Subroutine Type

Utility/General

Definition

Models a contact force or collision phenomena.

Use

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

Calling Syntax

Fortran

CALL IMPACT(X, XD, X1, K, E, CMAX, D, IORD, VALUE, ERRFLG)

C

c_impact(x, xd, x1, k, e, cmax, d, iord, value, errflg)

Python

[value, errflg] = py_impact(x, xd, x1, k, e, cmax, d, irod)

MATLAB

[value, errflg] = m_impact(x, xd, x1, k, e, cmax, d, irod)

Input Arguments

X [double precision]

The independent variable.  For example, to specify time as the independent variable, specify X as TIME.

XD [double precision]

The time derivative of the independent variable.

X1 [double precision]

The lower bound of X.  If Xis less than X1, the IMPACT function returns a positive value; otherwise it returns zero.

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, Emust 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]

The order of the derivative that IMPACT has to return.  Order can be 0, 1 or 2.

Output Values

Value [integer]

A value that the subroutine returns.

Errflg [logical]

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