This research studies an interafce of compressible flow with density and pressure coupling by sound speed. A phase field appoach is applied to evaluate a source of energy equation for deriving a progres of the fluid interfaces, which is identically formulated into a level-set equation extended to the finite thickness of interafce. A traditional time-marching algorithm for compressible flows can be operated by coupling to the physical behaviour of fluid interafce through the modified equation of thermodynamic states. This approach is investigated for an apprication to a numerical model of premixed combustion flame.

This study investigates stress field around a dislocation loop on the basis of linear theory of elasto-plasticity. As for the modeling of dislocation loop, we employed extended isogeometric analysis (XIGA), where a dislocation is expressed using an enrichment function whose support is set on a slip plane. The dislocation density is defined using Peierls-Nabarro model since it is free from stress singularity even at the dislocation core. The shape of dislocation loop is expressed by non-uniform rational B-spline (NURBS) and stress field is determined by numerically solving weak form stress equilibrium equation by XIGA.

In this study, the texture evolution of iron during cold rolling deformation is evaluated using molecular dynamics. Various properties of metallic materials change according to the crystal orientation. Therefore, controlling crystal orientation (promoting or suppressing the accumulation of specific orientation) is important. The change of crystal orientation due to deformation has been performed by experiments and the theory in the past, but there was a problem that it was difficult to consider the influence of initial defects. In this study, I used molecular dynamics to calculate the change in crystal orientation due to the cold rolling of single crystals containing dislocation loops. From the study of this paper, it was found that the crystal rotation in the molecular dynamics method showed the same tendency as the result of experiment and theory, and the stable crystal orientation did not change by the introduced dislocation loop.

We constructed a new fluid model, which gives low viscosity, by reference to Path Integral Molecular Dynamics (PIMD). PIMD maps the quantum systems into the classical molecular dynamics, and gives correspondence between the quantum systems and the classical systems by introducing fictitious particles. This new fluid model needs fictitious particles similarly to PIMD, and introduces a free parameter which rescales the Planck constant. When this constant is larger, it is expected that the viscosity becomes lower. We applied this new model to helium and argon, and computed their viscosities by simulating the Couette flow. We observed their kinetic viscosities are lower than the kinetic viscosities obtained by the conventional molecular dynamics.

It is well known that the embrittlement of metal materials is promoted by neutron irradiation. In order to improve the reliability of structural integrity assessment it is necessary to understand the embrittlement mechanism. Discrete Dislocation Dynamics (DDD) simulations have proven to be an effective tool for handling the dislocation and the movement of dislocation in infinite space. However, only the periodic boundary conditions are considered in traditional DDD simulation. In this paper, we develop a three-dimensional (3D) numerical model considering the actual boundary conditions by coupling 3D DDD and FEM to simulate the dislocation movement. The analysis is based on the superposition principle. We use the DDD code to compute the solution for dislocations in a nanoscale crystal. The external and internal boundaries are solved by parallel large-scale FEM code – ADVENTURE_Solid.

We are aiming to apply proper orthogonal decomposition (POD) and Galerkin Projection to piping fluid analysis for the purpose of shortening the calculation time of three dimensional fluid analysis for piping systems. In this paper, POD was applied to piping systems including elbows and branches, and the following conclusions were obtained. (1) The swirling flow occurred due to the influence of the curve flow path at the branch and the elbow. The vortex center region of the swirling flow coincides with the vortex center region of the basis extracted by POD, where the energy of the original velocity field is the largest. (2) It was confirmed that the flow velocity field can be approximated with a time average error of 1.0% or less by linear combination of 18 bases extracted by POD.

This study has made 3D finite element analyses on the stress intensity factors for semi-elliptical surface cracks in compression coil springs having cylindrical 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 cylindrical anisotropy was modeled by the stiffness tensor composed of the same components as those of the orthotropic material plus the additional C₄₅ component that corresponds to out-of-plane shear component. The results revealed that the mode-I correction factor FI was dominant and of the order of 0.7-0.9 around the periphery of the cracks in the cylindrically anisotropic coil springs. As the C₄₅ value increased, the FI value decreased around the periphery of the cracks except for the vicinity of the wire surface. The absolute values of F_II and F_III increased locally beyond 1.

