3 Replies Latest reply on Jan 11, 2010 12:05 PM by 1-34CXKG

    Space Truss Assembly Tension Cables

    John Bibaeff

      I have a space truss assembly that is supported by tension cables.  The device is similar to a construction crane, one end is supprted by a rigid structure and the free end is supported by tension cables.  I understand that the cables themselves will likily reposnd in a non-linear manner and can't really be modeled with solidworks simulation.  However, I'm trying to run a beam model simulation to determine the reactions at the connection points.

       

      I have tried creating a rigid bar member bewteen the points.  But since there are multiple points and both latetrally and vertial acting forces, the displacements run coming out in the unbelievable range this way.

       

      Anyone have an idea on a wwork around this issue??    

        • Re: Space Truss Assembly Tension Cables
          David Anderson

          any chance you can post a screen shot of the assy?

          • Re: Space Truss Assembly Tension Cables
            Bill McEachern
            Hard to tell what the situation is...you could just use the spring connector or the link connector, put in a beam or truss for the cable elements. If the cables are wire rope it is hard to imagine that their behaviour would be very non-linear.
              • Re: Space Truss Assembly Tension Cables

                I have simulated wire ropes in two ways:

                 

                1) Simulate the cable/wire rope with a thin member, like a pipe.  Assign the pipe a custom material which has near zero density.  The zero density is necessary if you are using gravity loads in order to prevent the simulated cable from experiencing large deflections and stresses due to self-weight.

                 

                2) Simulate the cable/wire rope with a "tension only spring" connector.  In order to do this, you have to create a shell or solid part on either end of the spring and bond it to your beam elements, because Simulation doesn't allow you to connect springs to beam elements or restraints.  You can set the spring constant to be the same as the proposed wire rope size.

                 

                I've never been able to get "truss" elements to work for me.  Of the methods above, I 1 is quicker and 2 is more accurate.  If you just want reaction forces, 1 would probably do.

                 

                Dave.