In the present paper, we attempted to polish the surface of hardened steel (JIS:SKD11) with our developed polypropylene nanofiber spherical buffing tool by using the 3-axes machining center. In this report, we investigated the influence of different grain size and pressing force on polishing efficiency. We also changed the processing angle between main axis and workpiece for complex curve surface polishing. Otherwise, the processing model also be proposed. As a result, the relations among workpiece inclination angle, grain size and pressing force were clarified. The Preston coefficient also be predicted with our proposed model.

This study has proposed the method for analyzing chatter vibration during cutting by the chatter mark formed on the machined surface using two-dimensional discrete Fourier transform. However, the chatter marks that could be analyzed by this method were limited to those formed on a planar machined surface. In this report, we improve the proposed method so that it can analyze chatter marks appearing on curved machined surfaces, and examine its effectiveness.

A transfer device used in a thin film coating process with high-performance such as an electrode of a lithium ion battery is required to have a significantly reduced pulsation rate. Further, there is a demand for quantitative transfer of difficult-to-transfer materials such as sedimentable slurries and high-viscosity liquids. In this study, in order to realize an ultra-low pulsation rate of ± 1% or less, high precision grinding technologies for alumina ceramics, which has excellent wear resistance and chemical stability were advanced, then precision ground alumina ceramic rotor was developed.

Developed to combination High precision Net shape forming and Cam type thread rolling system. Innovative method to complete metal plug screw thread process by one press machine

This paper describes the design and manufacturing technologies for sheet metal parts in the machine tools. In the present report, we focus on the size and the shape of expanding sheet metal to advance a novel technology in the sheet metal part fields. First, we discuss the aspect ratio and the mass for each expanding sheet metal considering the golden ratio. Next, we attempt to construct the smart sheet metal parts for the telescopic cover to monitor its strain during operation. As a result, it can be seen that the golden ratio is one of the effective parameters to estimate the sheet metal parts and the monitor of strain is considered to be useful as a smart state monitoring system.

We have developed a small size and high strength spiral bevel gear fabricated by the five axis controlled machining center. In the present report, we propose a novel spiral bevel gear with the rib at the end of face width to reinforce the tooth bending strength, which is machined with a ball-nose end-mill tool. We investigate the influence of the rib width and height on the maximum stress at the curved tooth root and rib joint part. As a result, a novel three-dimensional guideline is found to design the small size and high strength spiral bevel gear with the rib at the end of face width.

Nowadays, a monitoring technology has been attracted attention in the factory automation fields regarding IoT (Internet of Things). However, it is difficult to monitor the process information from a round tool during rotating operation in machine tools. We therefore develop a novel tool holder equipped with a wireless communication function to monitor tool vibration. In the present report, we attempt to measure the vibration of the tool holder during ball-end-milling processes and the servo driving information for different machine tools. As a result, we demonstrate that the developed tool holder with a wireless system makes it feasible to improve the machined free form surface by considering the servo driving information.

In the present paper, we investigated the filtration efficiency of polymeric nanofibers mass-produced by modified melt blowing and flash spinning methods. First, the filtration performance of the fiber was experimentally tested by varying the following parameters—fiber thicknesses, filling rate, and fiber diameter. And then, the CFD flow-analyzing software was used to simulate the pressure loss and flow resistivity. Furthermore, a three-direction physical model was proposed and used to calculate the gap size of fibers with different diameters but equal filling rate under the assumption of fibers which always have uniform distribution in 3-dimension. As a result, it can be confirmed that the tried produced filter shows very excellent filtration ability and the investigated data can be used for making nonwoven fabrics that can then be set as a standard for producing high-performance filters and face masks.

We focus on the frictional heat generated on the tool during the lathe processing. Thermal fatigue due to the frictional heat is one of several causes of breaking the cutting tool. The frictional heat can be calculated by the chip discharge speed, the contact length between the chip and the tool, and the friction force generated on the tool rake face. Therefore, these are measured using a high-speed camera and a tool dynamometer. The heat flux flowing into the tool is obtained. The temperature of the tool cutting edge is evaluated by finite element analysis from the obtained data.

Milling is an important manufacturing process in order to get smooth surface. Lack of surface and dimensional accuracy can cause serious incident. Tool life and machine accuracy are strongly affected by cutting heat. In milling，a heat cycle for raising temperature in cutting and lowering in idling is repeated in a short time. This cycle can causes the large periodic temperature fluctuations of cutting edge, thermal fatigue breakage of tool and deterioration in machining accuracy.

