In this study, a new tire mechanical model is proposed for the calculation of longitudinal stress distribution, taking into account the dependence of the friction coefficient on contact pressure and sliding speed. In the proposed model, the contact shape and contact pressure distribution are calculated based on the elliptical contact patch tire model. In the calculation of longitudinal stress in the adhesion range, not only longitudinal deformation in length direction caused by slip ratio but also nonlinear longitudinal deformation in width direction caused by tread radius was taken into account. The coefficient of friction in the sliding region was deduced from the viscoelasticity of rubber based on Persson's multiscale friction theory. Since the proposed model analytically links the longitudinal force of tire to the viscoelasticity of tread rubber, it can be applied to the design of rubber compounds to achieve the desired braking and driving characteristics. The validity of the proposed model was experimentally verified using an inside drum tester with the road surface segments equipped with a quartz piezoelectric sensor. The results show that with appropriate parameter settings, the model-calculated longitudinal stress distribution is in good agreement with the experimental results.

Friction stir welding (FSW) is a joining method which uses the frictional heat generation between a rotating tool and joining metals. Furthermore, cracks, residual stresses and distortions which are the problems of the conventional welding do not occur because FSW works in the solid state¹⁾. Cobalt alloys have high durability in high temperature, so that these alloys are used for the FSW tool material when it is predicted breaking. However, cobalt alloys were worn compared with steel tools in our previous study. Therefore, we carried out reciprocating wear test up to 200 °C in addition to the preceding presentation in this study. And we analyzed the under structure of wear scar using TEM.

Examples, whose causes are intrusions of foreign matter from outside in the damage of rolling bearings, are increasing. When the intrusions of foreign matter invade into a bearing, it will cause a flaking of surface origin type. Though researches for the flaking of surface origin type have been performed, there are few cases to study the influence to the increment of vibration. Therefore, this research investigates the influence of intrusions of foreign matter to the increment of vibration in rolling bearings experimentally with paying attention to the relationship between oil film thickness (formed between rolling elements and raceway), hardness of intrusion, intrusion diameter and consistency, with getting intrusions mixed in with lubricant oil.

SS400 is a steel material used in various fields because of its low cost. We considered the possibility of adding value to SS400 by applying boriding treatment to improve hardness and abrasion resistance. On the other hand, the hardened layer obtained by boriding consists of two layers, and the first layer is hard but brittle, so it has the disadvantage of biting the hardened layer that is peeled off during sliding. Therefore, in this study, we examined the possibility of adding a surface texture to the hardened layer to collect the peeled hardened layer and further improve wear resistance.

Molecular chains of vulcanized rubber are strongly linked by sulfur bridges, that is, covalent bonds via sulfur atoms. In order to recycle vulcanized rubber, it is necessary to cut sulfur bridges. We conceived the idea of shortening the desulfurization process, lowering the temperature, and making the desulfurization process dry by using plasma treatment, which can be expected to lower the activation energy of the cutting reaction by the action of radicals. As a first step, in this study, plasma treatment of vulcanized EPDM (Ethylene Propylene Diene Monomer) rubber was performed in a vacuum chamber. As a result, when hydrogen plasma was used, generation of sulfide water, which should be a product of the desulfurization reaction, was detected by QMS; in addition, the swelling rate of EPDM, or expansion rate after immersion in toluene container, after plasma treatment increased significantly compared to untreated EPDM. On the other hand, no such change was observed when argon or oxygen plasma was used.

Poly(vinyl alcohol) (PVA) hydrogels have been studied for potential applications in artificial cartilage. Compositetype PVA hydrogels (CP gels), which are prepared by combining the freeze-thawing (FT) and cast-drying (CD) methods, have been shown to change their frictional properties depending on the drying conditions. In this study, high-temperature drying time in preparation process of CP gel were varied from 6 hours (CP06), 12 hours (CP12), and 24 hours (CP24), and the mechanism of change in frictional properties with change in drying time was investigated by friction test and adhesion tests. CP06 showed the highest maximum friction coefficient, followed in order by CP 24 and CP12, and the sliding speed (transition speed) at which the maximum friction coefficient was taken was the largest for CP06 and the smallest for CP24. In the adhesion test, CP12, CP06, and CP24 were found to have the smallest adhesion force, in that order. These results suggest that less-crosslinked polymer layer on the topmost surface and higher-order crystalline structure changes depending on the high-temperature drying time and these may affect the frictional behavior of CP gels.

