In nuclear plants the head plate constitutes a part of the boundary of the containment vessel (CV), therefore, it is a very important issue if the function as the boundary is maintained or not in the case of severe accident (SA). Buckling and post-buckling behaviors of the head plate subjected to pressure load are affected by the thickness distribution of the head plate. In this paper a creation of 3-D thickness distribution of the head plate based on forming process simulation analysis was tried and the perspective of the modeling of 3-D thickness distribution of a head plate was discussed in comparison with the measured thickness distribution of the tested head plate specimen.

The demand for optimization of design and production is increasing in the industrial world. In order to realize this market requirement, Hexagon Manufacturing Intelligence (HMI) is developing a virtual prototyping system based on Digital Twin/Thread technology which is an advanced technology for virtually predicting actual phenomena by integrating metrology technology and CAE technology.

This paper introduces HMI's Smart Manufacturing solution, which utilizes Digital Twin technology and enables the elimination of physical prototypes.

When applying explicit Runge-Kutta methods to the system of equations derived from low-Mach number approximation, order reduction of the dynamic pressure may occur. It is discussed in the present account that the reduction of temporal order occurs because time derivative of the density or the dynamic pressure (or the Bernoulli function) is included in the source term of the Poisson equation, or in the computation of divergence of the velocity, respectively, depending on the algorithms. The situation is analogues to the case of the governing equations for the incompressible fluid flows. For the incompressible flows, temporal derivative of the velocity at the boundaries is approximated by a finite difference formula, whose coefficients are computed from the coefficients of the Runge-Kutta method, used for the temporal integration of the velocity. The order of accuracy of the finite difference formula is not same as that of the Runge-Kutta method, except for particular cases. In the present account, the remedy to recover the order of accuracy of the pressure is proposed for the system of low-Mach number approximation equations.

A lot of building equipment which can generate noise is installed in facilities such as factory, disposal center and data center. It is necessary to keep the complex noise levels below the limits stipulated by laws or regulations at the boundaries of the premises. When it is predicted that complex noise levels at site boundaries will exceed the limits during facility installation planning, acoustic silencers are sometimes installed on each piece of equipment as a countermeasure. However, since noise reduction performance and cost differ depending on the type of silencers, it takes a lot of labor when the number of equipment is several hundred, and it has been difficult to select the optimum in terms of performance and cost. In this study, an optimum attenuation design method using genetic algorithm is proposed. It took two days for the assignment of a silencer by a professional engineer for a facility. But now, with the optimization method, it can be automatically assigned in about one hour. In addition, we were able to reduce the total cost of the silencer from 50 million yen to 30 million yen when selected by a professional engineer.

This work presents a magneto-hydrodynamic (MHD) analysis method for studying pulsed arc discharges. A set of conservation equations for mass, momentum, energy, and current is solved by the coupling of electric, magnetic, thermal and fluid dynamic effects. The method is used for the research of pulsed gas metal arc welding as an indispensable technology in various industrial fields, and lightning impulse discharge occurred in the nature, which is always considered in the design of lightning protection equipment. The kinetics of gas flow and heating, and temporal change of electromagnetic field distribution in pulsed arc discharges are reported.

In a micro piezoelectric drive system for insect-mimetic flapping wing nano air vehicles, a small translational displacement of the piezoelectric bimorph is converted to a large angular displacement using a transmission based on the geometric nonlinearity of large bending of the elastic hinges. The piezoelectric bimorph and the transmission strongly interact with each other due to the scale effect. Furthermore, in the piezoelectric bimorph, the direct and inverse piezoelectric effects are coupled with each other. Hence, in the micro piezoelectric drive system, the direct-piezoelectric, inverse-piezoelectric, and structural coupling occurs. In this study, a finite element analysis method based on the block successive under-relaxation method is proposed for the dynamic analysis of this triply coupled phenomena, and the dependency of the convergence property on the relaxation coefficient is investigated.

To elucidate the corrosion mechanism on the inner wall of the bottom of a hydrothermal oxidation decomposition reactor that decomposes hazardous polychlorinated biphenyls (PCB) at high temperatures and pressures. The finite volume analysis using OpenFOAM has been used to analyze the coupled thermal flow of a mixture of PCB and water, and the heat transfer between internal fluids and the reactor vessel. In this paper, we discuss the effect of temperature dependence of viscosity of PCB.

In a previous study, an extended finite element method was applied to the fluid analysis of a two-dimensional channel flow obstructed by a thin membrane, and the analytical error increased for a case with small number of membrane nodes. In this study, the number of membrane nodes and their arrangement in the triangular fluid elements are varied, and their effects on the analysis errors are discussed. As the result, the error increases sharply when the number of the membrane nodes is small, but this is not due to numerical integration but to the number and arrangement of the membrane nodes.

Tires are the primary components that directly provide the mechanical grip for vehicles. Therefore, understanding tire behavior is of significant importance for improving vehicle performance. However, the tire’s conventional round shape, its fluid–structure interaction, and the thermodynamics environment make the research challenging. In this research, we study the deformation characteristics of an actual tire using steady-state analysis. The tire we study has a simple longitudinal-tread geometry. The material is mainly rubber, and several reinforcements are inserted. It is subject to internal pressure and contacting the road. We model the rubber with solid and the reinforcements using shell formulations. We start with non-uniform rational B-splines for discretization, and to ensure higher continuity, we apply T-splines. Employing these methods, we conduct a contact analysis to ascertain tire deformation

Topology optimization for elasto-plastic materials has so far been mostly limited to the SIMP method and 2-dimensional cases. In the proposed research, the topology optimization is performed for a 3-dimensional elastoplastic material based on the level-set method, and the explicit derivative with respect to the level-set function is adopted in sensitivity analysis. A comparison of the optimized structure between the 3-dimensional elastic case and the 3-dimensional elastoplastic case has been made.

In this paper, we propose a formulation of the topology optimization problem based on density variation type to suppress the heat transfer performance of heat conductors. Research on the optimum design of heat conductors has focused exclusively on finding cooling structures that allow heat to escape efficiently. In this study, we review the cost functions used for cooling structures and check that the negative values of those functions can not use for keeping heat. Based on the results, we propose to use the squared L2 norm of heat transfer on the heat transfer boundary as the cost function for heat insulation. In addition, the cost function is extended in the case including radiation. Volume constraint minimization problems of those cost functions are solved by the H¹ gradient method. Based on the numerical examples, there is possibility to use the proposed cost functions to suppress the heat transfer performance of heat conductors.

Kirigami is a traditional Japanese technique for deforming a two-dimensional incised sheet to form a three-dimensional structure. In this study, this process is reproduced with non-linear finite element analysis, in which (1) a tensil force is applied to the initial incised sheet, (2) the sheet is streched rotating in the out-of-plane direction, (3) the 3D structure is formed. After fixing the final 3D form, its basic mechanical properties are evaluated by linear finite element analysis. This process was repeated by changing the length and position of the incisions to create a response surface. The design parameters (i.e. number and length of incisions) that satisfy the desired mechanical properties are determined with sequential quadratic programming.

This research tackles topology optimization challenges with large deformation in hyperelastic materials. Utilizing nonlinear response characteristics and significant deformation capabilities, we introduced a novel sensitivity analysis method. large deformation finite element analysis was combined with an updating method using a reaction-diffusion equation (RDE) and SIMP (Solid Isotropic Material with Penalization) method. The optimization targeted the minimization of shape compliance. By assuming linear elasticity for sensitivity analysis to reduce computational cost, the optimal topology was determined, validating the effectiveness of the proposed method. This study contributes to the structural optimization design in hyperelastic materials and offers new paths for future applications.

In this study, we propose a new representation of objective or constraint function for topology optimization of fluid machine which rotates in the constant angular velocity. First, the governing equations for the fluid problem is described and the formulation of topology optimization for fluid machine is briefly discussed. Then, the energy conservation law of the flow in fluid machine is derived from both the governing equations itself and the Brinkman model, and the explanation of each term of the equations are discussed. Next, in order to verify those representations, two-dimensional fluid analysis is conducted for both cases in which the blades of centrifugal fan model are expressed by mesh geometry and Brinkman model. The result shows that those expressions agree within numerical error. Finally, the possibility of the novel formulation for topology optimization of fluid machine, such as the maximizing energy efficiency under the lower bound constraint of energy gain by the fluid, is discussed.

In this study, we performed density-based topology optimization for minimizing von Mises stress. Density-based topology optimization is often employed the optimality criteria (OC) method for design variable update equation. However, the OC method also has several problems. We developed a modified OC method based on the concepts of the conventional OC method and Newton’s method. In the results of the topology optimization analysis for minimizing strain energy using the modified OC method, the number of iterations and parameters settings have been reduced and the dependence on parameter settings has been pursued. Therefore, the modified OC method is also employed for topology optimization to minimize equivalent stress. As a result, in three dimensional von Mises stress minimization problems, it was also found that setting a move-limit not only worsen the rate of descent of the performance function, however also has the effect of creating more grayscale within the density distribution.

A new crack identification method that estimates the cracks in invisible locations based on the surface deformation measured by digital image correlation (DIC) is developed. An inverse problem is setup to estimate such invisible cracks from surface deformations. The inverse problem has an ill-condition because of noise contained in surface deformations. Our proposed regularization method uses prior information and Expectation a Posteriori (EAP) estimation. Prior information includes candidate crack shapes and surface deformations due to cracks. The candidate crack shapes are created by determining a crack's starting point and propagating it based on the force at its perimeter (ligament). A prior distribution is the surface deformations due to the candidate crack shapes. The likelihood distribution is a surface deformation measured by the DIC method. A posterior distribution is defined from the prior and likelihood distributions. In this study, the estimated result is the expected value of the posterior distribution. The validation test was performed, and the result shows that the proposed method superior to the conventional L1-norm regularization method.

In this study, defect topology identification analysis based on the level-set-based topology optimization is carried out by using oscillation waveforms obtained by hammering test. In defect identification analysis, sensitivity may cause numerical oscillations that affect the identified shape. To solve this problem, we employed a weighted sensitivity. Weighted sensitivity is a method to suppress sensitivity oscillations between iterations. In this study, weighted sensitivity was extended to element. In addition, comparison was made with conventional analysis by solving a defect identification problem. As a result, identification shape was better with weighted sensitivity than conventional analysis. This is presumably due to the fact that the weighted sensitivity suppressed the sensitivity oscillation, and the structural renewal progressed slowly. This paper reports the effect of weighted sensitivity for the defect identification problem based on numerical results.

Digital Image Correlation (DIC) is an optical method that employs tracking and image registration technique to measure surface displacement. In general, the relative attitude between the target object and the camera is required to be defined with high accuracy. When the attitude changes, virtual strain is observed since the scale of the taken image varies from place to place. Thus, the application of DIC has been limited. In this study, we propose a method to measure the strain even when the relative attitude changes. First, a strain distribution is calculated with DIC. The observed strain has both true and virtual strain. The virtual strain is estimated using optimized eight parameters in the homography transformation. The true strain is extracted by subtracting the virtual strain the observed strain. This procedure extracts the true strain without a linear component. The effectiveness of the proposed method is verified by measuring the deformation of an aluminum plate with a crack.

Nonlinear finite element analysis with deformed surface constraint created by scanned point cloud by Terrestrial Laser Scanner was performed. We scanned a deformed acrylic plate, and created a triangle mesh that represents the surface of deformed plate. We analyzed the plate to match the deformation to the scanned point cloud. The analysis result shows that the force residuals are very small and the solutions satisfy the deformed surface constraint well. Also, the displacement of the solution showed a natural shape. However, the Cauchy stress showed an unnatural distribution.

