6 Replies Latest reply on Jun 17, 2011 2:41 PM by Steve Fiacchino

    simulation shell definition question

    Steve Fiacchino

      I have a surface model to be analized. When creating the shell definition, is the value input equal to the overall part thickness, or is is equal to the offset of the shell on each side of the surface???

       

      Example:

       

      offset value input .010in

      Does that mean the overall part is .010 in thick (.005 offset per side) -or-

      Does that mean the overall part is .020 in thick (.010 offset) per side

        • Re: simulation shell definition question
          David Anderson

          total thickness is the norm. the usual assumption is distributed evenly about the surface unless an offset specified.

            • Re: simulation shell definition question
              Steve Fiacchino

              Are you sure? The analysis results don't seem to add up. When setting the value to X the results seem to indicate it is 2X thick and much more stiff than anticipated. Is there a document somewhere in SW universe which explains in detail?

               

              Is there a way to view the shelled model or measure the shell for confirmation?

                • Re: simulation shell definition question
                  David Anderson

                  yes, i am sure. in my 20 years of using FEA from NASTRAN, SDRC IDEAS, ANSYS, COSMOS (and yes unfortunately i have had the oppurtunity to use SW Sim) i have never come across a shell thickness that is twice what is input. it is customary that the input thickness is the total thickess but w/SW all bets are off as they tend to ignore standard conventions and make up their own.

                   

                  i am not sure what value you are setting to X or how you are interpreting your results but the best way to convince yourself is to model a cantilever beam, put a unit load on the end and run the analysis. it should compare to be near exactly the closed form solution for both stress and deflection, if not check mat props and units and your output as something is amiss.

              • Re: simulation shell definition question
                Bill McEachern

                If the surface representing your part is located at the center of the thickness you would use zero offset and put the total thickness in for thickness. IF the surface representing hte part in say on the inside the thickness stays the same and the offset is 50% of the thickness. the thickness is always the total thickness. If you had a doubler of the same thickness the thickness would 2x and the offset would be 25% (of 2x). Should be clear as mud. I make a drawing and figure it out or if things are really large then you can consider ignoring the offset globally and just use it for doublers, etc.. Everything is an approximation just keep an eye on how you are doing things and whether it matters.

                • Re: simulation shell definition question
                  Steve Fiacchino

                  Are there any SW tutorials that demonstrate the functionality of the shelling and offset features. I get what is going on but I would like to see how they demonstate this... Thanks for the feedback.