I am attempting to model the base of a machine structure that is mounted on isolators an need some advise on modeling. The isolators are elastomeric and I have the values for deflection/deformation. I'm not sure how to model the isolators as they allow for some displacement in all directions.
To add to the complexity of the model the base is mainly fabricated using C-channel and there are several warnings using non-symmetric beam shapes. Presently I have only attempted to model this using beam elements.
Based on the vibration analysis performed on this machine I believe there are natural frequencies of the base structure in the machine operating speed. I'd like to prove this out an model possible solutions for stiffening, etc. to push the natural frequencies out of the the fan operating speed range. Attached are some sketches of the fan layout and its base.
Any advice would be appreciated.
Thank you,
Keith
Comments
I have modeled and simulate a lot of engine mounts, but never replace it by springs for simulating the main behavieur of the powertrain (that part of the bussines was modeled in ADAMS entering the three curves of each mount)
I would model a simple rubber mount with his bumpers and limitations, compute the three load deflections curves, and then create a new model with springs using the computed data to compare with the first model. A very interesting problem!
Do you have more information on the issolators?
Information can be found here:
http://www.trelleborg.com/en/anti-vibration-solutions/products--and--solutions/rail--and--mass--transit--solutions/cushyfoot--product--range.
Max Load: 1280 kg, actual load: 1260 kg
Deflection: 16 mm at maximum load.
When modeling these would you use use a spring element length equal to the max deflection?
I would start defining a spring by two nodes separated by the issolator unloaded height, so when you apply the load (weight) you would have the preload state. You will need to define also the other two stiffness (by deflection and max load you can define the vertical, but still lack the lateral ones).
Will try to take a look on the Trellerbog model maybe during the weekend to see if I can compute some stiffnes values for the three directions.
Regards
Regards