The BISTOP(x,x',x1,x2,k,e,cmax,d) function models a gap element.
Use the bistop function to calculate force for the motion of a component within a gap, such as a ball rebounding between two walls, or a slider that moves within a slot.
Format
BISTOP(x,x',x1,x2,k,e,cmax,d)
Arguments
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x
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The independent variable. For a force calculation, define a displacement result to specify the x argument.
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x'
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The derivative of the independent variable. For a force calculation, define a velocity result to specify the x' argument.
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x1
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The lower bound of the independent variable. For a force calculation, the force is positive if x < x1.
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x2
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The upper bound of the independent variable, greater than x1. For a force calculation, the force is negative if x > x2.
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k
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A nonnegative value. For a force calculation, k is the stiffness of the boundary surface interaction.
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e
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A positive value. For a force calculation, e is the exponent of the force deformation characteristic. For a stiffening spring, enter e > 1.0. For a softening spring, enter 0 < e < 1.0.
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cmax
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A nonnegative variable. For a force calculation, cmax is the maximum damping coefficient.
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d
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A positive real variable. For a force calculation, d is the boundary penetration at which the maximum damping cmax is applied.
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Function Definition
BISTOP(x,x',x1,x2,k,e,cmax,d) =
max(k*(x1-x)e-STEP(x,x1-d,cmax,x1,0)*x',0)
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x < x1
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0
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x1 ≤ x ≤ x2
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min(-k*(x-x2)e-STEP(x,x2,0,x2+d,cmax)*x',0)
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x > x2
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