Problem with "_ConvertElementPairToBeam"

[LE Ba Danh]

Hello,
I have a problem with PlugIn "_ConvertElementPairToBeam".
In file.inp, I used:
<PlugIn Id="_ConvertElementPairToBeam" MacroYoungModulus="30e9" MacroPoissonRatio="0.2"/> 

It donne:
"Trying to compute automatically the coordination nummber value for automatic calibration
Ok, coordination number value is 6.212205e+00
The related microscopic parameters for E=3.000000e+01 GPa and Nu=2.000000e-01 are:
 - Em=4.250828e+01 GPa (cohesive beam Young's modulus)
 - Rm=9.611339e-01 (cohesive beam radius ratio)"

It compute automatically the coordination number value. With the coordination number value is 6.2, the calibration of microscopic parameters is not exact. How can I fix the coordination number value in this PlugIn  (EX: Cn=10)?
If I use only the PlugIn SetElasticProperty:
    <PlugIn Id="_SetElasticProperty" YoungModulus="30e9" PoissonRatio="0.2" CoordNumber="10.0"/> 
It OK without the PlugIn "_ConvertElementPairToBeam"?

Thank for your help.

Danh

[Damien André]

Hello Dhan,
you can use the granoo-gddutil executable for automatic calibration. For example, you can use as this :

granoo-gddutil --calib --E 60e09 --Nu 0.3 --Cn 8
** Automatic computation of microscopic elastic parameters**
The related microscopic parameters for E=6.000000e+01 GPa, Nu=3.000000e-01 and S=0.000000e+00 MPa are:
 - Em=6.715803e+01 GPa (cohesive beam Young's modulus) 
 - Rm=9.304695e-01 (cohesive beam radius ratio) 
 - Sm=0.000000e+00 MPa (microscopic failure strength for brittle material)Note that the 'Sm' feature is really experimental at this tim

The output of the program gives you autmatically the microscopic parameters values. Then, you can enter these values directly in the _ConvertElementPairToBeam plugin with the YoungModulus and RadiusRatio options.

[LE Ba Danh]

Many thanks Damien.

Danh

[LE Ba Danh]

Hi Damien,
The microscopic parameters change when I change the coordination number value. So, what is the value of coordination number to get a good result of microscopic parameters?

Danh

[Damien André]

Yes it's normal. There is no definitive answer for the coordination number value. The only rule is : if you want a high value of Poisson's ratio you must choose a low value of coordination number close to 6.2.
Common value of coordination number are in the [6.2, 12] range.

Damien.

[LE Ba Danh]

OK, thank my friend.
Danh