Railway, opening in 1825 for the first time in the world, has developed with influences of technology innovations and social situations. This article looks back the development and considers the relation among the development, technology innovations and social situations.
Wind Turbine Generation is considered to be the most reliable approach to the renewable energy, on the point of its reality. In this paper, various types of the innovations relating to its industry are discussed based mainly on some statistics data.
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 idling spindle rotation, boring and milling and investigate the machining performances among different machine tools. As a result, we demonstrated that the developed method with a wireless system is effective to evaluate the dynamic performance of machine tool during cutting.
It is demanded that the next-generation turning centers achieve process integration of cutting of complex-shaped workpieces, mainly cylindrical ones; heat treatment; and finishing. Laser hardening especially gains attention as a process integration technology for in-situ heat treatment. On the other hand, as the heat capacity of thin-wall cylindrical workpiece is small in the off-plane direction, highly sophisticated techniques are required to develop a laser hardening method with the self-cooling function. In this study, we developed a method for finding appropriate laser irradiation conditions by carrying out both FEM simulation and experiments using line-focused laser beam, and investigated its application to harden gear tooth surface.
In this report, we focused on three - dimensional deformation of laser quenching forming and its prediction and control method. Therefore, in order to fabricate strain-less objects, we proposed a constraint condition as one of methods to reduce deformation. Experiments were conducted to compare unconstrained conditions and constraints. As a result, it was possible to suppress the deformation in the constrained condition and to prevent the reversal of the deformation which was one of the problems. Also, under the constraint condition, it was effective to make strain-less things because it was able to produce small distortion.
In this report, we used the machining center and a rotational permanent magnet tool to process the surface of non-magnetic brass withmagnetic polishing method. And then, we considered the finished surface roughness with surface roughness measuring instrument, we also used precision electronic balance tomeasuring polishing amount of the workpiece due to the difference in the proportional distribution of the polishing paste composition. Finally we used a force sensor to examine the abrasive forcedue to the difference inpolishingtool. In conclusion, it has been clarified that it affects the polishing effect by the amount of iron powder.
The design and operation of distributed cogeneration systems may affect electricity supply by electric power companies and decrease the load factor for power generating facilities of electric power company. The time-of-use pricing of electricity is one of the effective approaches to keep the load factor as much as high. In this paper, a bilevel mixed-integer linear programming method is applied to analyze the cooperative relationship between power utility and cogeneration systems through time-of-use pricing. Through a basic case study, it is shown that the load factor for the power utility system can be kept high through appropriate time-of-use pricing.
This study proposed a production management system in companies that take high-mix low volume production. This system is composed by two subsystem. One is medium range scheduling planning system by proactive scheduling method with introducing dummy jobs. Result of case studies show the other is short range reactive scheduling system that is used on operation phase to cope with urgent job. Feasibility of the system was shown by case studies.
It is emphasized in general that the explanation for how the human feels the impression from the shape of the object is dependent on their individual sense. There are, however, also objective aspects, e.g., mechanics rationality, within that impression. We have hypothesized that the human intuitively sees the load level on the object in their mind and proposed a concept of “expression in mechanics sense”. In this article, we discussed the methodology to reveal a concept of “Mechanical Kansei” that is the capability of the human to recognize the shape in the mechanics sense through the case study.
We have developed a small size and high strength spiral bevel gear fabricated by 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 on the bending stress at the curved tooth root and demonstrate the effect of rib reinforcement at the proposed spiral bevel gear.
As a result, a novel guideline is found to design the small size and high strength spiral bevel gear with the rib at the end of face width.
The authors continued research on improving the precision of screw by deriving radial force (back force) using four-component piezoelectric dynamometer by thread cutting by helical interpolation motion using thread mill I came. In this manuscript, the accuracy of the screw when newly changing the hardness of the work material was discussed. In addition, by recording the position information at the time of thread cutting from the servo guide on the data logger using the analog cable, the relationship with the cutting force of the four components is confirmed, and the radial force (back force) Were confirmed by different methods, and consistency was confirmed.
