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fURTHER on equivalent stress

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From: Christopher Wright P.E.   
> The question on how to convert a given, multiaxial
> state of stress to the equivalent uniaxial one is quite old.
I'll quibble with this a little bit--you're not converting anything
using the von Mises equivalent stress. What you're doing is applying a
failure criterion based on a theory of failure. There are a number of
them, each based on the supposition that failure occurs when some
quantity, maximum principal stress, maximum shear, the strain energy,
what ever, reaches a limiting value. The von Mises criterion for
failure is based on strain energy of distortion. All this stuff comes
from sophomore strength of materials, which shows how the various
criteria provide a combined value to be compared with the material
yield strength obtained from a uniaxial test.
 
 
REPLY
 
If you admit the idea is to present the multiaxial stressing in terms
of uniaxial one, that could be caled converting, unless there is a better term.
 
I agree with you, in general.
With one minor correction: Huber-Mises formulas are about yielding,
although engineers often extrapolate them to failure.
 
The difference is pronounced for such materials like a mild steel.
(May sound like splitting hair unless you do work on extreme loads)

Sincerely, Gregory