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March 17, 2010 8:37am UTC in response to Nathalie G.

Re: how to model a spring?

Hi

well a spring gives a force as Fy[N]=-ksp[N/m]*v[m] so you can, if you have a simple beam modelled by a line in 2D attach a force on the tip with the value "-ksp*v" (that you define as a constant) if the motion is in v, I assume your line is along x (horizontal).

And this should do, no ?

Perhaps you want to add some damping ? it's done in a smilar way. For eigenfrequency models you need to change theequation to allow it to be modal compatible. That is a good exercice.

You can easily check your model by adding a point mass at the end of your beam.

For modal analysis it would show you the way one calibrates an accelerometer by doing a simple modal sweep test on a structure, and then by reapeqating with adding a known mass on the accelerometer

Good luck
Ivar

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