The power devices are used under the high and low temperature conditions. Therefore, the delamination between encapsulation resin and metallic components becomes a critical issue. In order to develop high reliability encapsulation resins, a technique to evaluate delamination quantitatively is necessary. We have been studying the mechanical fatigue test technique for the interface between encapsulation resin and metal. In this study, we investigated the possibility of adapting the mechanical fatigue test technique to the power device packages. It turned out that the normalized stress intensity factor obtained from the three-point bending test and FEM analysis is important for this technology. The mechanical fatigue test and the thermal cycle test with the same normalized stress intensity factor of crack gave the similar reliability results. As a result, the mechanical fatigue test technique can be applied to the delamination reliability evaluation analysis for power device packages.

In this study, we developed an effective numerical code to analyze the seismic motions of mechanical structure with screws. The numerical code was developed based upon the adaptively shifted integration (ASI)-Gauss technique. Loosening mechanism of screws was considered by employing a bearing-surface slip frequency dependent model. We carried out a shake-table test of a rack for electronic apparatus and simulated with three types of numerical models. The screw elements were not considered in the first numerical model. The screw elements were considered in the second numerical model; however, the loosening of screws was not considered. In the third numerical model, both the screw elements and the loosening mechanism were considered. As a result of each comparison, the numerical result of the third model agreed best with the test result. These results suggest that it is necessary to consider the loosening of screws when analyzing the seismic motions of mechanical structure with screws such as the racks.

In this study, the effectiveness of earthquake-resistant measures for suspended ceilings was examined through several finite element analyses of earthquake-resistant ceilings and three-types of partially earthquake-resisting ceilings (installation of 1. braces, 2. clearance beside walls, 3. reinforced clips). For the numerical analysis, the Adaptively Shifted Integration (ASI) – Gauss code was applied. Furthermore, the ceiling collapse simulation was improved by introducing the eccentricity of hangers to the numerical model of suspended ceilings. In the case of partially earthquake-resisting ceilings with braces installed, it was confirmed that the ceilings collapsed at the larger parts due to the differences of stiffness in the suspended ceilings than in the case of non-resistant ceilings.

We simulated microstructure evolution in heating process of quenched Fe‒C‒Mn steel based on the phase-field method in order to obtain precise knowledge on the carbide growth and diffusion behavior of alloy elements. Competition between diffusion of alloy elements and migration of the ferrite/carbide boundary was successfully simulated. In the heating process, volume fraction of carbide increased but it started to decrease before it reached equilibrium values. The carbide growth was suppressed with increasing heating rate, while the carbide growth was accelerated with increasing ferrite/carbide interface mobility. Furthermore, the value of diffusion coefficient of Mn in the carbide phase influenced the partitioning behavior of Mn from the ferrite to carbide phases and changed the stability of the carbide phase.

Phase-field method has been used to simulate microstructural evolution in metal materials and is expected to help improving the efficiency of development and manufacturing process of materials. However, some of model parameters and materials values required in phase-field models are difficult to be identified. Recently, data assimilation methodologies based on Bayesian inference have been attracting attention for estimating such parameters and values by assimilating experimental data into phase-field simulations. In this study, we implement the data assimilation algorithm that can incorporate constrains such as the conservation law to the phase-field simulation and validate it by conducting numerical experiments.

This paper presents the accuracy improvement of CFD analysis of transonic turbulent flow around a Transport Aircraft Model (NASA Common Research Model, CRM) using hierarchical Cartesian mesh, which is combined with immersed boundary method, wall function, and Solution-Adaptive Mesh Refinement (AMR). When analyzing transonic flow around a CRM, shock wave and wake in the region away from the surface of CRM should be also resolved sufficiently. However, hierarchical Cartesian mesh tends to be coarse in that region, and this can cause insufficient accuracy of analysis. To solve this problem, AMR based on flow field variables is introduced. AMR is applied to the CFD analysis of CRM using hierarchical Cartesian mesh. As a result, the shock wave and wake region are highly resolved, and the accuracy of analysis, especially for pressure drag coefficient, is improved.

We construct the atomic artificial neural network (ANN) potential for investigation of dislocation mechanics and dynamics in body-centered cubic (BCC) iron based on Density functional theory (DFT) reference data. The bulk properties and defect formation energies predicted by the constructed ANN potential are in good agreement with reference DFT calculations. The 1/2[111] screw dislocation core structure and its energetics predicted by the ANN potential are in excellent agreement with DFT calculations. These results clearly show the excellent reproducibility and generalization ability of the constructed ANN potential.

