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Tetsuo Yamaguchi Last modified date:2018.07.02

Associate Professor / Machine elements and design engineering laboratory
Department of Mechanical Engineering
Faculty of Engineering


Graduate School
Undergraduate School
Other Organization


E-Mail
Homepage
http://www.mech.kyushu-u.ac.jp/~design/
Machine Elements and Design Engineering Laboratory, Kyushu University .
http://www.mech.kyushu-u.ac.jp/~design/index_e_tyama.html
Personal Website .
Phone
092-802-3072
Fax
092-802-3074
Academic Degree
ph. D
Country of degree conferring institution (Overseas)
No
Field of Specialization
Soft matter physics, statistical physics, experimental seismology
Total Priod of education and research career in the foreign country
01years00months
Outline Activities
I have been working on interfacial and dynamical properties of soft visco-elastic solids, such as adhesion of soft rubber and sliding friction of gels. I have been also interested in fracture of network-like materials and mechanical meta-materials.
Research
Research Interests
  • Interfacial mechanics in soft matter (adhesion & friction)
    Laboratory experiment of earthquake phenomena
    High-precision prediction of catastrophic mechanical phenomena
    Topology and toughening of network-like materials
    Intersonic sliding contact
    keyword : adhesion, friction, tribology, fracture, earthquake, stick-slip, gel, pressure sensitive adhesives, topology, mechanical metamaterial, toughening, intersonic, catastrophic mechanical phenomena
    2004.10~2019.03.
Current and Past Project
  • In this study, we investigate the relationship between topology and toughening of network-like structures, and develop new type tough materials.
  • Our objectives of this study are to understand the mechanisms for transient mechanical responses like scuffing or running-in processes.
  • Recently, a new type of earthquake, called slow earthquake, has been discovered due to the development of new observation techniques like GPS. In this project, we have been studying slow earthquakes to understand the basic mechanisms based on geophysical or physical approaches.
  • In order to understand the basic mechanisms of earthquake occurrence, we develop laboratory models. We try to elucidate the details by performing In-situ visualization during the processes.
  • By mimicking ultra-low friction and wear articular cartilages, we develop hydrogel-based artificial articular cartilages.
Academic Activities
Books
1. Les Mousses Structure et Dynamique.
2. Tetsuo Yamaguchi, David Dillard, Special Testing, Springer, Vol.1, pp.533 - 549, 2011.01, 接着・粘着・シールなどの用途における特殊な試験方法について解説を行なった..
Papers
1. Tomohiko G. Sano, Tetsuo Yamaguchi, Hirofumi Wada, Slip Morphology of Elastic Strips on Frictional Rigid Substrates, Physical Review Letters, 10.1103/PhysRevLett.118.178001, 118, 17, 2017.04, 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 the 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 the 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..
2. Tetsuo Yamaguchi, Yoshinori Sawae, Shmuel M. Rubinstein, Effects of loading angles on stick–slip dynamics of soft sliders, Extreme Mechanics Letters, 10.1016/j.eml.2016.09.008, 9, 331-335, 2016.12, When soft gels move across a hard surface, stick–slip frictional sliding is mediated by propagation of adhesion and detachment fronts. Here we experimentally investigate the sliding dynamics of an extended frictional interface between soft Silicone gel and hard PMMA and identify three distinct sliding regimes. We directly visualize the interface and show that a minute manipulation of the initial loading angle results in a sharp bifurcation between the different sliding states. The phase diagram as well as universal scaling relations governing the dynamics is presented..
3. Tetsuo Yamaguchi, Yoshimi Tanaka, Risa Shimazaki, Solvent effects on fracture of chemically crosslinked gels, Soft Matter, 10.1039/C6SM01645F, 12, 8135-8142, 2016.10, We have investigated how the fracture behavior of a polyacrylamide hydrogel is affected by different types of solvents poured into its crack tips. We obtained the following results: first, when water (good solvent or reaction solvent for the polyacrylamide gel) is poured, the fracture energy Gamma becomes smaller than that measured in air for small crack velocities. Second, when good solvents other than water are poured, Gamma is enhanced for a large V region, but this effect is not observed for smaller V; Gamma(V) in good solvents converges to that in water as V approaches 0. Third, when ethanol (poor solvent for polyacrylamide) is poured, stick–slip-like crack propagation appears in the entire V range, and Gamma calculated from the time-average of the oscillating tearing forces is larger than that in air or in other solvents. We discuss the results on the basis of diffusion dynamics around the crack tips of the gel..
4. Tetsuo Yamaguchi, Hiroyuki Muroo, Yutaka Sumino, Masao Doi, Asymmetry-symmetry transition of double-sided adhesive tapes, Physical Review E, 10.1103/PhysRevE.85.061802, 85, 061802-1-6, 2012.06, We report on the debonding process of a double-sided adhesive tape sandwiched between two glass plates.
When the glass plates are separated from each other at a constant rate, a highly asymmetric extension of top and
bottom adhesive layers and bending of the inner film are observed first. As the separation proceeds, the elongation
of both layers becomes symmetric, and the inner film becomes flat again. When this happens, there appears a
local maximum in the force-displacement curve. We explain this asymmetry-symmetry transition and discuss
the role of the bimodal force-displacement relation of each adhesive layer.We also discuss the effect of the inner
film thickness and the separation rate on the debonding behavior, which causes undesirable early detachment of
the double-sided adhesive tape in a certain condition..