In this study, the slump flow caused by the fresh concrete is modeled by using an explicit incompressible Moving Particle Semi-implicit (MPS) method. In the numerical method, the spatial operators are from the MPS method, and the pressure field is calculated by an explicit scheme to solve the pressure Poisson equation. In simulating the concrete flow by the mesh-free method, a regularized Bingham model is employed to calculate the viscosity since the fluid belongs to the non-Newtonian fluid with varying viscosity. There are three parameters in the regularized Bingham model, including a coefficient m, the plastic viscosity, and the yield stress. These parameters are examined by simulating the slump flow. It is found that the plastic viscosity can affect the acceleration stage for the concrete spreading and the yield stress determines the final slow-moving stage.

Viscoelastic fluids, which are often found in synthetic resins, exhibit Barus effects and shear thinning. The Barus effect is a phenomenon that occurs when fluid is jetted out of a narrow tube(die) and expands at the outlet. Shear thinning is derived from the property that the viscosity decreases at high shear rates. The purpose of this study is to reproduce these phenomena on a computer by introducing the Giesekus model into the moving surface mesh-incorporated particle method. As for the calculation results, the velocity distribution of the Poiseuille flow was consistent with the theoretical solution, and shear thinning was properly expressed. The expansion diameter ratio of the spouting flow from a die had the similar large/small relationship as in the past papers.

A non-Newtonian dam break experiment is inversely simulated with the moving particle hydrodynamics (MPH) method by adapting physical parameters via the Bayesian optimization. Because of the physical consistency, which is asserted when the discrete system satisfies the fundamental laws of physics, the MPH method for incompressible flows (MPH-I) can robustly calculate wide range of viscosity without empirical parameter tuning. This feature was helpful in optimization process because the trial cases with various parameters could unconditionally be calculated stably. Specifically, the history of the front edge position could be reproduced with optimizing yield stress and plastic viscosity in the bi-linear Bingham model.

For a discussion of the high viscosity fluid dynamics, I devised two parameters “Deformation-Rotation-Ratio” and “Extention Mode” to evaluate extensional flow. Numerical simulation with the particle method shows that these parameters provide the characteristic of the flow.

In the production of ceramics used for multilayer ceramic capacitors, it is important to produce sheets of uniform thickness during the molding process. However, the flow around blade edges during the spreading of ceramic paste by the blade method has not been well studied, leaving room for improvement in process design. In this study, we use the moving particle hydrodynamic method, which can simulate high-viscosity fluid while considering negative pressure. In order to visualize the internal flow of the material, we conducted a simulation of the blade edge during sheet forming considering surface tension and negative pressure. The result shows that the negative pressure, which causes tensile stress has appeared in the downstream of the blade, and the thickness of the film in the downstream becomes thinner than the gap between the blade and the bottom surface.

In order to solve the problems, this study will conduct analytical verification of the fracture behavior of concrete using explicit finite element analysis, aiming to reproduce the mechanical behavior by structural analysis with higher accuracy. Specifically, we will attempt to reproduce and verify the fracture behavior of concrete by explicit finite element analysis using OpenRadioss, an analytical solver with material laws for crack propagation in brittle materials..

FEM_FrontISTR is a tool that calls the analysis functions of FrontISTR, a parallel finite element method structural analysis software, as a workbench of FreeCAD, a CAD application with users in many countries. FEM_FrontISTR can smoothly perform all processes of finite element analysis from model geometry creation to visualization of analysis results on the same screen, which is a significant advantage over the pre and postprocessing tools conventionally used in FrontISTR. As an external activity, it was introduced at an international FreeCAD user event in March 2023. In this presentation, we will introduce the new functions added to FEM_FrontISTR in 2022-2023, such as self-weight conditions and nonlinear material settings. The presentation will then discuss the features that should be developed in the future.

