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Two-sided Impact (BISTOP)

Returns a real number for a force magnitude corresponding to a two-sided collision, using a compression-only nonlinear spring-damper formulation.

Format

BISTOP (Displacement Variable, Velocity Variable, Low Trigger for Displacement Variable, High Trigger for Displacement Variable, Stiffness Coefficient, Stiffness Force Exponent, Damping Coefficient, Damping Ramp-up Distance)

Arguments

 

Displacement Variable	A measure of the distance between colliding bodies; defined by a run-time displacement function.
Velocity Variable	A measure of the time derivative of the distance between colliding bodies; defined by a run-time velocity function.
Low Trigger for Displacement Value	Lower value for independent variable at which to trigger the first side of two-sided impact.
High Trigger for Displacement Value	Higher value for independent variable at which to trigger the second side of two-sided impact.
Stiffness Coefficient or K	Stiffness coefficient for spring force; defined by a real number, a run-time function, a design-time function, a design variable or an expression.
Stiffness Force Exponent	Exponent for nonlinear spring force; defined by a real number, a run-time function, a design-time function, a design variable or an expression.
Damping Coefficient or C	Damping coefficient for damper force; defined by a real number, a run-time function, a design-time function, a design variable or an expression.
Damping Ramp-up Distance	Distance over which to gradually turn on damping once impact is triggered; defined by a real number, a run-time function, a design-time function, a design variable or an expression.

symbol

The BISTOP function turns a force on and off depending on the value of the independent variable q, as follows:

Mathematically, BISTOP is calculated as follows:

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You can use the BISTOP function for the system shown in the figure below:

BISTOP(DX(marker_1, marker_2, marker_2),VX(marker_1, marker_2, marker_2, marker_2),5.2, 22.4, 100, 1.2, 2.5, 0.005)where 22.4 was derived from 5.2 + 28.7 - 11.5.

BISTOP Example

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