The aorta is the thickest blood vessel in the human body. It is a strong and elastic blood vessel consisting of three layers: the intima, the tunica media, and the adventitia. Aortic dissection occurs when the intima tears and a new channel (false lumen) is created. Dissections may lead to various pathological conditions such as aneurysms and rupture. Recently, blood flow analysis has been looked into as a diagnostic tool to determine early stages of aortic dissection. Therefore, a Fluid-Structure Interaction (FSI) analysis between the blood vessel and blood flow of the aorta was conducted to investigate its applicability to a dissection.

An upwind interpolation based on characteristic variables is proposed for estimation of physical quantities of ghost cells of smaller squares. The time histories of L2-norm error plots indicate that improvement in the error values is observed when compared to the standard interpolation case. This proposed interpolation is expected to perform well for higher order schemes.

In this study, we developed a numerical simulation code to analyze the crystal plastic deformation in the hot rolling process. It consists of the two-scale finite element method based on the thermo-coupled elastic-crystalline plasticity constitutive law and the dynamic-explicit finite element procedure. It can analyze the heat generation and conduction, and the plastic anisotropy evolution at the macro-scale, and the crystal texture evolution including the dynamic recrystallization (DRX) due to the thermo-coupled crystalline plasticity deformation at the micro-scale. In order to predict DRX texture evolution, we propose a strain energy hypothesis to predict the bulging of crystal boundaries caused by the crystal rotation and merging of adjacent crystals. Symmetrical and asymmetrical hot rolling processes were analyzed to investigate the thermo-coupled plastic deformation and the thermo-coupled texture evolutions. We assess the drawability using Lankford value and the earing defects in the spherical cup deep drawing of disk by comparison with the cold rolled sheet.

This study investigates the mechanism of the interaction between a G-phase and a dislocation on {110} in spinodally decomposed Fe-Cr alloys using the dislocation dynamics (DD) method. The influence of the spinodal decomposition on the dislocation motion is modeled as the internal stress distribution calculated by the Cahn’s equation, and the increase of the Critical Resolved Shear Stress (CRSS) was evaluated. The main mechanism of the interaction between the G-phase and the dislocation is believed to be the Orowan type. The CRSS is determined mostly as the Orowan stress of the interaction, which is equivalent to the shear stress necessary for the dislocation bow-out between the G-phase and the internal stress. The CRSS can be categorized based on the diameter of the G-phase normalized by the wavelength of the internal stress modulation. Then, an equation for the CRSS is derived as a function of the normalized diameter of the G-phase. The CRSS of the dislocation interacting with both the G-phase and the internal stress is directly calculated using the DD method. The numerical results are then compared with the CRSS predicted by the proposed equation. The results are in good agreement in the Orowan part.

Fundamental aspects on the dislocation dynamics analysis of cyclic deformation of BCC iron single crystal were examined. To assume that the grain of the single crystal has a diameter of 10.0 μm, a grain boundary condition, which impedes the motion of dislocations, is applied. Then, the effects of the initial dislocation densities and the length of the dislocation sources, say Frank-Read source, on the mechanical response were examined. The difference of dislocation length with the same initial dislocation densities affects the magnitude of yield stress. The influence of the dislocation length on the yield stress is relatively small compared to the initial dislocation densities. The difference of the number of dislocations with the same initial dislocation length affects the slope of the stress-strain relationship in the elastic-plastic regime. Since the total displacement of dislocations contributing to the slip deformation varies with the number of dislocations, it could be found that the slope of the stress-strain relationship in the elastic-plastic regime is governed by the number of dislocations. The numerical result of the dislocation dynamics analysis of the cyclic deformation with a few numbers of cycles shows that the plastic strain can be generated by the evolution of dislocation structure, and the stress-strain relationship shows an elastic-perfectly plastic behavior.

