If a mass-spring system has Coulomb friction on the surface rather than viscous friction, its equation of motion is where is the coefficient of

If a mass-spring system has Coulomb friction on the surface rather than viscous friction, its equation of motion is

 

where µ is the coefficient of friction. Develop a Simulink model for the case where m = 1kg, k = 5 N/m, µ = 0.4, and g = 9.8 m/s². Run the simulation for two cases:

(a) The applied force f (t) is a step function with a magnitude of 10 N

(b) The applied force is sinusoidal: f(t) = 10 sin 2.5t. Either the Sign block in the Math Operations library or the Coulomb and Viscous Friction block in the Discontinuities library can be used, but since there is no viscous friction in this problem, the Sign block is easier to use.

-ky + f(t)- umg if > 0 -ky + f(t) + umg if