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Volume 80 , Issue 818
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New Developments on 2014 in the field of Design and Systems
  • Nozomu KOGISO
    Volume 80 (2014) Issue 818 Pages TRANS0283
    Released: October 25, 2014
    JOURNALS FREE ACCESS
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  • Hideyoshi YANAGISAWA, Kenji TAKATSUJI, Natsu MIKAMI
    Volume 80 (2014) Issue 818 Pages TRANS0284
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    A user's experience of a product involves a set of transitions from one sensory state to another. For example, in the user's perception of a product's qualities, the state of their sensory modality may shift from vision to touch. Between such state transitions, users have expectations regarding their subsequent states based on their experience of a current state event. A disconfirmation between prior expectation and posterior experience evokes emotions such as surprise, satisfaction, and disappointment. Such emotions affect the user's perception of the value of a product. A noteworthy phenomenon in the perception of expectation disconfirmation is that the expectation affects the perceived experience itself. This psychological phenomenon called the expectation effect affects the user's perception of expectation disconfirmation. This effect is a key element for designing the affective experience of a product. Although experimental findings on the expectation effect exist in a variety of research disciplines, general and theoretical models of the effect have been largely neglected. In this paper, we propose a theoretical model of the expectation effect using information theory. We hypothesize that Shannon's entropy of the prior subjective probability distributions of posterior experience determines the occurrence of the expectation effect and that the amount of information gained after experiencing a posterior event is positively correlated with the intensity of the expectation effect. To verify these hypotheses, we conducted an experiment in which participants responded to the tactile qualities of surface texture. In the experiment, we extracted the visual expectation effect on tactile roughness during a sensory modality transition from vision to touch and analyzed the causes of the effect based on our hypotheses. The experimental results indicated the appropriateness of the proposed model of the expectation effect.
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  • Wataru YAMAZAKI
    Volume 80 (2014) Issue 818 Pages TRANS0285
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    In this research, a Gradient-Vector Product (GVP) enhanced Kriging response surface model approach has been developed in which the GVP is defined by the gradient vector of objective function with respect to design variables as well as an arbitral unit directional vector in design variable space. When two sample points are given closely in design variable space, the correlation matrix in the Kriging formulation becomes ill-conditioned, which results in the inaccuracy of the constructed response surface model. In this research, therefore, we try to treat the two functional data as one functional datum with one GVP datum in the Kriging formulation. The conventional Kriging formulation is extended to make use of the GVP information, and then a global design optimization system is proposed with the developed GVP-enhanced Kriging model approach. The validity of the developed approach is investigated in analytical function fitting/minimization problems as well as a 2D airfoil shape optimization problem. The performance of the developed GVP-enhanced model approach overcomes that of the conventional Kriging model approach when additional sample points are given closely to existing samples. The effectiveness and robustness of the developed response surface model approach are clearly demonstrated in this paper.
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  • Hidekazu NISHIGAKI, Tomonori TADA, Tatsuyuki AMAGO, Tomokazu MATSUI
    Volume 80 (2014) Issue 818 Pages TRANS0286
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    In the recent manufacturing sector, various requirements, such as improving quality, improving performance, shortening the development period, cost reduction, energy saving and lightweight, are imposed. For satisfying the various requirements above, the engineering designers are required to optimize the entire system from components to combined products. In order to serve to solve the above problems, we implement improvements to add contact functions to the First Order Analysis (FOA) program which has been developed as an early design analysis method. Specifically, we add the self-contact function within parts and the contact function with outside parts to the three-dimensional nonlinear finite element program consisting of non-linear spring elements and beam elements, and carry out the verification analyses. As a result, this FOA program enables the nonlinear analysis on such a case as large deformation and contact. Because of its fast calculation speed, it enhances efficiency of the mechanical design. The case of our practical operation, which enables the design period reduction by perceivable system being embedded in 3D CAD system, is introduced in this paper.
