Who use FWD?
By maggiemoon
@maggiemoon (486)
China
December 28, 2007 2:59am CST
FWD(falling weight deflectometer) is a device for pavement detection and evaluation,which is my major about.Is here any expert study on it.
My problem is that FWD has 9 sensors for example,how can I deduce the corresponding relationship of the sensors and the each lay modulous.
I mean it's known that the further sensors is the token of roadbed's modulous,and I may make use of it as a known quantity and get a reverse deduce of the other pavement layer modulous.But how it works?is there any method help me to explore it?
1 response
@theprogamer (10532)
• United States
28 Dec 07
I actually don't know much on it. The reverse calculation is from the dynamic response of the pavement to the impulse load
I found this calculation, I hope its it. Its been awhile.
D0 = maximum deflection generated by dual tyre of a standard 8.2 ton axle.
D200 = deflection measured 200 mm from the point maximum deflection was generated (using the direction of travel).
Both deflections are used to determine the curvature function (CF):
CF = D0 - D200
So if you have the curvature function itself and you have the amount of deflection in question, you can just find the maximum deflection from there.
This website has information and even a program for reverse calculations
http://www.airporttech.tc.faa.gov/pavement/28ndt.asp
It would also be wise to further research this. Also ask classmates and/or the professor.
@maggiemoon (486)
• China
29 Dec 07
Thank you very much .I'll get it right away.And happy Christmas and happy new year!
