Authorship：Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)

DOI： 10.2208/jscejj.22-15009

Kyutacar

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)

DOI： 10.2208/jscejseee.78.3_480

Kyutacar

Language：English   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)

In July 2020, the Kyushu region experienced record-breaking heavy rains from July 4 to7, causing extreme floods in the Kuma and Chikugo Rivers. This was followed by atmospheric instability over a wide area from western Japan to the Tohoku region, resulting in heavy rainfall on July 13-14 in the Chugoku region, and on July 27-28 in the Tohoku region. There was also flooding of large rivers including the Go River and the Mogami River. In recent years, record-breaking torrential rainfall disasters have been occurring every year. The heavy precipitation scale has been increasing in space and time as well as in rainfall intensity, resulting in spatio-temporal expansion of the damage. Furthermore, in 2020, the disaster occurred amidst the restriction of social activities due to the COVID-19 pandemic. The compilation and dissemination of disaster survey data and lessons are essential for the sustainable development of society. Therefore, JSCE has planned a special issue on the July 2020 torrential rain disaster to share and disseminate disaster information and to contribute to the advancement of technology and science related to disaster prevention and mitigation.

DOI： 10.2208/JOURNALOFJSCE.10.1_545

Kyutacar

Scopus

Other Link： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85148295769&origin=inward

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)

Japan   Tokyo   2019.11.09  -  2019.11.11

Authorship：Last author   Language：English   Publishing type：Research paper (international conference proceedings)

Japan   Tokyo   2019.11.09  -  2019.11.11

Language：English   Publishing type：Research paper (scientific journal)

DOI： 10.1002/nag.2711

Kyutacar

Other Link： https://www.scopus.com/pages/publications/85026375110?origin=resultslist

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)

Japan   Sapporo   2013.09.11  -  2013.09.13

Some kinds of element test are generally conducted in order to evaluate mechanical characteristics of structural members that have complex microstructures such as steel and concrete composite beams. However, the element test with a part of the structural member can not faithfully reconstruct deformation state in actual structures. To that end, we formulate a beam with averaged mechanical properties in order to evaluate mechanical properties of Timoshenko beams with microstructures.

Other Link： https://www.scopus.com/pages/publications/84905248341

Language：English   Publishing type：Research paper (international conference proceedings)

Japan   Sapporo   2013.09.11  -  2013.09.13

For better design and construction of steel-concrete hybrid structures, it is important to evaluate the strength and behavior of their joints: e.g. headed studs. However, the contribution of the adhesion and friction along the steel-concrete interface are ignored in such mechanical joints. We here try to propose a new torque shear test system by which the shear strength of the friction and adhesion can be evaluated appropriately. The test specimen has a cylindrical interface in mortar block, and it becomes the interface subjected to the torque shear loading. The results showed that cracks initiated on the side of the specimen were due to the boundary conditions rather than strength of steel-mortar interface and they should be prevented, and the maximum shear stress and residual shear stress were insensitive to the additional reaction force on the steel cylinder of the torque shear test system.

Other Link： https://www.scopus.com/pages/publications/84905216507

Language：English   Publishing type：Research paper (scientific journal)

A modification of the Mori–Tanaka method is proposed to evaluate the average elastoplastic behavior of composites and polycrystals in a virtual matrix. The virtual matrix is an elastic material in which real matrix material and inhomogeneities are embedded, and its volume vanishes as a limit after homogenization. With regard to elasticity, depending on the choice of material properties of this virtual matrix, many kinds of average moduli between the classical bounds can be predicted. In this paper, we extend the application of this method to elastoplastic materials. Furthermore, Weng's approximate model of interfacial debonding between the inclusions and the matrix is installed, because of its very simple criterion for the initiation of debonding to simulate progressive debonding phenomena. Several numerical examples without interfacial debonding show the applicability of the virtual matrix concept to elastoplastic materials. The characteristics of the model and its overall behaviors are described through the use of typical numerical simulations with debondings. Finally, comparisons with experimental results including debondings demonstrate the eligibility of the proposed method and models, and the application of the present method to designing a hybrid FRP is overviewed.

DOI： 10.1016/j.mechmat.2011.06.010

DOI： 10.1016/j.mechmat.2011.06.010

Other Link： https://www.scopus.com/pages/publications/80051576868

Language：English   Publishing type：Research paper (scientific journal)

The development of plastic deformation after uniaxial plastic strain along [0 0 1] is analyzed in two types of domains in γ–γ′ nickel superalloys. These domains are the horizontal matrix channels normal to [0 0 1] and the vertical channels normal to [1 0 0] and [0 1 0]. By using a mean field method, an elastic energy increase due to the introduction of plastic strain (elongation or compression) in the two types of domains is calculated. The analysis of a mixed mode, where horizontal and vertical channel deformation occurs, is also conducted. Results show that plastic deformation is primarily initiated in a particular type of channel. The choice of the deformation configuration is related to the sign of misfit strain. After a critical amount of plastic strain is reached, the deformation expands through all the matrix channels. This conclusion is supported by the dependence of a flow stress on the deformation mode. FEM calculations are also conducted and compared with the analytical calculation. Except when the strain is extremely small, the two methods give almost the same result.

DOI： 10.1016/j.mechmat.2009.10.001

DOI： 10.1016/j.mechmat.2009.10.001

Other Link： https://www.sciencedirect.com/science/article/pii/S0167663609001720

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)

Formulations of linear and nonlinear multiscale analyses for media with lattice periodic microstructures based on the homogenization theory are proposed. For continuum media, the conventional homogenization theory leads to boundary value problems of continuum for both micro- and macroscales. However, it is rational to discretize lattice microstructures, such as cellular solids, by frame elements since they consist of slender members. The main difficulty in utilizing structural elements, such as frame elements, for microscale problems is due to the inconsistency between the kinematics assumed for the frame elements and the periodic displacement field for the microscale problem. In order to overcome this difficulty, we propose a formulation that does not employ the periodic microscale displacement, but the total displacement, including the displacement due to uniform deformation as well as periodic deformation, as the independent variable of the microscale problem. Some numerical examples of cellular solids are provided to show both the feasibility and the computational efficiency of the proposed method.

DOI： 10.1615/IntJMultCompEng.v4.i4.20

DOI： 10.1615/IntJMultCompEng.v4.i4.20

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)

By virtue of the development of metallurgy and the theory of dislocation, one can qualitatively anticipate the mechanical properties of a material from its microstructure. Moreover, not qualitative but quantitative and precise anticipation is more beneficial for efficient development of new materials. In this context, we utilize a multi-scale method with atomic model, which is a particle system that has potential, and discuss the possibility of quantitative anticipation of material properties including plastic deformation through several representative numerical examples.

DOI： 10.2208/jsceseee.22.209s

DOI： 10.2208/jsceseee.22.209s

Kyutacar

Other Link： https://www.scopus.com/pages/publications/31444434690