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  • Kazuhisa CHIBA, Shin'ya WATANABE, Masahiro KANAZAKI, Koki KITAGAWA, To ...
    Volume 80 (2014) Issue 818 Pages TRANS0287
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    A single-stage launch vehicle with hybrid rocket engine has been conceptually designed by using design informatics, which has three points of view, i.e., problem definition, optimization, and data mining. The primary objective of the present design is that the down range and the duration time in the lower thermosphere are sufficiently obtained for the aurora scientific observation, whereas the initial gross weight is held down to the extent possible. The multidisciplinary design optimization was performed by using a hybrid evolutionary computation. Data mining was also implemented by using a self-organizing map and the stratum-type association analysis. Polypropylene and liquid oxygen with swirling flow are adopted as solid fuel and liquid oxidizer, respectively. The condition of single-time ignition is assumed in flight sequence. Consequently, the design information regarding the tradeoffs and the implication of the design variables for the objective functions has been obtained in order to quantitatively differentiate the advantage of hybrid rocket engine.
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  • Izumi NITTA, Sachio KOBAYASHI, Hiroki KOBAYASHI, Masayoshi HASHIMA, Yu ...
    Volume 80 (2014) Issue 818 Pages TRANS0288
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    In this paper, we propose a practical simulation method for designing Loop Heat Pipe (LHP) which is applied to cooling system for electronic devices. To realize rapid evaluation of cooling performance of LHP, the proposed performance estimation method calculates maximum heat transfer of LHP using 1D thermal-fluid network analysis. However, it is difficult to simulate phase-change of working fluid in LHP accurately with 1D model, since each component of LHP is modeled into a simple 1D network and its detailed shape is not considered enough. Especially, evaporator wick is indispensable component of LHP for determining its maximum heat transfer, and it is required to predict wick dry-out, where working fluid is dried in many pores of wick and LHP does not work as a result. The proposed simulation method introduces a wick pore inactivation model which depends on both input heat and wick pore diameter distribution to consider wick dry-out. The inactivation model applied to calculating wick permeability which determines pressure loss of wick. By fitting the wick permeability model to measured temperature distribution and maximum heat transfer of a LHP prototype for server systems, we show that our model estimates maximum heat transfer within allowable error compared to the experimental value.
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  • Kazutaka UEDA, Yuji MENO
    Volume 80 (2014) Issue 818 Pages TRANS0289
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    A consumer's emotional response to a product is influenced by cognitive processes, such as memories associated with use of the product and expectations of its performance. Here, we propose a cognitive neural model of Expectology, called PEAM (Prediction - Experience - Appraisal - Memory), as a novel tool that considers consumers' emotional responses in order to aid in product design. The PEAM model divides cognitive processes associated with product use into 4 phases: prediction, experience, appraisal, and memory. We examined the spatiotemporal changes in brain activity associated with product evaluation and memory during the prediction phase, by obtaining electroencephalograms (EEGs). EEGs of 10 healthy participants with normal or corrected-to-normal vision were recorded while they viewed images of products as well as when they provided a preference rating for each product. Our results revealed significantly increased neural activity in the gamma frequency in the temporal areas, the brain regions where declarative memory is stored, and in the prefrontal area for products that were rated as preferable. Our data suggest that memory is used for product evaluation in the prediction phase. These findings also suggest that activity in these specific brain areas are reliable predictors for product evaluation.
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  • Naoya MIYAJI, Yumi SHIRAISHI, Shinichi FUKUSHIGE, Yasushi UMEDA
    Volume 80 (2014) Issue 818 Pages TRANS0290
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    This paper proposes a design method for dismantling a product by adding split-lines to the product. This method aims at extracting target components for their reuse, recycling, and proper disposal. The split-lines enable to destruct a product into desired shapes, like pull tabs of cans and caps of PET bottles. The proposed design method supports a designer in determining split-lines to extract a target component. This method classifies the components of the product into shells that surround the target component and finds out the areas in which split-lines can be added for each shell. Then the method finds out candidates of dismantling sequences with split-lines from the candidates of each shell's split-lines. A case study shows that the dismantling of a LCD TV with split-lines reduces the number of manual operations needed for extracting a target component.