Honeycomb sandwich panels, which is a kind of composite structure, are composed of thin plate surfaces and honeycomb cores, and utilized in various industrial fields because of its properties such as lightweight and high rigidity. However, JIS standards for experimental evaluation on mechanical properties of such honeycomb sandwich panels bonded with different material-made thin surfaces and honeycomb cores are not standardized. Therefore, we introduce adhesive-bonded sandwich panels consisting of aramid honeycomb structures as panel cores and CFRP (carbon fiber reinforced plastic) laminate for panel surfaces for experimental approaches in this research. 4-point bending test results of the aramid honeycomb cored composite panels were utilized to grasp the influence on bending rigidity and specific bending elastic modulus etc. by the design parameters of constituent materials and the structural dimensions of composite panels. Furthermore, analytical evaluation on the aramid honeycomb cored composite panels were performed using finite element analysis software ANSYS. Comparison between analytical and experimental results is executed to confirm the validity of analytical approach on high performance evaluation of such composite panel structures.

The purpose of this study is to evaluate the ability of non-body fitted Cartesian grid to solve aeroacoustic problems around simple geometry. In order to investigate the aeroacoustic flow simulation ability of the Hierarchical Cartesian grid-based flow solver with immersed boundary method, aeroacoustic sound generated by the flow past NACA0012 airfoil is investigated. By using fourth order schemes at most to discretize the two-dimensional compressible Navier-Stokes equation, the sound scattered on each surface is directly resolved as an unsteady pressure fluctuation. To validate the ability of the code to describe those phenomena, the flow and the acoustics radiation are compared to the result with those of the body fitted grid from the literature.

In this study, we conduct isogeometric analysis (IGA) on non-uniform dilatational deformation of a two-dimensional circular medium. Our formulation is based on the nonlinear elasticity on Riemannian manifold. The dilatational deformation is expressed by Riemannian metric tensor g_[0] defined on an intermediate configuration. Elastic deformation, which is understood as an embedding mapping from the manifold to Euclidean space R², is determined so as to minimize the strain energy density under suitable boundary conditions. Namely, we solved the weak-form equilibrium equation by Galerkin method with NURBS basis functions. Present numerical analysis showed quantitative agreement with those obtained from the analytic solution.

The phenomenon which a cylindrical structure vibrates in a direction perpendicular to the wind flow when the wind velocity is fast is called vortex excitation. This is a vibration that occurs due to the mutual interference between the periodic vortices generated behind the cylinder and the vibration of the cylinder itself, and it is necessary to estimate the amplitudes of the displacements from the viewpoint of wind safety and maintenance of the structure . In this study, it is aimed to capture the hydrodynamic force characteristics and the hydrodynamic oscillation of the cylinder at the Reynolds number of the critical region where the Reynolds number drops sharply. The reduced speed U_r is set to 2 to 15.

Model-based development (MBD) has been widely used in automotive industry. Here, we apply the MBD to the last 4 stages of steam turbine to maximize the turbine efficiency using an optimization technology. First of all, the 1D CAE model of the last 4 stages composed of 186 variables were developed using the 3D CFD result. Secondly, optimization of the 1D CAE was carried out to maximize turbine efficiency and, based on the result, the cross-sectional nozzle and blade shapes were also optimized using 2D CFD. Finally, 3D CFD of the Optimized last 4 stages was conducted and compared with the one of the initial design. This demonstration shows that the combination of MBD and optimization method is useful to design problem with many design variables.

Recently MPFI(Moving Particle Full-Implicit) is advocated as an analytic method for the high viscous fluid flow with the free surface. But there are still few quantitative evaluations about its utility. I expanded MPFI method into 3D and wall boundary model without using wall particles. I held simple validation cases of the hydrostatic pressure and the Hagen-Poiseuille flow, and also held cases of liquid rope coil to check the conservation of angular momentum and got satisfactory results.

In this study, we consider a simple flow field around a circular cylinder discretized by multi-block Cartesian meshes. Block-wise switching of full-order model (FOM) and proper orthogonal decomposition (POD)-based reduced-order model (ROM) is conducted to realize a FOM/ROM hybrid prediction of the flow field. The FOM and ROM are switched dynamically during the unsteady flow simulation by in-situ evaluation of the ROM accuracy in comparison with FOM. The accuracy of the FOM/ROM hybrid prediction was evaluated by comparing with the FOM prediction with the same flow conditions. It is expected with the present approach that data-driven methods such as the POD-based ROM can be utilized to accelerate time consuming unsteady flow simulation.