A numerical simulation model for fluid-structure interaction (FSI) based on the partitioned coupling approach was developed, to investigate the Turek-Hron benchmark case as a simple FSI model. In addition, dynamic mode decomposition (DMD) was applied to displacement of the elastic flap by the FSI simulation, to extract the fundamental structure of complex spatiotemporal data. The present FSI model reproduced well the limit-cycle oscillation derived by the elastic deformation and fluid flow in the Turek-Hron case. The DMD with a mode-sensing approach based on the Greedy algorithm revealed the dominant structures of the deformation of the elastic flap with unique frequencies.

These days, with the increasing demand for renewable energy, steam turbines used in power plants needs to be operated under wide range of steam condition. The last stage blade of LP (Low Pressure) turbine is designed very long and thin to reduce kinetic energy of the exhausted steam, which often adopts structural limit design. To operate LP turbine safely, reversed flow phenomenon under very low volume flow condition need to be considered. With similarity to the phenomenon in axial compressors, we call this reversed flow as “stall cell” in this paper. One-way coupled Fluid-Structure Interaction analysis was conducted with open-source parallel Finite Element Method structural analysis software FrontISTR, which was customized for applying fluid traction on the surface of turbine blades. The result of calculation was consistent with a model experiment in terms of peak frequency excited by stall cell and its overall vibration stress.

For sliding bearings, which are often used in high-speed rotating equipment, it is important to design them so that unexpected shaft vibration does not occur, and evaluation methods using RD (Rotor Dynamics) and CFD (Computational Fluid Dynamics) have been studied. RD is used in many design sites because it is relatively easy to use. However, local conditions such as oil flow and pressure are averaged, it is difficult to analyze oil whip caused by oil damping characteristics. On the other hand, CFD can evaluate more complicated phenomena by grasping the three-dimensionally distributed oil flow. However, it is difficult to apply it to the design development process because it requires a huge analysis cost such as software, hardware, and the period required for evaluation. In this study, we developed a simulation method using OpenFOAM, which is a CFD solver of OSS (Open Source Software), for the purpose of reducing the analysis cost and investigating the possibility of evaluation by CFD. Then, to confirm the validity of the method, an analysis considering the multiphase flow of oil and air, and an analysis considering the whirling excitation of the shaft were performed. This research was conducted as part of the activities of the Multidisciplinary Dynamics Design Research Subcommittee of the Turbomachinery Society.

Reduction of the number of design variables is one of major issues in surrogate modeling and various methods are being proposed. In this paper, a method based on statistical analysis and can work with small size sample is argued. Three different DOE samples are considered and examined for constructing variable reduction model. It is concluded that adequate treatment of interaction effects among design variables is essential and hence resolution IV DOE is required for modeling samples.

Coronary stents are small wire meshed tubes used to help restore blood flow in arteries blocked by a buildup of plague. Understanding the uncertainties in the manufacturing as well as operation of stents are vital in order to ensure performance of the device and more importantly the safety of the patient. By combining Finite Element Method (FEM) and Machine Learning (ML), a robust design to account for these uncertainties is made possible. In this study, the effects of geometry parameters along with operational parameters of the expansion of a Palmaz-Schatz stent model were studied. Simulations were conducted using an FEM model build with COMSOL Multiphysics^®, and the results were fed into ML software SmartUQ to build a surrogate model. Stochastic optimizations were performed accounting for uncertainties, and performance were compared to other literatures.

Although recent improvement in parallel computing enables us to perform large-scale analysis within practical computational time, it is necessary to accelerate simulations because many parametric studies are required in the product optimization design process. One of the promising approaches for reducing computational burden is reduced-order modeling (ROM). We have been working on proper orthogonal decomposition (POD)-based ROM in conjunction with empirical quadrature method, which is one of the hyper-reduction methods. The present study pursues further acceleration of simulations. To this end, we investigate efficient ROM under parallel computing environments.

In this study, multi-fidelity analysis is investigated for global optimization of a small vertical-axis wind turbine. Both low- and high-fidelity models are evaluated by ANSYS Fluent based on unsteady computational fluid dynamics analysis. The differences in fidelity are given from the resolution of computational grids and the number of simulated rotations. The low-fidelity model with a coarser grid and fewer number of simulated rotations can be evaluated at about 8 % of the computational cost of the high-fidelity model. The correlation of a performance value between the high- and low-fidelity models is about 0.874. The low-fidelity model is considered to be useful for efficient global design optimization because it can obtain similar trends to the high-fidelity model with a smaller computational cost.

