## General Mechanical

#### How Ansys calculates Von Mises Stress ?

• HarsihilZLHZ
Subscriber

I am calculating Von Mises stress using Maximum,Middle,Minimum Principal Stress and Shear Stress (i.e. XY, YZ,XZ) (Values from Ansys results)

Ansys shows Von Mises 286.04

• Ashish Khemka
Ansys Employee
nnYou need to use the normal stress component instead of the principal ones.nnRegards,nAshish Khemkan
• HarsihilZLHZ
Subscriber
Using Normal Stress in X (17.303), Y(5.7838), Z(13.458) direction I am getting 288.52 and ANSYS shows 286.04. nWhy is this difference in Answer?nCould you explain me difference between Normal Stresses in X,Y,Z direction and Maximum,Middle,Minimum, Principal Stresses ?.
• Mike Rife
Ansys Employee
The principal stresses have directions such that the shear stresses are zero. Please see this page for a more in depth discussionnnOne thing to watch out for is averaging. That is are the values you are working with the nodal averaged values, or unaveraged? The node will have a value from each element it is connected to. There will be a slight difference if you use the average node values to calculate the VM stress. Versus using the unaveraged values, then find the averaged VM stress for the node and report that.nMiken
• HarsihilZLHZ
Subscriber
I got it.nThanks.n