yadeusers team mailing list archive

yadeusers team

Mailing list archive

Message #17662
Re: [Question #670047]: Determining macro parameters in uniaxial compression
Question #670047 on Yade changed:
https://answers.launchpad.net/yade/+question/670047
Status: Open => Answered
Jan Stránský proposed the following answer:
> I see there are 6 components for stress and strain so I guess they
represent
stress tensor has 3 normal components (11,22,33) and 3 shear components (23,31,12) [1]
Strain is deformation conterparts. 3 normal strain (stretching along 3 axes) and 3 shear strains (skewing in 3 planes)
Shear parts are not important for this stuff, so you can just take the first 3 rows and first 3 columns of the matrix stress=stiffness*strain laws
Than s11,s22,s33 are stresses along x,y,z axes and e11,e22,e33 are "stretch ratios" (Delta L)/L along x,y,z axes
> but how could I get e22 and e33
this is just theoretical point how Poisson's ratio is defined, as a
lateral strain in uniaxial stress load. How to compute it in DEM is the
tricky part*. We avoid it using a different simulation (uniaxial
strain** of triaxial loading) evaluating one more elastic constant (e.g.
bulk mudulus).
*: see my comments in #1
**:
uniaxial stress = one stress is nonzero and the lateral stresses are zero > all normal strain are in general nonzero
uniaxial strain = one strain is nonzero and the lateral strains are zero > all normal stresses are in general nonzero
concerning changing stresses and strain, in the elastic regime the
stresses and strains are changing, but not independently, e.g. for
uniaxial stress, s11=E*e11, in general
stressTensor=stiffnessMatrix*strainTensor
Jan
[1] https://en.wikipedia.org/wiki/Cauchy_stress_tensor
PS: I will give short answers, do not hesitate to ask what you do not
understand. We can also change to personal communication..

You received this question notification because your team yadeusers is
an answer contact for Yade.