Von Mises and Tresca SCL Results

What you are seeing is normal.

• Generally using the von Mises criterion overestimates burst pressure and provides an upper bound. (in other words, has lower stress)
• Generally the Tresca criterion underestimates burst pressure and provides a lower bound. (gives stresses that are higher than reality)

This can be seen by the fundamental definitions of the two criteria:

Tresca:

von Mises:

where σ₀ is the yield strength in tension.

Which leads to the yield criterion of failure :

Tresca: (σ₁-σ₃)/σ₀ = 1

von Mises: (σ₁-σ₃)/σ₀ = 2/[√(3+μ²]

where μ is the Lode stress parameter = (2σ₂-σ₁-σ₃)/(σ₁-σ₃)

You are welcome, here is a simple example/derivation:

Which is in agreement with the failure map of the two theories: