Torsion Test Simulation: Understanding Von Mises Criteria and Its Approximations

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SUMMARY

This discussion focuses on the simulation of torsion tests using the Von Mises criteria for equivalent tensile stress and strain. The user, Vishal, reports a 6-8% variation in results when comparing torsion test outcomes to uniaxial tension and compression tests. He notes that the equivalent tensile stress is calculated as shear stress multiplied by the square root of 3, and equivalent tensile strain as shear strain divided by the square root of 3. Vishal concludes that torsion equivalent stresses are approximately 6.5% lower than those derived from uniaxial tension, suggesting the Bishop-Hill formulation provides a more accurate assessment.

PREREQUISITES
  • Understanding of Von Mises criteria in material mechanics
  • Familiarity with torsion testing methodologies
  • Knowledge of equivalent stress and strain calculations
  • Experience with tension and compression test simulations
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  • Research the Bishop-Hill formulation for torsion testing accuracy
  • Explore advanced material behavior models beyond Von Mises criteria
  • Learn about the impact of shear strain on material properties
  • Investigate experimental validation techniques for torsion test simulations
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Mechanical engineers, materials scientists, and researchers involved in material testing and simulation, particularly those focusing on torsion and stress analysis.

svishal03
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Hi all,

I am simulating torsion tests (after being successful with tension and compression tests). For tension and compression, I got a good comparsion with experimental and behaviour in tension is same as in compression (of course leaving the necking part).

For torsion tests, I have taken equivalent tensile stress = shear stress*sqrt(3) and equivalent tensile strain as = shear strain / sqrt (3).

This is based on Von Mises criteria.

But I have a problem, doing this I find that there is a variation of about 6-8 % from the uniaxial tension test and compression test . IS there some approxiamtion in Von Mises criteria of equivalent tensile stress and strain?

I tried to google and more and this what I found:


http://books.google.co.in/books?id=...orsion test equivalent tensile strain&f=false



From this ; am I correct below (you can read the abstractabove as well):

“Torsion equivalent stresses obtained using Von Misesrelationship (as I have done) are 6.5% lower than those obtained using BishopHill formulation which is more accurate”

So, can we say that torsion equivalent stresses will bearound 6.5% less than that obtained using uniaxial tension ?

Warm regards,

Vishal
 
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Please can anyone help?
 

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