loads and restraints with no visual holes or abnormalities. It just can not, for some inexplicable reason, generate a matching body or surfaces. And there are no known alternatives, options, or settings that will allow it to recreate a pretty simple bent beam. I have created more complex deformed shapes that have successfully created solid bodies.

                                             

                                            I stand by my statement that this is a software BUG. Fully justified.

                                             

                                            I have worked with SolidWorks since 1997, and have a deep appreciation for all that it can do. I wouldn't even be an engineer if it wasn't for software like SolidWorks. That doesn't change the facts.

                                      • Re: Unable to sew surfaces together
                                        Scott Chabineau

                                        I have been through over 30 iterations of this this morning alone. Changing the mesh size from .001mm to over 1.5mm, adding, subtracting, and modifying restraints, adding split faces, radii, etc.... everything results in a flavor of the same thing - a bad surface.

                                        I hope someone out there has a chance to try this themselves and can give me some insight - or better yet, a reasonable solution. 

                                          • Re: Unable to sew surfaces together
                                            Jared Conway

                                            please post your most current model.

                                             

                                            have you contacted your reseller about this?

                                             

                                            my experience with this function is similar to bills, it is somewhat hit or miss.

                                             

                                            that being said, generally people have trouble because their mesh is far too coarse or there is an error during solving. if you get a large displacement error, if you're using soft springs or similar to hold things in space, you can't output a deformed shape.

                                             

                                            if you work with your reseller, they can get this to the developers and get an SPR and confirm that this is a software issue. that will get it on the path of a software improvement.

                                             

                                            i'm not super familiar with ansys or comsol, but can their software do this better than solidworks simulation? is it worth the additional cost for just this one feature?

                                             

                                            the other thing is, usually when i get stuck on an exported model, i pull out the points that are important, plot them and then use that rather than just relying on the deformed shape. doesn't always work, but it might. maybe some info on your application can drive a different solution. (i think there was on recently on a 2d model that we discussed this as well)