Electrical contact resistance plays important role in melting and bonding of steel sheets interface for resistance spot welding. Although many researchers have proposed theoretical models of electrical contact resistance, microscale structural and electrical coupled finite element analysis is required to evaluate electrical contact resistance because its characteristics depend on the real contact surface, elasto-plastic large deformation contact behavior, electric current and temperature. In this study, we discuss a microscale structural and electrical coupled finite element analysis for the electrical contact resistance. In this analysis, the structural analysis with elasto-plastic, large deformation and contact effect is performed using measured surface based finite element analysis model and temperature dependent material properties. Deformed shape obtained by the structural analysis is used for the electrical analysis considering temperature dependent electrical resistivity. The electrical contact resistance analyses are performed to discuss the SS–RVE (Statistically Similar Representative Volume Element) size and computational cost, and to confirm the validity of the proposed analysis method. The dependency of the electrical contact resistance on the contact pressure and the temperature are compared with those of Babu's model and experimental results from the viewpoint of these path dependencies.

Two-dimensional (2D) materials have attracted attentions as unique functional materials. Among them, graphene is well-known as a fundamental structure of 2D materials of nano-carbon. In 2D materials, lattice defects, such as dislocations and disclinations, cause out-of-plane deformation. In this study, we focus on the fundamental mechanism which can explain how the shape of 2D materials with defects is determined. Typical four structure models of GS with defects are studied, i.e. positive perfect wedge disclination, negative perfect wedge disclination, positive partial wedge disclination, and negative partial wedge disclination. The partial wedge disclinations are implemented by the array of edge dislocations in which the local structure consists of pentagon-heptagon atomic bonds. The equilibrium configuration is calculated by using large-scale atomic/molecular massively parallel simulator. After a detail examination, we found the site potential energy is proportional to the square of curvature. The fundamental knowledge obtained would be applicable to desgin/control the shape of 2D materials.

We report sound transmission loss of double wall structures included thin film cells. Experiments have shown that this double walls have higher sound insulation performance than double wall separated by air space. Transmission loss of double wall structures included thin film cells were calculated by numerical analysis using FEM and transfer matrix method (TMM). By numerical analysis, assuming that the sound wave is refracted inside the thin film cells and converted from oblique incidence to vertical, the transmission loss of the experiment and calculation agree well.

Peridynamics is a particle method with an advantage in fracture simulation of solid bodies. In the fracture simulation, one can easily delete the bonding between the Peridynamics particles to model the fracture if the bonding energy reaches a certain criterion such as a release energy rate. In this research, we have examined the applicability of the Non-Ordinary State-Based Peridynamics in orthotropic elasto-plastic materials. NOSB Peridynamics is a variant of the Peridynamics which allows us to implement any kind of constitutive law to Peridynamics framework. Thorough a unidirectional tensile simulation for a rectangular box, the obtained stress-strain relationship in the elastic limit is compared with the FEM. The results show that examined our Peridynamics code can accurately estimate the stress consistent with the FEM result. Crack propagation under unidirectional tension in orthotropic elastic material was also performed to confirm the validity of the program in fracture simulation.

Network-like materials are made of sparse elastic networks. The network-like materials can be found in our daily lives, such as graphene, rubber, hydrogel, foam, mesh, net, torus etc. Toughening of such materials is one of the most important problems in materials science and structural mechanics, and there have been many studies so far. For example, novel types of tough hydrogels have been developed by material scientists in the last decade. However, the toughening principle is not well established: most researchers pay much attention to chain length heterogeneity, but little attention to other aspects. In this study, we focus on network topology, which is believed to be essential in the field of complex network. We create macroscopic polymer models made of rubber strings and connecters, and perform fracture experiments of such model polymers with different topological structures. We find that periodic but systematic modifications in local coordination number with keeping the constant mean number (4, in 2D) exhibit great improvement in toughness compared with regular square lattices. Furthermore, the star polymer network shows the best performance. In our talk, we will explain the details of our experiments and discuss the results by comparing with numerical simulations. If time permits, we will report our recent experiments using mechanical meta-materials.

