4.8.2.9. NODAL_FORCE_EXT
This subroutine defines a user - defined nodal force. NODAL_FORCE returns the total nodal force for the defined node set or sheet bodies, whereas the NODAL_FORCE_EXT returns the nodal force for each node belonging to the defined node set. The outputted data is here.
Language type |
Subroutine |
FORTRAN |
nodal_force_ext (ID,TI ME,UPAR,NPAR,IFBODY,NODARR,NONDE,JFLAG,IFLAG,RESULT) |
C/C++ |
nodal_force_ext (int id, double time, double upar[], int npar, int ifbody, int nodarr[], int nonde, int jflag, int iflag, double result[]) |
Variable Name |
Size |
Description |
id |
int |
Nodal Force sequential identification |
time |
double |
Current simulation time of RecurDyn/Solver. |
upar |
double * |
Parameters defined by the user. There is no limit about the maximum size of array. |
npar |
int |
Number of user parameters. |
ifbody |
int |
FFlex body sequential ID. |
nodarr |
int[nonde] |
Node sequential ID array of input node set. |
nonde |
int |
Number of nodes of a node set |
jflag |
int |
When RecurDyn/Solver evaluates the Jacobian, the flag is true. Otherwise, the flag is false. |
iflag |
int |
When RecurDyn/Solver makes its initial call to this routine, the flag is true. Otherwise, the flag is false. |
result |
double[no nde*6] |
Nodal forces. Acting point of the nodal force is each center of each node. Reference frame of each force vector must be the ground inertia marker. |
Example
This subroutine returns an air resistance force to a sheet as nodal force.
Figure 4.113 Air resistance model
Note
If the user wants to run this model using a user subroutine, the user can refer it in the directory (<install dir>\Help\usub\**).
C---- SUB. NODAL_FORCE_EXT
SUBROUTINE NODAL_FORCE_EXT
& (ID,TIME,UPAR,NPAR,IFBODY,NODARR,NONDE,
& JFLAG,IFLAG,RESULT)
C---- TO EXPORT * SUBROUTINE
!DEC$ ATTRIBUTES DLLEXPORT,C::NODAL_FORCE_EXT
C---- INCLUDE SYSTEM CALL
INCLUDE 'SYSCAL.F'
C---- DEFINE VARIABLES
C Parameter Information
C ID : Nodal Force sequential identification. (Input)
C TIME : Simulation time of RD/Solver. (Input)
C UPAR : Parameters defined by user. (Input)
C NPAR : Number of user parameters. (Input)
C IFBODY : FFLEX Body sequential ID. (Input)
C NODARR : Node sequential ID array of input node set. (Input)
C NONDE : Number of node of node set. (Input)
C JFLAG : When RD/Solver evaluates a Jacobian, the flag is true. (Input)
C IFLAG : When RD/Solver initializes arrays, the flag is true. (Input)
C RESULT : Returned nodal force vector. Acting point of the nodal force is each center of each node.
C Reference frame of each force vector must be Ground.InertiaMarker. (Output, Size : nonde * 6)
DOUBLE PRECISION TIME, UPAR(*)
INTEGER ID, NPAR, IFBODY, NODARR(*), NONDE
LOGICAL JFLAG, IFLAG
DOUBLE PRECISION RESULT(*)
C---- USER STATEMENT
c local variable
integer i,j,nodeid,errflg
double precision Area, Cd, rho
double precision vn(3), vn_mag, ucf, scale
integer MKID(2), nMK
Cd = upar(1)
rho = upar(2)
scale = upar(3)
call rd_ucf(ucf)
MKID(1) = 0
MKID(2) = 0
nMK = 0
do i=1, nonde
call get_fflex_nodetvel(ifbody,nodarr(i),MKID,nMK,vn,errflg)
vn_mag = dsqrt(vn(1)**2+vn(2)**2+vn(3)**2)
call get_fflex_nodeid(ifbody,nodarr(i),nodeid,errflg)
if( nodeid .eq. 10000 .or. nodeid .eq. 10001) then
Area = 100
else if (nodeid .ge. 20000 .and. nodeid .lt. 30000) then
Area = 200
else Area = 400
endif
do j=1, 3
if(vn_mag .eq. 0.0d0) then
result((i-1)*6+j) = 0.0d0
else
result((i-1)*6+j)=-1.0d0/2.0d0*Cd*rho*vn_mag*vn_mag*Area
& *(vn(j)/vn_mag) ! direction
& /ucf ! making force unit
& *scale ! an amplifier
endif
enddo
enddo
RETURN
END
#include "stdafx.h"
#include "DllFunc.h"
#include "stdlib.h"
#include "math.h"
NodalForceExt_API void __cdecl nodal_force_ext
(int id, double time, double upar[], int npar, int ifbody, int nodarr[], int nonde, int jflag, int iflag, double result[])
{
using namespace rd_syscall;
// Parameter Information
// id : Nodal Force sequential identification. (Input)
// time : Simulation time of RD/Solver. (Input)
// upar : Parameters defined by user. (Input)
// npar : Number of user parameters. (Input)
// ifbody : FFLEX Body sequential ID. (Input)
// nodarr : Node sequential ID array of input node set. (Input)
// nonde : Number of node of node set. (Input)
// jflag : When RD/Solver evaluates a Jacobian, the flag is true. (Input)
// iflag : When RD/Solver initializes arrays, the flag is true. (Input)
// result : Returned nodal force vector. Acting point of the nodal force is each center of each node.
// Reference frame of each force vector must be Ground.InertiaMarker . (Output, Size : nonde * 6)
// User Statement
int i, j, nodeid,errflg;
double Area, Cd, rho;
double vn[3], vn_mag, ucf, scale;
WCHAR NodeName[256];
char strNodeName[256];
if (iflag) {
for(i=0;i<nonde;i++){
get_fflex_nodestringname(ifbody,nodarr[i],(TCHAR*)NodeName,&errflg);
wcstombs(strNodeName,NodeName,256); // Wide-byte character --> Multibyte character
printmsg("========================",(int)strlen("==================="));
printmsg(strNodeName,(int)strlen(strNodeName));
printmsg("========================",(int)strlen("==================="));
}
}
Cd = upar[0];
rho = upar[1];
scale = upar[2];
rd_ucf(&ucf);
for(i=0;i<nonde;i++){
// Set velocity vector of node
get_fflex_nodetvel(ifbody,nodarr[i],NULL,0,vn,&errflg);
vn_mag = sqrt(pow(vn[0],2)+pow(vn[1],2)+pow(vn[2],2));
get_fflex_nodeid(ifbody,nodarr[i],&nodeid,&errflg);
if (nodeid == 10000 || nodeid == 10001)
{
Area = 100;
}
else if (nodeid >= 20000 && nodeid < 30000)
{
Area = 200;
}
else
Area = 400;
for(j=0;j<3;j++){
if (vn_mag == 0.0)
result[i*6+j] = 0.0;
else
result[i*6+j] = -1.0/2.0*Cd*rho*vn_mag*vn_mag*Area
*(vn[j]/vn_mag) // Set negative direction of the nodal velocity
/ucf // Making force unit
*scale; //
result[i*6+j+3] = 0.0;
}
}
}