If you're interested in possibly trying to do some of this yourself I would contact the ModalShop. They'll rent you all the equipment to let you do it yourself, I think they even will send someone to teach you the basics (for a price of course). They rent equipment for almost any...
Here's a situation that I've never seen come up on here. How does everyone here feel about offering testing services that may include information and procedure that one can only learn through engineering school or years of experience? These may include strain gaging, vibration analysis, etc...
No it will be 1/50*10=0.200g all the gain does is amplify the signal form the amplifier outward it will not change the actual output from the sensor itself.
You should also be able to find it at the University of Cincinnati Sructural Dynamics Research Lab's (SDRL) website. If you go to www.sdrl.uc.edu and go to the academic course info section there should be course notes for all courses. It derives H1, H2, and Hv.
What type of vib testing are you looking for? Are you looking for standardized testing to meet some spec, or are you looking for a more comprehensive study?
I've directly compared the results from OMA and traditional modal analysis for a few simple test cases and for some theoretical derived lumped mass systems. My overall feel is that OMA, when properly applied, is very good at determing natural frequencies. However, depending on the structure...
I suppose it is possible if a mode at 12Hz were sufficiently lightly damped and you happened to place an accelerometer directly at a node of that mode you could see a response similar to this. Although it is odd that you only see this response at a higher amplitude, which would point to a...
Rob45, I would suspect that the attenuation of the signals you're seeing is due to differences in anti-aliasing and AC-coupling filters rather than the WAV format. A less expensive data acquistion system may have filters with ripple or other effects that effect the low and high frequency...
I've not talked to anyone that has used the 1432 boards for long term type monitoring. They've traditonally been used in the NVH field for transient capture, modal analysis or similar work. They'll record any type of voltage signal but can have the option to interface directly with IEPE/ICP...
VXI Technology is now manufacturing and supporting the 1432 cards. You should contact them, they'll tell you everything you need.
http:\\www.vxitech.com
Does anyone know of any good stand alone Rotor Dynamics modeling programs? I know that any FEA program could handle this. However, what I'm think of would allow me to place discrete components at the required locations then assign each component the appropriate specifications.
I agree with Tom. Not only could you use CEA but any other form (Least Squares Complex Exponential, Rational Fraction Polynomial, Ibrahim's Method). Depending on if you have multiple inputs and outputs then other methods may work better (Eigensystem Realization Algorithm, Poly-Reference Time...
The wavelet transform could possibly be of use to you. The kernel of the wavelet transform is a generic form and changing it changes the type of wavelet you form (Harr, Morlet, Meyer, Shannon, etc.) There has been work of forming kernels that produce results similar to 1/3 or 1/12 octave...
Mikey P,
I've read some conference proceedings that show a modal analysis being done on a bridge. The modal analysis is used to form a modal model of the structure and then the modal model is interpolated back to zero frequency to obtain the static deformation of the bridge due to certain...
Greg,
Have you ever suspended a simple beam from fishing line or dental floss and then struck it to see how long it rings. Then add a single accelerometer to the beams and compare the ring down times. The accelerometer certainly affects the system.
Valley,
There has been a lot of work in the modal testing of turbine blades for defect detection. The most sucessful methods I know of used a change in the damping from a good blade to a bad blade rather than the natural frequency. However these methods also used microphones instead of...
What is your reason for using a response only method to extract the modal parameters over a tradition modal analysis method? A traditional modal analysis will typically give you a better estimate of frequency and damping especially in the case where a system is excited only at a few points. It...
