Structures such as ships are produced through cutting, forming, fitting, welding and straightening processes. Since most of these are thermal processes, distortions and residual stresses are produced as inevitable consequences. In this report, computational methods for industrial applications to predict distortions and residual stresses produced by various thermal processes are presented.
The conference party of mechanical engineering in JSME Kansai branch proposed a historical view of human technology that technologies developed by external factors such as society and economy, and the logic structure inherent in the technology, resulting in growth of industry and economy. In this paper we focus on technology of ships and examined the influence of technological innovations on industry and economy from the trend of annual shipbuilding tonnage.
Innovations in Technology of Aircrafts and their Development into Industry were studied. Firstly, the history of innovation on aircraft technology and industrial application was investigated. Secondly, the number of military aircraft and commercial aircraft manufactured after the 19th century were confirmed. Compared to the macroscopic economy of the United States, Western Europe and Japan, the effect of the aviation industry on the social richness was discussed. As a result, it became clear that the aviation industry has a high possibility of affecting the macroscopic economy of GDP since 1975 until today.
This paper presents multi-functional OCT, i.e. Dynamic Optical Coherence Stressgraphy (D-OCSE), Dynamic Optical Coherence Straingraphy (D-OCSA) and Optical Coherence Thermoghraphy (OCTH), which can diagnose mechanical properties of polymer matrix materials tomographically. In this study, the proposed system was constructed, and the validation experiment was carried out. Consequently, micro-tomographic distribution of stress & strain rate as well as temperature can be measured simultaneously and non-destructively. It was, therefore, concluded that D-OCSE & D-OCSA and OCTH could provide micro-mechanical information experimentally like FEM analysis, which is a fracture diagnosing tool of polymer matrix materials.
Gas-turbine combined-cycle (GTCC) power generation is clean and efficient, and its demand will increase in the future from the economic and social perspectives. Raising turbine inlet temperature is an effective way to increase combined cycle efficiency. However, increasing turbine inlet temperature can lead to the increase of NOx emissions. To deal with this issue, MHPS (MITSUBISHI HITACHI POWER SYSTEMS) have developed Dry Low NOx (DLN) combustion techniques for high temperature gas turbines. Fuel flexibility is one of the most important features for DLN combustors to meet the requirement of the gas turbine market.
Investigation for effects of fuel gas composition on knocking tendency in gas engines revealed that addition of hydrogen and carbon dioxide with a same volumetric amount to methane showed no impact on the knock resistance of the ternary-component fuels. This is due to the fact that positive and negative effects of hydrogen and carbon dioxide addition on knocking tendency cancel out each other. Furthermore, results of chemical equilibrium calculations showed that selective steam reforming of heavier hydrocarbons in natural gas is effective to suppress knocking due to change in gas quality.
We assume scenarios to test our hypothesis; that is, the integration of waste water treatment plants (WWTPs) and incineration plants would enhance the whole energy efficiency of the two plants. We proposed a method for modeling WWTPs and incineration plants as a sequence of processes. By assuming two scenarios (i.e., status quo scenario and integration scenario), we evaluated the effect of the integration of WWTPs and incineration plants from economic and environmental viewpoints. The results revealed that the integration was effective in reducing economic cost and CO2 emissions.
With the two-stage combustion method being utilized in practical combustors, inverse diffusion flame is formed as secondary combustion air is blown into fuel atmosphere. An experimental study is conducted in our research to investigate lifting behavior of the inverse diffusion flame formed in the secondary combustion region. As a representative of behavior of lifted flame, lift-off heights of lifted flame in varying by dilution conditions are measured and compared to investigate effects of dilution gas addition to secondary oxidizer. We choose N2, CO2 and H2O as the dilution gases.
A detailed reaction mechanism for five-component gasoline surrogate fuels containing isooctane, normalheptane, isooctene, methylcyclohexane, and toluene, consists of 1759 species and 5799 elementary reactions. Ignition characteristics for regular gasoline were simulated with the mixing fractions of 0.238247, 0.199032, 0.121247, 0.053173, and 0.38830 for isooctane, normalheptane, isooctene, methylcyclohexane, and toluene, respectively. Reaction paths during ignition process for each component were analyzed with the initial temperatures of 650 K, 850 K, and 1100 K located in the cool-flame dominant, negative temperature coefficient, and blue-flame dominant regions, respectively. Based on full knowledge derived from the reaction path analysis, a skeletal reaction mechanism for regular gasoline consisting of 46 species and 80 reactions, was developed and validated. Ignition delay times with initial temperatures between 600 K and 1200 K using the skeletal mechanism, agree well with those using the detailed mechanism.
