# Yield And Von Mises Stress
When a material is loaded the stress experienced by the material can be considered as two components a mean hydrostatic stress and a deviatoric stress.
The mean stress is defined as
The deviarotic stress is often represented by the von Mises stress is
Yield depends on the type of material and the material model which represents the behaviour of that material. For the most commonly used structural materials, steel is not sensitive to pressure or mean hydrostatic stress while for concrete failure depends on the mean hydrostatic stress
For a material like steel the normal yeild condition is when
The yield and ultimate stress and the hardening parameters are not used in linear analysis. For non-linear analysis in GSA, only the yield stress is used and ultimate stress and hardening parameters are ignored.
In general, material yielding follows the line defined by the hardening
modulus. Either isotropic hardening
If the hardening parameter,
For material like concrete a more advance material yield condition is required.