How can I get the Parameters for Contact stiffness and contact damping

What are plausible Values for Contact stiffness and Contact damping at a Hydraulic Cylinder. How can I calculate them? Gives it lookup tables for standart Cylinders? I read in a Forum that is your modell instable increas the Hard stop properties. But I think its not the best way to find the parameters with traying.

Answer 1

[Yifeng Tang]

Not sure about the RIGHT way to do this, but here is my two-step approach:

1. set a reasonable stiffness: set up the model to approach the hardstop at a typical hydraulic pressure and speed; play with the contact stiffness so it will stop (or bounce back) within a short distance, say 0.1-1mm. This is to make sure the hard stop spring provides enough stopping force.

2. with the stiffness set, observe the bouncing/oscillation behavior. Adjust the damping so there is very little, if any, oscillatory behavior. Over-damped behavior is OK in my opinion. The value I get is usually much larger than the default 150 N/(m/s).

Of course, this is a behavior-oriented approch with little physical justification. The material & contact property and details on the small-gap near dead-volume are difficult to obtain using first principles. I've found the two-step method above tends to give me good balance between hardstop effectiveness and numerical efficiency and stability.