[78-L] RCA Victor reverse side "spider web" etching name?

[Eric Jacobs]

On Wed, 2009-01-07 at 15:43 -1000, Malcolm Rockwell wrote:
> Okay, then how about possible added structural integrity? Wouldn't a 
> disc with a design be less apt to break than one with a plain, flat side?

On Wednesday, January 07, 2009 8:43 PM, Michael Shoshani wrote:
> I would think just the opposite. The disc will be narrower in thickness
> where the groove is, so if the disc suffers any shear stress at all,
> that will be its weakest point.

Michael is absolutely correct - such designs create a point of stress
concentration.  In civil and mechanical engineering, this is 
characterized by "notch factor", a number which increases the 
calculated stress (and hence reduces the strength) at the point of
the pattern.

Eric Jacobs
The Audio Archive, Inc.