Conventional finite element analysis （FEA） requires the selection of parts to be modeled and the simplification of the CAD shape prior to meshing, and requires a large number of man-hours. Furthermore, even at the mesh creation stage, in order to properly use 1D elements, shell elements, and solid elements, analysts with knowledge and experience of FEA needs to perform work with a large number of man-hours, which is expensive. In this study, it is shown that the time from loading CAD shapes to obtaining analysis results is dramatically reduced by the meshless method finite element analysis. The analysis results are also considered.

We attempt here to identify and visualize the governing pieces of information about the evolving inhomogeneities that ultimately brings about system-wise instabilities (e.g., fracture modes) by cluster analysis based on “K-Shape” clustering method. Time-series data are analyzed, i.e., the incompatibility, dislocation density and the strain energy fluctuation, against two representative simulation results reported so far for FCC single crystal models yielding stable or unstable deformation modes, respectively. Since the elastic strain energy fluctuation exhibited clearer distinctions between regions to be and not to be unstabilized among others, the clustered data are further utilized to visualize the incompatibility and the dislocation density contours.

Numerical simulation model was developed to simulate the competition between short-crack propagation and wear, and was applied to the rail head. The locations of crack initiation were given by a random generator in the ferrite regions at the beginning of the simulation. The crack was assumed to initiate when the total accumulated plastic shear strain in the region reached the critical shear strain value. The crack initiation at non-metallic inclusion was also considered. The two stage crack growth model proposed by Hobson was adopted as the short fatigue crack propagation. With regard to wear, the Archard model was adopted as the basis. The wear depth can be calculated from the normal pressure distribution in the wheel-rail contact region, the sliding velocities etc. The result of example simulation indicated that it was hard to achieve the ‘magic wear rate’ uniformly in the whole rail head by natural wear only of the single steel because the region of maximum wear rate and maximum crack propagation rate were generally different in the region.

The mechanisms of the seawall destruction have been studied and the following three causes have been investigated in general; 1) horizontal force due to the water level difference, 2) soil scour and erosion behind the seawall during overflow, 3) seepage failure associated with the reduction of the bearing capacity. Whereas, the collapse predictions by complex destruction factors have not ever been realized. Hence, to predict various destruction due to interaction between water and soil, a multiphase flow simulator utilizing the Incompressible Smoothed Particle Hydrodynamics method (ISPH method) for water and Discrete Element method (DEM) for soil is developed in our research group. In this research, scouring phenomena in particularly gravel compared between vertical jet flow experiment and simulation. The authors proposed modifying drag force model in the vicinity of ground focused on gravel movement affected by turbulent eddy. We confirmed necessity of modified drag force in turbulent through comparison between experiment and calculation.

Indwelling of stents is performed as one of the treatment methods for stenosis and obstruction such as blood vessels etc., while medical stents are still required to have much higher flexibility and durability. In spite of concerns about stress concentrations and fatigue failures caused by pulsations due to design and manufacturing methods of shape structures in conventional medical stents, new medical stent devices with higher strength and flexibility to follow the bending, twisting, stretching etc. in blood vessels such as the femoral artery etc. are desired and evaluated in this research. Mesh structures with high strength and high flexibility are firstly designed for medical stent models using 3-dimensional CAD tools. Different design variables such as basic mesh shape (Triangular and Quadra), arm angle (θ) and shape number (n) are introduced for parametrical evaluations. The influences of design variables of mesh structures on meshed stent models’ surface void content, compressive properties etc. were evaluated through finite element analysis. Further studies on three dimensional bending and torsional properties of such meshed stent models need to be carried out to realize the practical medical meshed stents with higher performances of flexibility and durability etc.

When a material defect (initial crack) exists near high speed collision point, fracture resulting from the initial crack shows complicated crack propagation behavior shows dependency on the condition of the collision. In this research, the collision fracture phenomenon is observed using a high-speed camera, and the experimental results like the geometrical conditions, the start time of crack propagation, the crack propagation direction, and the crack propagation rate are recorded, the numerical simulation to model the crack propagation phenomenon is conducted. Base on the results of the numerical simulation, we examined the stress distribution and transition of fracture mechanics parameters, the application of contact - non-contact condition between specimen and strikers is discussed.

