Static and Coulomb friction coefficient vector

I'm now using the disc brake block form Simulink, and I want to know how to set the Static and Coulomb friction coefficient vector about the block. I only know the mean value of static friction coefficient and I want to know how to chang it into vector form, and how to get the Coulomb friction coefficient.

Answer 1

[Abhijeet]

Hi,

Given the value of static friction, it is not possible to obtain the static friction coefficient vector and Coulomb friction coefficient with certaininty.

However, we can assume the values for the static friction coefficient. However we can not precisely determine its exact values as it may vary in different directions of the contact plane.

You can get the estimated value of static friction coefficient by using the formula:

μ_s = μ_s * [1 1 1]

For example if the mean value of static friction coefficient is 0.3 then the static friction coefficient vector will be: μ_s = [0.3 0.3 0.3]

The Coulomb friction coefficient is the ratio between the maximum force of friction required to maintain that motion and the normal force between the two surfaces. The Coulomb friction coefficient can be estimated to be the same as the static friction coefficient, assuming that the block is already in motion with a constant speed. However, if the block's speed changes, the frictional force required may no longer be proportional to the normal force, and the Coulomb friction coefficient may change.

Thanks

[yanshu]

Can I simply think the friction coefficient vector as friction coefficient value of three axis to the disc?