Funny you should mention that ...
I'm dong that right now.
I have an excel spreadsheet that does it for
the Pattern Effect of round holes for S.E.
I would direct you to "Noise Reduction Techniques
in Electronic Systems" by Henry Ott. I'm using
his 1976 Edition although there is a 2nd Edition.
In my book page 167, the following formula is used:
SE = 20log[ (c^2*l)/d^3 ] + 32(t/d) + 3.8 dB
where c = center to center hole dimension
d = hole diamter
t = length of the hole
l = squareroot(l1 * l2) where l1 and l2
are the length of sides of a rectangular
array of holes.
All dimensions are in inches.
----------
> From: POWELL, DOUG <[email protected]>
> To: [email protected]
> Subject: Perforated Metals
> Date: Thursday, October 30, 1997 5:00 AM
>
>
> Hello group,
>
> Some years ago I had a copy of a design guide for perforated metals and
how
> to calculate attenuation factors at various frequencies. This guide
> included information on different types of metal, thickness, lamination
and
> hole size/pattern.
>
> I am able to locate websites that address airflow issues and effective
> cross-section but not emissions.
>
> Can anyone point me in the right direction?
>
> Doug Powell
> Compliance Engineer
> Advanced Energy Industries, Inc.