Titanium is used in various fields from aircraft and automobiles to implants as a lightweight, corrosion-resistant material and high specific strength. Titanium is known to have poor wear resistance, which can be improved by forming a hardened layer on the surface, such as by nitriding. Boriding is one of the methods to generate a hardened layer on the surface, but there are few reports on the application of boriding to titanium and its mechanical properties. In this study, boriding with boron powder was applied to pure titanium to investigate the improvement of mechanical properties. As a result, higher hardness and wear resistance were obtained than a pure titanium.

One of the most important factors in evaluating the performance of a ski board is its sliding performance. In order to improve sliding performance, it is necessary to reduce sliding resistance. Sliding resistance is affected by the physical properties of the surface material and wax, as well as the shape of the surface. In this study we have investigated the influence of microgrooves, called "structures", on the sliding performance in order to improve the sliding performance. The relationship between the coefficient of friction and the ice temperature was investigated quantitatively. The results of the friction experiments indicate that when the temperature inside the freezer was -25°C, the static friction coefficient was lower with the structure compared to without the structure. Both the static friction experiment and the dynamic friction experiment showed this trend. Additionally, the dynamic friction experiment demonstrated that the coefficient of dynamic friction was lower with the structure at both -20°C and -25°C inside the freezer.

The purpose of this study is to elucidate the boundary lubrication mechanism of the cooperation of hyaluronic acid (HA) and phospholipids (DPPC) between articular cartilages. As the cartilage tissue model, polyvinyl alcohol (PVA) hydrogel, which has similar water content and elasticity. PVA hydrogel was prepared as follows; PVA powder was solved into deionized water completely, then set in an environmental tester for repeat freezing and thawing to grow physical crosslinks. A rotational rheometer was used for the friction test since this apparatus could realize the evaluation in wide sliding velocity, between 10^-5 to 10³ mm/s. As a result, characteristic frictional behavior was observed, friction coefficient increased in the boundary lubrication range with sliding velocity. Comparing PBS, adding HA and DPPC changed the friction behavior. Especially, 0.02wt% of DPPC solution indicated a significant friction reduction, with or without HA. And in the case of 0.01wt% of DPPC, friction decreased with HA concentration. These results implied that the roles of HA and DPPC for the friction were different and the appropriate ratio of them would exist to minimize friction.

In this study, flat DLC (diamond-like carbon) coated samples and micro-patterned DLC coated samples were prepared to investigate the effects of surface topography and atmosphere on friction properties. Two types of ball-on-plate friction testers were used for the experiments at high and micro loads. Tests were conducted at a load of 1 N in the high load range and 1 mN in the micro load range. The atmosphere was changed between air and vacuum, and the sample was reciprocated 3000 times, and the friction coefficient was determined as the average of 50 reciprocations. In the high load range, the friction coefficient in vacuum was higher than that in air. The micro-patterned sample showed a lower friction coefficient than the flat sample after continued sliding. This could be attributed to the film regeneration as the solid lubricant was transferred from the grooves. In the micro load range, the coefficient of friction in vacuum was lower than that in air.

Reaction films derived from lubricant additives have a significant impact on friction and wear properties, especially under boundary lubrication. However, the formation process and friction mechanism are not yet fully understood due to the complex phenomena at the friction interface, such as dramatic changes in temperature and stress with sliding time, and the state of various molecules in the lubricant. To understand the friction mechanism dominated by the reaction film, in-situ observation of the friction interface is effective because it makes it possible to grasp the accurate phenomena.

In this study, we have developed an in-situ tribometer with a Raman spectrometer incorporating a scanning probe microscopy that can simultaneously measure the surface profile and chemical composition in a minute area on the sliding surface while applying high stress (approximately 1.0 GPa). As a result, we confirmed Raman shifts of the reaction film between atmospheric and high pressure. This new device will lead to a better understanding of accurate friction phenomena at high contact pressure.

Articular cartilage is an excellent bearing material for articular joint with extremely low friction. Cartilage has a specific hierarchical structure with lower elastic modulus on upper layer, and that may contribute to the lubricating function of cartilage. In this study, poly(vinyl alcohol) hydrogels with layered structure prepared by cast-drying method were used as cartilage model material and the influence of layered structure on friction property was investigated. Stiffness was obtained by indentation test, and friction coefficient was measured in reciprocating friction test with a friction pair of hydrogel sheet and glass ball. The results indicated the hydrogels that have thin and soft upper layer on harder layer showed higher stiffness and lower friction. The thinner the soft upper layer, the more the deformation of upper layer is constrained by hard lower layer. This may contribute to suppressing squeeze-out of interstitial water and maintaining biphasic lubrication function at higher level.

