[MBDyn-users] Constitutive law for a chain

masarati at aero.polimi.it masarati at aero.polimi.it
Fri May 9 15:11:50 CEST 2008


> Dear Dr. Masarati,
>
> thank you for all your help.
>
> You could rather try something like
>
> set: real eps_min = -1;
> set: real f_min = 0.;
> set: real eps_max = 1.;
> set: real f_max = 1.e9;
>
> scalar function:
>  "k_step_fun", multilinear,
>   -eps_min, f_min,
>   0., f_min,
>   eps_max, f_max;
> Shouldn't it read: eps_min, f_min, above?

Yes, sorry for the typo.

> I haven't figured out a way to have scalar functions with prestrain.
> It results in a request for a semicolon in line n+1, if a definition
> is used like the one below (I'm still using mbdyn-1.3.1-Alpha - maybe
> that's the reason).
>
> constitutive law:
>      cl_rod,
>      1,
>      scalar function elastic,
>      "k_step_fun",                            <-Line n
>      prestrain,
>      single,
>      parabolic,
>      0.,
>      0.,
>      -0.2;

Can't check right now, sorry.  Probably, something in the parsing of
either the constitutive law or the scalar function is screwed.  I'll let
you know and eventually fix it, if possible.  I suggest using the "nlsf
elastic" function, which is a bit more flexible (I didn't even recall the
existence of the "scalar function elastic" constitutive law).  The syntax,
in your case, would be something like

constitutive law:
     cl_rod,
     1,
     nlsf elastic,
     0.,               # linear part
     "k_step_fun",
     prestrain,
     single,
     parabolic,
     0.,
     0.,
     -0.2;

For a glance of the formulas, please have a look at
<http://www.aero.polimi.it/~masarati/MBDyn-input/manual-HEAD/node19.html#SECTION006927000000000000000>

Hope it works.

Cheers, p.






More information about the Mbdyn-users mailing list