Infinite loop simulating a mass-spring-friction system (Simulink)

Hello folks,

Here's the deal. I'm trying to simulate a horizontal mass-spring system with friction, on simulink. As the Friction force changes direction depending on the velocity direction, I used a Sign block to extract the signal from the velocity function and multiply by the Friction coefficient and the Normal force. But, as I connect it to the whole system, it cannot simulate and gets trapped in a infinite loop. It works if I reverse the signal of the friction force, as you can see in the screenshots below. But I need it to be negative in the sum block.

To simulate, I used m = k = u = Fext = 1.

[MatlabYGuser]

Hi, did you solve it?