• • Pad A, rich in graphite and low hardness, achieved the lowest friction coefficient and vibration amplitude, demonstrating that lubricating film formation reduces interfacial shear and normal stiffness, critical for suppressing noise in AMC brake systems.
• • Pad B, with highest surface hardness, exhibited high and fluctuating friction coefficient, leading to pronounced vibration and noise; its high hardness increased normal contact stiffness, promoting modal coupling and dynamic instability.
• • Pad C, with least lubricating phase but low hardness, formed stable third-body layers that buffered loads, yielding moderate friction and lowest normal stiffness, effectively attenuating vibration and noise.
• • Numerical simulations confirmed that friction coefficient and normal contact stiffness synergistically regulate system stability; high friction and large stiffness (Pad B) induce modal coupling, while low friction and low stiffness (Pads A and C) enhance stability, guiding material selection for low-noise lightweight brakes.