The unified fluid interface model, which is also related to the viscous solution of the level-set function and the phase-field method, provides a physical model of the fluidinterface phenomena such as the gas-liquid in terface and the reaction interface. We investigated how to apply the fluid phenomena modeling by the diffused interface with such a finite width to the solid wall boundary. By assuming a porous flow as a fluid solution in a solid, the flow field equations immersed in the solid are derived using the unified fluid interface model approach.

For evaluating wettability of micro-structured solid surface, a phase-field model (PFM)-based computational fluid dynamics (CFD) method was applied to fine droplet motion on the surface in three dimensions. Instead of the Cahn–Hilliard equation, the conservative Allen–Cahn (CAC) equation was adopted to calculate the advection and construction of diffusive interfaces. A lattice Boltzmann model-based scheme was used to solve a set of the Navier–Stokes equations of fluid and the CAC equation for an immiscible incompressible isothermal liquid-liquid system with equal densities and viscosities. The surface wettability was numerically evaluated from the mobility of a single droplet under external force on grooved, square-pillar-arrayed, and flat sold surfaces. Through the CFD simulations in qualitative comparison with available data, it is demonstrated that the PFM-CFD method has a potential capable of simply estimating the wettability of the surfaces with 3D patterned structures. It is therefore expected that the functions of micro-fluidic devices in various fields of science and engineering would be optimally designed by the PFM-CFD analysis.

A solidification during an additive manufacturing (AM) process is occurred under a highly non-equilibrium condition such as high cooling rate and large thermal gradient. In this study, we use the non-equilibrium multi-phase-field (NEMPF) model coupled with the CALPHAD-based thermodynamic database to simulate the solidification behavior in a SUS316L stainless steel during AM. Although the NEMPF model is capable of describing the microstructure evolution and the partitioning of solute atoms at the solid-liquid interface under the non-equilibrium condition, its computational cost is high. Therefore, we reduce the computational cost of the NEMPF simulation by replacing the CALPHAD-based thermodynamic calculation with the machine learning method where the trained neural network estimates the chemical free energy and chemical potential as a function of temperature and chemical composition at the solid-liquid interface. In this paper, we show the rapid solidification process in SUS316L stainless steel simulated by the NEMPF coupled with the trained neural network. The results show that the dendrites without secondary arms form and the solute atoms segregate at the interfacial region.

This re search propose s a new fundamen ta l equation that can be so lved with a f inite resolution grid in a f low f ield in which a solid region is immerse d. He re, th e so lid boundary is d efined not as a wall condition but as an interfacial layer r egion with a finite thickne ss by a level-set func tion. A new fundamental equation for the flow is derived. Stable numer ical ca lculations of the model equations corresponding to the wall conditions with and without slip ar e verified on a two-dimensional equ idistant gr id without using upwind diff erencing, artificial viscosity, or additional filter operations.

Lattice Boltzmann Method (LBM) fluid analysis solver FFX is developed. FFX has high sustained performance on supercomputer computers such as Fugaku, and can perform flow analysis around arbitrary complex geometries by automatically generating computational grid at the run time. In this paper, we report the results of weak-scale benchmark tests, isotropic homogeneous turbulence, and flow around a sphere computed by FFX on Fugaku.

In our research, we explore the complex behavior and dynamics of thin liquid films within two-phase flows, with a focus on the influence of surfactant transport. Addressing these multiscale challenges, we utilize the Adaptive Mesh Refinement (AMR) method, enabling precise, dynamic grid adjustments based on the solution complexity. The fluid solver in use is the weakly compressible scheme, complemented with an evolving pressure projection method. These tools, combined with the Langmuir model for surfactant transport and the Marangoni effect calculation, provide a nuanced understanding of liquid-gas two-phase flows, paving the way for improved practical applications.