However, there are few studies on evaluating temperature amplitude in milling.

This study assesses the effect of temperature fluctuation in milling with experiments and FEM analysis.

The CMP (Chemical Mechanical Polishing) process is essential for improving the performance of semiconductor devices. In CMP processing, it is necessary to perform a conditioning process on the polishing pad in order to maintain the polishing rate of a wafer. However, the details of the surface condition of the polishing pad obtained by the conditioning are not yet clear. In this study, we investigate the effects of a conditioning process on a surface condition of pad by conducting a FEM analysis in consideration of the viscoelastic properties of pad and performing a experiment of conditioning with a lathe.

Knurling is the machining method which produces periodic fine grooves on the metal surface and works for anti-slipping. In its process, inexperienced mechanics sometimes fail to achieve the required knurling quality. If they know the optimum processing conditions，they can produce high-quality knurling regardless their experiences．For the purpose of stabilizing the quality of knurling, we evaluated the relation between conditions and qualities of the knurling process.

Although application of CFRP has been expanding in recent years, there are problems such as remarkable tool wear and surface damage during cutting. In this study, effects of endmilling conditions on surface damage and the mechanism of defect generation during machining was investigated in order to reduce surface damage in endmilling of CFRP. As a result of an experiment, it was found that a better machined surface was obtained by up-cutting, and the defect area ratio became lower as the cutting speed decreased and the inclination angle increased.

A robust optimal design method of energy supply systems under uncertain energy demands has been proposed using a mixed-integer linear model for constituent equipment. However, this method takes a long computation time, and thus it can be applied only to small-scale problems. In this paper, a hierarchical optimization method is applied to two types of optimization problems for evaluating robustness to solve them efficiently. In a case study, the proposed method is applied to a cogeneration system with a complex configuration, and the validity and effectiveness of the method are ascertained.

To attain the highest performance of energy supply systems, it is necessary to determine design specifications optimally in consideration of operational strategies corresponding to seasonal and hourly variations in energy demands. A hierarchical mixed-integer linear programming method has been proposed to solve such an optimal design problem efficiently. In this paper, a method of reducing model by clustering periods with the k-medoids method is applied to the relaxed optimal design problem at the upper level. Through a case study, it is clarified how the proposed method is effective to enhance the computation efficiency in a large scale optimal design problem.

It is expected that energy saving may be attained by connecting heat source and air conditioning equipment with piping network and operating them flexibly in consideration of heat loads. However, it is difficult to find the optimal operational strategy of such a heat supply system with piping network because of its discrete and nonlinear characteristics. In this paper, the optimal operational strategy is investigated by a mixed-integer nonlinear programming approach. This optimization problem is solved efficiently by a hierarchical optimization method. The validity and effectiveness of the proposed approach are shown through a case study.

The trend in manufacturing is moving towards an era of reform. The innovation driven manufacturing is required to revolutionize the conventional high performance oriented manufacturing, which brings new value creation such as mass-customization and innovative products with services. It is essential to develop the predictive control type manufacturing system with self-recognition ability aided by the connected smart in-process and on-machine measuring systems which is integrated by Internet of Things and Cyber-Physical System. The paper introduces the smart in-process and on-machine measuring systems based on integrating different measurement principles and multi-scale data fusion as well as the conventional one using multi-sensor fusion and cooperation.

The purpose of this research is to elucidate the influence of spray atomization on PM emissions when changing fuel components. In this report, free spray was visualized to evaluate the basic spray characteristic in detail by using two components fuel mixture of low boiling component simulating gasoline fuel and high boiling component. As a result, there was region that atomization characteristic by mixing high boiling component became almost the same as gasoline spray characteristic by increasing injection pressure.

The Purpose of this study is to construct a spray breakup model that can predict the breakup process of direct injection gasoline spray with high accuracy by paying attention to the breakup form of spray directly under the injection hole of the nozzle for direct injection gasoline engine.

The purpose of this study was to clarify the effects of injection hole shape and high pressure injection on spray formation process. Using injectors with straight, nozzle, and diffusr injection holes, we evaluated the spray characteristics by focusing on the effects of changing the injection hole shape and increasing the fuel injection pressure on the spray formation process.