In this study, a collapse analysis of a concert hall's box-type suspended ceiling containing level gaps was performed. A numerical model of the concert hall and ceiling, constructed with linear Timoshenko beam elements, was simulated by applying a seismic wave. The adaptively shifted integration (ASI)-Gauss code, which can stably simulate such phenomena with strong nonlinearities such as fractures and contacts, was used in this analysis. The numerical results revealed that the collapse of the ceiling was caused by the detachment of clips connecting the ceiling joists to the ceiling joist receivers. The detachment of clips, in turn, was caused by the propagation of the impact force that was generated when the suspended ceiling collided with the wall. Furthermore, it was confirmed that the detachment progressed because the load distribution supported by the clips changed from its initial state. The results also showed that the locations of the clips detached by the collisions were strongly affected by the geometrical shape of the ceiling.

Peridynamics(PD), which was formulated based on non-local interaction inside materials just like molecular dynamics (MD), is applied to the simulation study of heavily deformed glass materials. The study focuses on the relation between elastic-plastic deformation and fracture behaviors, by using a micrometer-sized model of indentation test onto the surface of glass material. Some mechanical properties of soda-lime glass are derived from nano-sized MD result and are applied to PD simulation. Since how glass materials show hardening or softening response after yielding is not clearly understood and perhaps it will depend on the viewpoint of size-scale, simulated plastic properties for PD model are provided with a variety and results are compared. In addition, one of parameters for PD calculation, e.g. critical stretch, is compared between some values. The results of indentation show that a drop of force acting on the indenter obviously depends on after-yielding property. Damage of particle is accumulated near the contact region only by plasticity, but, in some cases, subsequently the damage starts propagating locally along several thin planes in a radial fashion, which seems coincident with a crack propagation in experimental fracture of glass material.

This study has made 3D finite element analyses on the stress intensity factors for semi-elliptical surface cracks in helical compression springs having orthotropic anisotropy in order to clarify the effects of the anisotropy on the correction factors F_i (i=I, II and III) for the three modes of the stress intensity factors. The analytical results revealed that the mode I correction factor, F_I, was dominant and of the order of 0.9 in the orthotropic coil springs. The absolute values of the other correction factors, i.e., F_II and F_III remained less than 0.2 and reached the highest value in the vicinity of the wire surface. Not only the values but also the distributions of the three kinds of correction factors around the crack periphery in the orthotropic coil springs were found not so different from those of the semi-elliptic surface cracks in isotropic helical compression springs.

A scale dependency of plastic deformation, i.e., a smaller crystal grain provides a higher flow stress, is an important characteristic of metallic materials. In the higher-order gradient plasticity, an additional governing equation expressing the dislocation field is introduced to represent the scale effect. In this study, the reproducing kernel particle method (RKPM) is introduced to solve the higher-order crystal plasticity. The numerical integration scheme is essential in a meshfree analysis. In this study, the Gauss quadrature and the stabilized conforming nodal integration (SCNI) are introduced. The accuracy of both integration schemes is evaluated. It is shown that the performance of the SCNI in the higher-order gradient plasticity analysis is better than that of the Gauss quadrature.

Recent rapid development of deep machine applications presents its capability to be applied to the practical engineering problems. One of the most important issue is an appropriateness of the algorithm and application data. Fundamentally deep learning has capability of learning everything including several laws and superposed phenomena. Of course, the simple laws and phenomena can be easily trained than multiplex phenomena. In order to accelerate training process of a neural network, an appropriate machine learning technique should be employed. In this study, Paris’ law with concerns to stress ratio are trained by random forest method. When the machine learning can predict crack propagation rate correctly, a good convergence of a neural network is achieved by the less multiplex phenomena. Random forest techniques also have several hyper parameters to obtain a good prediction. In order to ensure the prediction, we’d like to survey the hyper parameters. We discuss the results of the trained decision tress by the random forest method.

In this paper, we consider the propagation of sound in a narrow path of an occluded-ear simulator, which is generally used for measurement of insert type earphone. The simulator has a standardized frequency response compliant with international standard (IEC 60318-4). With a narrow path, the speed and phase of the acoustic waves are changed by viscous air damping. For that purpose, we have formulated a formulation that can take attenuation due to air viscosity in the acoustic transmission path. And we tried numerical analysis method in the frequency domain with an acoustic analysis solver using the finite element method. The subject of comparison is the ear frequency characteristic of the person. First, we measured 18 males and females sound and pressure frequency characteristics by inserting a small microphone into the auditory canal of a human ear. In addition, Finite element method model based on three dimensional digital data created from the ear canal shape of an adult male was created. Finally, the analysis result of the ear simulator FEM model and the analysis result of the three-dimensional artificial ear finite element model created from the computed tomographic image are compared with the measured frequency response data of 18 persons' ear canal.

