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how to set our own stress limit like chosing ultimate tensile in thermal stress analysis?

Question asked by sri mad on Mar 23, 2011
Latest reply on Mar 23, 2011 by Bill McEachern

i am performing thermal stress analysis of ceramic tube and i would like to apply von-mises stress criterion to set my own stress limit, as it is said below in solidworks help.




The maximum von Mises stress criterion is based on the von Mises-Hencky theory, also known as the Shear-energy theory or the Maximum distortion energy theory.

In terms of the principal stresses s1, s2, and s3, the von Mises stress is expressed as:

svonMises  = {[(s1 - s2)2 + (s2 - s3)2 + (s1 - s3)2]/2}(1/2)

The theory states that a ductile material starts to yield at a location when the von Mises stress becomes equal to the stress limit. In most cases, the yield strength is used as the stress limit. However, the software allows you to use the ultimate tensile or set your own stress limit.

svonMises ≥ slimit

Yield strength is a temperature-dependent property. This specified value of the yield strength should consider the temperature of the component. The factor of safety at a location is calculated from:

Factor of Safety (FOS) = slimit / svonMises

Pure Shear

In the case of pure shear t, von Mises stress can be expressed as: svonMises = (3)1/2 t

Failure occurs if: tmax = 0.577 syield