In order to suppress the vibration during thin-walled part machining, a pivot support has been investigated. The support has two rollers that make contact with workpiece and fit to the workpiece surface. This paper presents the effect of contact length and contact force on vibration suppression performance.
Industries and economies develop together with external factors such as social matters and technological developments based on inherent logic structure. In this study, we focus on the advancement of vapor compression refrigeration cycle technology, which has greatly contributed to the development of air conditioning equipment, which is one of the products that has been rapidly spreading mainly in emerging countries. Then, by overviewing the history of the technology, we examine the relationship between technological innovations of air conditioning and economic development.
This paper aims at describing attractiveness of high temperature material researches. A definition of high temperature in the researches is firstly introduced and attractive key points of the researches are presented next. Application areas of the researches, which spread over the wide range of materials and their mechanical behaviors from ice glacier to gas turbine engine blades, are explained. Finally, topics of recent high temperature R&D researches are explained.
This paper discusses the primary challenges associated with manufacturing industries in Japan in the era of digitalization. Based on such challenges, it aims to address some prospects with regards to policies and enabling technology that combines cyber-physical systems and intelligent activities by engineers working at factories, which is the strength of manufacturing in Japan.
To clarify the creep crack propagation mechanism of submicron gold films, we conducted creep crack propagation experiments using in situ FESEM observation and EBSD analysis in Au freestanding films with 300 nm and 100 nm thickness. In the experiments, void nucleated along grain boundaries, regardless of the film thickness. In 300 nm-thick films, transgranular fracture accompanied by necking-like deformation were observed in the entire region. In addition to the same mechanism as 300 nm-thick films in 100 nm-thick films, there were regions where void growth and crack propagation occurred via grain boundaries without necking-like deformation.
In order to investigate the creep properties of submicrometer-sized material, we conducted long-term creep experiments for submicrometer-thick single-crystal Au thin film under in situ FESEM observation. At low stress, the creep strain was induced by intermittent strain burst. On the other hand, at high stress, the creep strain continuously increased with an increase in time.
Recently, the application of indentation test has been attempted as a method for investigation of creep property. It is because indentation test is efficient and small size of specimen is enough to be tested. This research aims to develop testing system for evaluation of creep property by indentation test. Two testing machines are developed according to testing materials; solder and heat-resisting steel. The other is the improved version of the testing machine for heat-resisting steel. The performances of the three testing machines are investigated.
This study discusses a method for the evaluation of multiaxial creep remaining life of a Mod.9Cr-1Mo steel and SUS304 steel based on the creep life of samples obtained from components subjected to multiaxial creep damage. Experimental multiaxial creep tests were carried out to demonstrate whether the remaining life can be evaluated with the linear cumulative damage rule even for multiaxial creep damaged material. Equi-biaxial tensile creep tests were carried out using a cruciform specimen up to half of time to rupture. Subsequently, miniature specimens were cut out from the specimens, and a uniaxial creep test was performed. The results suggested that the linear cumulative damage rule is not suitable for the evaluation of remaining life of component which underwent multiaxial creep damage.
To investigate the effects of surface oxide layer on fracture toughness of freestanding submicrometer-thick films, we conducted in situ field emission scanning electron microscopy (FESEM) fracture toughness tests in roughly 500-nm-thick Cu films with nanometer-thick oxide layer. We prepared three types of specimens; native oxide specimens, thermal oxide specimens (oxide layer thickness: 5.9 nm), and oxide removal specimens. In all specimens, the critical crack tip opening displacement (CTOD) for crack initiation was evaluated on the basis of FESEM micrographs. Oxide removal specimens have larger critical CTOD than native oxide specimens and thermal oxide specimens.
Cyclic load is applied on a thin film comprising of copper helical nano-elements which is fabricated by glancing angle deposition technique in order to investivate its fatigue strength. The thin film does not fracture at 106 cycles in strain range of 9.2×10-2, which is 30 and 90 times higher than the fatigue strength of Cu solid thin film (grain size: 1000 nm) and bulk. This fatigue strength is caused by the increase of allowable strain due to the nano-element shape and the improvement of material strength due to small grain size.
