shock absorption and phase angle
shock absorption and phase angle
(OP)
Hi, I did a test with a material under 20Hz cyclic loading MTS. To evaluate the force absorption, two load cells were used to simultaneously measure the applied (input) load and transmitted (output) resultant force. For a stiff material, the force applied was the force transmitted to 100% with no phase shift. For another material there was 30% less force measured at the second load cell. I would assume 30% were absorbed/dissipated. But the phase angle was the same (no shift there). How comes? Wouldn’t the phase angle between both signals be an indication of the damper coefficient? How can I have 30% absorbed but 0 phase shift in the signals?
Thanks!!!
Thanks!!!





RE: shock absorption and phase angle
RE: shock absorption and phase angle
/I/ wouldn't.
Cheers
Greg Locock
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RE: shock absorption and phase angle
thanks!
RE: shock absorption and phase angle
Is it a simple one degree of freedom or a distributed system.
From the "description" of the problem you gave, Greg's answer was more than you could expect.
RE: shock absorption and phase angle
Second test. Similar system but with some hydraulic fluid. Mts measures 70% of the applied load with 0 phase angle shift. My thoughts: hydraulic dissipate energy. But wondering about the phase angle (damping?).
Is that making it any more clear?
Thanks
RE: shock absorption and phase angle
Patricia Lougheed
******
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RE: shock absorption and phase angle
You have correctly identified that energy absorption without a phase shift is unlikely. So....
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: shock absorption and phase angle
thanks!
Diana
RE: shock absorption and phase angle
Compositepro is right. There is some phase shift but the delay is small because speed of sound through oil is about 4ft/ms. You may not be able to detect such a small delay.
MTS systems are not cheap. Teachers or students wouldn't have access to them.
sonnenshein987, how fast does the MTS system sample?
Peter Nachtwey
Delta Computer Systems
http://www.deltamotion.com
RE: shock absorption and phase angle
Diana
RE: shock absorption and phase angle