In today's society, plastic products are used everywhere. Injection molding is mainly used for mass production of plastic products. In this process, there is the problem of increased costs due to the time required to cool the resin filled into the mold. If the mold is released with insufficient cooling, adhesion will increase, resulting in defects such as increased roughness, and cracks on the product surface. In this study, a coating was applied to the mold surface to reduce adhesion and prevent product defects. Previous studies have shown that both Si-doped Diamond-Like Carbon (Si-DLC) coated and non-coated steels exert a large force to pull the mold surface and Poly Ether Ether Ketone (PEEK) resin apart. In this work, we further tried boron nitride (BN) coatings, which has a high hardness next to diamond, a high-temperature durability, electrical insulating properties, and chemical stability, being expected to have low adhesion to resins. Adhesin-Peeling tests of h-BN, c-BN, Si-DLC against PEEK showed that the peeling strength of BN coatings was significantly lower (1.64 MPa at the peeling temperature of 80℃) than that of Si-DLC coatings (11.6~22.2 MPa at peeling temperatures from 30 to 100℃). Note that the peeling strength of the Si-DLC coating with release agent was 0.43 MPa at the peeling temperature of 80℃).

Biphasic lubrication is one of the factors that enable articular cartilage to achieve excellent lubrication. In order to elucidate the biphasic lubrication mechanism, it is important to understand the behavior of water inflow/outflow at the friction interface. In this study, poly(vinyl alcohol) cast-drying gel (CD gel) which has water content and permeability similar to articular cartilage, was used as a model material for cartilage. And then, relationship between water inflow/outflow at the friction interface and friction property of biphasic material was investigated. The internal water in CD gel was replaced by heavy water and it was used as a tracer of water squeezed out from CD gel. The unidirectional friction test was conducted by using rheometer, and amount of water squeezed out from CD gel during the test was estimated by measuring infra-red spectrum of heavy water in the lubricant. The results indicated that the squeezing out of water from CD gel was suppressed under higher sliding speed condition. It is considered that generation of hydrodynamic pressure between the frictional surfaces under higher sliding speed condition suppressed the squeezing out of water from CD gel, and it contributed to maintaining biphasic lubrication function at higher level.

Recent years have seen a number of large-scale earthquakes, resulting in the derailment of trains, including the Shinkansen. It has been pointed out that a derailment of a high-speed train can cause extensive damage. However, there are many unknowns regarding the behavior of trains after derailment. Although numerical approaches have been studied in various fields, few analytical methods have been established that include post-derailment. In this study, an analytical method that can evaluate the post-derailment behavior of a stopped vehicle during an earthquake is developed as a basic study to establish an analytical method that can represent a series of train behavior before and after derailment. This proposed method combines a dynamic model of a railway vehicle based on multibody dynamics theory, with a finite element model to represent the contact between vehicle and track components, such as wheel/rail contact. The proposed method enables the representation of a series of behavior of a stopped vehicle before and after derailment, while taking into account the contact between complex three-dimensional geometries such as wheel/rail. The proposed method has been verified by comparing the time history waveforms of vehicle behavior and the derailment safety limit line for sinusoidal excitation with the results of an existing vehicle motion simulation program whose accuracy has been verified.

Gas circuit breakers (GCBs) are commonly used equipment in transmission and distribution systems. GCBs are designed to protect the system from over voltage and over current. When GCBs are damaged, conducting operations can cause expansion of failure parts and delay their restoration, therefore diagnostic methods for GCBs are needed to ensure a stable power supply. In this study, simulation model that can predict behavior of GCBs in the opening operation was constructed with one-dimensional computer aided engineering (1D-CAE). Then, data were generated by the model alternatively measured by sensors for diagnostics. Machine learning method which uses the data for training was employed for anomaly detection and the results showed that it could predict the status of GCBs with good accuracy.

We conducted a feasibility study for the development of a drone (quadcopter) using Model-Based Design (MBD). Using the simulation tool MATLAB/Simulink, we created the physical model of the quadcopter and its flight controller model. We then investigated the stability and efficiency of the flight by varying the battery size. The simulations allowed us to adjust the flight controller gains to achieve stable flight under different conditions and to observe how factors such as battery capacity and weight, which have opposite effects on the flight performance of the drone, affect the flight performance and ultimately the range of the drone. By performing specific analyses before building a physical prototype, we were able to proactively identify potential problems and quantitatively assess the desired performance. This demonstrated the usefulness of MBD in drone development. It allowed us to validate the benefits of using MBD for drone development.

In various press forming and deep drawing processes, it is important to predict the forming limit under multiaxial stress conditions. Even in the uniaxial tension test, it is necessary to consider stress triaxiality to accurately predict failure strain, because after necking occurs, the neck portion, which is locally deformed by loading, is in a multiaxial stress state due to the change in the local cross-sectional area. In recent years, some damage and fracture models have been proposed focusing on the effect of stress triaxiality, while most of them are simple phenomenological models that do not consider the mechanical framework. In this study, the constitutive equation and damage evolution equation, which are based on a second-order symmetric damage tensor within the framework of the continuum damage mechanics, are constructed as a function of stress triaxiality to analyze damage and fracture of materials under multiaxial stress conditions. FEM analysis of an example problem was also performed, and the occurrence of anisotropic damage and the correlation between damage and equivalent plastic strain were confirmed.

In this study, we propose a method of determining the degree of separation between normal and abnormal vibration level distributions as a means of extracting characteristic information that is easy for users to understand from the vibration data obtained and improving the accuracy of abnormality diagnosis for a problem for which no evidence is generally provided during abnormality diagnosis by machine learning. We propose a method of determining the degree of separation between normal and abnormal vibration level distributions. We then apply this method to the unbalanced load and abnormal gear conditions of actual gear device, and show that it is possible to improve the accuracy of abnormality estimation by limiting the vibration data to frequency components and measurement positions where the degree of abnormality is significant.

Visualization and characterization of changes in equipment conditions over time based on precise Lissajous curves are discussed. Enhancing the performance of condition monitoring and diagnostic technology based on vibration measurement requires the use of vibration phase information. The commercialized 3-axis high-precision digital vibration sensor, M-A342, combined with the proposed algorithm that suppresses the effects of external interference, make it possible to draw accurate and high SNR Lissajous curves. The trajectories of precise Lissajous curves corresponding to equipment vibrations are observed to be distributed in certain planes in many cases. We propose that the vibration surface angle (θv, φv), which is a vector perpendicular to the vibration surface expressed as an angular component in polar coordinates, can be used as an indicator. The standard deviation of the variation of θv, φv and the fluctuation of θv, φv well reflect changes in the equipment operating conditions over time, indicating the possibility of detecting changes in the operating conditions earlier than conventional methods such as using RMS values. Since these indicators are dimensionless quantities and can be calculated independently of the type and size of the equipment, direct and absolute value comparisons may be performed even if the equipment and measurement location are different. In addition to these results, we will introduce an example in which the index can stably monitor the status of equipment even under operating conditions where the amplitude and frequency change.

Interior stress is researched by FEM.But FEM with small mesh need long time for the calculation.Therefore it is necessary to research more convenient method. Load displacement curve of the test piece shows internal stress-strain curve. The internal stress-strain equation can be converted into compatibility equation in this report. I compared with the analysis in Fig.6, the total time required for the FEM with a 5 mm mesh was 64 s. The proposed analysis method required 26 s (using a Core i7 PC). This demonstrates that the computational load of the proposed method is low.

Model reduction for numerical simulation is a key topic in the area of computational mechanics and system identification. In this study we propose a Bayesian model reduction method with the use of Gaussian process and Stein variational gradient method. As an application of the proposed method for flow field, we estimate a reduced model of one-dimensional advection diffusion equation. In this procedure, the parameter of the Gaussian process is estimated by posterior distribution by Bayes’ sense.

All-solid-state batteries (ASSBs) represent a promising alternative to lithium-ion batteries (LIBs), overcoming the flammability risks associated with organic electrolytes in LIBs. ASSBs employ non-flammable solid electrolytes, offering enhanced lifespan, capacity, and charging performance. The two main configurations of ASSBs are bulk-type, ideal for large-scale applications, and thin-film type, suitable for small devices and already commercialized with proven cycle and shelf life. However, bulk-type ASSBs present challenges in forming high-quality interfaces between the solid electrolyte and electrodes, resulting in increased interfacial resistance. Unlike previous research, this study focuses on the critical interface shape between composite anodes and electrolytes. It introduces the use of topology optimization to design these interfaces, providing a physics-based optimal design approach. First, the optimization problem for enhancing the efficiency of ASSBs is formulated by introducing a new objective function for ASSBs, which aims to reduce the computational cost and provide a good approximation to the original objective function. Then, the sensitivity for the formulated optimization problem is derived using the adjoint variable method. We confirm the validity of the derivation through comparison with numerical finite differences.

