daranguiz - those stress models are not appropriate for many many materials. The OP provided no information to suggest that they would be OK to use. What do you think could happen if he or she used VM or Tresca for some sort of concrete or structural glass design? Think and then think again before you post.
"It is imperative Cunth doesn't get his hands on those codes."
hsemus- another thing is that in a lot of applications, allowable stress is specified by some code, and that same code says or implies how that stress is to be calculated as well.