Subroutine Type

Modeling

Definition

Used to compute a custom modal damping ratio for a flexible body.

Use

Flexible Body using the damping ration computed in a DMPSUB:

<Body_Flexible

    id                  = "30103"

    lprf_id             = "63330103"

    h3d_file            = "../qa_depot/h3d/beam.h3d"

    is_user_damp        = "TRUE"

    usrsub_param_string = "USER(30102020,30101010)"

    usrsub_dll_name     = "NULL"

    flexdata_id         = "30102"

    v_ic_x              = "0."

    v_ic_y              = "0."

    v_ic_z              = "0."

    w_ic_x              = "0."

    w_ic_y              = "0."

    w_ic_z              = "0."

    v_ic_x_flag         = "FALSE"

    v_ic_y_flag         = "FALSE"

    v_ic_z_flag         = "FALSE"

    w_ic_flag           = "FALSE">

 </Body_Flexible>

Calling Syntax

Fortran

SUBROUTINE DMPSUB (ID, TIME, PAR, NPAR, FREQ, NMODE, H, CRATIOS)

C

void STDCALL DMPSUB (int *ID, double *time, double *par, int *npar, double *freq, double *nmode, double *h, double *cratios)

Python

def DMPSUB(id, time, par, npar, freq, nmode, h):

    return cratios

MATLAB

function cratios = DMPSUB(id, time, par, npar, freq, nmode, h)

Input Arguments

[integer] ID

The flexible body identifier.

[double precision] TIME

The current simulation time.

[double precision] PAR

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

[integer] NPAR

The number of entries in the PAR array.

[double precision] FREQ

The array of natural frequencies.

[double precision] NMODE

The number of modes associated with the flexible body.

[double precision] H

The integrator step size.

Output Values

[double precision] CRATIOS

The vector output value of dimension NMODE that contains the damping ratios as a fraction of critical damping.

Example

def DMPSUB(id, time, par, npar, freq, nmode, h):

    cratios = nmode*[0.0]

    [nq, errflg] = py_nmodes(id)

    if nq<=30:

        [mode, xfreq, errflg] = py_modinf(id)

    for i in xrange(nmode):

        if freq[i] < par[1]:

            cratios[i] = par[0]

        elif freq[i] < par[3]:

            cratios[i] = par[2]

        else:

            cratios[i] = par[4]

        return cratios