09:04 Sep-12-2005 Bill Weber Director IMPACT-ECHO INSTRUMENTS,LLC, USA, Joined Mar 2003 2
Re: impact echo : limited to concrete ? ----------- Start Original Message ----------- : All I read about Impact-Echo deals with concrete structures, but I'd like to know if it can be used for other materials (such as wood, metal...) : Any information about that? : Thanks in advance... ------------ End Original Message ------------
Hi There, Yes, Impact-Echo can be used for other materials such as wood and graphite, but not steel, because the wave speed is way too high in steel. Have you visited our website, www.impact-echo.com? We have a new 9 page downloadable brochure.
I'm interest with impact echo. Is impact echo able to used detect the composite of material?for example. If we have damaged concrete. the best material on one side and the poor material on the aother side, but we don't know the material in the middle part. Is impact echo able to detect the the wave speed or properties material of the damaged side?and the middle side?thank you
For wood composite we have DIO2000- Air couplant 50 kHz -400 kHz
200 mm thickness (CSCAN)
Contact transducerDIO2000 LF with burst pulser for True transmition up to 2 m lenght wood, 8 m concrete (manual measurement)
DIO1000LF for measurement of Velocity, Elasticity
The impact-echo method is able to detect boundaries between homogenous materials with different acoustic impedance (wave velocity, density) - as is the case for any method using elastic waves. If you have a clear boundary between one and the other material you will get a reflection as a positive indication.
Unfortunately, poor concrete with decreased compressive strength, enhanced porosity, and/or small cracks will not reflect. In this case you can use the damped and/or delayed back-wall reflection as a negative indication. (More advanced methods would investigate the spectral properties of backscattered waves.)
Differences in propagation speeds can also be detected indirectly by the placement of the back-wall indication. Results are integral through the complete material. For a spatially-resolved propagation speed, a tomographic method is necessary.
10:47 Mar-30-2011 rma Student Indonesia, Joined Dec 2010 2
Re: impact echo : limited to concrete ?In Reply to Martin Schickert at 09:01 Mar-30-2011 .
It means that if i use damper or black wall, impact echo can detect the inner condition of concrete including modulus of elasticity, strength, poisson ratio and density. Is that right?
If we have damaged concrete because of high temperature, concrete will change the properties material or conditiuon of concrete from surface until inner concrete until botoom concrete gradually. But we don't know how much layer will be happend. So, what is the function of damper or black wall?do we take the impactor on 2 sides?
I don't understand what you mean by "damper or black wall".
If you measure a single parameter - resonance frequency in case of impact-echo - you can only draw conclusions on a single property of your test object. And even this holds only if all other influencing parameters remain constant.
In your case of partially damaged concrete, you might get a qualitative survey of damaged areas if you perform single-sided impact-echo measurements on a grid covering the complete test range.