Quantum annealing enables a global minimum search for quadratic functions in binary integer variables. It should be applied to more general problems. Therefore, in this research, we investigate the extension of the method to solve global minimum search by the quantum annealing method. There are three issues that need to be addressed: (1) conversion of decimal integer variables to binary integer variables; (2) binary discrete variable approximation of decimal continuous variables; (3) extension to general non-quadratic functions. This paper aims to develop the basic mathematics necessary for expanding the scope of application of the quantum annealing method, which was created as a solution to the minimum problem of quadratic functions of binary integer variables.

For reducing the unbalance of rotating bodies, baffle plates in a fluid balancer regulate the movement of the fluid. Baffle plates are used to suppress the beat vibration caused by the fluid flowing in the circumferential direction. The advantages of a pattern in which the baffle plates are placed on the inner or outer side of the flow path were investigated. The dimensions of the flow channel and baffle plates were kept constant. The amount of unbalance and fluid were varied. Vibration measurements, observation of fluid behavior and theoretical analysis were carried out and the following results were obtained. The state of the fluid eccentricity before the onset of the whirring depends on the arrangement pattern. It was found that the arrangement on the outer side was superior for reducing the beat vibration, as the fluid movement during the whirring occurrence was more easily reduced in the outer circumference arrangement.

We have developed a business process mining technology that utilizes the creation history of deliverables to facilitate business process reform and promote the adoption of digital transformation (DX). Our approach involves capturing the real-time history of business activities and representing them in the cyberspace through the depiction of business processes. This study specifically focuses on upstream operations, such as design, and introduces a technology for presuming business processes, proposing task execution order and transitions, which are characterized by the following three points: (1) Tasks are defined as the necessary work involved in creating various deliverables documents to facilitate progress in the project. (2) Tasks containing similar content are identified as the same task. (3) The date and time of document creation are used as the task's completion date and time. To evaluate the effectiveness of our technology, we have applied it to the patent application work of researchers and conducted a comprehensive analysis. The results have demonstrated the effectiveness of the our approach.

This paper focuses on the transfer characteristics of the structure and describes the investigation of structural modifications aimed at vibration reduction during operation. Numerical analysis is being conducted to investigate a structure that lowers energy transmittance, namely, lowers coupling loss factor, by providing the vibration-reducing ribs for preventing vibration transmission to the evaluation element. We applied the proposed method to a handheld vacuum cleaner with three elements connected in series, and examined the effectiveness of the vibration reduction effect on the handle element by using experimental SEA.

This paper describes a shape design for velocity control in internal viscous flow considerning fluid-structure interaction. The shape design for velocity control problem is formulated. A numerical program for shape design using FreeFEM is developed and the validity of the proposed method is confirmed by the numerical results of 2D problem.

This paper presents numerical examples of shape optimization of unsteady viscous flow fields.We formlate shape optimization problem for vorticity minimization and maximization. Reshaping is carried out by the H¹ gradient method proposed as an approach to solving shape optimization. Numerical analysis program for the shape optimization is developed by using FreeFEM, and the validity of proposed method is confirmed by results of 2D problems.

This paper presents numerical solution to a shape optimization of unsteady fluid-structure-interactive(FSI)fields. This paper formulates shape optimization for flow velocity control. Reshaping is carried out by the H¹ gradient method proposed as an approach to solving shape optimization. Numerical analysis program for the optimization problem is developed by using FreeFEM, and the validity of proposed method is confirmed by results of 2D problems.

To design a structure, it is important to achieve both strength and stiffness. To achieve both, we use Ant Colony Optimization (ACO) a swarm intelligence algorithm inspired by the foraging behavior of ants in nature as topology optimization. Furthermore, we add principal stress constraints to the optimization to consider the flow of forces which is generally checked in mechanical design. The objective of this study is to eliminate the loop phenomenon called ant mill that occurs which is observed in topology optimization using ACO.

Cardiovascular and cerebrovascular diseases based on stenotic lesions are serious problems in the super-aged society. Stent placement has been clinically applied as a minimally invasive treatment for these diseases. However, this procedure has raised new problems such as restenosis and late thrombosis. We have focused on the contact force exerted by the stent on the vessel wall, which causes restenosis, and aim to establish a design theory for a stent that can expand the stenotic area and has an appropriate contact force distribution. In this study, we evaluated the correlation between the stent expansion force, the contact force acting on the vascular wall, and the expanded diameter of the blood vessel. It was confirmed that the expanded diameter of the blood vessel directly depends on the value of the stent expansion force, while the contact force is affected by the hysteresis characteristics of the stent expansion force.