In this study, we conduct isogeometric analysis to obtain a internal stress field around a dislocation loop. Our formulation is based on the continuous theory of dislocations developed by Kondo. In this framework, distributed dislocations are identified as the torsion tensor in Weitzenböck manifold and following elastic deformation is characterized by an embedding mapping to Euclidean space which minimizes the strain energy functional. Note that, from a kinematical viewpoint, this is a fair generalization of multiplicative decomposition of elasto-plasticity to differential geometry. Metric tensor in the Weitzenböck manifold is determined from the given configuration of dislocation loop using Cartan structure equation, Bianchi identities and linear homotopy operator introduced by Edelen. The elastic deformation is determined by numerically solving weak form stress equilibrium equation. Present analysis revealed that the second Piola-Kirchhoff stress tensor on a cross-section of slip plane showed quantitative agreement with those obtained by conventional linear elasticity.

The boundary element method is used as an efficient analysis method for the 1-periodic boundary value problem in the 2D Helmholtz equation. However, in the boundary element method for 1-periodic problem, we need to evaluate slowly-convergent Green’s functions. In this research, we implement a fast boundary element method with the Ewald method. We also show the application of the proposed boundary element method to a topology optimisation problem.

Peridynamics is a particle-based method to simulate fracture phenomena of continuum bodies. In the peridynamics, crack inside a body can be easily modeled by erasing bonds between particles, so that it does not require any special treatments to model fracture phenomena. We have developed a peridynamic formulation called the Non-Ordinary State-Based (NOSB) peridynamics since the NOSB formulation allows us to explicitly consider the constitutive law in the continuum mechanics unlike the Ordinary-State-Based (OSB) peridynamics. The peridynamic code has been parallelized based on a domain-decomposition scheme called the Orthogonal Recursive Bisection (ORB) method to simulate a model with a huge number of particles. In this paper, we show the result of a contact-impact analysis performed by the ORB-parallelized NOSB peridynamics as an simulation example.

Due to future tsunami disaster prevention planning, it is strongly desired a simulation tool that accurately predicts possible damage level for structures and human resources in the inundation area. For the tsunami run-up simulation, we must calculate the crustal deformation as an input of the initiation of tsunami wave around the seismic fault. A stagger elasticity theory, in which homogeneous and spatial infinity is assumed to formulate the theory, is applied in practical and conventional crustal deformation estimation. But in this paper, we conducted a series of disasters simulation from earthquake scenario, crustal deformation and tsunami propagation sequentially in order to discuss the necessity of consideration of seismic fault rupture propagation in tsunami simulation.

When modeling the entire city with a high fidelity particle model, one must deal with an enormous number of degrees of freedom, and implementation of highly parallel calculation is indispensable. In this paper, 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, we propose an expanding slice grid method to utilize maximum efficiency on memory utilization and computational speed. At the end of this paper, high fidelity tsunami run-up simulation in Kochi City by the Expanding slice grid method were conducted, and the utility of the proposed method was discussed.

Continuous cooling transformation (CCT) diagram is useful for understanding phase transformations from austenite to ferrite, pearlite and bainite in steel. CCT diagram is also important to estimate and control the final microstructures produced by complex thermal cycle during welding process. In particular, a phase-field method has been applied to simulate the microstructure changes in the Heat-Affected Zone (HAZ) that is the area heated just below the melting point. In this study, we proposed an integrated microstructure simulation system which predicts the microstructure developments in HAZ by combining multi-phase-field method and CCT diagrams. This simulation system provides an efficient materials design framework that would be able to continue to grow even in the future. The output microstructure data calculated from the system will be expected to contribute accurate mechanical properties of welding steel.

Honeycomb sandwich panels (referred as composite panels) are adhesive-bonded structures between thin plate surfaces and honeycomb cores with uniformly arranged hexagons. Honeycomb sandwich panels have the features of lighter weights and higher compressive/bending stiffnesses etc. Adhesive strength between surfaces and honeycomb cores of such panel structure is considered most important for its function realization because of honeycomb core’s structural feature. In this research, adhesive strength improvements are carried out through experimental approaches by changing different bonding process and method. Pure aluminum thin plates and aluminum alloy honeycomb structures are introduced for 4-point bending experiments. Comparisons on adhesive strengths of prototype composite panels fabricated using the conventional and new approached adhesion process method were performed. Improvements on adhesive strengths, reductions of adhesive amounts and costs were confirmed from experimental results under proposed adhesion process/method for composite panels having honeycomb structures as cores.

