[ExI] classic material fail

[spike at rainier66.com]

The engineering types among us will recognize the classic material failure
mode in the image below.

 

I installed shelves in my house about 25 years ago.  The top shelf was
grossly overloaded (and I knew it (but hoped for the best.))

 

Yesterday it failed catastrophically, bringing down the shelf which took out
the shelf below it.

 

This is the primary failure mode, a classic stress concentration serial
fail: metal close to its yield strength will have its covalent bonds give up
one after another until one day BOOM.

 

The metal thickness is about 1.5 mm and length of rupture about 6 mm.  Just
for fun I calculated how many covalent bonds were giving up per second.  I
calculated about half a million failed bonds per second, day and night for
most of my adult life.

 

Since the other side (not visible in this image) also had a similar failure,
I could say a million covalent bonds broke every second for a quarter of a
century.

 

 



 

spike

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.extropy.org/pipermail/extropy-chat/attachments/20200628/23af77b3/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.jpg
Type: image/jpeg
Size: 17234 bytes
Desc: not available
URL: <http://lists.extropy.org/pipermail/extropy-chat/attachments/20200628/23af77b3/attachment.jpg>