A two-phase flow simulation was applied to the flow in the bearing gap using the level set method and the ghost fluid method, which is a sharp interface model. The immersed boundary method was used to define an object with a herringbone-shaped hydrodynamic groove. As a result, the pressure at the bearing increased as the width of the hydrodynamic groove increased. In the two-phase flow simulation, the pressure was lower than in the single-phase flow case due to forming an air region in the groove. Visualization of the particle pathlines revealed that the accumulation of lubricant in the groove is dominated by flow entrainment.

Baseball pitchers commonly throw a 2-seam low sidespin rate Slider. Recently, some have started to throw a “Sweeper”, a pitch that includes a gyro-spin with a higher spin rate. A representative example of this is the “Sweeper” thrown by Shohei Otani. We study the aerodynamics of the “Sweeper” by using the Lattice Boltzmann Method with a cumulant collision term for numerical simulation. While the conventional Slider produces a certain side force due to the Magnus effect from the sidespin, it does not generate a vertical lift force. In contrast, the “Sweeper”, which includes a gyro-spin, demonstrates a lift force in both the horizontal and vertical directions due to the asymmetry of the seams. As a result of seam asymmetry, the boundary layer separation points become asymmetrical, the wake region is obliquely lowered, and the ball experiences vertical lift force. The flight trajectory data from Shohei Otani’s pitches show good agreement with our computational results. Our findings underscore the unique aerodynamics of the “Sweeper” and the substantial influence of gyro-spin on both aerodynamics and flight trajectories.

Delta wings used for supersonic aircraft have to take a large angle of attack at takeoff and landing due to their low aerodynamic performance at low speed, which causes leading-edge vortices over the wing's upper surface. The previous paper used a hierarchical Cartesian grid flow solver to conduct steady flow analyses based on Navier-Stokes equations (NS) around flat-plate delta wing. This research uses steady flow analyses based on Reynolds-averaged Navier-Stokes equations (RANS) with two turbulence models (SA-noft2 and SA-noft2-R). This study examines the difference in the vortex phenomena between the results with different turbulence models and the suitable governing equations comparing the results of NS and RANS. The SA-noft2-R model shows better results than the SA-noft2 regarding the reproducibility of vortex flow pattern, but SA-noft2 predicts the primary vortex core location better than SA-noft2-R. Also, it is interesting to note that NS results are better than the RANS result compared to the experimental results. From these results, the analysis using NS is appropriate for estimating the vortex position around the delta wing under the flow field conditions conducted in this study.

Flexible membrane wings, which could passively deform their shape owing to the aerodynamic forces distributions around the wing, have been considered for use in Mars exploration aircraft wing. In this study, coupled aerodynamic-structural calculations of flexible membrane wings with different material properties were performed to investigate the effects of these differences on aerodynamic performance. As a result, a larger deformation was observed in the softer elastic membrane. When flow separation is observed on the upper surface of the wing, a smaller modulus shifts the reattachment position toward the leading edge, resulting in a reduced deceleration area, which affects the drag coefficient. When the elasticity was too small, the drag force was found to increase due to excessive camber formation.

Power modules are key devices in power converters. An important part of the power module is the bonding area between the wires and the semiconductor chip. This bonding area is subject to damage due to cyclic thermal loading caused by short-cycle operation of the power module. Thermal-elastic-plastic creep analysis is required to accurately analyze this phenomenon. Al wire shows a transient creep phenomenon for a short time, and a recovery phenomenon of creep strain has been reported. The conventional strain-hardening rule cannot sufficiently represent these creep phenomena, and it is necessary to apply a modified strain-hardening rule based on ORNL. In this study, thermo-elastic-plastic creep analysis was performed for the phenomenon of delamination due to crack propagation in wire bonds of power modules subjected to repetitive thermal loading, and the ORNL modified strain-hardening rule was applied to the transition creep. The results of applying nonlinear fracture mechanics parameters in post-processing are reported.

