Can anyone help me how to calculate

[aleks1409979]

Can anyone help me how to calculate von mises stresses in beam elements ( i/m using beam188 in ansys) ? maybe some books or links where i can find ?

von Mises stress = (0.5*((s1-s2)^2+(s2-s3)^2+(s3-s1)^2))^0.5 according to definition, becouse s2 and s3 are 0 von miss=s1=sx is it correct?

regards

 

[lopessilva]

Hello,

s1,s2, and s3 are the main stresses. They depend on the state of stress you have. if you have only axial stress two of them are 0. If you have a plane stress state, you have two of them, and if you have a more complex state, you will have all 3.You can even have more than 3 if the shear stress effects are not negligible. Check on your university library for the book "mechanics of materials", from Beer, Johnston and De wolf. It is applied to structural mechanics. It focus metallic parts, but for what you want to know, it is there. The formula you stated is the Von Mises stress. You should add 6(s12^2 +s23^2 + s31^2)to the formula if you want to apply the formula to a case where shear stresses are not negligible, which is certainly not the case if you are applying only axial loadings

on

http://en.wikipedia.org/wiki/Von_Mises_yield_criterion

,you can see a table with the von mises criterion solved for different load conditions



regards,
Hugo