The purpose of this study is to develop an optimization method to determine a heat exchange system for efficiently cooling a high-temperature medium. As a first step in constructing the heat exchange system, the shape of the high-temperature medium is considered to be a semi-infinite body, and point heat sources are arbitrarily distributed in this medium to form a temperature field. Then, the optimal shape of the heat exchange string is searched to efficiently reduce the temperature field in a semi-infinite body. Transfer matrix method was also developed to solve temperature distribution in the string.

In this study, we measured the axial surface pressure distribution of an axial type of slot restrictor Aerostatic bearing. Conventional slot restrictor aerostatic bearings, in which the air supply orifice is arranged in the center of the bearing on the circumference, have a problem of contact between the shaft and the bearing end when an eccentric load is applied to the shaft. However, there has been no detailed investigation of the shaft surface pressure distribution in axial-type slot drawing hydrostatic gas bearings. Therefore, measurements were taken from both CAE analysis and experimental approaches. Comparing the experimental and CAE analysis results, it was found that the accuracy of the CAE analysis was sufficient. In the shaft eccentricity condition, the direction of the shaft eccentricity was found to be high pressure and the opposite side was found to be low pressure. We have concluded that the load capacity was generated by the pressure difference that occurs within the bearing.

In topology optimization for fluid problems, the Brinkman model is commonly used to extend the Navier-Stokes equations to the entire fixed design domain. This model allows solutions where the solid domain exists in the fluid. However, such a structure implies a solid region floating in the fluid in a three-dimensional problem, and such a solution does not make engineering sense from a manufacturability standpoint. In this study, we propose an optimal design methodology for topology optimization of fluid problems with consideration of manufacturability introducing a fictitious physical model to realize constraints that prohibit floating solid regions. First, the formulation of governing equations of fluid and fictitious physical problem is discussed and a density-based topology optimization is described. Then, an optimization problem for Tesla valve, which is a check valve without moving parts, with a floating island exclusion constraint is formulated. As a numerical example, the proposed method provides two-dimensional optimal solutions which contain less floating solid regions compared to the original design.

In recent years, Aerostatic bearings have been considered for use in the medical, semiconductor, and food industries because of their ability to operate cleanly. when a hydrostatic Aerostatic bearing is used to support a large load, the air supply aperture is often arranged in the center of the bearing in a circumferential direction. However, Aerostatic bearings with multiple air supply apertures in the axial direction have been devised to further increase load capacity. However, there are no examples of measured load capacities during shaft rotation. In this study, the load capacity and flow rate were measured by rotating the test shaft with an Aerostatic bearing. The shaft eccentricity ratio ε was set to 0.1 and 0.2. CAE analysis was performed under the same conditions to compare the experimental results and investigate the effect of shaft rotation on load capacity. It was found that the shaft rotation speed had little effect on the load capacity.

In this paper, we propose an optimization method for designing microstructural geometry to maximize the vibration eigenvalues of a laminated shell structure. The material properties of the porous material are calculated using the homogenization method, and the homogenized elastic tensor and density obtained are applied to the macrostructure mathematically linking the microstructures and the macrostructure. In maximizing the vibration eigenvalues, a KS function is introduced to avoid the repeated eigenvalue problem. The area-constrained microstructure optimization problem is formulated as a distributed-parameter optimization problem, and the shape gradient function is theoretically derived using the Lagrange multiplier method. The microstructures are optimized with the H¹ gradient method, using the shape gradient function derived. The optimization system was constructed combining a C language program with a commercial FEM code. Numerical results showed that the microstructural shapes are optimized with increasing vibration eigenvalues for the cantilever macro-model.

This study was performed to manufacture a new desktop type 5-axis NC precision grinder. A table-on-table type 5-axis grinder with three linear axes on the tool side and two axes on the workpiece side was designed and manufactured. The positioning accuracy of the prototype grinder were evaluated. The positioning accuracy of three linear axis were measured and those of Y and Z axis were satisfied. Therefore, the positioning accuracy of X-axis was improved with additional machining. Grinding experiments using zirconia ceramics were carried out and the workpiece actual depth of cut were measured using laser displacement sensor. From these results, the improvement of positioning accuracy was reflected in workpiece depth of cut.

This study proposes a conical 3D printer dedicated to the modeling of conical Archimedean screws. This 3D printer is being developed to model parts of the propulsion mechanism of a snow-mobile robot. It features a conical print bed made of styrene foam. By stacking molten filaments while properly controlling the rotation of the print bed and the movement of the extruder, it is possible to form a cone and a screw blade of any size. Printing a screw blade with a large overhang from the base cone without any support material is also possible. This paper proposes a method for printing a screw blade and verifies its effectiveness through actual modeling.

