BISTOP
The BISTOP function models a gap element.
Format
Description
It can be used to model forces acting on a body while moving in the gap between two boundary surfaces, which act as elastic bumpers. The properties of the two boundary surfaces can be tuned as desired.
Arguments
- The expression used for the independent variable. For example, to use the z-displacement of I marker with respect to J marker as resolved in the reference frame of the RM marker as the independent variable, specify as DZ({marker_i.idstring}, {marker_j.idstring}, {marker_rm.idstring}).
- The time derivative of the independent variable. For example, if is specified as above, then will be VZ({marker_i.idstring}, {marker_j. idstring}, {marker_rm.idstring}).
- The lower bound of . If is less than , the bistop function returns a positive value. The value of must be less than the value of .
- The upper bound of . If is greater than , the bistop function returns a negative value. The value of must be greater than the value of .
- The stiffness of the boundary surface interaction. It must be non-negative.
- The exponent of the force deformation characteristic. For a stiffening spring characteristic, must be greater than 1.0 and for a softening spring characteristic, must be less than 1.0. It must always be positive.
- The maximum damping coefficient. It must be non-negative.
- The penetration at which the full damping coefficient is applied. It must be positive.
Definition
Example
<Force_Vector_TwoBody
id = "30101"
type = "ForceOnly"
i_marker_id = "30102031"
j_floating_marker_id = "30101031"
ref_marker_id = "30101010"
fx_expression = "BISTOP(DX(30102030,30101010,30101010),VX(30102030,30101010,30101010),0.5,9.5,10000000,2.1,1,0.001)"
fy_expression = "0"
fz_expression = "0"
/>