Subroutine Type

Modeling

Definition

Used to extract rigid body contact results.

Use

This subroutine can be used to extract rigid body contact results from a MotionSolve simulation which can then be used to generate an output file or process the results programmatically.

<Force_Contact

    id                  = "303001"

    ...

    cpost_dll_name      = "my_contact_post_sub"

    cpost_param_string  = "USER(1000) "

    cpost_fnc_name      = "CONTACTPOST"

/>

Calling Syntax

Fortran

SUBROUTINE CONTACTPOST (ID, I_GRA_ID, J_GRA_ID, TIME, PAR, NPAR, IFLAG, ENDFLG)

C

void STDCALL CONTACTPOST (int *id, int *i_gra_id, int *j_gra_id, double *time, double *par, int *npar, int *iflag, int *endflg)

Python

def CONTACTPOST(id, i_gra_id, j_gra_id, time, par, npar, iflag, endflg):

Input Arguments

[integer] ID

The ID of the contact force modeling element (Force_Contact in XML) for which the results are desired.

This argument is automatically populated and passed in by MotionSolve.

[integer] I_GRA_ID

The ID of the I body’s graphic representation.

This argument is automatically populated and passed in by MotionSolve.

[integer] J_GRA_ID

The ID of the J body’s graphic representation.

This argument is automatically populated and passed in by MotionSolve.

[double] TIME

The current simulation time.

This argument is automatically populated and passed in by MotionSolve.

[double] PAR

An array that contains the constant arguments from the list provided in the user-defined statement. 

This argument is defined by the user in the model.

[integer] NPAR

The number of entries in the PAR array.

This argument is automatically populated and passed in by MotionSolve based on the size of the PAR array.

[integer] IFLAG

The initialization flag. See Comment 3 for more details.

[integer] ENDFLG

The end flag. See Comment 3 for more details.

Output Values

None.

Comments

Further, if the I and/or J bodies defined in the contact statement refer to more than one graphics, the CONTACTPOST is called for each combination of the I graphic (I_GRA_ID) and the J graphic (J_GRA_ID).

Example

The following example retrieves the penetration depth and total force at each time step for a simulation that models rigid body contact:

<Force_Contact

    id                  = "303001"

    label               = "Contact 0"

    num_i_graphics      = "1"

    i_graphics_id       = "90001"

    num_j_graphics      = "1"

    j_graphics_id       = "90000"

    cnf_type            = "Impact"

    stiffness           = "1000."

    exponent            = "1.2"

    damping             = "1."

    dmax                = "0.01"

    cff_type            = "Coulomb_Off"

    cpost_dll_name      = "my_contact_post_sub"

    cpost_param_string  = "USER()"

    cpost_fnc_name      = "CONTACTPOST"

/>

The contents of CONTACTPOST in my_contact_post_sub are:

void STDCALL CONTACTPOST (int *id, int *i_gra_id, int *j_gra_id, double *time, double *par, int *npar, int *iflag, int *endflg)

{

/*

Input argument

----------------------------------------------------------

 id    Identifier of calling CONTACT statement

 i_gra_id Identifier of calling I_GRAPHIC

 j_gra_id Identifier of calling J_GRAPHIC

 time  Time of contact

 par   Array containing passed parameters

 npar  Number of passed parameters

*/

  int nof_contacts;

  bool errflg;

   c_get_ncontacts(*id, *i_gra_id, *j_gra_id, &nof_contacts, &errflg);

  int ipar[4] = {30102020, 0, 0, 0};

  double states[6];

  int nstates;

  int ierr;

   c_sysary("tdisp", ipar, 1, states, &nstates, &ierr);

   printf(" I gra %d - J gra %d  time : %f  nof %d \n", *i_gra_id, *j_gra_id, *time, nof_contacts);

  for (int i=0; i<nof_contacts; i++)

  {

      double pd;

      double f[3];

      int n_results;

       c_get_contact_post(*id, *i_gra_id, *j_gra_id, "PD", i, &pd, &n_results, &errflg);

       c_get_contact_post(*id, *i_gra_id, *j_gra_id, "TOTAL_FORCE", i, f, &n_results, &errflg);

       printf(" %d PD = %f, F=[%f %f %f] z = %f \n", i, pd, f[0], f[1], f[2], states[2]);

   }

}