In recent years, machine tools are required to be compatible the processing accuracy with the speed. However, the accuracy is generally decreased in case the processing speed is increased by the vibration. In this study, we then investigated the relationship between the processing accuracy and the vibration of a gear honing machine. Many gears were processed under various processing condition and the vibration acceleration were measured during the machining process. After then, we considered the relationship between various vibration characteristic such as gear order vibration and the accuracy. As the result, the first order vibration of the gear rotational speed was found to correlate with the accuracy and a multiple regression equation using the vibration could be proposed to express the accuracy.

End mills that are cantilever-mounted on machine tools are prone to chattering vibration that degrades the quality of the machined surface. This is caused by the reduced rigidity when mounted with high L/D (protrusion length/tool diameter) required for deep side wall machining. To address this problem, researchers have proposed to use particle dampers with a simple structure that encloses particles having a diameter of millimeter scale in the end mill. However, particle size is an important factor in determining the damping characteristics of particle dampers, and for frequencies ≥ 200 Hz and large vibration acceleration, large damping coefficients can be obtained with finer particle sizes of 50 μm to 100 μm. In this study, an end mill with a tapered internal space filled with tungsten powder having a grain diameter of 33 μm at a filling ratio of 27 % was fabricated. The surface roughness of the machined specimen was evaluated from cutting tests using a vertical machining center at L/D = 11 and 5 levels of rotation speed in combination with 8 levels of depth of cut (total 40 conditions). Results show that smooth machined surfaces without chatter vibration were obtained under 30 conditions for the endmill with enclosed powder, while only under 16 conditions for the solid endmill without powder. Thus, it was confirmed that fine particle dampers are effective against chatter vibration of endmills.

In recent years, against the background of reducing environmental pollution, in the field of transportation equipment such as automobiles and aircraft, there has been an active movement to use light metals as a substitute for steel materials. Magnesium alloys and aluminum alloys are characterized by high specific strength due to their lightness. However, these light alloys have the problem of lower corrosion resistance and wear resistance than steel materials. Therefore, when used as the actual materials, it is necessary to apply surface treatment. In the present study, to improve the corrosion resistance of magnesium alloys, we performed jointing of dissimilar metal foils using shot peening. In the joining of metal foils, bondability and corrosion resistance were investigated. The experimental materials were extruded round bars of commercially available Mg alloys AZ31, AZ61, AZ80 and AZX611. The different metal foils were pure titanium foil, pure copper foil, pure nickel foil, and stainless steel foil with a thickness of 0.02 to 0.04 mm. Joining was performed using a centrifugal shot peening device with a prototype heating device built into it. The workpieces were heated to 300 to 350°C to improve the bondability between the metal foil and the base material. Using a digital optical microscope, the surface and cross-section observations of the joined workpieces were performed. In addition, a three-point bending test was performed to examine bondability. To examine corrosion resistance, immersion in a supersaturated sodium chloride aqueous solution was performed. Joining of dissimilar metal foils such as titanium foil and nickel foil to magnesium alloys showed good bondability at a working temperature of 300°C. In corrosion test, the corrosion resistance of magnesium alloy was improved by joining the corrosion-resistant metal foil. The joining of corrosion-resistant metal foils by this technique was effective in improving the corrosion resistance of magnesium alloys.

Transport equipment is being made lighter and stronger, and surface treatment is being actively carried out to improve surface properties. Shot peening is known as one of the surface treatment techniques. A work-hardened layer and compressive residual stress are applied to the surface by colliding small steel balls against the metal surface. This technology is expected to improve the fatigue strength and stress corrosion cracking resistance of machine parts. In the present study, the effect of microshot peening (MSP) on the tensile properties of austenitic stainless steel treated with water from high temperature was investigated. Austenitic stainless steel has been widely used as a member of chemical plants and buildings for a long time because of its excellent mechanical properties, workability, and heat resistance in addition to corrosion resistance. The test material was a commercial austenitic stainless steel SUS304 rolled sheet. Tensile test workpieces were cut from the rolled sheet to half size of JIS No. 13 B type. Heat treatment was carried out in the temperature range of 400°C to 1100°C, and water quenching was performed after holding for 1 hour. MSP was applied to the stainless steel after heat treatment and evaluated by a tensile test. A rapid increase in tensile strength and a decrease in elongation at break were observed in the heat treatment temperature range of 600–900°C. In addition, MSP increased the tensile strength.

