12 Replies Latest reply on Dec 18, 2013 4:04 PM by Jerry Steiger

    Extrusion Simulation

    Niels Van Swaemen

      Hello,

      First of all I'm new here so I hope I'll do everything as it should be and I'll try to give you enough information.

       

      I'm trying to create a simulation model for an extrusion.

      I have two parts: a die and a shaft.

      The material of the die is some high strentgh steel, the material of the shaft is aluminum.

      The extrusion will be from 3.9 mm to 3.2 mm.

      The purpose of the study is to get the force that will be needed for the extusion.

      The shaft has to be plastic deformed and the die only elastic.

       

      The material for the shaft is set on Plasticity Von Mises with Etan set on: 75500 MPa (A higher value as the Emod. otherwise I

      get this error: "Incremental plastic strain is too large"

      I guess the Etan has to be around 10% of the Emod but I'm not sure.

      Material properties.png

       

      For contact set I've selected the outside of the shaft and the inside of the die. (No friction)

      Advanced contact settigs: Surface to Surface

       

      The bottom of the die is Fixed.

      Both Planes are set to symmetry fixtures.

      The shaft has a diplacement downwards of 6.4 mm so the top planes of both parts will be equal.

      I've set up a time curve this way:

      Time Curve.png

      When the displacement is returned to it's origin I would like that the part is still deformed.

      But that isn't working.

       

      I've created a coarse mesh with a mesh control on the outside of the shaft and the inside of the die.

      Mesh and Fixes.png

       

      These are the settings I've used in the study properties:

      Study properties.pngStudy properties advanced.png

       

      Results:

      Displacement.png

       

      The volume of the shaft is the same as the open volume in the die so I don't understand why the shaft don't fill up the die.

      I understand that the die will deforme a bit as I can see when I plot the displacement in Z. But that isn't that much.

       

      I hope someone can help me with this.

      Thanks in advance.

       

      Niels

        • Re: Extrusion Simulation
          Jared Conway

          Setup sounds ok to me

           

          Is the contact actually happening? When you hide the block can you see it compressing?

           

          Also, why not do this as 2d axisymmetric?

           

          The model looks simple and non proprietary enough to post here. Best next step I think.

            • Re: Extrusion Simulation
              Niels Van Swaemen

              Thank you for your reply.

              I'm pretty new to nonlinear simulations.

              What exactly do you mean with the contact? I assumed that the surface of the shaft wil be in contact

              with the die all the time.

              I have no experience with 2D axissymmetric model but I will definitely have a look at it.

               

              Thanks again.

                • Re: Extrusion Simulation
                  Jared Conway

                  when you look at the results are the components overlapping or are they touching face to face? it is hard to tell in that screenshot

                   

                  also, just to double check, you might want to check that your volumes are exactly the same.

                    • Re: Extrusion Simulation
                      Niels Van Swaemen

                      The components aren't overlapping as you can see:

                      Result.png

                      Result Displacement Z.png

                       

                      There's just a slight difference in the volume before and after (0.08%).

                       

                      I've also tried to solve with 2D axissymmetric, but i keep getting the warning: "Incremental plastic strain is too large"

                      2D Failure.png

                      I've tried the solustions that are suggested but it keeps giving me that error.

                        • Re: Extrusion Simulation
                          Jared Conway

                          Is suggest posting the model

                            • Re: Extrusion Simulation
                              Niels Van Swaemen

                              Here is the model.

                                • Re: Extrusion Simulation
                                  Jared Conway

                                  a couple of things that i notice, your poisson's ratio is only 0.33, to get the effect that you want, isn't poisson's ratio going to have to be closer to 0.5?

                                   

                                  second, your contact isn't perfectly being captured, the parts are overlapping each other slightly

                                   

                                  do you have physical testing that confirms that your plug should perfectly fill the hole?

                                    • Re: Extrusion Simulation
                                      Niels Van Swaemen

                                      I've tried to solve it with a poisson's ratio of 0.5 an near to 0.5, but than I get this error:

                                      "Solution failure in a Step>1, ..." Again I've tried teh suggested solutions but it won't work.

                                       

                                      I can see that the parts are overlapping. Is there a way to fix this?

                                       

                                      I don't have physical testresults.

                                       

                                      Also I'm still in doubt about the Tangent Modulus. The solver only completes when I use

                                      a Etan higher than the Ex. I think this value has to be about 10-20% of the Ex. But when I

                                      try to solve with this value I keep getting the warning: "Incremental plastic strain is too large"

                                        • Re: Extrusion Simulation
                                          Jared Conway

                                          i wouldn't spend too much more time on this problem until you have a valid material definition

                                           

                                          and yes, there is going to be some challenges with making it 0.49, i would follow the instructions that are throw with the error and look at the customerportal.solidworks.com about the error and using a poisson's ratio near 0.5

                                            • Re: Extrusion Simulation
                                              Niels Van Swaemen

                                              I've made some progression in the last days.

                                               

                                              I have valid material specifications.

                                              Now using CuZn37Pb2.

                                               

                                              E-modulus:           105 GPa

                                              Poisson ratio:        0,35

                                              Tensile strength:    370 MPa

                                              Yield strength:       180 MPa

                                              Etan:                    1100 MPa (about 10% of E: https://forum.solidworks.com/thread/39599)

                                              Using a poisson ratio of (near) 0.5, than the material will act as rubber.

                                               

                                              Although the study was not completed (85,3 %), the results are better than before, because now the material flowed.

                                               

                                              Result URES.png

                                               

                                              There a still a couple of problems:

                                              The solver keeps warning: "Incremental plastic strain is too large" an tells me to raise the ETAN.

                                              I've tried to find the solution in the CustomerPortal but without any succes.

                                               

                                              The volume of the the plug is the same as the open volume inside the die, so it should be filled up almost perfectly.

                                              I guess it doesn't fill up beacuse of the study is not completing.

                                                • Re: Extrusion Simulation
                                                  Jared Conway

                                                  Your material definition says the v is 0.35, but you are overwriting to 0.5? What are you trying to learn in this study? Also, for etan, you should be getting it from the stress strain curve if possible. With the material assumptions you are making, is this more of an Academic study than an actual application?

                                                   

                                                  Regarding the warning, I assume that you have followed the recommendations given by the solver already? In the message that pops up on failure? Once you have exhausted those, I would suggest re looking at your materials. If they aren't compatible, the solver may be telling you that this is not possible. Do you know it is possible physically? If it is, I would engage your reseller to engage swx technical support to confirm this problem is possible with swx sim. But not until you confirm your materials and expectations.

                                                  • Re: Extrusion Simulation
                                                    Jerry Steiger

                                                    Niels,

                                                     

                                                    The error sounds like one I sometimes get in ANSYS. If so, it is telling you that you need to take smaller steps to get a solution.

                                                     

                                                    Jerry S.