Monday, February 16, 2015

Torsional vibes worksheet to help with the how to solve torsional vibration problems post...

Here's an example of a Holzer method worksheet with sample values and cell equations. I suggest you use other example that you have worked out to verify the cell equations. This is just something I spin up every now and then to solve normal modes torsional vibes problems.  Hope you find it helpful.  Use at your own risk, if I've made an error in a cell equation please let me know.  I leave it to my readers to proof the equations and test the suitability for their own use.  There are many ways to add forced response and damping to the analysis, but that gets a little more involved.

Holzer's method uses excel's goalseek function to iterate or more exactly, to step or march to a solution.  There are as many modes as there are torsional springs so you will have to goal seek different ranges until you find them all. The plot is meaningful as it will show you nodal crossings and help guide your seek ranges until you converge on the next mode.  As always, just send me a comment and I'll try to help you out.

Watch your UNITS! 

Formulas are pretty straight forward...

Use goalseek to converge on a mode

Some common unit conversions
Simple stuff, but handy.

Have a great day!

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