Structured ridges orchestrate squeaks at soft–rigid interfaces
Using high-speed imaging and acoustic analysis, the study shows that squeaking at soft–rigid interfaces is governed by opening slip pulses that travel near the soft material’s shear wave speed; on flat samples these pulses produce irregular, broadband noise, but introducing a thin surface ridge confines pulse propagation and yields a uniform, one-dimensional pulse train with a squeak at the first shear mode frequency, revealing a structure-driven mechanism to stabilize rupture across bimaterial contacts.