Linear acceleration is one thing. Acceleration combined with random 
vibration or shock is different. Electronics in a grenade can withstand 
150,000 G's (we make such) but same parts can crash at random vibration at 
1000 G's. Sounds crazy?
/Inge

----- Original Message ----- 
From: "Chris Mahanna" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, December 16, 2009 9:30 PM
Subject: Re: [TN] Tensile strrength


The mechanical test guys look for centrifugal force damage by "constant 
acceleration testing" and they use the unit of G.  The velocity vector 
changes equal amounts over equal time periods.  10,000Gs is not terribly 
uncommon.  For "larger" SMTs you better have class 3 fillets!

Chris

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Louis Hart
Sent: Wednesday, December 16, 2009 2:42 PM
To: [log in to unmask]
Subject: Re: [TN] Tensile strrength

Ahne, Technetters, keep in mind Newton's second law. If something is being 
accelerated, it is experiencing a force. If it is not being accelerated, 
there is no net force.

A force is required to keep an object moving in a circle, or ellipse (as the 
Earth in its orbit), since the object's velocity is changing and it is 
accelerating, constantly. After the part is ripped off, the only force it 
experiences is that of gravity so it will be accelerated toward the center 
of mass of the Earth.

A while back I read something by some philosopher, something like 'Newton's 
theory of motion is the greatest intellectual achievement in human history'.

Einstein's General Theory of Relativity connecting gravitational mass with 
the mass in Newton's second law must be way up on the list of intellectual 
achievements, but I haven't gotten a good grasp of it. Any Technetters who 
can help me understand it, please let me know offline.

Louis Hart

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ahne Oosterhof
Sent: Wednesday, December 16, 2009 12:37 PM
To: [log in to unmask]
Subject: Re: [TN] Tensile strrength

And I expected to see "force", not "acceleration".
(The acceleration comes after the force has ripped the part off the board.)


Having fun,
Ahne

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Thayer, Wayne - IIW
Sent: Tuesday, 15 December, 2009 17:10
To: [log in to unmask]
Subject: Re: [TN] Tensile strrength

Just to add a number to this, I get over 9000G's of acceleration on the 
parts near the ends of this board!

Wayne Thayer

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