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. |
Equation
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:
Example
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