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  • Miki YAMAZAKI
    Volume 80 (2014) Issue 818 Pages TRANS0291
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    For the stabilization of insulation performance in the resin-molded insulators, strong adhesion between the resin and metal is required. In this paper, design method of fatigue strength on adhesive interface between metal and resin in consideration of multiple scales was investigated. Test pieces were made by covering Cu and SUS cylinders, which have some values of surface roughness, with epoxy resin. The interfacial strength was evaluated with shearing tests of these test pieces. The effective adhesive surfaces of those cylinders were evaluated from surface observation with a laser microscope. The interfacial strength increased with surface roughness and the adhesion-strength index (μ+B). The adhesion-strength index (μ+B), which had been proposed in previous paper, were calculated with the effective adhesive surface and the interfacial strength. The adhesion-strength index (μ+B) gave a constant value with various surface roughnesses for each metal. Based on the strength evaluations, the interfacial strength could be controlled, and it became clear from the results that the interfacial strength can be improved up to the confidence level. The results also show that design of the interfacial strength over multiple scales can help improve the reliability of electric power equipment.
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Solid Mechanics and Materials Engineering
  • Satoshi IWATA, Masanori TAKUMA, Kenichi SAITOU, Junki MATSUI, Yoshimas ...
    Volume 80 (2014) Issue 818 Pages SMM0292
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    A6061-T6 alloy has been used in the liner material of high-pressure hydrogen gas storage container that is mounted on a fuel cell vehicle. The degradation of the properties such as strength, toughness and hydrogen embrittlement resistance, etc., has been pointed out, because the grain structure of the mouthpiece part of the liner becomes coarse in the manufacturing process. The tensile and fatigue test for the specimens with different grain size were done, and the detected AE signals during the testing were analyzed. In the tensile test, the characteristics of the signals on dislocation motion, transgranular and intergranular fracture were extracted. In the fatigue test, it was shown that the possibility of which the damage is evaluated by the spectral analysis that utilizes the slope of an approximation straight line in the both logarithmic scale display of FFT analysis result. Then we proposed the amplitude ratio Rv that is the parameter which divided the maximum amplitude of signal for intergranular fracture by that of detected signal, and the correlation between the grain size and the Rv was recognized. These proposed information are able to be utilized in order to evaluate the damage of the container.
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  • Seiji IOKA, Shiro KUBO, Mayumi OCHI, Kiminobu HOJO
    Volume 80 (2014) Issue 818 Pages SMM0293
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    Thermal fatigue may occur in a pipe with high temperature stratified flow. To avoid the fatigue damage by the stratified flow, it is important to know a history of temperature and thermal stress distribution in the pipe. This paper describes a heat conduction inverse analysis method using a plate model as a basic study for estimation of a temperature history on the inner surface of an elbow where a thermal stratification occurs. It was made clear that the relation between the surface temperature and the other surface temperature of the plate model was characterized by the reduction ratio of an amplitude R and time delay Δt dependent on the cycle of the temperature history. The reduction rate R and time delay Δt may change with the boundary condition. Therefore, it is necessary to calculate R and Δt numerically in accordance with the boundary condition. The surface temperature history was estimated by dividing the magnitude of the other surface temperature by the reduction ratio R and by advancing the time by the time delay Δt. It was found that the surface temperature history was estimated with good accuracy by the inverse analysis method proposed in this study.
