5 Replies Latest reply on Sep 19, 2008 3:28 PM by Chris Frye

    Thermal expansion modeling

    Tobin Munsat
      I have a part I need heated to 800C and I have three different unconnected materials in it. I need to figure out how all the different components will expand and move in relation to eachother during the heating process.

      When I click on the COSMOSXpress button in the tool bar it tells me that "Cosmosexpress can be used with assemblies only after preforming Physical Simulation." But when I try to run physical simulation it gives me 4 options none of which have anything to do with my part (Linear Motor, Rotary Motor, Spring, Gravity).

      First, is what I'm trying to do even possible with the student version of COSMOS?

      Second, if it is, what am I doing wrong with the Physical Simulation and how do I get through it?
        • Thermal expansion modeling
          Tobin Munsat
          Also, one of my materials is sapphire, is there some way to get a "sapphire" program in my Materials list, or some way to model something close to it?
            • Thermal expansion modeling
              Steven Dinsdale
              The short answer is that COSMOSXpress will not be able to do what you are asking.

              First, it cannot define contact in assemblies, second, it cannot perform thermal studies, third, you cannot define your own materials. COSMOSXpress is basically a marketing gimmick to get you to buy the full version. Sorry :/

              -Steven
            • Thermal expansion modeling
              Mahir Abrahim
              If all you want is a quick interference check, you can try the Scale feature. You would have to add Scale to the bottom of the feature tree for each part, with the scale factor being (change in temp) * (CTE).
              • Thermal expansion modeling
                Tobin,

                If you have the REAL cosmos student version, then you need to click Tools-->Add-Ins and check the box next to CosmosWorks. CosmosWorks should be able to handle this. I am not sure what kinds of studies can be done with the Student version.


                Ignore the red circle in the picture below. The CosmosWorks product matrix is no longer on the Solidworks website. This is from an email I sent a long time ago. You only need the Linear Static study type. The thermal type is more for conductive heat transfer.



                An alternative is search the web for CAELinux if you are a computer geek. It has some free tools that are good for learning but are hard to justify using in industry.
                  • Thermal expansion modeling
                    Chris Frye
                    Since Sapphire is a trigonal crystal with monoclinic properties, and the closest thing Cosmos allows is an Orthotropic material, you won't be able to model exactly. You will need to approximate the material as either Orthotropic or Isotropic, depending on how accurately you want to predict the behavior. Once you decide how you are modeling the material, you need to enter the material properties in the material manager. Do the same with your other materials unless they are already in the database.
                    If you only need to know what is happening at the 800C once everything has stabilized, you can use a linear static analysis. Then set the reference temperature at zero strain to room temperature. Create a load temperature and select the entir assembly from the temporary feature tree (on the upper left corner of the model space). Set the temperature to 800C. Define your mesh etc. You will need a constraint (maybe one surface is fixed) you can use soft spring option in the study properties if this is not the case. Once you have all that defined, you can run the analysis and view the results.
                    If you need to see what the assembly might do as the temperature is rising, you will need to do a thermal analysis (with transient solution). Once that is complete, the results (from any time step) can be used as input to a Linear Static analysis. Then you have to run the linear analysis. You will need to make sure you enter the specific heats of the materials for the transient thermal analysis.
                    If you don't think the heat is not being applied uniformly in the real experiment, you would need to model that situation (i.e., heat flux, heat power, convection, etc.), using a thermal analysis (transient or steady-state). The thermal analysis will only give you the temperature distribution. You will have to run the linear static analysis afterward, to see what the deformations/stresses are.