7 Replies Latest reply on Sep 27, 2011 6:52 PM by Philippe Carette

    Meshing problem

    Philippe Carette

      Hi,


      Considering the difficulty to get something stable, just with design of the piece and SW, I wasn't very optimistic about any FEA.


      I tried yet, and I was right.


      Meshing step and the begining of messages in red.


      If somebody knows what is failing, since SW does all in black box.


      Red and black, my favourite when a Lady is in long line bra and suspenders.


        • Re: Meshing problem
          Deepak Gupta

          Please move the thread to Simulation

           

          Did you tried reducing the mesh size. Also before starting the FEA it's a god practice to run a quick check on the model using Check Under Tools.

          • Re: Meshing problem
            Wayne Matus

            Are you running Simulation Xpress of full Simulation? If Xpress, you are right, no diagnostics, but what do you expect for free software. Full Simulation does have some diagnostics, not perfect, but better than nothing. It also gives you the ability to apply mesh controls on your model to make mesh on features smaller than global mesh setting.

             

            I did look at your model, and one thing you might try if you do have xpress is to split the helical surfaces along the axis of the helix. I had issues meshing helical threads before where splitting long helical surfaces into many 180 degree rotation surfaces.

              • Re: Meshing problem
                Philippe Carette

                You are right : I didn't use the symetry of the body.

                 

                Yet, something very strange : a Check Under Tools detects one wrong vertex, and one wrong edgde (locally, apparently).

                 

                Yet, the model having a plane of symetry, a checking should detect 2 occurences of defaults, or am I wrong ?

                 

                I was using Xpress. ....

                 

                Btw, about Check UT, it should be very nice to have a feature to save the checking, because it's all but obvious to retrieve the defaults, since the box disappears as soon as you want to click on a plane to make a sketch to fix what is wrong.

                  • Re: Meshing problem
                    Jerry Steiger

                    Philippe,

                     

                    Symmetric models sometimes have non-symmetric problems. I don't have a clue how this can happen, but I have seen it many times. But sometimes it seems like the Check tool doesn't find all of the problems with a part. I've had the tool find a problem with one side of a symmetric part. I've cut the part in half at the symmetry plane and then run the Check tool on the "good" half. Now it finds the problem in the position opposite.

                     

                    On the other hand, I have fixed problems with a symmetric part that occurred on only one side by cutting the bad half off, mirroring a copy of the good part, and joining the two halves together again. Problem gone!

                     

                    Being located in the Boston area, I guess the SW people are strongly influenced by the Transcendentalists. It was Ralph Waldo Emerson who said the "A foolish consistency is the hobgoblin of little minds..."

                     

                    Jerry Steiger

                    • Re: Meshing problem
                      Wayne Matus

                      I did not mean to cut away half of your model. I meant to create a split line to split the surfaces into multiple surfaces. I had issues before with helical threads would not mesh. I created a split line along the axis of the thread and was able to mesh it. It did make it harder to apply loads and contact surfaces though.

                        • Re: Meshing problem
                          Philippe Carette

                          Tx I will try your idea

                           

                          I never splitted something in such way, but I will try it.

                           

                          Tx a lot

                          • Re: Meshing problem
                            Philippe Carette

                            Paying attention to your advice, I re-modelized a part, without helical profile, but a sequence of revolved profiles.

                             

                            So, the shape isn't exactly what i want to get, but close of it.

                             

                            Meshing - and simulation - works well.

                             

                            At least, I get a result.

                             

                            So, as SW seems to be able to run this simul, can you post some example of this mysterious splitting ?

                             

                            Where have I to split, considering the meshing defaults ?

                             

                            and btw, to locate a default on the part, considering the list of defaults is pretty boring, with this SW interface.