Learning Forum

[prakhars962]

In material nonlinearity, the yield criteria is used to check whether the stress within an element has exceeded the uniaxial yield stress of the material or not. There are many yield criterions that can be used to approximate the equivalent stress in an element to compare with the uniaxial yield stress.nIs there any way to change the yield criteria in ANSYS mechanical? I have to compare the evolution of plastic zone for a mechanics problem using different yield criterions.n

[1shan]

,nFrom what I understand you want to calculate the stress intensity factor (max equivalent stress/max shear/max tensile to the yield stress), right? You could use the stress tool (RMB>Solution>stress tool), and select the theory to 'max equivalent stress', stress limit type to custom value and insert the yield stress value.nRegards,nIshan. n

[prakhars962]

I know that I can easily get the equivalent von-mises stress. I am talking about the yield criteria. For elastoplastic material, there is an algorithm called the Elastic Predictor and Plastic Corrector that is employed at each iteration for the incremental boundary value problem. In order to initiate the plastic corrector, the algorithm checks for the plastic state using the yield criteria. Here, if I choose von-mises or Tresca both might start the plastic corrector algorithm at different load increment resulting in a difference in the solution near the yield point depending on the yield criteria that I choose.nAnd this is what I am trying to compare for complex structures.nn

[BenjaminStarling]

The yield surface for most plasticity models in APDL is implemented as the von Mises yield criterion. The other yield surface is the hill yield criterion. You cannot choose tresca or any other yield surface unless you delve into defining your own material models (of which I am not experienced in and cannot gaurantee is actually possible).nhttps://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v211/en/ans_prog/Z7K4r1e5lcd.htmlnYou can also head to your install directory to check out examples of subroutines.nC:/Program Files/ANSYS Inc/v202/ansys/customize/usernIt seems as though other codes also operate like thisnhttps://www.sciencedirect.com/science/article/abs/pii/S0308016118305350n