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Squeaking at soft–rigid frictional interfaces

Article

Published: 25 February 2026

Squeaking at soft–rigid frictional interfaces

Adel Djellouli

orcid.org/0000-0001-9565-75711 na1,

Gabriele Albertini2 na1,
Jackson Wilt1,
Vincent Tournat

orcid.org/0000-0003-4497-57423,

David Weitz

orcid.org/0000-0001-6678-52081,

Shmuel Rubinstein

orcid.org/0000-0002-2897-25791,4 &

…
Katia Bertoldi

orcid.org/0000-0002-5787-48631

Nature

650, 891–897 (2026)Cite this article

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Subjects

Applied physics
Mechanical engineering

Abstract

Squeaking is a constant companion in various aspects of our daily lives, whether we slide rubber-soled shoes across hardwood floors1, scrape chalk on a blackboard2, engage the brakes on a bicycle3 or walk with a hip replacement4,5. When two rigid bodies slide over each other, squeaking is widely understood to result from self-excited stick–slip oscillations, triggered by a decrease in the friction coefficient with increasing slip velocity6,7,8,9,10. However, sliding of extended interfaces can involve crack or slip-pulse propagation11,12,13,14,15,16,17,18,19,20,21. This distinction is amplified when a soft body slides on a rigid one, in which large deformations and material mismatch can cause detachment by opening slip pulses22,23,24,25,26,27. Previous studies focused mainly on slow sliding17,26,28,29,30,31,32,33,34, in which pulses are slow and squeaking is absent. Although squeaking at soft–rigid interfaces has been linked to stick–slip oscillations35,36,37, the mechanisms remain unclear. Here we experimentally investigate soft–rigid interfaces sliding at velocities that produce squeaking. High-speed imaging and acoustic analysis show that opening pulses propagate at approximately the shear wave speed of the soft material, mediating local slip across diverse materials. In flat samples, these pulses are irregular and generate broadband acoustic emissions. Introducing thin surface ridges confines pulse propagation, yielding a consistent repetition frequency matching the first shear mode of the sliding block and squeaking at that frequency. These findings show a structure-driven mechanism that stabilizes rupture in bimaterial friction. Geometric confinement suppresses competing modes, transforming irregular two-dimensional dynamics into coherent one-dimensional pulse trains, offering new insights into frictional rupture from engineered surfaces to geological faults.

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Fig. 1: Squeaking of basketball shoes.

Fig. 2: Squeaking of flat and patterned elastomer cuboid samples.

Fig. 3: Cuboid samples featuring a single ridge.

Fig. 4: The height of the samples controls the frequency of squeaking.

Fig. 5: Squeaking across materials.

Squeaking at soft–rigid frictional interfaces