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  • Yasuhiro MUKAI, Hiroyuki KAGAWA, Motoki SAKAGUCHI, Masakazu OKAZAKI
    Volume 80 (2014) Issue 818 Pages SMM0294
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    Out-of-phase thermo-mechanical-fatigue (TMF) crack propagation tests were performed under load control condition by using compact tension specimen made of Ni-based single crystal superalloy, CMSX-4, and the effect of temperature range during loading cycle on crack propagation behavior was studied. The tests were conducted in the temperature range of 200-500°C and 200-800°C. For comparison, isothermal fatigue crack propagation test at 200°C was additionally performed. In the specimens tested under 200°C isothermal and 200-500°C out-of-phase conditions, the fatigue cracks propagated on {111} slip planes. In the specimen tested under 200-800°C out-of-phase condition, the crack propagated on the plane normal to the loading axis independently of crystallographic orientation, when the applied ΔKI was lower than about 50 MPa・m0.5, in spite of the fact that the maximum tensile loading during cyclic loads was applied at 200°C. When ΔK was larger than about 50 MPa・m0.5, the crack propagated on {111} planes near the specimen side faces. These crack propagation rates in the specimens tested under 200-500°C out-of-phase and 200°C isothermal conditions could be evaluated by using the resolved shear stress intensity factor range. Crack propagation rate in the specimen tested under 200-800°C out-of phase could be evaluated by energy release rate for an anisotropy body. A reasonable interpretation was proposed on the transition of fracture mode between the sliding mode to opening mode, by an aid of the resolved shear stress intensity factor range.
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  • Toshimichi FUKUOKA, Masataka NOMURA, Koichi OKAYAMA
    Volume 80 (2014) Issue 818 Pages SMM0295
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    Rigid flanged shaft couplings are commonly used to connect two shafts that transmit large torque. A pair of flanges is clamped by multiple reamer bolts since they are subjected to large shear force. In JIS B 1451, it is assumed that the shaft torque delivered to shaft couplings is transmitted only through the cylindrical surface of reamer bolt as shear forces, although it is also supported by the friction force on the contact surfaces. In the previous paper, Shear Force Transfer Ratio (SFTR) is defined in order to evaluate the ratio of the shear forces supported by the reamer surface and the action of friction. Then, the distributions of SFTR and the bending stresses along the reamer surface are analyzed by three-dimensional FEM, focusing on the effect of the fit between the cylindrical surface of reamer bolt and the bolt hole. In the actual rigid flanged shaft couplings, it is predicted that the scatter of initial bolt stress among multiple bolts and the misalignment between the two shafts significantly affect the SFTR and the bending stresses to be produced. Commonly observed misalignments are parallel misalignment or offset, axial misalignment or endplay, and angular misalignment. In this study, the effects of the scatter of initial bolt stress and the misalignments listed above are analyzed by three-dimensional FEM, in which an engaged thread portion with complex geometry is replaced by a simple cylinder. By conducting parametric calculations, it is concluded that the bolt force scatter has a minor effect under the commonly encountered tightening conditions, and the angular misalignment specifically affects the load capacity and the bending stresses generated in reamer bolts. It is also found that unlike the other types of misalignments, a harmful influence of angular misalignment cannot be mitigated even if the initial bolt stress is increased.
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  • Terutoshi YAKUSHIJI, Kyogo WATABE, Masahiro GOTO, Yoshikazu TODAKA
    Volume 80 (2014) Issue 818 Pages SMM0296
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    Aiming at an enhanced fatigue strength of Ti-6Al-4V alloys, the severe plastic deformation was given to the specimen surface at the final stage of lathe turning. The main findings of this study can be summarized as follows. A chip with unique shape for the surface treatment was developed. By using the chip, a fine-grained structure was formed on the entire surface of the Ti-6Al-4V alloy specimen during the cutting and rubbing process. The fine-grain structure with 500nm grain size was generated at about 20μm below the surface. Vickers hardness values (HV) of the specimen surface after the cutting and friction processing was reached about HV of 500 (40% higher than preprocessing). Although some studies indicated negligible increases in fatigue strength of titanium alloy specimen processed by surface treatments such as nitriding, shot-peening, the fatigue life of the cutting and friction processed specimen was much longer than that of non-surface treated specimens. Regarding the fatigue strength at 107 cycles, no enhancement due to the present surface processing was attained, because of the fish-eye fracture. The fracture was brought by the cracking of α grains located beneath the fine-grain surface layer.