For the purpose of elucidating the tensile and fatigue properties of the submicrometer-thick single crystalline copper thin film, in-situ FESEM observation of tensile/fatigue test was performed on a micro specimen having an in-plane dimension of several μm cut out from a freestanding single crystalline copper thin film with a film thickness of about 350 nm. As a result, reproducible tensile property evaluation is obtained, and it is clarified that the fatigue strength of the submicrometer-thick single crystalline copper thin film is increased compared to the single crystal copper bulk material.
Reliability of the hydrogen tanks and accumulators, used in fuel cell vehicle as instance, have to be strictly ensured due to the huge hazards inherent to high-pressure hydrogen. Thus, it is necessary to understand the influence of hydrogen on the metallic materials’ strength to establish safety this type of mechanical parts. Previous studies underline the heat treatment influence on the hydrogen sensitivity of SCM 435 properties. In this study, 4-point bending fatigue strength and evaluation of notch sensitivity on the fatigue limit of heat treated SCM435 low alloy steels are carried out under high-pressure hydrogen gas environment.
The dissipated energy was measured for FSW and FSW with polishing during fatigue tests and the relationship between fatigue strength and dissipated energy was investigated. Compared with FSW, the dissipated energy of FSW with polishing was lowered due to surface roughness of the welding zone. The increase in dissipated energy of FSW was related to fatigue strength.
This study discusses creep-fatigue strength of Mod.9Cr-1Mo steel at 823K to develop the method of life prediction based on linear cumulative damage rule for creep-fatigue. Fatigue tests with different strain rate were carried out using hollow cylinder in order to investigate the effects of strain rate and stress. In addition, evaluation of creep-fatigue properties was carried out considering the influence of stress relaxation during holding time. In this study, holding time were 3 and 10 minutes with tension hold. This material was almost not affected by the creep damage with tension hold for 3 minutes.
In this research, a testing machine which can apply impact cyclic tensile loads by a freefall striker to smooth specimens was constructed, and the dynamic low cyclic loading tests were performed to clarify the influence of strain amplitude and number of cycles to fracture to their fracture transition modes of SS400 and SUS316.As a result, it is found that fracture modes are necked-out type and fatigue type fracture in SS400 and SUS316.it is also found that fatigue type fracture of SS400 was observed in higher number of cycles than it of SUS316. From these experiment results, we considered the cause.
The time-dependent crack initiation from the interface edge of adhesively bonded butt joints(epoxy/SUS) was investigated. The crack initiation life, tC, was found to vary about four orders of seconds with the change of applied stress, σn. Then, the near-edge stress/strain field at the crack initiation was evaluated by applying the time-hardening creep law to the epoxy resin. It was found that the strength was uniquely represented by the combination of singularity index (λ) and singularity parameter (K) of total normal strain (εyy) irrespective of the (σn, tC) condition and edge shape.
The behavior of an End Notched Flexure (ENF) specimen subjected to impact loading was investigated by transient finite element analyses. Finite element results showed that crack propagation behavior and fracture toughness are identified correctly by measuring strain distribution transient near crack tip even specimen subjected to impact loading. Furthermore, the mode II fracture characteristic of Zanchor reinforced composites was studied experimentally using the technique that proven by numerical analyses.
Evaluation error of energy release rate that caused by deformation by shearing force in ENF tests was minimized by proposed method. The exponent of mode II fatigue crack growth curve in adhesively bonded joints that used brittle adhesives is smaller than used ductile adhesives. Microscopic fracture morphology of brittle adhesive was not depend on crack growth rate, however, ductile adhesive depend on that.