We propose the use of an unfueled prechamber as an amplifier of the lean burning efficiency of the gasoline engine and explore the possibility of charging the prechamber with a rich mixture without using additional fuel, by modeling a prechamber without additional scavenging systems. According to our previous research charge possibility of the unfueled prechamber is realizable and classified into two main charges including the first charge in the inlet stroke and second charge in the compression stroke. This time we consider the second charge in the compression stroke. The charge flow of the unfueled prechamber is numerically studied according to the design configuration of the prechamber. Most importantly we found that the first charge mostly depends on the inlet velocity of the engine while the second charge mostly relies on the coincidence tumble directions of the main and chamber. This coincidence will decide the leaking or mixing quality rich mixture inside the prechamber with a lean mixture in the main chamber.

The purpose of this study is to construct a model that can easily and accurately predict the engine performance without experimental data when the engine parameters such as compression ratio and operating conditions are changed in the early stage of engine development.

The Livengood-Wu integral has been widely applied as the simplest and most practical model to predict knocking. For high-accuracy knocking prediction using the Livengood-Wu integral, ignition delay time equations for a premium-gasoline surrogate fuel were developed, which can reproduce the temperature-, pressure-, and equivalence ratio-dependences of ignition delay time and H₂O₂ loop induction time produced using a detailed reaction mechanism. In the present study, in-cylinder autoignition prediction using the Livengood-Wu integral along with the ignition delay time equations has been investigated, and error factors in the Livengood-Wu integral have been elucidated. Errors are accumulated during the H₂O₂ loop induction part of ignition process. An idea of error correction has been proposed.

In this study we tried to predicition of spray characteristic under low pressure such as 800kPa by numerical simulation of Euler spray simulation using with gas-liquid two phase flow analysis. The result are presented as followed.Two phase flow before breakup from continuous liquid to particle are computed by VOF ,LES and DES models. We identified the splitted particle individually, and determine velocity and diameter. Motion of particles are computed by Euler spray simulation using with previously mentioned gas-liquid two phase flow analysis. Particle size of spray of the experimental result and calculated result are in error by 20%.

In order to simulate the spray near the diesel nozzle with high accuracy, the experimentally observed liquid column region where the velocity at the spray does not decay, and the time-series change of the spray angle are expressed by changing a droplet drag model and spray angle value in numerical calculation depending on time and space. As a result, it is considered that the spray characteristics near the nozzle hole were reproduced with higher accuracy.

At present, diesel engine having higher thermal efficiency than gasoline engine is attracting attention, and further improvement in thermal efficiency and lower emission are required.

Therefore, we have been focusing on techniques for forming lean and homogeneous mixture at early stage by dissolving EGR gas into fuel and releasing dissolved gas with decompression.

In this report, we evaluated the characteristics of fuel spray using CO2 gas dissolved fuel. We evaluated the effect of dissolved gas effervescence on spray shape by comparing gas effervescence model and the results of spray visualization experiment with shadowgraph photography.

The purpose of this study is to grasp the spray shape and atomization characteristics of free spray, the stage before the impingement of the spray against the wall, in order to further increase the efficiency and reduce the emission of PFI engine. This report focused on the fuel injection pressure drop and investigated the spray characteristics over the entire spray area.

According to IEA, the number of automobiles with internal combustion engines is expected to increase even in 2050. Furthermore, the ratio of automobiles equipped with gasoline engines for approximately 45%. Therefore, it is demanded that gasoline engine should improve the thermal efficiency in order to make effective use of limited resources. It is considered effective to use taper nozzle in direct injection gasoline engines as one way to improve atomization characteristics. However, there are few researches on using taper nozzle. In this report, we investigated the influence of gasoline spray characteristics using straight nozzle and taper nozzle.

For further improvement of thermal efficiency in diesel engine, reduction of cooling loss is essential. It has been reported that compact spray is an effective means for reducing cooling loss. In this study, using tapered nozzle that can realize compact spray, spray characteristics are macroscopically estimated by shadowgraph photography. The effective compact spray characteristics are clarified by connecting the spray shape with engine performance and heat release rate. The results show that thermal efficiency of tapered nozzle decreases by restricting the air entrainment amount due to increasing spray corn angle.

The boiling point of biodiesel fuel can be lowered by the cross-metathesis reaction with short-chain olefin using ruthenium catalyst. The objective of this research is to clarify the metathesis reaction condition for fitting the distillation curve of biodiesel fuels to that of petro-diesel fuel. In this report, the effects of the molecular size of olefin (C5~C11) and its double-bond position (1-, 2-, 4-octene) on the chemical component and boiling point curve of reaction products were investigated.

