How to decide the stiffness and damping values in the Spatial contact forces block in Simscape (multibody dynamics)?

I am modelling a multibody dynamics model of a crane using simscape multibody. To model contact between the metallic plate and ground (concrete or sand), I am using the spatial contact force block. I am unable to decide the values of parameters of this block like stiffness, damping, etc. I referred to some examples of simscape multibody(like forklift, humanoid robot, etc), but there is no justification for these values. It would be great if someone can suggest to me how to find these values with some references like scientific papers, books, etc. Please refer to the pictures for a better understanding. Thanks in advance.

Spatial contact forces

Answer 1

[cindy lemoine]

Think of the spatial contact as a spring.

Imagine having two flat plates attached to each end of a spring that is compressed together such that the plates surfaces slightly overlap by some distance z say .1 in or 2.5mm

The weight of the top plate is 5 pounds or 22 N The stiffness k can be calculated using hooks law K=F/z=22/0.0025=8800

Now…without damping if you were to t let the spring go the plates would bounce up and down

You can control this motion or velocity with the damping coefficient

D=F/v. Let’s say you really did not want the plates to move when the spring is released so make the velocity very small. D=22/0.005m/s=4400.

The above example would basically represent the contact force between the two plates and how they move in relation to each other

Hope this helps. You can literally model the scenario I described with two solid block cubes and a prismatic joint to control the distance between the blocks and let gravity act on the top block/plate as an experiment to get a feel for the spatial contact block

[cindy lemoine]

I forgot to mention that the force from the weight of the block would represent the normal force in the spatial contact block

[Jnanashekar Prakash Reddy]

Hello Cindy, thanks for your explanation.

[cindy lemoine]

your welcome

[cindy lemoine]

I am having issues with the spatial contact block. Frictional force is not changing when i change the coefficient of firction