The results obtained from cyclic peel tests conducted at the PH/Cu interface indicated that, similar to the PI/Cu interface, a Paris law was observed between the fatigue crack growth rate and the energy release rate range. Additionally, a threshold energy release rate range ΔGi_th was identified. Comparing the resistance to crack propagation at the PH/Cu interface with that at the PI/Cu interface, it was observed that crack growth at the PH/Cu interface was significantly faster, and the ΔGi_th value was only half of that observed at the PI/Cu interface. This showed that the PH/Cu interface is weaker in terms of crack propagation compared to the PI/Cu interface. FEM using a simplified three-dimensional structure of a semiconductor package revealed that interface cracks did not propagate from initial defects in either dielectric film under a temperature cycling. However, it was confirmed that PI is superior to PH as an interlayer dielectric with fewer delamination concerns.

A user subroutine has been ingeniously developed and integrated into the general FEM code ANSYS, dedicated to the evaluation of cure shrinkage stress in UV curable adhesives. Through experimentation, the user subroutine has exhibited exceptional accuracy in computing the relaxation behavior for varying degrees of cure. Moreover, an analysis employing dynamic mechanical analysis has convincingly demonstrated the ability of user subroutine to adeptly capture the intricate interplay between curing degree and frequency, manifesting as phase differences between displacement and stress. Finally, an analysis assuming curing shrinkage was performed. The results proved to be exceptionally encouraging, as the subroutine aptly reproduced the characteristic dependency of illuminance and film thickness on curing stress, which is notably distinctive to UV adhesives.

A power module is a key product for energy saving, and an important part of it is the junction between wires and semiconductor chips. At this joint, damage occurs due to repeated thermal loads due to shortperiod operation of power devices. One of the Al-Si junction damages due to thermal fatigue is the wire-liftoff phenomenon in which the Al wire separates from the Si chip. It is known that the thermal fatigue life of Al tends to saturate at high temperatures above 200°C due to the wire-liftoff phenomenon. To clarify this phenomenon exactly, it is necessary to perform a thermo-elastic-plastic creep analysis. One of the purposes of this study is to confirm the relationship between the fracture parameter and the thermal load cycle pattern that can analytically reproduce this saturation tendency. Thermo-elastic-plastic creep analysis was carried out by modeling the delamination phenomenon. As a result, it was found that the initial temperature at the start of the thermal load cycle has a large effect on the temperature characteristics of the fracture parameters.

Applications of quantum computing to numerical simulation are reviewed. The first example is a phase field equation implemented in the Ising Hamiltonian and computed by a digital annealing machine. Second and third examples are the use of variational quantum algorithms running on a universal quantum computer to solve Poisson's equation and the topology optimization problem. The last example is an efficient evaluation method of the quantum expectation value, which is suitable for an observable with narrow bandwidth, which often appears in the application of numerical simulation.

The purpose of this research is to develop a simple sound-reducing shade to enjoy playing music at home. The requirements for the shade are relatively inexpensive, foldable, suitable size and acoustic environment, and most importantly sound dampening ability. Normally, the development of such a product requires many prototypes and verifications, but in this research, by utilizing finite element analysis, it is possible to find the optimum material and shape without producing a large number of prototypes. In this paper, we designed a new sound-reducing shade that incorporates the ideas of Origami engineering. We also report the results of the feasibility study by FEM analysis of the sound-reducing shade.

In the midst of the coronavirus pandemic, more people are enjoying music at home, and noise complaints are increasing in densely populated areas. As a result, simple soundproofing rooms are also being sold. Here, soundproofing walls that reduce the sound in one direction only are focused on. Compared to the weight of 50 kg for commercially available simple soundproofing rooms, it is aimed for less than 14 kg that adults can easily carry around, and also making them foldable for normal use is considered. The diffraction of sound and the effect of double or triple walls are also taken into account, and how much weight and how much soundproofing are possible with the optimal combination of shape and material, using simulation and measurement of prototypes are examined.