Mixing hydrogen with gas fuel is attempted in order to enable high efficiency operation in a spark ignition engine using hydrocarbon fuel. Therefore, in this research, higher efficiency and lower emission are aimed in a lean-burn gas engine using hydrogen addition for power generation at WOT. In the tests, excess air ratio is changed from 1.0 to 2.0 with various hydrogen additional ratios. As a result, it is revealed that hydrogen addition into city gas in lean burn is effectual not only for increasing brake thermal efficiency but also for reducing NOx, THC and GHG emission factor

Ammonia is attracting attention as an energy carrier that emit no CO₂ during combustion. However, ammonia emits a large amount of NO_x. Previous studies have shown that thermal and fuel NO_x are reduced by two-stage combustion, but the mechanism is far from clear. In this study, three dimensional numerical study were performed for a 10 kW class test furnace with methane and ammonia/methane as fuel for which gas sampling were performed. The result showed that the behavior that NO decreased by specific GER was observed when two-stage combustion was performed. It was also found that specific GER area was expanded by two-stage combustion.

In this study, we evaluated the effect of wall cooling on CO generation and emission in a one-dimensional laminar flame. The CO distribution was measured using gas sampling and CO-TALIF. In the region where quench occurs (flat flame edge), the amount of CO is large, and in the region where stable flame is formed (flat flame center), the amount of CO is small. At the flame edge, the lower the flame temperature, the higher the CO concentration. At the center of the flame, the lower the flame temperature, the lower the CO concentration.

In this study, an analytical solution of cylindrical coordinate system has been derived for flame kernel development in a turbulent flow by introducing assumptions. The solution results and characteristics are compared with that obtained by the analytical solution of spherical coordinate system in our earlier study. Furthermore, by implementing in the ignition model, the minimum ignition energy (MIE) for the premixed gas is predicted in the new ignition model. As a result, the tendency of MIE equivalent ratio dependence and the tendency of MIE increase due to turbulence are reproduced.

The oil dilution process in post fuel spray has been simulated to understand oil dilution under a non-reacting condition.The wall film dynamics is simulated with two-dimensional governing equations along the wall, while the fuel spray and cylinder flow are simulated with three-dimensional governing equations. The surrogate fuel that is composed of seven alkanes is proposed to improve the evaporation simulation of diesel oil. The results show that good agreements of dilution ratios at different injection timings are quantitatively obtained between the experiment and the simulation.

Novel approach to reduce Diesel engine emissions by using several kinds of mixing fuels with relatively low injection pressure is proposed. In the mixing fuels, additives or lower boiling point fuels, such as CO2, gas fuel and Gasoline component, are mixed into higher boiling point fuel such as Diesel gas oil, through vapor-liquid equilibrium with a formation of two-phase region in pressure-temperature diagram, where liquid and vapor phases of both components are mixed in. In this scheme, we intend to control both physical process, that is the fuel vapor formation rate or spatial vapor distribution, and chemical processes, those are the mixture ignition, emission reduction of NOx and PM, and HC burn out.

The purpose of this study is to clarify the relationship between solder cracks of power modules and thermal resistance as an indicator of heat radiation. We conducted thermal transient analysis of the power module by measurement and calculation, and improved the calculation accuracy by considering the anisotropic heat conduction of single crystal silicon.

In important structures, welded join stiffeners area used as crack arrester. Dependence of crack arrest effect on sheet thickness is required for safety design and maintenance of huge structure. In this study, 2D moving finite element analyses to simulate crack propagation in the specimen with welded join parts. These numerical simulations are operated as generation phase simulation based on the experimental results. Fracture resistance during dynamic crack propagation is discussed from numerical results.

To investigate the effects of oxide layer on fatigue crack propagation properties, fatigue tests in about 500-nm-thick copper films with a thickness-controlled oxide layer and without an oxide layer were conducted. Specimens with native oxide layer with a thickness of about 2 nm, those with thermal oxide layer with a thickness of about 20 nm and those without oxide layer were prepared. The results showed that fatigue crack propagation rate (da/dN) of specimens with thermal oxide layer was faster than of specimens with native oxide layer and without an oxide layer in higher ΔK and was smaller in lower ΔK.

Fatigue crack propagation test was performed on a compact tension (CT) specimen of pure iron polycrystal. Misorientation angles from a reference matrix were estimated along a line perpendicular to fracture surface with a help of the EBSD technique. The misorientation angles increased with decreasing distance from fracture surface: fatigue crack propagation should induce lattice rotation locally near a crack tip. The lattice rotation was small near the flat fracture surface where a fatigue crack was grown along a single slip band. In contrast, large lattice rotation was detected near the fracture surface having a zigzag shape.