In the analysis of free-surface flows by using the particle method, the initial particle distribution based on the regular Cartesian grid is widely used, however, it is difficult to represent arbitrary boundaries such as slopes, curved walls, and fluid surfaces, and then has negative effects on the precision of the numerical calculation. Moreover, a particle distribution on vertices of a triangular or tetrahedral mesh has a capability to capture the curvature of the boundary but difficulty in evenly spaced particles. To solve this issue, we propose an initial particle distribution determined by the centroidal Voronoi tessellation (CVT), which is a special type of the Voronoi diagram. By the famous Gersho's conjecture, Vonoroi cells of CVT asymptotically agree to regular hexagon grid in the two-dimensional case. Therefore, our proposed method is expected to space out particles evenly. Note that the findings of CVT leads to NP-hard problem. In this paper, we evaluate computational performances of CVT with the Lloyd algorithm.

Free-surface flow simulations require high-resolution mesh near the interface and huge computational resource. We develop a simulation method to realize large-scale free-surface flow simulations using the lattice Boltzmann method and multiple GPUs. By using the adaptive mesh refinement (AMR) method which adapts high-resolution grids to the free-surfaces, the number of lattice points can be greatly reduced. In multiple GPU implementation, we use the dynamic domain decomposition method based on the space-filling curve. We demonstrate a large-scale dam-breaking simulation using 64 GPUs on the TSUBAME3.0 supercomputer at the Tokyo Institute of Technology.

In order to obtain precise knowledge on the carbon partitioning during quenching & partitioning (Q&P) process in steel, we simulated carbon diffusion in martensite-austenite two-phase microstructure in Fe-C steel based on the phase-field method. The initial two-phase microstructure was obtained in advance by a three-dimensional phase-field simulation of martensitic transformation. Then, using the simulated two-phase microstructure, the carbon diffusion was calculated without solving the time evolution of martensite-austenite microstructure. It was observed that carbon distributed heterogeneously in martensite phase before it diffused from martensite to austenite phases. It has been revealed that the elastic strain energy potential has a significant effect on the carbon diffusion in martensite phase.

When carrying out numerical analysis for the entire gas turbine engine, it is necessary to numerically model the flow field, heat conduction, and combustion in the compressor, combustor, and exhaust turbine section, which are its components. The calculation cost tends to increase because it is necessary to consider the complexity of shape, non-stationaryness, and the time scale of each physical phenomenon being largely different. In this paper, we apply approximate solution method of unsteady calculation with using nonlinear harmonic method, and introduce the analysis result of the whole engine including combustion analysis with comparison with the steady calculation result.

Dependence of high polymer's fracture strain on stress triaxiality is very important to develop stronger and lighter materials. Our research group conducted tensile tests by using notched cylindrical test pieces of Polycarbonate and reproduced numerically these fracture phenomena by using LS-DYNA in order to obtain the relationship between fracture strain and stress triaxiality. Numerical result in regard with the dependence of fracture strain on stress triaxiality is in good agreement with the experimental result.

Wheelchair fencing is the official event of the Paralympic Games, wheelchairs are fixed on a frame called a piste and played. The piste consists of boards to fix the wheelchair and a metal bar, which called central bar. It makes keeping the players at a certain distance to play the game. The player's quick weight transfer causes the central bar to generate large bending stress due to the lifting of the piste. However, the required strength of the central bar has not been clarified for the safety of the athletes. In the past, it was necessary to use expensive equipment such as motion capture to solve problems with movement. However, techniques like Convolutional neural network (CNN) have the potential to simplify the solution of these problems. CNN is a neural network which contains various layers of which some of them are a convolutional layer, pooling layer, activation layer. This paper presents a method of the measuring rotation angle of piste for calculation of moment. This proposed method was used the CNN, and this method aims at realizing simple evaluation of moment.

