Brake pedal simulator, master cylinder for a vehicle and method of operation of said simulator

The simulator has a resistant unit with a friction unit acting between a simulation piston (32) and a fixed part (34). The friction unit is controlled by an electronic unit having a ring-shaped magnetostrictive component (46). The component contacts in friction with the surface (48) of the part (34) delimiting a chamber (36) in which the piston slides. The component is deformed in radial direction under magnetic field effect. Independent claims are also included for the following: (A) a master-cylinder for a brake of a motor vehicle (B) a method for controlling a brake actuation simulator.