To conduct elasto-plastic fracture toughness evaluation in submicrometer-thick metallic films, we evaluated the elasto-plastic properties of ~500-nm-thick freestanding copper films by tensile experiments using micro specimens. The micro specimens having micrometer-scale in-plane dimensions were cut out from a freestanding film by using focused ion beam. In situ field emission scanning electron microscope tensile experiments were performed, and the result showed that elasto-plastic properties including high stress/strain region were successfully evaluated by this method.

The applicability of the fracture mechanics criterion to micro-components with different interface free-edge shapes is studied in detail. Quantitative fracture tests using silicon (Si)/copper (Cu) interface are conducted in an electron microscope. It was found that the fracture strength expressed by stress intensity factor K was unique regardless of the outer shape of specimen, and the conventional K-λ criterion for different free-edge shape was also confirmed. The effect of gaseous environment on fracture strength was found to be different for specimens having different interface free-edge shape.

Steel plates used in electric equipment are often processed into each parts by shearing. Although the shearing process has high mass-productivity, fatigue properties of the sheared parts are known to be bad. In contrast, in laser processing, a high quality processed surface can be obtained, and the fatigue properties are expected to be good. In this study, fatigue tests were performed using laser-processed specimens, and the fatigue crack initiation and propagation behavior were investigated.

ZK60A Mg alloy was processed by ECAP and then annealed. In monotonic tensile tests, the samples processed by 2-pass ECAP revealed the highest tensile strength. The low-cycle fatigue tests were conducted under a constant plastic strain amplitude of 2x10^-3. Fatigue cracks of the ECAPed samples were initiated along shear bands, while fatigue cracks were initiated at the edge of deformation twin and slip bands in the as-extruded samples. In the ECAPed and annealed samples, fatigue cracks were nucleated frequently along grain boundaries. The crackings along the shear bands were suppressed by the annealing after the ECAP processing.

The time-dependent crack initiation from the interface free-edge of adhesively bonded butt joints (epoxy/SUS) was investigated in detail. A clear time-dependent relation between nominal stress, σ_n, and time to crack initiation, t_c, was obtained experimentally. The local stress/strain distribution was evaluated by FEM. It was found that the combination of two parameters, λ_e^cr (creep strain singularity index) and K_e^cr (creep strain intensity factor), satisfies a unique relation irrespective of the (σ_n, t_C) condition and the free-edge shape.

In order to clarify fracture strength of the single crystalline metallic nanowires having a notch, we conducted tensile test. A notch was introduced to aluminum nanowires with a diameter of ~200 nm by using a helium ion beam. The tensile test on the smooth specimen showed that the fracture strength was higher than bulk materials due to size effect. The tensile test on the notched specimens showed that fracture occurred at the notch, and the fracture strength decreased as the notch depth increased.

When a defect (initial crack) exists near high speed collision point, fracture caused from the initial crack shows complicated crack propagation behavior. In this research, we study the crack propagation phenomenon under eccentricizing the striker collision loading, Non-straight-line fracture behavior is observed by using a high-speed camera, in which recording the experimental results such as the crack propagation start time and crack propagation velocity.Based on the results of numerical simulations, the transition of fracture mechanics parameters is derived and discussed.

In this study, an effect of high-pressure H₂ gas on tensile and fatigue properties of high-strength spring steel ITW^® SWI-200 were investigated by means of the internal high-pressure H₂ gas technique. By comparing the test results obtained under H₂ and ambient air environment, the effect of H₂ on this materials were investigated.

High carbon steel like S55C shows high tensile strength without additional expensive elements. However, S55C is difficult to apply arc welding process. Here, Linear Friction Welding (LFW) is expected for application to S55C welding, because LFW is suitable for control of maximum temperature at joining process. Then, the effect of welding conditions on fracture toughness in LFW joints is studied. It was clarified that high applied pressure improves fracture toughness.

To investigate vacuum effects on the mechanisms and strength of fatigue crack initiation in submicrometer-thick freestanding copper (Cu) films, fatigue experiments were conducted on roughly 500-nm-thick freestanding Cu film specimens with a single side edge notch inside a field emission scanning electron microscope (FESEM). Grain boundary and twin boundary ahead of the notch were identified by electron backscatter diffraction (EBSD) analyses. Local stress distribution was evaluated by three-dimensional elastic finite element method (FEM) analyses, take account of the grains and twin boundaries around the fatigue crack initiation site.