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  • Masayuki KAMAYA
    Volume 80 (2014) Issue 818 Pages SMM0297
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    Testing and estimation procedures for obtaining true stress-strain curves of stainless steels were discussed in order to calculate load carrying capacity of nuclear power plant components by elastic-plastic finite element analyses. Type 316 stainless steel specimens of various degrees of cold working were subjected to tensile tests with different test speeds. It was shown that faster test speed reduced elongation and ultimate strength of the specimens. The strain on the specimen surface measured by the digital image correlation (DIC) technique exhibited an inhomogeneous strain distribution even when the strain was less than the uniform elongation (necking strain). The strain was elevated locally at the center of the specimen and its magnitude was about 1.2 times the nominal strain measured by an extensometer. A testing method (IFD method) has been developed to obtain the true stress-strain curve including post-necking strain by using an hourglass type specimen. In this study, the IFD method was improved so that it was applicable to the round-bar smooth specimens used for the tensile tests. Then, the stress-strain curves were estimated from the 0.2% proof and ultimate strengths by the K-fit method, which has been proposed by the current author. It was shown that K-fit method could estimate the stress-strain curves including the post-necking strain. Finally, a tensile test was carried out using a plate specimen with round notches. Elastic-plastic finite element analyses using the stress-strain curves estimated by the improved IFD method and K-fit method could simulate the deformation and strain distribution. The load carrying capacity obtained by the finite element analyses were almost equivalent to that obtained by the tensile test. However, the yielding load obtained by the finite element analyses were slightly higher than that obtained by the test due to the strain rate dependency of the stress-strain curve.
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Fluids Engineering
  • Yoshifumi YOKOI
    Volume 80 (2014) Issue 818 Pages FE0298
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    In this study, the flow features of vortex shedding from a pair of tandem arranged circular cylinders oscillating along the direction of the flow were observed by visualizing water flow experiment at the ranges of the frequency ratio f/fK=0~6.2 (28 steps), the amplitude ratio 2a/d=0.25, 0.5, 0.75 and 1.0, the distance ratio L/d=1.5, 2.5 and 5.5 and Reynolds number Re=640. The variations of mean vortex shedding frequency were investigated. Although the cylinder oscillation frequency f is lower than the natural Karman vortex's frequency fK, the lock-in phenomenon can be seen even in tandem arrangement case. The lock-in ranges have been shown in each distance ratio L/d. It is found that the lock-in ranges become wide when comparing with the single cylinder case. The typical flow patterns of the lock-in or un-lock-in states were shown every distance ratio L/d. In distance ratios L/d=2.5 and 5.5, the twin vortex street from the 2nd cylinder (rear set cylinder) was not seen. The 2nd circular cylinder has more flow patterns than the 1st circular cylinder. The flow pattern of the 2nd circular cylinder was complicated, and various.
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  • Kei ITO, Toshiki EZURE, Hiroyuki OHSHIMA
    Volume 80 (2014) Issue 818 Pages FE0299
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    A vortex is considered as one of significant phenomena which may cause gas entrainment (GE) and/or vortex cavitation in sodium-cooled fast reactors. In our past studies, the vortex is assumed to be approximated by the well-known Burgers vortex model. However, the Burgers vortex model has a simple but unreal assumption that the axial velocity component is horizontally constant, while in real the free surface vortex has the axial velocity distribution which shows large gradient in radial direction near the vortex center. In this study, a new vortex model with realistic axial velocity distribution is proposed. This model is derived from the steady axisymmetric Navier-Stokes equation as well as the Burgers vortex model, but the realistic axial velocity distribution in radial direction is considered, which is defined to be zero at the vortex center and to approach asymptotically to zero at infinity. As the verification, the new vortex model is applied to the evaluation of a simple vortex experiment, and shows good agreements with the experimental data in terms of the circumferential velocity distribution and the free surface shape. In addition, it is confirmed that the Burgers vortex model fails to calculate accurate velocity distribution with the assumption of uniform axial velocity. However, the calculation accuracy of the Burgers vortex model can be enhanced close to that of the new vortex model in consideration of the effective axial velocity which is calculated as the average value only in the vicinity of the vortex center.
