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Subject: Re: High tech shock absorber dreams
From: Neon John (johngd_at_bellsouth.net)
Date: 2003-09-25


I haven't seen the commercial but I am familiar with the technology. The
materials are all of a class called high hysterises polymers. That is,
materials with high internal friction (damping) such that the energy of
deflection is dissipated as heat instead of being restored to the impacting
body on rebound. The extreme opposite of a high hysteresis material is the
common superball which uses a silicone rubber with practically no internal
friction.

At the top of the heap is probably Sorbathane. This is a rubber-like material
that has practically no rebound. It is popularly used in athletic shoe
inserts to absorb some of the pounding energy delivered to the foot during
running. It is also popular amongst vinyl enthusiasts as padding for
turntables and records. It is very effective at absorbing even low frequency
vibration.

The major disadvantage is that it is very easy to tear, having little tensile
strength. It would be much too fragile for bumpers, though it would work well
as internal shock mounts for the hard drive. To be used as a bumper material
it would have to be encased in something tougher which would make it
expensive.

The basic problem here, as with most every mass produced consumer good, is
cost. Using the rule of thumb that every dollar involved in production
reflects 4 dollars at retail, adding even a few dollars' worth of added bumper
material would raise the cost of the end unit considerably. Archos (or their
Chicom surrogates) had to make the tradeoff between the cost of shock
absorption and cost. None of us probably agrees with that point but given
that we alpha geeks are only a small part of the market....

John

On Thu, 25 Sep 2003 12:49:49 -0500, LoveLearn <LoveLearn_at_iw.net> wrote:

>Archos products have four deformable plastic wrap-around corner bumpers
>apparently present for mechanical impact protection. I'm sure they
>increase impact measurements necessary to damage both spinning hard
>drives and comparatively less elastic outer cases. While their
>appearance causes a few negative aesthetic opinions, even Archos seems
>quiet about their shock protecting capabilities. That makes me think
>their design and material selection were never optimized.
>
>I'm sure lots of us have seen TV demonstrations showing an egg dropped
>onto a hard surface and breaking, then another egg dropped from the same
>height onto a little blob of super shock absorbing material lying on
>that same surface without breaking.

---
John De Armond
johngdDONTYOUDARE_at_bellsouth.net
http://bellsouthpwp.net/j/o/johngd/
Cleveland, Occupied TN



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