Since structural fasteners using screw-structured bolts s are inexpensive and easy to be installed and removed, they are used in a wide range of fields such as precision equipment, machine tools and medical equipment. However, loosening problems caused by screw-structured bolts can't be avoided within structural fasteners. As the results of loosening bolts, there are possibilities that not only the decreases in axial forces but also different accidents due to the breakages of bolts. In this study, shrink characteristics with tightening load and swelling characteristics with loosening load of spring structures are interested. Spiral cutting structures were introduced to turn the bolts into plurality spring structures intersected with the thread portion of the off-the-shelf screws. Then the screw-structured bolts got the anti-loosening effect with the applied swelling characteristics of spring structures. Three-dimensional CAD tools were used to create the hexagonal bolt models introduced with different helical cuttings in the threaded portions. Finite element analysis to evaluate the influence of various design parameters of helical cuttings on the loosening prevention effects and the changes in strengths of fastening structures were executed and reported in this study.

A fuel cell can convert from chemical energy into electric power. Oxidant and reductant supplies are necessary to keep operating the fuel cell. Lack of the supplies leads to the cell degradation. However, gas utilization ratio which means the supplied gas consumption ratio for power generation should be higher for highly efficient energy conversion. The effect of cell structure modification for resolving the cell degradation issue is evaluated using two dimensional numerical analysis.

FTMP-based multiscale modeling and simulations aiming at the inhomogeneous recovery-triggered accelerated creep rupture processes, observed commonly in high Cr heat-resistant ferritic steels, are attempted using embedded packet models, accommodated with interaction field formalism. After presenting recent results yielding successful reproduction of the above processes, detailed examinations are further made focusing on the recovery-induced “unstabilized” incompatibility fields, based on newly proposed duality diagram representation schemes. Some still-unclear but intriguing results are demonstrated.

In this presentation, we propose the simplified model order reduction of interior permanent magnet (IPM) motors for fast dynamical simulation with a behavior model. In the proposed method, the magnetic field distribution is reconstructed for arbitrary mechanical angles and input currents. The magnetic field is expressed by the linear combination of the basis vectors obtained by the singular decomposition of the data matrix which consists of the snapshots of the field. The proposed method does not solve the reduced equation for fast computation unlike the model order reduction based on the conventional proper orthogonal decomposition. Numerical accuracy of the proposed method is reported.

We have implemented the orthogonal recursive bisection method to parallelize the non-ordinary state-based peridynamics aiming for massively parallel supercomputers. The fracture phenomena expected to be explored by the peridynamics could be extremely complicated and possibly require a vast number of particles. Hence, it is believed that the parallelization is one of the mandatory tasks in the development of the peridynamics. In this study, we examined the parallel performance of our peridynamics code based on the orthogonal recursive bisection method. Using this domain decomposition method with 512 computational cores, we achieved a peridynamic simulation with more than 6 millions particles. It is also shown that the obtained weak scaling performance was close to the ideal one.

Mechanical behavior of thermosetting polymer was modeled by the molecular chain network theory. To represent the nonlinear response of the material, we introduced the bonding by the intermolecular force, in which the number of the bonding is developed with increase in the deformation, into the molecular-chain network theory. The proposed model could predict the elastic-viscoplastic response accompanied by the true strain softening in the uniaxial tensile test, and the ratchet behavior during the cyclic tensile test in very small strain range.

The present paper proposes a topology optimization method considering finite deformation for loading uncertainty. The loading angle is assumed to be uncertain as a condition. The objective is to minimize mean and standard deviation of structural compliance. In case of finite deformation theory, an analytical estimation of the mean and the standard deviation is not allowed. In order to solve this problem, we approximate the objective function by a Taylor series expansion and derive the mathematical formulation. In this approach, the second derivative of the objective function is necessary to keep the accuracy in sensitivity. This phenomenon is investigated in terms of numerical validations. Finally, some numerical examples demonstrate the usefulness of the proposed method.

