Subroutine Type

Utility/General

Definition

Evaluates a BISTOP function (gap element).

Use

This function can be called by any user-defined subroutine.

Calling Syntax

Fortran

CALL BISTOP (X, XD, X1, X2, K, E, CMAX, D, IORD, VECTOR, ERRFLG)

C

c_bistop(x, xd, x1, x2, k, e, cmax, d, iord, vector, errflg)

Python

[vector, errflg] = py_bistop(x, xd, x1, x2, k, e, cmax, d, iord)

MATLAB

[vector, errflg] = m_bistop(x, xd, x1, x2, k, e, cmax, d, iord)

Input Arguments

X [double precision]

A variable that specifies the deformation to be used to compute the force.

XD [double precison]

The first time derivative of X.

X1 [double precision]

The lower bound value of X.  If X is less than X1, the BISTOP function returns a positive value.  The value of X1 must be less than the value of X2.

X2 [double precision]

The upper bound value of X. If X is greater than X2, the BISTOP function returns a negative value. The value of X2 must be greater than the value of X1.

K [double precision]

The stiffness of the boundary surface interaction.  It must be non-negative.

E [double precision]

The exponent of the force deformation characteristic.  For a stiffening spring characteristic, E must be greater than 1.0.  For a softening spring characteristic, E must be less than 1.0.  It must always be positive.

CMAX [double precision]

The maximum damping coefficient.  It must be non-negative.

D [double precision]

The penetration at which the full damping coefficient is applied.  It must be positive.

IORD [integer]

A variable that specifies the order of the derivative that BISTOP returns.  It can be 0, 1 or 2.

Output Values

VECTOR [double precision]

It returns the value calculated by the subroutine.

ERRFLG [logical]

A logical (true or false) variable that BISTOP returns to the calling subroutine.  If BISTOP detects an error while calling the subroutine, it sets the error flag to true.