In order to improve the combustibility of ammonia fuel, plasma assisted combustion by using the dielectric barrier discharge (DBD) was experimentally investigated. Particularly, effects of the superposition of DBD on the unburned premixed gas were evaluated by measuring the laminar burning velocity and the emission spectra from DBD and the flame. Results show that the laminar burning velocity was increased as the frequency of DBD became higher and the DBD superposition time became longer. In addition, it was found from the emission spectra that ammonia was decomposed and intensity of OH chemiluminescence was increased with the superposition of DBD.
For the purpose of measuring turbulent burning velocity of methane/hydrogen/air premixed flame at high pressure, experimental systems were established which hold stable turbulent combustion at high pressure. Optical measurements below were applied to turbulent flames. Two-dimensional number density distribution of OH radicals near the flame, the image of which is sufficient to reflect the reaction region of the turbulent premixed flame, was measured by using OH-PLIF. The average flame structure can be estimated from the accumulated image of OH-PLIF. By extracting the inclined flat flame region excluding the tip and root of the flame, the turbulent burning velocity was calculated.
For obtaining the data that contributes to propose detailed chemical reaction mechanism including the evaporation process of the liquid fuel, experimental study of counterflow pool combustion was conducted. The double flame that is known as a feature of Monomethylhydrazine (MMH)/Nitrogen Tetroxide (NTO) non-premixed flame was formed in this experiment. With respect to the counterflow pool combustion of MMH/NTO in this study, we carried out the high speed shooting and chemiluminescence measurement. The results obtained by the experiments were compared with the numerical simulation with OPPDIF/CHEMKIN-Pro. Results showed good agreement with experimental results in combustion area.
It was difficult to install auto-steering system for agriculture in the rice transplanter because of its high cost. We focused on the possibility of standard precision GPS, which can maintain the required precision for transplanting if it takes a short time. Today, we developed "straight keeping system". It realizes steady high-precision operation on any condition without complicated settings, even with inexpensive and standard precision GPS.
Karman vortex shedding occurs when the gas passes through the duct with tube bank of the heat exchangers, such as gas heaters and boilers. Very high level sound in called “self-sustained tones” occurs due to the interference of the vortex and the sound field in the duct. In general, baffle plates are used to suppress the self-sustained tone. However, it is difficult to use them effectively, because insertion conditions have not been established. Then, perforated plates are installed in both sides of the duct to suppress the self-sustained tones. As a result, it was clarified that the perforated plate could suppress the self-sustained tone as expected. This paper aims to clarify the role of the perforated plates when it changes the acoustic natural frequency of the duct. In this study, one dimensional duct will be used for simplicity and the relationship between the aperture ratio and the acoustic natural frequency will be obtained analytically and experimentally.
This paper describes optimum values of a circuit and an additional vibration system for energy harvesting using electromagnetic induction or the piezoelectric effect with considering the vibration characteristics of vibration sources. When the mechanical impedance of the additional vibration system is significantly smaller than that of the vibration source, the vibration characteristic of the vibration source is negligible. However, in certain cases, the mechanical impedance of the additional vibration system is not significantly small. Therefore, the optimum values for such cases were formulated in this study. The effectiveness of the optimum values was verified through simulations.
In this study, the optimization of supporting of the piping system by using elasto-plastic damper based on the dynamic reliability is considered. First, an analytical model of an L-type cantilevered piping system with weight at the top end subjected to seismic input was derived, considering the nonlinear characteristics of the elasto-plastic dampers. Seismic input was modeled as white Gaussian noise. The vibration behaviors were calculated for various seismic inputs. After that, the complex evaluation indices, which consist of the dynamic reliability, the energy absorption ratio, and the balance of energy absorption, were derived for optimization of supporting.
This paper considers the optimal design of double-mass dynamic vibration absorbers (DVAs) attached to an undamped single-degree-of-freedom system for minimizing the mobility transfer function (velocity output / force input). The author previously performed similar optimization on the compliance transfer function (displacement output / force input). Three different optimizaiton criteria (the H∞ optimization, H2 optimization, and stability maximization criteria) were considered for the design of the DVAs.
Dynamic FE analysis is valid for designing rotating machinery to reduce its vibration. So the accuracy of the analysis is required for this purpose. Multiple objective optimization method is available for structural identification improving the FE analysis model to adjust the natural frequency analysis results to the experimental results. In this study the structural identification method is applied to a stator coil of a turbine generator to determine the Young's modulus of the insulation components minimizing the analysis errors of the natural frequencies to the corresponding experimental results. The accurate FE model of the coil is obtained by this method.
For mechanical structures, it is important to prevent the self-loosening of threaded fasteners, but there are unclear points about locking performance under small transverse vibration. In this paper, we experimentally examine the performance of some locking fasteners, and we found that almost all the parts preventing loosening are reduced bolt tension little by little under small transverse vibration, while bolted joints using spring washers or conical spring washers are no effect of preventing loosening under small transverse vibration.