This paper presents a topology optimization based on a covariance matrix adaptation evolution strategy (CMA-ES) for bifunctional cloaks controlling both thermal flow and direct current governed by Laplace equations. The structures of bifunctional cloaks are expressed by an immersed boundary-level set method and optimal sets of the level set function — design variables in the presented optimization — are explored by the CMA-ES with a box constraint handling with an adaptive penalty function.

The ride comfort evaluation is currently done for a driver, and in the future with realization of automatic driving, the evaluation will be carried out for crew members. In this study, we aim at predicting crew members' states from their expressions in order to optimize their ride comfort evaluation. As the first report, we measured a state of a passenger in virtual self-driving car using his expression and brain waves. We removed unnecessary information from the monitored animation and developed an algorithm to search quickly for a crew member's face part using the color of his face. Here we discuss the merits and demerits of our developed algorithm comparing with Viola–Jones which is a generally used object extraction algorithm.

SBD with UQ (Simulation-Based Design with Uncertainty Quantification) is a design process that quantifies the uncertainty of design information using a new simulation and derives robust design solutions. And also there are many kinds of uncertainties in an engineering simulation. Furthermore, engineering simulations are essential for product development, but the fact that uncertainties effect its accuracy and result. Therefore, applying SBD with UQ to engineering simulations is expected to get them robust and stable. We actually apply SBD with UQ to a benchmark analysis project using NAFEMS's verification problem and verify the usefulness of this process.

In this report, we present GPU-based implementation techniques of the BiCGSafe method and its application to the solver of Navier-Stokes equations discretized by finite element formulations. We also show simulation results of blood flow in arteries.

Following our previous work, we first overview the formulation of the isogeometric boundary element method (IGBEM) for 3D Helmholtz equation and its application to the shape sensitivity analysis. Then, after investigating the accuracy of the IGBEM, we apply the IGBEM to solve a scattering problem and shape sensitivity analyses when the shape of boundary is relatively complicated.

Peridynamics is a particle method, where a material failure is expressed by a breakage of the interparticle bonding. The NOSB peridynamics is a variant of the peridynamics which allows us to implement any kind of constitutive law to the peridynamics framework. In the present paper, we report the NOSB peridynamics results for a contact and fracture simulation using unstructured particle arrangement, required so as to properly treat contact problems. To deal with the ununiform particle arrangement, we incorporated the weight function employed in the Hamiltonian particle dynamics into the peridynamic framework. This treatment allows us to easily perform the simulation using the unstructurally positioned particles without any difficulty related to the partial volume estimation required in the original formulation. The results show that this approach is effective to tuckle to the contact problem and it works even for the fracture simulation.

Pop-in phenomenon that corresponds presumably to local plasticity initiation or subsequent plastic deformation was detected on load-displacement curves with major parameters of critical load Pc and corresponding excursion depth Δh. Since the maximum shear stress underneath the indenter upon plasticity initiation is estimated in an order of a theoretical strength, the event can be understood as dislocation nucleation from defect-free region in a crystal. A probability of Pc for thousand measurements on [001] oriented bcc single crystal Fe shows Gaussian distribution, suggesting a thermally-activated process as an elementally step of the event. On the other hand, the second or later event indicates power-law function like Gutenberg-Richter model, which presumes a collective avalanche-like motion of preexisting dislocations.

Polyhedral-structure formation process was simulated using a phase field model. A three-dimensional multi-phase field model was applied. Nuclei were set on geometrically regular points and the growth process was simulated by numerically solving the phase field equations. A regular structure consisting of truncated octahedral cells, well-known as a Kelvin cell, were obtained when the nuclei were set on body-center-cubic points, and rhombic-dodecahedral structure was obtained for fcc nuclei. Additionally, nuclei were set on the conjugate points of fcc lattice. A structure with a combination of regular octahedra and regular tetrahedra were generated, while rectangular face appeared on the four edges of the tetrahedra. The former two structures based on bcc and fcc arrangements were stable, while the latter structure by fcc conjugate were instable and transformed to cubic cells finally.

