IMPACT
The IMPACT function models impact forces acting on bodies during collision. The elastic properties of the boundary surface between the two bodies can be tuned as desired.
Format
Arguments
- 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 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 impact function returns a positive value, otherwise it returns zero.
- 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
<Reference_Variable
id = "30300700"
type = "EXPRESSION"
expr = "IMPACT(DZ(10301030,30302030),
VZ(10301030,30302030),2.5,2500,1,1000,2.5)"
/>
OR
<Force_Vector_TwoBody
id = "10501"
type = "ForceOnly"
i_marker_id = "10515721"
j_floating_marker_id = "10516722"
ref_marker_id = "10516720"
fx_expression = "0"
fy_expression = "0"
fz_expression = "IMPACT(DZ(10515720,10516720,10515720),
VZ(10515720,10516720,10515720),1,10000.0,1.0,0.5,0.1)"
/>