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# [ABAQUS] Receptance FRF with zero displacement at resonance. What is the best way to obtain it?

## [ABAQUS] Receptance FRF with zero displacement at resonance. What is the best way to obtain it?

(OP)
Hi everybody.

I've been trying to compute the vertical receptance of a rail in its midspan; after the natural frequency extraction (0-20Hz) i've performed a Steady state modal dynamics with a concentrated vertical force in the point of interest. What i get as vertical displacement is the plot depicted in this picture.

Actually, i'm looking for a plot like the one in this picture.

How come the response is negative for frequencies slightly lower than the resonance ones? And to the best of your knowledge, what is the best way to obtain a Receptance function?

Warm regards,

Omar

### RE: [ABAQUS] Receptance FRF with zero displacement at resonance. What is the best way to obtain it?

I suspect you need to plot the magnitude as opposed to the real component. But I don't understand what is meant by "receptance" The options are real, imaginary, phase and magnitude and at phase angle. These are in result options under the complex form tab. You control the phase resolution by adjusting the harmonic animation options - its a post processing operation. The peak response is usually at a phase of 90°. the default options don't resolve that but they get close at 77.1°. Hope this helps.

Bill McEachern, P.Eng.
Redstone Six Consulting Ltd.
www.redstone6.com

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