Stress equations

Tobi · September 8, 2015, 08:07

Dear all,

does anybody have references to the equations used in the stress solvers?
Thanks in advance,

JonW · September 13, 2015, 12:37

Hi T.
Are you thinking about the sigmaEq = sqrt((3.0/2.0)*magSqr(dev(sigma))) in calculateStress.H ??
I have been thinking about the same thing. The best I have come up with is what is written in the book by Mase (Schaum's Outline of Continuum Mechanics by George Mase). See Equation (8.24), page 182. But that chapter is about "strain hardening rules" (increase in material strength by strain) which I dont think is relevant in the solidDisplacementFoam (Lamé constants of elasticity are constants here, i.e. not dependent on stress). So it would be nice to have another reference to the application of equivalent stress, in which constant elasticity is assumed. I have also just added von Mises (i.e. sqrt(S:S/2)) in to this part and used that. But I dont know how correct that is since I am not a specialist in solid mechanics.

Hope this helps

cheers
J.

Tobi · September 14, 2015, 07:29

Hi, your eqn is correct. Search for elastic Stress and Wikipedia. There are good references.

Kind regards
Tobi

September 8, 2015, 08:07	Stress equations	#1
Tobi Super Moderator Tobias Holzmann Join Date: Oct 2010 Location: Tussenhausen Posts: 2,708 Blog Entries: 6 Rep Power: 51	Dear all, does anybody have references to the equations used in the stress solvers? Thanks in advance, __________________ Keep foaming, Tobias Holzmann

September 14, 2015, 07:29		#3
Tobi Super Moderator Tobias Holzmann Join Date: Oct 2010 Location: Tussenhausen Posts: 2,708 Blog Entries: 6 Rep Power: 51	Hi, your eqn is correct. Search for elastic Stress and Wikipedia. There are good references. Kind regards Tobi __________________ Keep foaming, Tobias Holzmann

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September 13, 2015, 12:37		#2
JonW Senior Member Jon Elvar Wallevik Join Date: Nov 2010 Location: Reykjavik, ICELAND Posts: 103 Rep Power: 19	Hi T. Are you thinking about the sigmaEq = sqrt((3.0/2.0)*magSqr(dev(sigma))) in calculateStress.H ?? I have been thinking about the same thing. The best I have come up with is what is written in the book by Mase (Schaum's Outline of Continuum Mechanics by George Mase). See Equation (8.24), page 182. But that chapter is about "strain hardening rules" (increase in material strength by strain) which I dont think is relevant in the solidDisplacementFoam (Lamé constants of elasticity are constants here, i.e. not dependent on stress). So it would be nice to have another reference to the application of equivalent stress, in which constant elasticity is assumed. I have also just added von Mises (i.e. sqrt(S:S/2)) in to this part and used that. But I dont know how correct that is since I am not a specialist in solid mechanics. Hope this helps cheers J.