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  • Makoto WASADA, Masaki ENDO
    Volume 80 (2014) Issue 818 Pages FE0300
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    In recent years, the number of cars and motorcycles has increased around the world and now reached more than a billion. The environmental pollution is caused by the traffic emissions, being critical problem. As one of the countermeasures, higher and higher level standards of emissions have been defined in developed countries. A catalytic converter is one of the most important parts of vehicles' emissions control system, its operating temperature being very high. Vehicles emit most of their pollution during the first a few minutes of engine operation before the catalytic converter has warmed up sufficiently to be effective. Therefore, this study focuses on heating the converter up to the operating temperature, using wave phenomena formed in the exhaust pipe. A real automotive exhaust pipe is modelled as a straight pipe with an obstacle having honeycomb structure, instead of the catalytic converter. A pulsating flow is generated in the pipe using a rotary valve of which opening area changes with time corresponding to that of the exhaust port in a real engine. The pressure histories along the pipe and the temperature in the obstacle are measured. Analyzing the measurement data, the formation of shock is found to play an important role in the temperature rise of the obstacle. Furthermore, the relation is discussed between the wave phenomena and the heat transfer to the obstacle.
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  • Takuji NAKASHIMA, Makoto TSUBOKURA, Yoshihiro OKADA, Takahide NOUZAWA, ...
    Volume 80 (2014) Issue 818 Pages FE0301
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    The objective of this study is to investigate aerodynamics and its generating mechanism of a road vehicle in steady-state cornering, which is the most basic cornering condition. The vehicle motion in the steady-state cornering was defined on a frame of reference fixed on the vehicle and it was divided into a rotation around a vertical axis and a sideslip. Then, aerodynamic force generated by each motion and its generating mechanism was discussed. In order to reproduce an effect of the rotational motion, a towing tank experiment was conducted to measure the fluid-dynamic force acting on a one-fifth-scale model of a sedan-type road vehicle. Assuming that the fluid-dynamic forces are expressible as a linear superposition of effects of the rotation and sideslip, first derivatives of the side force and yaw moment with respect to the yaw rate and the lateral velocity were analyzed by a multiple linear regression analysis. From the results of measurement and analysis, it was clarified that the assumption can provide good approximations of the force and the moment within a range of measurement conditions in this study. Regarding the fluid-dynamic side force, the rotation generates a centripetal force of the circular motion and the sideslip generates a force suppressing the slip motion. Regarding the fluid-dynamic yaw moment, the rotation generates a moment suppressing the rotation, and the sideslip generates a moment enhancing the vehicle's slip angle. Aerodynamics of a sedan-type road vehicle was estimated quasi-steadily by multiple regression equations with measured vehicle motion in an on-road test. From this estimation, the effects of both the rotation and the sideslip had the same order of magnitude. This result indicates that the effects of the vehicle's rotational motion have the same level of importance as the effects of the sideslip in vehicle aerodynamics in steady-state cornering.
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Thermal, Engine and Power Engineering
  • Ryo SHIRAKASHI, Takanori KOIKE, Mitsuhiro UEMURA, Isao HAGIYA, Yuki WA ...