The design process is highly dependent on individual sensibilities in general. There are, however, also implicit objective factor in this process, such as physical rationality. In order to support the design, revealing the connection between the sensory- and the objective-factors is a key. We focused on the process providing the impression from the product shape, and proposed a concept of “expression in mechanics sense” by means of the spatial pattern of stress level that might be implicitly perceived by human. The term of expression is a metaphor of human facial expression. Finally, in order to collect the various impressions, we showed the scheme to synthesize the various shapes that can even provide the negative impressions.
In the present report, we focus on screw cutting performance by three axis controlling helical interpolate motion with a machining center. A thread mill tool is used to perform the screw cutting. We measured the cutting forces and the cutting torque in screw cutting, and proposed a novel method to derive the radial force component from the measured ones. As a result, it could be seen that the machined accuracy was discussed based on it.
The magnetic abrasive finishing (MAF) process is well known because of its high efficiency in yielding a mirror gloss finish zone. However, this process yields unevenness, which is often evident on the workpiece surface. So in this paper, we observe the characteristics of the polishing force and contact condition for these three different iron particle shapes and for different particle numbers, using a force sensor and a high-speed camera. The relationship between the particle shape and the polishing force is also explored in an attempt to construct a predictive model for the polishing force. It is found that the force variation can be reduced by adjusting the particle shape and number, which effectively reduces the damage caused when the brush approaches the workpiece surface.
We have developed direct drive motors for rotary axes of machine tools by the quality engineering and FEM analysis of electro-magnetic field. As a result, findings on how to design a large-torque and low-torque-ripple motor is obtained. By using findings, we designed a motor for a spindle axis of a machine tool, and moreover we considered how to design a high-speed motor with higher torque at low speeds than induction motors. In this paper, by comparing a newly designed motor for a spindle axis to already developed motors for rotary axes, we attempt to consider motor characteristics and design methods.
Various fine patterns by chasing were sculptured to a copper plate by a non-rotational cutting tool using a 5-axis machining center. The 6th axis control was installed for rotation control of the spindle in the machining center. In this paper, out of the chasing technique, a consideration result by a force cut method for the traditional “KEBORI” technique using the 6-axis machining center was reported.
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 tooth width to reinforce the tooth bending strength, which is machined with a ball-nose end-mill tool. We investigate the influence of the rib shape on the bending stress at the tooth root and the tooth deflection and demonstrate the effect of rib reinforcement at the proposed spiral bevel gear. As a result, a guideline is found to design the small size and high strength spiral bevel gear with the rib at the end of tooth width from a view of rib shape.
We developed a wireless multifunctional tool holder system to monitor the processing vibration of a rotating machining tool. This report presents an estimation of the processing vibration at tapping and end-milling. We succeeded to monitoring the vibration of the stick-slip at tapping and the chatter vibration at end-milling by using this holder system. As a result, the developed holder system is found to be effective to estimate the machining conditions with a machining center.
Aiming to enhance functionality of titanium cup, the formability of titanium/mesh/titanium laminated sheet by deep drawing was investigated. In the experiment, the materials were pure titanium and stainless steel mesh. The laminated sheet was constituted by interposing mesh between two titanium sheets. Each sheet in stacked condition was not joined each other. In the deep drawing process, the laminated sheet was employed and a flat sheet blank was formed into a circle by a punch. The deep drawing was carried out to investigate the formability. The laminated sheet was successfully drawn without the cracks.
The fatigue improvement of titanium alloy by microshot peening and ultrasonic peening was investigated. In the peening process, the equipment were used an air-type machine and ultrasonic peening machine. The microshot used were high-carbon cast steel with an average diameter of 0.1mm. The surface hardness data showed that, in the case of microshot peening, work hardening extended deeper than the mean diameter of the media. In addition, in the case of ultrasonic peening, 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 both treatments.
Orientation changes during the fatigue crack initiation process in ferritic steels with different grain size and ferritic-pearlitic steels with different carbon content were evaluated by the electron backscatter diffraction (EBSD). EBSD measurements and fatigue tests were alternately carried out using small specimen. Crystal rotations were evaluated by two misorientation parameters; Grain Reference Orientation Deviation (GROD) and crystal misorientation at the same point before and after fatigue testing (Δθ). Both parameters increased and then remained constant at crack initiation. The variation in GROD was approximately 0.1° and that in Δθ was 1.0 to 2.0° regardless of the grain size and the carbon content. Therefore, Δθ is more sensitive to orientation changes under cyclic loading.
It is investigated the rigidity improvement about thin aerogel non-woven composite insulator by orientation design of the non-woven fabric in the insulator by structural analysis. As a result, it was found that orientation affects the rigidity of the insulator. In addition, it was confirmed using the models that orientation does not affect thermal conductivity of the insulator by heat transfer analysis.
