yade-users team mailing list archive

[Dominik Boemer <question253045@xxxxxxxxxxxxxxxxxxxxx>]

New question #253045 on Yade:
https://answers.launchpad.net/yade/+question/253045

Hi everyone,

I have been reading the reference paper [Pournin2001] of the constitutive law "Law2_ScGeom_ViscElPhys_Basic".  I have two questions about it:

1.  In equation (22) [Pournin2001], cn and ct should have similar expressions as these are the solutions of similar differential equations with similar conditions.  Thus, there seems to be missing a factor 2 in the expression of ct.  Is that right?  If yes, has the eventual bug been fixed?

2. In the documentation (Release 2014-08-08.git-b1621bc, August 10, 2014) on page 457, some formulas are given for the conversion between en, et and tc, and kn, kt, cn in order to replace the deprecated function "yade._utils.getViscoelasticFromSpheresInteraction".  These formulas should be the simplified version of equation (22) in [Pournin2001] for spherical bodies.  This is why, 1/mref = 1/m + 1/m.  Thus, mref = m/2.  Furthermore, I1 = I2 = I = 2/5mr^2.  If these variables are replaced in equation (22)[Pournin2001], I get:

kn = m/(2*tc^2) * (pi^2 + ln(en)^2)
cn = -m/tc * ln(en)
kt = m/(7*tc^2) * (pi^2 + ln(et)^2)
cn = -m/(7*tc) * ln(en)

These expression are different from those given in the documentation (p. 457).  Which version is correct?  And where does the error come from?

Thank you in advance,
Dominik

-- 
You received this question notification because you are a member of
yade-users, which is an answer contact for Yade.