Modal Plate Benchmark

[haynesj]

Our vib lab just purchased some modal software. I have lost the a resulsts of a modal analysis done on a plate published by the IES as a benchmark (probably ~15 years old). I was wondering if there was a relatively simple and cost effective benchmark we could use to verify and train people?

 

[GregLocock]

In the UK there was a round robin by various labs, who all analysed the same test piece. We didn't take part unfortunately, but I am 99% sure that D Ewins at Imperial College London had something to do with it. That would be about the right timeframe. It may not have been a good training project, I expect it had a few very close coupled modes.

On the other hand why not use a simplified structure typical of your normal test items? For extra marks get them to build an FE model of it and see if they can get good correlation. Very evil grin. Once they've been through that exercise they will be amongst the best dynamic analysts around!

What sort of business are you in? Cheers

Greg Locock

 

[MikeyP]

Are you thinking of the Garteur test structure? Shaped a little bit like an aeroplane? I have some info on that somewhere.

I would suggest that a flat plate with close modes is a good way of testing your modal analysis software. The way to achieve close modes on a freely suspended rectangular plate is to make the dimensions in the golden ratio

(sqrt(5)+1)/2 = 1.618033989...

The first twisting and first bending modes should be on top of each other. Try it with an aluminium and acrylic plates (say ~800*500*10 mm) to get different orders of magnitude of damping.

Its a good training piece as well. Most people find it easy to visualise modes on a free flat plate. You can easily see of you have the "right" answer.

Cost approx euro/$ 200 for the materials. No difficult manufacturing involved.

M

M

 

[haynesj]

Thanks, we are planning on correlating modal results in FEA. The plate I remember was just a flate plate with closely spaced modes. I believe it was a round robin exercise conduted by IES as GregLocock stated.