arXiv subjects

Tetsuo Yamaguchi

Publications and source records attributed to Tetsuo Yamaguchi.

4 recordsLinked to original sources

arXiv2025

Anomalous Enhancement of Yield Strength due to Static Friction

Friction is fundamental to mechanical stability across scales, from geological faults and architectural structures to granular materials and animal feet. We study the mechanical stability of a minimal friction-stabilized structure composed of three cylindrical particles arranged in a triangular stack on a floor under gravity. We analyze the yield force, defined as the threshold compressive force applied quasi-statically from above at which the structure collapses due to sliding at the floor contact. Using singular perturbation analysis, we derive an expression which quantitatively predicts the yield force as a function of the static friction coefficient and a small dimensionless parameter $\epsilon$ characterizing elastic deformation.

cond-mat.soft↗

arXiv2022

Spatio-temporal chaos of one-dimensional thin elastic layer with the rate-and-state friction law

Independent of specific local features, global spatio-temporal structures in diverse phenomena around bifurcation points are described by the complex Ginzburg-Landau equation (CGLE) derived using the reductive perturbation method, which includes prediction of spatio-temporal chaos. The generality in the CGLE scheme includes oscillatory instability in slip behavior between stable and unstable regimes. Such slip transitions accompanying spatio-temporal chaos is expected for frictional interfaces of a thin elastic layer made of soft solids, such as rubber or gel, where especially chaotic behavior may be easily discovered due to their compliance. Slow earthquakes observed in the aseismic-to-seismogenic transition zone along a subducting plate are also potential candidates. This article focuses on the common properties of slip oscillatory instability from the viewpoint of a CGLE approach by introducing a drastically simplified model of an elastic body with a thin layer, whose local expression in space and time allows us to employ conventional reduction methods. Special attention is paid to incorporate a rate-and-state friction law supported by microscopic mechanisms beyond the Coulomb friction law. We discuss similarities and discrepancies in the oscillatory instability observed or predicted in soft matter or a slow earthquake.

nlin.AO↗

arXiv2020

On/off switching of adhesion in gecko-inspired adhesives

In this study, the adhesion-detachment behaviour of a gecko-inspired adhesive pad was investigated to understand the on/off switching mechanisms of adhesion in gecko feet. A macroscopic spatula model was fabricated using silicone rubber, and adhesion tests combining lateral sliding and vertical debonding were conducted. It was observed that the contact state and the adhesion force of the pad vary considerably with the direction of lateral sliding prior to debonding, and that the pad achieves adhesion during debonding even when it loses contact due to excess lateral sliding. These results explain the mechanisms behind the on/off switching and stable adhesion of gecko feet, and suggest the possibility of developing new-generation adhesives capable of switchable adhesion.

cond-mat.soft↗

arXiv2017

Slip Morphology of Elastic Strips on Frictional Rigid Substrates

The morphology of an elastic strip subject to vertical compressive stress on a frictional rigid substrate is investigated by a combination of theory and experiment. We find a rich variety of morphologies, which -when the bending elasticity dominates over the effect of gravity- are classified into three distinct types of states: pinned, partially slipped, and completely slipped, depending on the magnitude of the vertical strain and coefficient of static friction. We develop a theory of elastica under mixed clamped-hinged boundary conditions combined with the Coulomb-Amontons friction law, and find excellent quantitative agreement with simulations and controlled physical experiments. We also discuss the effect of gravity in order to bridge the difference in qualitative behaviors of stiff strips and flexible strings, or ropes. Our study thus complements recent work on elastic rope coiling, and takes a significant step towards establishing a unified understanding of how a thin elastic object interacts vertically with a solid surface.

cond-mat.soft↗