FTMP concept is applied to computationally fabricate complex microstructured samples to be further utilized in various deformation analyses based on, e.g., FEM. Here, we focus on the process of modeling single lath-block structures provided the corresponding eigenstrain distributions based on the Bain lattice correspondence is initially introduced. One of the keys for the lath-block modeling is the development of misorientation across the lath boundaries, together with the attendant internal stress fields. FTMP-based approach exhibits spontaneous evolution of such misorientation when substantial contribution of the incompatibility tensor is introduced in the hardening law. Here we decompose the incompatibility tensor into (a)pure deformation and pure rotation, (b)edge and screw, and (c)spherical (isotropic) and deviatoric components, respectively, to examine the mechanisms for the misorientation developments.Analyses are conducted using two basic models for a single lath block structure. Demonstrated for (a) is that the pure deformation part shows relatively larger contributions to the misorientation developments, while, for (b), dominant contributions of the screw component are confirmed. For (c), on the other hand, the weighted spherical part is shown to have weak but basically the same contribution.

One of the critical issues about multiscale polycrystalline plasticity modeling are ultimately consolidated into those about “information transfer and exchange” concurrently taking place among plural scales of spontaneously evolving kinds. In tackling these, we make an attempt here to introduce the duality diagram-based scheme of FTMP into multi-grained models under tension, where FTMP stands for Field Theory of Multiscale Plasticity. The model used is composed of systematic combinations of representative crystallographic orientations. Strongly orientation-dependent intragranular substructure evolutions, successfully reproduced solely via FTMP-based finite element analyses, result in distinct overall deformation/fracture modes, including, e.g., local instability-induced brittle-like fracture modes. Phase space diagrams are introduced to further examine the behavior of incompatibility. Demonstrated thereby is the models yielding “in-phase” responses roughly correspond to the cases that exhibit relatively stable and ductile deformation/fracture modes.

Geometrically-necessary boundaries (GMBs) of dislocations are one of the typical deformation-induced substructures that effectively accommodate intragranular inhomogeneities, which thus generally have a role to mediate between those in the grain aggregate scale and the dislocation cell scale in polycrystalline metallic materials. This study attempts to reproduce GMBs via FTMP-based FE simulations for single crystal models. We here choose a model that was reported to exhibit GNB2, consisting of three Burgers vectors, at the outset, where not only the component-wise evolved patterns of the dislocation density tensor but also the corresponding duality diagrams are examined.

In this study, grain and grain boundary quality in terms of order of atomic arrangement of electroplated copper thin films was evaluated by using the IQ (Image Quality) value obtained from an electron back-scatter diffraction (EBSD) method, and the grain and grain boundary strength was evaluated by applying micro tensile test. In addition, in order to investigate the relationship between the strength and grain boundary quality, molecular dynamics (MD) simulations were applied to analyze the deformation behavior of a bicrystal sample and its strength. The variation of the strength and deformation property were attributed to the higher defect density around grain boundaries than that in grains, which impeded the development of slip systems.

This study deals with the ideal topological design of vibrating structures. For static structures, well-known compliance minimization is defined as the inner product of the external force and static displacement. However, for dynamic structures with time-varying forces and displacements, defining a measure for dynamic stiffness are required. Therefore, various objective functions have been proposed to suppress the response of vibrating structures. In this study, these various objective functions are compared from the viewpoint of vibration suppression. The examples of numerical calculation when adopting mean strain energy and mean squared dynamic compliance as objective functions are presented.

In this research, we investigated the possibility of predicting pressure field from velocity field using Deep Learning. We choose supervised learning and adopted convolutional neural networks (CNN) as architecture, because with CNN we can treat physical quantities considering their spatial distribution. The flow data is generated by carrying out two-dimensional CFD simulation. We used unsteady 2-D flow around NACA0012 airfoil as both training and validation data, which contains separated vortices. In this report, we propose a very simple CNN model. As a result, after training, our model succeed in predicting the locations of separated vortices.

When modeling the entire city with a highly detailed particle model, one must deal with an enormous number of degrees of freedom, and implementation of highly parallel calculation is indispensable. In this study, we developed a computational algorithm with high parallelization efficiency for the liquid spreading phenomenon over a flat plane problem, for later apply on tsunami run-up simulation. In particular, using a slice grid together with a dynamic load balancer as a method for dividing the domain, we propose an Expanding slice grid method to utilize maximum efficiency on memory utilization and computational speed. In this method, we gradually expand the analysis domain along with the fluid spreading. Finally, we measured the parallelization efficiency under highly parallel environment by calculation example. For the measurement, we used 256 and 4096 nodes of K computer. As a result, the calculation using 4096 nodes results in about 35 % efficiency compared with 256 nodes. It is necessary to further improve the efficiency by improving the program.

