|Tetsuo Yamaguchi||Last modified date：2020.01.29|
Associate Professor / Machine elements and design engineering laboratory
Department of Mechanical Engineering
Faculty of Engineering
Department of Mechanical Engineering
Faculty of Engineering
Machine Elements and Design Engineering Laboratory, Kyushu University .
Personal Website .
Country of degree conferring institution (Overseas)
Field of Specialization
Soft matter physics, statistical physics, experimental seismology
Total Priod of education and research career in the foreign country
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 also been interested in fracture of network-like materials and mechanical meta-materials.
Research InterestsMembership in Academic Society
- Large deformation behavior of mechanical metamaterials
keyword : mechanical metamaterial, large deformation, buckling, fracture, non-affin deformation
- Topology and toughening of sparse elastic networks
keyword : network-like material, topology, fracture, toughening
- Studies on intersonic sliding friction
keyword : friction, contact, intersonic, subsonic, fracture
- Laboratory experiments of earthquakes
keyword : Earthquake, experiment, visualization
- Interfacial mechanics in soft matter (adhesion & friction)
keyword : adhesion, friction, tribology, fracture, gel, pressure sensitive adhesives
- 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.
|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..|
|1.||Tetsuo Yamaguchi, Sliding friction of polymer gels at various sliding speeds
, Okinawa Colloids, 2019.11, Polymer gels are sparsely cross-linked polymers with a large amount of solvent. When polymer gels are slid against their counterparts, the system exhibits a variety of frictional behavior, depending on the combination between the materials and the sliding conditions. In this talk, we will focus on the sliding speed dependence on the frictional behavior. We will firstly give an overview of the sliding mechanisms for polymer gels, and then will introduce several results at various sliding speeds, from 10-6 to 10 m/s. In such a wide range, the dominant mechanisms switch from molecular adsorption, diffusion-mechanical coupling, hydrodynamics to inertia, and the targets are spanning from laboratory experiments of giant earthquakes, articular cartilage in hip or knee joints, to high-speed braking of Formula-1 car. Throughout these topics, we will stress the importance of “softness” of polymer gels in sliding friction..
|2.||Tetsuo Yamaguchi, Yudai Onoue, Yoshinori Sawae, Fracture of Model Polymer Networks, The 7th Pacific Rim Conference on Rheology, 2018.06, [URL], Toughening of crosslinked polymers like rubbers or gels is one of the most important problems in polymer science. While novel types of tough gels have been developed in the last decade, the toughening mechanism is not well understood: for example, it is not still so clear whether heterogeneous structures enhance the fracture toughness or weaken the system. In this study, we focus on geometrical aspects of crosslinked polymers (how the molecular weight distributions of partial chains affect toughness) as well as topological ones (how the spatial structure of connectivity between crosslinking points controls toughness). We created macroscopic crosslinked polymers made of rubber strings and connecters, and performed fracture experiments of such model polymers with various degrees of molecular weight variations and different topological structures. We found that small degrees of heterogeneity of molecular weight contribute to weakening while large variations to slowing down of crack propagation and significant toughening. We also found that small change in network topology results in great improvement in toughness due to weakening of stress concentrations. In our talk, we will explain the details of our experiments and discuss the results by comparing with numerical simulations. .|
|3.||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..|
|4.||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. .
|5.||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..|
|6.||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. .|
|7.||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. .|
- 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
- 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.