Div.2 - Stress Intensity vs. Von Mises

[rmartin00]

Just curious why Div. 2 is based on stress intensity (as opposed to Von Mises stress). I believe the max shear stress theory (basis for SI) is more conservative than the distortion energy theory (basis for VM). Is it just "history" that SI was chosen, or is there a technical reason. Thanks in advance.

 

[LSThill]

rmartin00 (Mechanical)
This may lead to a nother question:

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The Pressure Vessel Research Council (PVRC), a key source of new design and fabrication technology for over fifty years, is offering a unique 2-1/2 day conference to present new and practical information on fatigue of structures and welded components. Leaders in the field will provide you with problem-avoiding solutions for design, life assessment and other practical matters that will help you improve equipment reliability.
The Master S-N Curve Approach was developed and will be explained by Pingsha Dong of Battelle Memorial Institute. The Master S-N Curve is based on a structural stress parameter rather than a hot spot or nominal stress, providing far superior correlation with performance of weldments. The resulting fatigue analysis procedures can be used for life estimation for structures containing welded joints under a wide range of loading conditions. The method is general and can be used with other cumulative damage theories. Statistical analysis can be used to establish the design fatigue curve and structural reliability methods, i.e. probabilistic analysis can also be used in the design process.
Additional topics to be covered include:
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[jte]

Rumor (ok, well founded discussion) has it that the new Div. 2 will be based on Von Mises instead of Stress Intensities.

jt

 

[TGS4]

Stress intensities were originally used when Div. 2 was first developed because the math was easier. However, the point that you make about the von Mises stress is correct, and I can confirm jte's rumour thta the new Div. 2 will use the equivalent stress method (von Mises).