3 Replies Latest reply on Apr 20, 2012 9:37 AM by Shrikant Savant

    Motors, acceleration and DOF

    Ryan Pagnacco

      I'm a relatively new user of SW Motion Analysis (Engineering Student) and have run into a few issues while working on an assignment.

      The teacher for this course went over how to use SW Motion Analysis briefly, but didn't cover some of these aspects;


      1) How to include acceleration/decceleration when applying a rotary motor. The assignment is an analysis of a 4-bar mechanism, wherein the driving link is rotating at a given speed (rpm) and is deccelerating at a given rate (rad/s^2). I've added the rotary motor to the analysis, but I have no idea how to incorporate the decceleration.


      2) Degrees of Freedome. This might be an interpretation issue, but the assignment asks for "a screen shot of the DOF dialog box with explanation of why the DOF suppressed by the software do not affect your results."  I have not been able to find any information regarding a "DOF dialog box" anywhere; could anyone provide any insight into this?


      Any information regarding these issues would be greatly appreciated.



        • Re: Motors, acceleration and DOF
          Ryan Pagnacco

          Ok... since this has been viewed 40+ times and no one has responded....   After much digging through 'help' in SW (which has very little information), I figured out the expression editor under the motor options. Now I'm stuck trying to figure out how to form an expression that will allow the input of 50 RPM (rotational velocity), decelerating by 1 rad/s^2...  Any information about this issue would be greatly appreciated.

            • Re: Motors, acceleration and DOF
              John Sutherland

              1) First convert RPM into rad/sec so that your units are uniform.


              Then set initial motor velocity as the equivalent of 50 RPM, and separately write an expression to decrement the velocity over your timeline.


              2) In Motion feature tree, right click on Mates then left click on Degrees of freedom report.

            • Re: Motors, acceleration and DOF
              Shrikant Savant

              You can also define an acceleration motor and specify the deceleration as a negative constant number. Just make sure that you apply the proper initial velocity to the driven part.