Ultrasonic testing is applied to evaluate cure degree of resin in GFRP laminates. Polymer based composites are widely used to repair aged structures in civil engineering because of their high specific strength and good corrosion resistance. In order to prevent inappropriate repair works, nondestructive inspection of resin cure after construction is required. In this study, GFRP laminates with cure distribution in the thickness direction is evaluated using ultrasonic waves, which is compared with surface hardness. It is found that frequency characteristics are more reliable as cure index.
Steady and transient CHF (critical heat flux) were measured in a platinum vertical samll tube with exponentially increasing heat inputs. A platinum test tube with an inner diameter of 1.0 mm and a length of 40.9 mm was used as test tube. The flow velocities (u=1.0～7.5 m/s),inlet liquid temperatures (Tin=300.04～357.28K), and inlet pressures (Pin=738.54～805.00kPa) were systematically measured by a forced convection test loop comprised of a multistage canned-type circulation pump with high pump head. The heat generation rate was raised with an exponential function, Q0exp(t/τ),where Q0(W/m3) denotes the initial heat generation rate, t(s) represents time, and τ(s) indicates the e-folding time,respectively. The e-folding time ranged from 33 ms to 20 s. It was understood that the CHF can be divided to three groups depending on the e-folding time. The CHF at a small e-folding time showed a higher value compared to that a large e-folding time.
The purpose of this study is to clarify compounds of a tar (a light tar and a heavy tar) in which are produced in a fluidized bed gasifier. In steam gasification of lignite, the tar generated in syngas was collected. The tar was analyzed by combination of gas chromatograph mass spectrometer (GC/MS) and field desorption mass spectrometer (FD-MS). On the FD-MS spectra, It was found that A rule based on structural formula of tar compounds was found on FD-MS spectra. By using of the rule, it was found that main tar components were polycyclic aromatic hydrocarbon (PAH) without functional group substitutions.
It is considered that the Nanofiber including the almost sub-micro order size fiber has unimaginable characteristics and effectiveness, such as specific surface area effectiveness, nano-size effectiveness, and molecular arrangement effectiveness, and is attracting attention as next-generation technology. In the present report, we investigated its various features, such as oil adsorption, sound absorption, thermal conductivity and gas adsorption features produced by stable mass manufacturing method for polymeric nanofiber, for which we initially used the modified melt blowing method. We also investigated the relationship between its fiber diameter and various features. As a result, it shows potential as a next-generation low cost high performance new material by utilizing in various industrial field.
In the previous report, we developed the chopsticks-type meal support system which improved operability using KINECT sensor. However, food shape is not only the round that is able to catch with chopsticks from which direction but also the long shape. And the function which grasp food shape from its video image by web camera and turn chopsticks to catch food from the long distance direction if it was the long shape was added to meal support system.
This paper present on minimum course search methods after discovering twin goals by double agents in a court overlapped partially two agent areas with functionality and hierarchical walls. Each agent cannot be passed original outside walls though they can pass the inner walls that have invaded each formation areas.
We studied how to improve blowing efficiency and reduce the weight of propeller fans for room-use air conditioners by eliminating the boss on the central part of the fan. We analyzed the effect of taking this approach, and the results showed that the lower rigidity causes structure-induced noise from the fan. Consequently, we designed the shape of the ribs on the central part of the fan by analyzing the airflow. The results showed that turbo-machinery ribs improved rigidity and efficiency. By applying the turbo-machinery ribs, we have succeeded in improving efficiency and reducing weight while maintaining an acceptable noise level.
We performed direct numerical simulation to clarify the relationship between heat transfer and flow feature of the intermittent flow in channel flow for transitional regime. The target flow is Couette flows at transitional region with/without stable system rotation in spanwise direction. The Prandtl number is 0.71 to assume air. We confirmed that the thermal fields well corresponded to the velocity fields. Appearance of the stripe makes the turbulent Prandtl number lower. As the turbulent region enhances friction and heat transfer, the temporal and spatial oscillations occurred.
We have investigated the sedimentation phenomena of a colloidal dispersion composed of spherical ferromagnetic particles using Brownian dynamics simulations. We have attempted to clarify the conditions under which all particles subside and the thin film is formed, by varying the applied magnetic field, magnetic force between particles, mass density, and temperature of solution. For strong magnetic force between particles, thin film formation is difficult, since the particles combined with each other to form clusters. Furthermore, the random force by Brownian motion is required for the cluster collapse and lead to thin film formation.
In a hydraulic system, physical properties of hydraulic oil can change together with operating condition, however, relationship with speed of sound in the oil which affects the dynamic characteristics such as pressure ripples has not been revealed. This study shows the factors and the influences of change of the speed of sound in agricultural and construction vehicles.