2 Replies Latest reply on Oct 30, 2012 11:21 PM by Third J

    About linear simulation

    Third J

      I cannot understand a parameter "acceleration" in the result of sine vibration simulation.
      What's the meaning of "acceleration"?

      I design a simple object and I want to figure out the acceleration in sine simulation of this object.
      After I run the program to simulate this object, the result is really unbelievable...1000G !!

      Can anyone give me some advise? I really need some help...

        • Re: About linear simulation
          Anthony Botting

          It may not be unreasonable depending on forcing frequency and displacement amplitude.

          If "omega" is the forcing frequency of vibration (radians/second), and "A" is the vibration displacement amplitude:

          displacement: x(t) = A sin (omega*t)

          velocity: v(t) = [omega*A] cos (omega*t)

          acceleration: a(t) = [-](omega)^2 *A sin (omega*t)


          So the magnitude of acceleration can be quite large = (omega squared) * A.


          For example, if forcing frequency, omega = 223 Hertz = 1401 radians/second, and forced vibration amplitude is A= 0.005 meter (5 millimeters), then:

          Magnitude of acceleration (ARES) = (omega squared) * A = 9816 m/s^2 = 1,000 g's (approximately).


          As a check you could also plot Displacement Resultant and Velocity Resultant and hand-calculate the Acceleration Resultant to see if the values work-out.

          Also, if the forcing frequency is near or very near any of the structure natural vibration frequencies, the values can get very large (especially with no damping). You can list the structure natural vibration frequencies and see if any of them are near the forcing frequency.