Welcome to Adams/Solver Subroutines - Kxcad.net

Output Arguments
Extended Definition
Welcome to Adams/Solver Subroutines
errflg A logical (true or false) variable that IMPACT returns to the calling
subroutine. If IMPACT detects an error during its calculations, it sets errflg
to true.
vector A double-precision vector of length 3, that returns the values calculated by
the subroutine. The following table indicates the information in vector.
IMPACT models collisions and contact. It evaluates a force that turns on when a distance falls below a
nominal free length (that is, when two parts collide).
The force has two components: a spring or stiffness component and a damping or viscous component.
The stiffness component opposes the penetration. The damping component of the force is a function of
the speed of penetration. The damping opposes the direction of relative motion. To prevent a
discontinuity in the damping force at contact, the damping coefficient is, by definition, a cubic step
function of the penetration. Thus at zero penetration, the damping coefficient is always zero. The
damping coefficient achieves a maximum, cmax, at a user-defined penetration, d.
An object colliding with ground is an example of a system that can be modeled with the IMPACT
function.
Let x be the instantaneous distance, x1 be the free length (when x is less than x1, the force turns on), x1
- x be the penetration, and d be the penetration at which Adams/Solver applies full damping (cmax).
• When x x1, force = 0.
(1)
• When x < x1, force is positive.
vector
returns: For iord values:
(2) 0
• When (x1-d) < x < x1, force is positive; there is damping, but it is less than cmax.
• When x (x1-d), force is positive and damping = cmax.
0 1 2
F( x, x′ )
∂ F( x, x′ )
---------------------
∂ x
∂ F( x, x′ )
---------------------
∂ x′
(3) 0 0 0
∂ 2 F( x, x′ )
∂ x 2
------------------------
∂ 2 F( x, x′ )
------------------------
∂ x′∂ x
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