The default failure criteria for ANSYS is Von Mises however

The default failure criteria for ANSYS is Von Mises, however you have been asked to complete a FEA on a brittle material, what failure criteria would be more appropriate and why? How would you apply this criterion if there is no option for it within the program?

Solution

For brittle material, maximum principal stress theory is used over von - mises stress theory. It is so because unlike ductile materials brittle materials do not have plastic deformation and their primary mode of failure is due to high principal stresses rather than shear stresses.

For applying maximum principal theory, one can simply note down from the FEA results the maximum value of pricnipal stress occuring the material and compare it to the yield strength to find whether failure is occuring or not.