21 Replies Latest reply on May 28, 2012 9:43 AM by Nandish Datti

    Material Properties

    John Smith

      Hi,

       

      I am trying to see how much a coplex model with tons  of different parts will deflect under the weight of water... the water follows tons of different surfaces so i think its easiest to model the water that way and just give it gravity in Solidworks Simulation.....

       

       

      However... what is the modulus of elasticty of water? i am getting some crazy numbers on the internet of 2.2 GPa... thats unreal!

        • Re: Material Properties
          David Maxham

          Do you care what the water's modulus of elasticity is for this problem?  Couldn't you pick any reasonably, and perhaps low value and just let the water conform to the surfaces, just like it does in real life?  I think the important physical characteristic of water for this problem may only be its density, which, when entered correctly, will give the correct forces on your tons of different surfaces.

           

          Dave

          • Re: Material Properties
            Nandish Datti

            Hi John,

             

            Its better to analyze such problems using the non-uniform distribution pressure condition. Since the hydrostatic pressure varies with respect to depth we can easily represent this condition using non-uniform distribution pressure.

              • Re: Material Properties
                John Smith

                Hi Nandish... Thats all fine and well if you just have a simple cylinder or a box - but what happens if you have a complicated object... do you guys feel this would be something solidworks should work on...? i dont know - maybe there is no real need for something like this?

                  • Re: Material Properties
                    Nandish Datti

                    John,

                        

                         As we know that pressure is atmospheric at the water surface and increases linearly as we go deeper into the water. So irrespective of the geometry as per the coefficients we are specifying under nonuniform pressure definition the water pressure varies over the walls of the object.

                      • Re: Material Properties
                        Anthony Botting

                        What Nandish says should work automatically. Just use the hydrostatic equation in the non-uniform pressure distribution dialog and select all the wetted surfaces. The loading will take care of itself automatically, no matter the geometry complexity, according to the hydrostatic equation. You can locate a coordinate system at the top of the unit for the zero reference and use that in the non-uniform pressured distribution dialog.

                  • Re: Material Properties
                    Walter Fetsch

                    It's been a long time since I studied such things, but I believe that modulus of elasticity is undefined for water.  The modulus is the amount of force applied divided by the amount of deflection.  Water doesn't deflect, it flows, so unless the water is confined, the force will always go to zero and the deflection will also be zero.

                      • Re: Material Properties
                        Jerry Steiger

                        Walter and John,

                         

                        I believe that water actually does have a modulus of elasticity, just not the classic Young's Modulus that we are used to. As I recall, there is a property called the Bulk Modulus of Elasticity, which accounts for the change in volume as you compress a material uniformly. Water is slightly compressible, so it has a Bulk Modulus. That is probably the value that John found.

                         

                        Jerry Steiger

                         

                        Message was edited by: Jerry Steiger

                      • Re: Material Properties
                        Reza Yahyazadeh

                        maybe its good idea to try vibration simulation to analyze worst condition results.