5. Tetsuo Yamaguchi, Masatoshi Morishita, Masao Doi, Takane Hori, Hide Sakaguchi, Jean-Paul Ampuero, Gutenberg-Richter’s law in sliding friction of gels, Journal of Geophysical Research, Solid Earth, 10.1029/2011JB008415, 116, B12306-1-8, 2011.12, We report on experimental studies of spatio-temporally heterogeneous stick-slip
motions in the sliding friction between a hard polymethyl methacrylate (PMMA, plexiglass)
block and a soft poly-dimethyl siloxane (PDMS, silicone) gel plate. We perform
experiments on two PDMS gels with different viscoelastic properties. For the less viscous
gel, large and rapid events are preceded by an alternation of active and less active periods.
For the more viscous gel, successive slow slip events take place continuously. The
probability distributions of the force drop, a quantity analogous to seismic moment, obey a
power law similar to Gutenberg-Richter’s empirical law for the frequency-size statistics of
earthquakes, and the exponents of the power law vary with the plate velocity and the
viscosity of the gel. We propose a simple model to explain the dependence of the power law
exponent on the plate velocity, which agrees with experimental results..
6. Tetsuo Yamaguchi, Satoshi Ohmata, Masao Doi, Regular to chaotic transition of stick-slip motion in sliding friction of an adhesive gel-sheet, Journal of Physics: Condensed Matter, 10.1088/0953-8984/21/20/205105, 21, 205105-1-7, 2009.04, Spatio-temporal pattern of the stick–slip motion of a gel-sheet pulled on a glass substrate is observed. The sliding takes place via the propagation of the wave of detachment (Schallamach wave). At large pull velocity, the detached region is a stripe which moves regularly with constant speed and the frictional force shows a periodic time dependence. As the pull velocity is decreased, the detached region is separated into bubbles which move around irregularly. In the irregular state, the frictional force shows chaotic time dependence and the statistics of the event of the force drop obeys a power law similar to the Gutenberg–Richter law known in
earthquakes. In the regular region, the detachment wave is analyzed theoretically and the velocity and lengths are obtained as a function of the pull velocity. The transition from the regular to chaotic behavior is shown to be related to the spontaneous wetting of the gel..
Presentations
1. Tetsuo Yamaguchi, Effects of electric fields on sliding friction of hydrogels, IUMRS-ICA2014, 2014.08, Frictional properties of hydrogels have attracted much attention due to its low friction. In particular, friction coefficient of polyelectrolyte hydrogels can be as small as 0.001. In this talk, we report our studies on friction of polyelectrolyte hydrogels and electric field effects, i.e., 1) friction control of polyelectrolyte hydrogels using electric fields and 2) preparation of polyelectrolyte hydrogels under electric fields. Through the discussions, we will point out the importance of electric charges for reduction or control in friction of hydrogels..
2. Tetsuo Yamaguchi, Sliding friction of sticky gels, Gordon Research Conference on Tribology, 2014.07, When a soft and sticky gel is slid against a smooth surface, stick-slip motion does not occur grobally but in a localized manner.
As slip regions propagate, they move randomly: they start to move and arrest suddenly, coalesce with each other, break into several parts, or even wander around the frictional interface in backward direction. Furthermore, the slip size statistics follows the power law, like Gutenberg-Richter law for earthquakes. In this talk, we discuss why and how such complexity emerges during friction through the in-situ visualization of frictional stresses. .
3. Tetsuo Yamaguchi, Sliding friction of polymer gels: from slippery to sticky surfaces, Joint Symposium of ISPMS'12 & OUMS'12, 2012.11, In this presentation, we introduce our two different topics discussing low friction and high friction in polymer gels. The first topic is the effects of stress-diffusion coupling (“biphasic lubrication” in biomechanics society) in sliding friction of PVA (poly-vinyl alcohol) hydrogels, where frictional behavior is dominated by transient diffusive process of water. In the second part, we discuss spatio-temporally heterogeneous stick-slip motions in sliding friction of adhesive gel-sheets. The system shows formation of the inchworm-like detachment waves (Schallamach waves) in the frictional interface and exhibits regular-chaos transition of the detachment wave patterns, dependent on the driving velocity. Through these two examples, we will stress the importance of coarse-grained or mesoscopic description on frictional properties for polymer gels..
4. Tetsuo Yamaguchi, Non-linear Mechanics in Debonding of Pressure-Sensitive Adhesives, The Adhesion Society Annual Meeting, 2013.03, We report on the debonding process of a double-sided adhesive tape sandwiched between two glass plates as an example showing the importance of non-linear mechanics in pressure-sensitive adhesives. .
5. Tetsuo Yamaguchi, Sliding friction of sticky gel-sheets, The Adhesion Society Annual Meeting, 2013.03, We report our recent results on the image analyses of the spatio-temporal patterns of the stick-slip motions. .
Membership in Academic Society
  • American Geophysical Union
  • Japanese Society of Tribologists
  • The Adhesion Society of Japan
  • The Japan Society of Mechanical Engineers
  • The Seismological Society of Japan
  • The physical society of Japan
Awards
  • Best Presentation Award was awarded in the Malaysian International Tribology Conference, held in Penang Island, Malaysia.
  • He has been working on experimental and theoretical studies on adhesion phenomena based on his original view points.
Educational
Educational Activities
I have been giving lectures for 5 courses to undergraduate students and 2 courses (including Soft Matter Engineering) to graduate students.