Amorphous alloys have no long-periodic ordered crystalline structure; hence no magnetic anisotropy or pinning effect of the magnetic wall due to crystals is present, resulting in high soft magnetic properties. Material properties of amorphous alloys vary depending on the constituent elements. In particular, Fe-based amorphous alloys have high saturation magnetic flux density and low iron loss. Therefore, they are expected to be applied to core materials of motors with high energy-saving effects. However, the mechanical properties of materials, such as their high strength, hardness, and toughness, can present difficulties in machining. The magnetic properties that determine product performance and the mechanical properties that cause difficult machinability are all derived from the amorphous structure. The author aims to improve machinability by controlling the microstructure of amorphous alloys while preserving their soft magnetic properties. In this paper, the author outlines a new machining method utilizing microstructure control of Fe-based amorphous alloys and describes prospects.

In the present work, the high-cycle fatigue properties of high-strength interstitial-free steels have been investigated and compared with its conventional (low Al) grade. The case of Al-rich steel is able to arrest fatigue crack propagation at the earliest stage by the generation of dislocation substructure, which induces the superior fatigue endurance of this grade in comparison with its conventional counterpart despite their similar static tensile properties.

To elucidate the phenomenon of molten condensation in the metal PBF-LB method, we present the conditions of borehole generation based on the analysis of the wetting phenomenon between the molten pool/powder and the molten pool shape by the Rosenthal solution for the moving heat source and show it on the scanning speed - laser power process map. The results are compared with the experimental results of the Inconel 718 under high-speed scanning conditions.

To diversify the shape of the hole which removal machining can fabricate, our laboratory has developed the devices which can fabricate a hole on the inside wall of another hole by using them with a die-sinking electrical discharge machine (EDM). In the developing process, it was found that an elastically supported electrode can fabricate a hole with high aspect ratio under stable electrical discharge machining and at high material removal rate. In order to make a comparison, the laboratory developed the device which can realize electrical discharge machining using the elastically supported electrode under the identical conditions with electrical discharge machining using an ordinary electrode. The last study made it clear that a certain amount of pressing force applying to the elastic support is the key to achieve both the stable electrical discharge machining and the high material removal rate. However, the relationship between the pressing force and the material removal rate was unknown. Therefore, this study has revealed this relationship quantitatively.

In the evaluation of the surface condition of polishing pads in Semiconductor CMP (Chemical Mechanical Planarization), the objective was to elucidate the polishing mechanism of the pad surface state that enhances the polishing rate through the frictional force between the wafer and various polishing pad conditions．As a result, it was found that the chemical factor influencing the frictional force between the SiO₂ film and the pad is attributed to the generation of SiOH (silanol groups) under SiO₂ film polish. Silanol groups attach to polar molecules of polyurethane in the pad, which makes the pad slide on the SiO₂ film. In the case that Si surface is polished by the pad attached to the silanol groups, the frictional force increases because the silanol groups on the pad surface are removed by the Si surface during polishing..

The deep drawability of carbon fiber reinforced thermoplastic laminates was evaluated. Deep drawing was performed on the twill weave laminates by changing the mold temperature. When the mold temperature was 160°C, large wrinkles were observed on the specimens and fiber breakage occurred. In the case of 210°C, deep drawability was good and no fiber breakage was observed. From the load-displacement diagram during molding, that the load required for molding decreased with increasing temperature during molding. Deep drawing was also performed on laminates with various laminate configurations. In the woven laminate, the flange area deformed significantly. As a result, large wrinkles occurred. The generated wrinkles spread to the dome section and affected the formability of the dome section. In the quasi-isotropic laminate, wrinkles were dispersed throughout the laminate and the generation of large wrinkles was suppressed. The shape of the dome section was better molded in the quasi-isotropic laminate.

Deep-drawn products include batteries and sensor covers, which are becoming lighter and stronger in response to recent social demands for energy conservation. In the present study, we attempted to form lightweight corrugated clad cup with voids similar to the cross section of corrugated paper. To reproduce this shape, the roller ball die with steel balls placed without gaps in the die shoulder was used. In the experiment, the drawn cup was formed using a combination of a normal die and the roller ball die. The thickness of the blank was 0.3 mm to reduce the weight of the cup. Pure titanium sheet and mild steel sheet were used as experimental materials. The relationship between die geometry and formability and the formability of the three-layer clad cup were investigated. It was possible to form the drawn cups without wall cracks or bottom cracks.