This paper proposes an approach for the study of complex turbulent transition flows that integrates sparse measurement and computational fluid dynamics (CFD) by using a data assimilation technique. The approach aims at representing complex turbulent transition flows more properly than measurements and computations. To this end, the ensemble transform Kalman filter (ETKF), a sequential advanced data assimilation method, is employed for the estimation and applied to turbulent transonic flows. In this paper, the effectiveness of the approach is shown through a numerical experiment. In the numerical experiment, turbulent viscosity around the NACA0012 airfoil is estimated by the surface temperature on the airfoil. The result shows that the turbulent viscosity is properly estimated, and the skin friction coefficient that is important to represent the turbulent transition flow is estimated more properly than the computation alone. These findings suggest the effectiveness of this approach using data assimilation to represent turbulent transition flows.

In this study, we revisit the theory of lattice defect and its relation to differential geometry. Since the pioneering works by Kondo and Bilby, defects in crystal, such as dislocation and disclination, can be understood as torsion and curvature of connection in a non-Euclidean manifold. Such a mathematical foundation seems to be essential to understand the mechanism of kink deformation in crystalline materials. Here, we briefly review the theory, i.e., differential geometry of lattice defects both in linear and nonlinear cases, and discuss how it is applicable to kink deformation with the aid of non-local elasticity and modern numerical analysis.

We have been developing an efficient algorithm based on a geometrical multigrid approach, named “Multi-level Hierarchical Domain Decomposition Method” (MHDDM), for the large-scale finite element analysis. A MHDDM has a multi-level hierarchical structures of subdomains and make a coarse-grid-based preconditioner easy to apply for the large-scale analysis. In this paper, we performed benchmark test using some test models and assume the relation between the number of subdomains and the number of DDM iteration and threshold of residual.

FTMP-based rational descriptions of three typical fracture modes are described: (1) ductile fracture, (2) creep rupture and (3) fatigue crack initiation, whose evolutions are respectively triggered or promoted by deformation-induced substructures. For (1), critical conditions governing the outsets of macro/micro instabilities are discussed, while (2) is concerned with localized recovery-induced rupture in packet models for lath martensite structures, in connection with the interaction fields. The mode (3), on the other hand, is partly reproduced via evolving PSB ladder structure. Some noteworthy outcomes based on the corresponding duality diagram representations are presented. In particular, the phase space trajectories for the incompatibility field are demonstrated to be able to “sensitively” capture the detailed evolutionary pieces of information about the deformation-fracture transition processes within the targeted system.

We present some preliminary simulation results aiming at reproducing the kink deformation modes, recently observed in Mg alloys with mille-feuille structured LPSO phase. Single crystal Mg models with layered undulations of orientation and/or strengths are compressed longitudinally to the c-axis under plane-strain condition, where FTMP-based deformation twining model as well as the lattice rotation modification scheme is additionally introduced. Demonstrated are some variations of emerging mutually-intersecting “wedge-like” patterns in deformation-induced manners.

This paper presents a topology optimisation for designing elastic wave absorber with a periodic array of viscoelastic inclusions using the boundary element method. First, we describe the model of the elastic wave absorber, which consists of an unbounded two-dimensional elastic matrix and viscoelastic inclusions periodically embedded in the matrix. The elastic wave scattering is accurately analysed by the boundary element method. After that, we explain the algorithm of our topology optimisation and topological derivative, which is employed as the design sensitivity in the optimisation. Finally, we demonstrate a numerical example of the topology optimisation and confirm its effectiveness.

In this study, the electronic band structure of dumbbell-shape graphene nanoribbon (DS-GNR) is calculated by the first-principles calculations performed by density functional theory (DFT). The DS-GNR is consisted of two GNRs with different width connected to each other directly. Therefore, the electrodes and sensing part of DS-GNR has only carbon atoms which are beneficial to enhance the performance of electronic devices. The change of electronic band structure on DS-GNR is considered by the combination of the ribbons of electrodes and sensing part. Furthermore, the orbital distribution of DS-GNR is also changed from that of single graphene nanoribbons (S-GNR). Hence, the dominant factors of the localized orbital distribution are also examined in this study.

The effect of hydrogen on the mobility of edge dislocation in Palladium using Molecular dynamics. The dislocation mobility is increased as the concentration of hydrogen is increased. As for the critical resolved shear stress(CRSS) is also increased as the concentration of hydrogen. The hydrogens located in the slip plane of the edge dislocation substantially increases the CRSS. Whereas those located in the nearby slip plane decreases the CRSS.