Steels have been applied for many machine structures, and strength and heat resistance of that materials are required more recently. The purpose of this study is evaluating and comparing the fatigue damage of the low alloy steel castings which changed the addition quantity of Vanadium to improve the strength and the resistance or gave heat damage. In this report, tensile fatigue testing was done and fracture characteristics of that materials were researched with AE method. As the results, the effectiveness of Vanadium about the strength of that materials affected by heat was confirmed by Chaos analysis results of AE signals.
The applicability of the active pulse echo method to defect identification was investigated. In this method, ultrasonic waves are activated by applying an electric pulse to the piezo film and waves reflected at crack tip are received on the piezoelectric film. The influence of the probe arrangement on the crack identification was investigated. The method was applied to actual data. The effectiveness of the method was confirmed.
The interest for a wider range of usable materials for the technology of Selective Laser Melting (SLM) is growing. In this study, the manufacturing of AC8A parts using SLM technology was systematically investigated. The effect of processing parameters on the density of the fabricated AC8A specimens was studied. It shows that the laser energy density plays a significant role in the densification behavior of the AC8A powder during the SLM process. The laser energy density value of 100 J/mm3 is found to be the threshold, above which high density specimens without imperfections and cracks can be obtained.
Thinning of a die-cast heat sink is required to meet weight reduction demands by automakers. Our laboratory focused on the property of Al-25%Si that it is hard to solidify, and produced thin walled heat sinks, which are said to be quite difficult to manufacture. Using ADC12, the fin tips of thin walled heat sinks were unfilled. This result made us think that various alloys have a difference in filling and we investigated the relation between aluminum types and the condition of the fin tips. The result showed that whether the temperature of molten metal in mold can be maintained or not was most important factor, not the alloy types.
Ripple marks are generated on the lower roll surface of the Al-Mg alloy strip produced by the twin roll method, and porosity is generated in the final solidified part. At the solidification distance of 100 mm, many ripple marks occurred at the roll speed of 20 m/min and roll load of 16 N/mm. By cladding with an alloy other than the Al-Mg alloy that has a higher solidus temperature than the liquidus line of the Al-Mg alloy in the 2nd layer and the AlMg alloy in the 1st layer, the formation of porosity was suppressed.
The effects of projection conditions on the fatigue characteristics of stainless steel were investigated. In the peening process, the equipment was used an ultrasonic peening machine. The surface hardness data showed that the surface hardness increased slowly with the projection time. The rotary bending fatigue tests were carried at a frequency of 3150 cycles/min. Improvement of the fatigue strength was observed by USP treatment, because a work-hardened layer was formed deeper in the material.
In this study, in order to effect of process parameters on residual stress distribution, cantilever test and numerical analysis was carried out. These results shown the scan pattern is effect on residual stress distribution and deformation. The hatch size was important parameter because that become larger, the deformation and residual stress reduced. And, in numerical analysis result showed shorter hatch size occurs big residual stress. It is thought that the hatch was shrinked like one bead because as hatch size be shorter, laser moved fast and make a round trip.
In this study, the microscopic maximum stress observed in heterogeneous materials are estimated by image recognition using machine learning. Especially, unidirectional fiber-reinforced composite material considering random fibers arrangement under a transverse direction load tensile is considered as a target material. The image data of the microscopic stress distribution is employed as input data. Effectiveness of the presented approach is discussed with the numerical results.
Nonlocality is one of the undiscovered mechanical behaviors which is determined at any material point and is also affected by the local surrounding around it. To model this effect, the gradient term or the additional degree of freedom at the material point has been supplemented theoretically. Micromorphic body adopts the additional deformation gradient tensor of the material point. In the present research, the homogenized structure consisting of the orthogonal lattice framework with the micromorphic beam was investigated using the two-scaled homogenization finite element method. The results suggest the clear size effect and the possibility of the macroscopic characteristic length.
66-Nylon materials are used in a variety of fields such as building materials and electronic devices. Although it is well known fact that flow stresses of most engineering materials including polymers are affected by strain rate, their mechanical property, especially strain rate dependence, is not investigated enough. Modellings of these strain rate sensitivities of materials are, therefore, very important for the analysis and design of mechanical parts and structures that are used under various strain rates.