Honeycomb sandwich panels bonded to FRP thin plates on both sides of honeycomb structures having air ratios of 95% or more are lightweight and high-strength structural materials, and are widely used from building materials to the aerospace field, etc. When using the honeycomb sandwich panel structures, local buckling behaviors caused by the local compressive loads from the colliding objects on the composite panels will lead significant reductions in strength and rigidity of the whole panel. In this study, different design variables of honeycomb structures like the cell size, foil thickness, panel core height, etc. are evaluated for their effects on compressive properties and buckling behaviors of honeycomb structures. Then, the compressive properties and buckling behaviors of composite panels including honeycomb structures are examined experimentally. And in comparison with the experimental results, reasonable model analysis method for buckling characteristics of composite panel is established.

Stiffness of structures for long time operation gradually decreases by stress or strain cyclic loading. Full field strain measurement technique can determine the distribution of decrement of the stiffness or a degree of material damage. Since the error occurs due to several noise source, 0.1% strain becomes a measurement limit. Digital Image Correlation (DIC) has been well studied and employed for such a strain measurement, however DIC needs random dot pattern, complete uniform lighting and computation time for wide view. Accordingly, the authors have employed Dot Centroid Tracking (DCT) at high speed and with high accuracy. DCT can be measured with minimal image processing and centroid location computation. The objective of this study is a determination of a dot mark size and the distance to keep accuracy of the measurement at 0.01% strain. An object with four dots is illuminated with light and photographed with a digital camera to obtain an average value. Based on the average value of the coordinates of 4 points obtained, Bayesian estimation is performed with a small number of sheets, and the average and variance are determined and expressed as a probability density function. We determine the dot size at which 0.01% strain can be measured by changing the dot radius and the distance between centroid.

FTMP-based duality diagram representation scheme has been demonstrated to capture overall pictures about the stability/instability characteristics of discrete dislocation wall systems, including those classified as GNBs. (geometrically-necessary boundaries), where the complimentary interrelationships between the evolving incompatibility fields and the associated elastic strain energy fluctuation are visualized. We here deal further with unstable wall structures consisting of mixed dislocation networks with arbitrary combinations of the Burgers vectors for BCC. The wall models thus simulated mainly exhibit unstable behaviors, i.e., some collapse into fully dispersed states and the others ultimately into nearly-complete annihilations, while a few tend to yield meta-stable configurations, maintaining their initially-given lattice-like morphology. Demonstrated is that the corresponding duality diagrams can clearly distinguish these trends. Extended comparison with those for the GNBs suggest not only a consistent overall picture but also a candidate stability/instability criterion based on both the magnitude and the relative incompatibility to the concomitantly stored strain energy.

With the progress of VR (Virtual Reality) and AR (Argument Reality) technologies, many new technologies and products are developed in every year. Many technologies are used in various fields, such as those used to enrich people's life, as well as in the field of education, video technology, and entertainment. They has made it possible to create reality-like simulated experiences that appeal to the unrealistic experiences and human five senses. And, the spread of development environment makes it easy for users to develop advanced software or applications. In this paper, we have developed simulation software that can observe stars scattered in space that simulates space from arbitrary angles using the cross platform compatible development environment Unity.

Measurement of material resistance toward imposed impact loading are required for safety design and safety maintenance. The common method of evaluating impact resistant is Charpy impact test. This is an impact test for evaluating the energy required for breaking the specimen. Result of the Charpy impact test is derived from absorbed energy of the specimen. The absorbed energy consists of kinetic energy, strain energy, fracture energy. Therefore, we cannot treat Charpy impact value as dynamic fracture toughness. So we make 3D simulation based on the Charpy impact test to clarify correlation between material fracture resistance and the Charpy impact parameter. In the 3D moving finite element analyses, fracture resistance is estimated based on dynamic J integral.

In recent years, spinal degenerative diseases caused by aging and bad posture are at a sign of epidemic, and the number of patients tends to increase year by year. If the spine become ill and the vertebra and disc are removed, the defect is fixed and stabilized with a metal implant. However, currently practiced treatments called spinal fusion surgery using metal implant products have the problem that the load s on the natural bone of the human body are large and will cause overloading on healthy nature bones. Therefore, the purpose of this research is to study the structural design of a flexible medical meshed plate from the viewpoint of elastic rigidity by applying a mesh structure to a pure titanium plate. Basic mesh shape are designed, mesh plate models are crated using 3D CAD tolls. Mesh plate models are evaluated for Maximum Von Mises stress and pseudo elastic modulus by finite element analysis. In addition, tensile fatigue properties of sample meshed plate specimens are evaluated by experiments.