maixmum principal stress greater than von mises stress
maixmum principal stress greater than von mises stress
(OP)
hello,
I ran my static analysis on curved beam subjected to bending loads and found that the maximum principal stress is greater than the vonimises stress at a particular node.Both the stresses below the yield st. Can any one explain what accounted for this differnce.
meher.
I ran my static analysis on curved beam subjected to bending loads and found that the maximum principal stress is greater than the vonimises stress at a particular node.Both the stresses below the yield st. Can any one explain what accounted for this differnce.
meher.





RE: maixmum principal stress greater than von mises stress
That is perfectly acceptable. If the 3 principal stresses are S1, S2 and S3, the von Mises stress
Sv = sqrt( (S1-S2)^2 + (S1-S3)^3 + (S2-S3)^2 )/sqrt(2).
So, the principal stresses can be greater than the von Mises stress. Consider, for example, S1=S2=S3=1000. The von Mises stress in that case is 0!!
Nagi
RE: maixmum principal stress greater than von mises stress
Note that high stress triaxiality is associated with low ductility behavior, and some codes (e.g. Section VIII, Div 2, Appendix 4) specify limits on the sum of the principal stresses.
RE: maixmum principal stress greater than von mises stress
Meher, what was the value of the maximum principal stress, the v.Mises stresses and the other 2 principal stresses? They should satisfy the equation I stated earlier.