5 Replies Latest reply on Nov 2, 2012 9:17 AM by Mike Price

    Rubber expansion

    Mike Price

      Hi all,

       

      I'm trying to run a nonlinear study and am running into issues.  I am trying to see how the rubber will deform with temperature and am setting up a nonlinear study.

       

      fixture.jpg

      The gray blocks are aluminum and the green is rubber.  I have assigned a hyperelastic - Mooney Rivlin type of material to the rubber, and while I have not quite been able to determine the proper material constants (if anyone knows material constants for Dow Corning Silastic J that would be nice ), I still have put something in for that.

       

      I have created a bonded component contact between the two gray parts.  I have then created a no penetration contact set between the upper gray and green part and lower green and gray part with friction, and then the two green parts.

       

      My thought is that since the green parts are geometrically constrained within the gray, the appropriate contraints are implied.

       

      However, that isn't the case apparently as the simulation will not run.  If the contact sets are changed from a "no penetration" to a "bonded" the model will run, but the scenario is not that of a bonded one.

       

      For a global constraint, I have fixed one of the gray mating surfaces.

       

      Any advice would be appreciated.

       

      Thanks.

        • Re: Rubber expansion
          Jerry Steiger

          Mike,

           

          I don't have any advice on your solver problem. On your material properties, by far the best approach is to have the material tested by someone like these guys:

           

          http://www.axelproducts.com/

           

          As I recall, it costs about $1K to get the data you need. You need to supply them with a sheet of the material.

           

          It's possible that Dow Corning already has the data, but I've never seen it published. You might ask them.

           

          Jerry Steiger

          • Re: Rubber expansion
            Steven Brncic

            Mike,

             

            Did you ever hear back from Dow regarding the material constants?  I am working on a part that will made from Silastic, if you have the data, do you mind sharing?


            Thanks.

             

            Steve

              • Re: Rubber expansion
                Mike Price

                Hi Steve,

                 

                Unfortunately not.

                 

                Considering its widespread use, I am going to go out on a limb and say that somebody has this information.

                 

                I stopped pursuing it as the funds for this project dried up.

                 

                Jerry's comment above about axelproducts is a good one.  I have someone else I can contact too, but don't hold out much hope with that.  I will let you know though.

                 

                On a side, do you know what the vacuum boiling point conditions are for this material?

                 

                Thanks,

                 

                Mike