This are the equations given to convert the new spring model to a classic mass, stiffness, damping model.
mass = 1
stiffness = (2π ÷ duration)^2
damping = 1 - 4π × bounce ÷ duration, bounce ≥ 0
4π ÷ (duration + 4π × bounce), bounce < 0
The damping equation is wrong.
This is what I worked out from playing with the spring model:
The cleanest relation is to express the dampingRation (friction ÷ (2 × sqrt (stiffness × mass)))
dampingRatio = 1 - bounce, bounce ≥ 0
dampingRatio = 1 ÷ ( 1 + bounce), bounce < 0
Then the damping becomes
damping = ((1 - bounce) × 4π) ÷ duration, bounce ≥ 0
damping = 4π ÷ (duration × (1 + bounce)), bounce < 0