I am referring the code IS : 15592 : 2005 and it is claimed that it is identical with ISO 8608 : 1995 ‘Mechanical vibration — Road surface profiles — Reporting of measured data’.
The road profiles are classified A-H according the degree of roughness which is the PSD G(n) m^3/cycle at reference frequency no = 1/(2*pi) cycle/m or in circular units G(w) m^3/rad and reference frequency wo = 1 rad/m.
The relation between the two PSDs is: G(n) = 2*pi*G(w) = 6.28*G(w).
Now referring to the attached sheet it, the degree of roughness are expressed in both the units which is not confirming to the above relation, the relation seems to be G(n) = 16*G(w). This confusion is also seen in many standard journal papers.
Which one is correct Table C.2 a) or b)?
Is anyone have the original ISO 8608 code?
One is measuring the amplitude and one the frequency - both are tied together by the laws of physics. Both are needed - although this is qute crude.
This issue is explained for example in my paper (stored at RG)
"Simulated road profiles according to ISO 8608 in vehicle vibration analysis" (10.1520/JTE20140493) in Journal of Testing and Evaluation.
Both Table C.2 a) or b) are correct.
Following conversion relationship holds between Gd(Ω0) and Gd(n0)
Gd(Ω0) (m3/rad) = Gd(n0)/2π (m3/cycles) (3)
For two alternative reference spatial frequencies, Ω0 = 1 rad/m and n0 = 0.1 cycles/m, the following conversion for w = 2 holds
Gd(n0) = 2πGd(Ω0)[Ω0/(2πn0)]w = 15.91Gd(Ω0) ~ 16Gd(Ω0)
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