Harmonic Beam Resonance???? 1

[ras203]

I am investigating the change in frequency of a center beam which is attached to the mid-point two thinner beams either side of the center beam. This means the resonant freq of the center beam can be controlled by tensioning the two side beams.

I am using Ansys 10 to simulate this, and can achieve a good animation of the center beam resonating in harmonic mode when i fix the end points of each of the side arms.

However, now I want to change the tension in the side beams and simulate again to see the effects on the resonant frequency of the center beam but cant seem to do it. I have tried using the 'remote displacement' constraint to specify the amount of displacement i want in the side beams, but because it is a harmonic environment, the model oscillates in the x plane as the side arms extent and compress, and oscillates in the y plane as the center arm moves up and down.

What have i missed, how can i change the tensioning in the beams to set amounts to achieve different resonate frequencies?

 

[Drej]

Take a look in the manual at the "Pre-stressed Modal Analysis" section. You'll need to tension the side beams first and perform a static analysis with PSTRES,ON. Then you must re-enter solution and perform a modal run (antyp,modal) also with PSTRES,ON. It sounds as though you're using Workbench, so it should be straightforward as this is now an automated procedure for later versions of that software.


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