Appropriate operation of charging infrastructure such as fast charging station (FCS) plays an important role in the future spread of electric vehicles (EVs). However, since the concentration of excessive charging demand on specific FCSs may cause a heavy load on the power grid, it is necessary to distribute these loads by appropriate navigation of the EVs to FCSs. In this paper, we assume that by considering the waiting time information of all FCSs, EVs can be navigated to the most time-efficient FCS, and as a result electrical load can be distributed. To show that this assumption is correct, we model this function in a traffic simulator, and carry out simulation under an appropriate condition. Simulation results indicate that as more EVs can obtain waiting time information of all FCSs, the number of EVs using each FCS is disperses.

In this study, the influence of anisotropic dislocation mobility on the mechanical strength in spinodally decomposed Fe-Cr alloys is investigated using the dislocation dynamics (DD) method in conjunction with a dislocation orientation-dependent dislocation mobility model. The dislocation orientation-dependent dislocation mobility model can describe the anisotropic behavior of dislocations in the DD simulations. In the DD simulations, an infinitely long straight dislocation is placed at the center of simulation volume, and the influence of the anisotropic dislocation mobility on the critical resolved shear stress increase (ΔCRSS) and flow stress is investigated. As the result, it could be found that the anisotropic dislocation mobility does not affect the ΔCRSS. Likewise, the flow stress is only slightly affected by the anisotropic dislocation mobility. Thus, the results suggest that the anisotropic dislocation mobility can be negligible, particularly for the straight dislocations.

A numerical analysis method of cracks considering dislocation nucleations on various slip plane and dislocation shielding effect near the crack tip was developed. A mode I through wall crack was modelled with discrete dislocations, and the relaxed dislocation arrangement was obtained using dislocation dynamics method. The Burgers vector of dislocations are controlled in accordance with the estimated crack opening. A dislocation emission model from the crack tip on arbitrary slip plane was newly developed. The dislocation emission was modeled by introducing a dislocation loop surrounding a crack tip. Using the developed method, the influence of the slip plane of dislocation emission on the dislocation shielding effect. The numerical results showed that the dislocation shielding effect appeared only at the inside of the dislocation loop. The dislocation anti-shielding effect appeared near the dislocation loop. The strength of dislocation shielding was strongly affected by the direction of slip plane.

We have been investigating topology optimisations in which the level-set function is employed to represent design targets and evolved by the topological derivative. We are especially interested in developing topology optimisations for desgining wave devices. In this study, the applicability of our topology optimisation is extended to periodic structures since they may play a major role in realising innovative wave devices such as photonic crystal, metamaterial and so on. After presenting the formulation of our topology optimisation for singly-periodic BVPs in 2D Helmholtz’ equation, we show an application of the methodology to a design of an acoustic diode.

Halide chemical vapor deposition is used in developing thick silicon carbide film which is used to fabricate semiconductor devices. Chemical vapor deposition process involved with many complex phenomena and better understanding of kinetics, flow and heat is needed to improve the process further. In this study, a simple hot horizontal reactor model is used to investigate physics involved in the chemical vapor deposition and its effect on silicon carbide film growth by the optimized IH heat source distribution.

This paper presents a new topology optimization of rotating machines using deep learning. The classifiers of the relations between the motor shape and its torque characteristics are made by training of a convolutional neural network (CNN). The training data is obtained during a topology optimization of torque characteristics based on the finite element method (FEM). Then the minimization of the iron loss with maintaining the torque characteristics can be processed effectively using the classifiers.

A gradient-based shape and topology optimisation method is presented. In most of structural optimisation methods which have been proposed so far, either shape or topological derivative is used to update both shape and topology of the design object. In this study, configuration of the design object is expressed as a distribution of a level set function (LSF). By using both shape and topological derivatives, the variation of the objective functional due to shape deformation and topological change can approximately be expanded into a quadratic function of the variations of the LSF. This expansion of the objective functional makes it possible to treat shape and topological derivatives simultaneously. The LSF at each point is updated in a way to maximise or minimise the variation of the expanded objective functional iteratively. Through an example of optimisation problem of cloaking devices, it is shown that the proposed method can optimise both shape and topology simultaneously.