The purpose of this study is to investigate the influence on interfacial properties between matrix and carbon fiber by imparting polarity of matrix of CFRP. It was found that interfacial properties were improved by imparting polarity of matrix, because the bridging was promoted between matrix and carbon fibers.
There are many mechanical factors which affect fatigue strength of materials. However, studies on the influence of strain rate on impact loading are not enough. In addition, when fatigue fracture causes in a machine or a structure, its initiation points at the shape changing part. From the viewpoint of these, our purpose is to experimentally clarify how the strain rate and shape changing portion affect the material strength. As a result，we derived empirical formulas on impact loading of SS400 steal and clarified their coefficients.
We proposed a new reinforcement layer for CFRP bolted joints C layer and R layer that is in accordance with maximum stress and minimum stress. And tried to elucidate their reinforcement effect. C layer has the effect of increasing the ultimate bearing strength because of the hoop effect. C layer has the effect of reinforcement for shear failure mode. R layer has the effect that is to weaken the stress caused by initial bearing stress and ultimate bearing stress when broken by bearing failure mode.
This study investigated the influence of molding atmosphere condition and temperature condition on the change of mechanical strength of CFRTP fabricated with MXD10. In vacuum condition, interfacial strength between carbon fiber and resin was improved due to molding with high temperature. It was found that interfacial strength was improved even if molding temperature was elevated. Vacuum condition is effective at molding to improve interfacial strength even when the molding temperature was elevated. In that case, effective condition on temperature was appeared to obtain the maximum improvement.
Bolted joints are widely used in constructing machines and structures. Many cases of troubles, such as loosening and fatigue failures, have been reported. It is important to prevent loosening of bolts in order to ensure machine safety. In this study, about the embedment that the plastic deformation of the microprotrusions existing on the contact surfaces of plate progresses and the bolt force decreases, it was examined the effects of grip-length, position of plate surfaces and the number of contact surfaces on embedment. In addition, based on experimental
The objective of this study was to reveal the improvement effect of the fatigue life on the metal-CFRTP bolted joint by the additional heat pressing. The fatigue life of metal-CFRTP bolted joint was improved due to the prevention of crack propagation around the hole by the additional heat pressing, if the cyclic loading level is so low that fatigue was extended over about 10^5 cycles. The additional heat pressing during fatigue was effective for repairing the CFRTP joint damaged at early stage of the fatigue.
In this study, we propose the polyhedral block structure with negative Poisson's ratios in the in-plane and out-of-plane directions, which is created by reference to the orthotropic open-cell structure developed in our previous research. We formulate the two types of the structural model with a single and two degrees of freedom, and analyze mathematically and numerically the equilibrium paths as a function of the two geometric and rotational parameters in order to evaluate their mechanical properties including three-dimensional auxetic effects.
This study describes a simulation method to estimate structural failure probability using “all quadrants sampling method” and the variance reduction techniques of “partition of the region.” Every time a real sample point is generated in a certain quadrant, pseudo samples corresponding to the real sample are determined in all other quadrants by applying previously proposed “inter-quadrant relational expression.” By using all of real and pseudo samples in the estimation of the structural failure probability, the sampling efficiency is increased. Numerical examples to estimate the structural failure probability show that the proposed method gives accurate estimations efficiently.
Multiphysics wave propagation among thermal conductivity, elasticity and electricity fields was investigated with the emphasis on thermal relaxation and coupling effect. Dimensionless equations of the three multiphysics governing equations are formulated and the effect of dimensionless parameters related with thermal relaxation and coupling coefficient was surveyed systematically. As a result, due to the coupling with the stress field, the thermal conductivity driven by the hyperbolic (wavy) or the parabolic (diffusive) property was more strongly affected by the thermal relaxation time. In addition, the coupling coefficients have a large influence on the repartition of the energy between the temperature and the stress fields. On the other hand, the contribution from the electric to both fields is not dominant by these parameters.