    Volume 80 (2014) Issue 818 Pages TEP0302
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    A microgroove evaporator is expected to achieve a high heat transfer coefficient despite its simple structure. However, the mechanism of high heat flux in association with the groove structure is still not clear enough to design its thermal performance. In this research, we propose the numerical simulation model of evaporation in a single groove that enable predicting its thermal transport characteristics and capillary-rise length. The proposed simulating method consists of three steps. First, we calculate the cross sectional profiles of working liquid meniscus in a rectangular groove. Secondary, the evaporative rate, the capillary force and the flow resistance that correspond to each cross sectional profile are calculated assuming one-directional viscous flow and the evaporation limit at vapor-liquid interface. Finally, the capillary-rise length and the evaporative rate of single groove are calculated using the steady-state momentum and mass conservation equations of working liquid. We verified the proposed method by comparing the calculated meniscus profile with the microphotos taken by Confocal Laser Scanning Fluorescent Microscopy. We also perform experiments for measuring the capillary-rise length and transported heat rate (evaporative rate) of several microgroove evaporators in a certain condition (superheat: 6K, inclination: 60 degree) to compare these values with the calculated values. Both experimental results showed good agreements proving that the proposed simulation method might be useful for designing microgroove evaporator. From the experimental and numerical results, we found that the capillary-rise length is maximum at the groove width of 200µm, and that the broader the groove width is, the lower the effective heat flux and the higher the transported heat rate per groove are.
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  • Junpei YAMASHITA, Yoshio UTAKA
    Volume 80 (2014) Issue 818 Pages TEP0303
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    The new type heat exchanger, in which fuel gas flows inside thin tubes and water is shell-side, was proposed to develop the performance and compactness of shell & tube type heat exchanger for latent heat recovery from flue gas. The effects of tube diameter (1.0~5.0 mm) and heat exchanging length (7~100 mm) on the heat transfer characteristics of a single tube were systematically investigated. Moreover, the variations of gas inlet temperature or velocity conditions are studied considering the diverse usage of the gas water heater. It was shown that the usage of thinner tubes was remarkably effective to achieve high performance. That is, since the steep temperature drop near inlet occurred and high heat transfer rate was realized for thinner tubes of 1.0mm and 2.0mm in inner diameter compared with thicker tubes. In addition, the increase in the volumetric heat transfer area in thin tube type heat exchanger contributed to the compactness. Furthermore, the non-dimensional correlations concerning non-dimensional bulk mean temperature and specific enthalpy are proposed by using the ratio of effective tube length and thermal entrance region and correlate well with the measurement data regardless of diameter or inlet conditions. It is possible to predict the heat exchanger performance by using the correlations. As a result, it was elucidated that the using mini-tubes is remarkably effective to reduce the size of heat exchanger. For example, the volume with 1 mm inner diameter of tubes is approximately 4 percent of that with 5 mm in diameter.
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  • Atsushi KUBOTA, Hirokatsu KOUSOKABE, Tetsuya TADOKORO
    Volume 80 (2014) Issue 818 Pages TEP0304
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    This paper proposes a new method for predicting the supercharging effect to easily and precisely design the dimensions of the suction line in inverter rotary compressors, including two-stage ones. First, we obtained experimental data on the rotational speed characteristics of volumetric efficiency ηv and overall adiabatic efficiency ηad with three types of single-stage one-cylinder compressors using R22 and a two-stage two-cylinder one using R410A. We introduced a function for only increasing ηv with supercharging by approximating the phenomenon by simple acoustic theory and calculated the numerical constants of the function by fitting dimensionless experimental data. Second, we proposed a basic prediction equation for only the resonant rotational speed fn, which was adjusted for the effect of the crank angle where the suction process ended, by modeling the interaction between the constant acoustic wave in the suction pipe and the roller movement as a rectangular wave. Additionally, we introduced the damping factor β to express the effect of the scale of the suction chamber in relation to the constant acoustic wavelength in the suction pipe. We confirmed that 95% of the predicted values of increasing ηv were within an accuracy of ±3% when the rotational speed ratio (f/fn) was 0.8 - 1.2 and all predicted values of fn were within an accuracy of -3 - +1%.
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Dynamics & Control, Robotics & Mechatronics
  • Yutaka YOSHITAKE, Hiroyuki KATAHARADA, Ryohei KONDOH, Suguru NOZAKI, G ...
    Volume 80 (2014) Issue 818 Pages DR0305
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    This paper deals with the quenching problem of electromagnetic vibration of the motor stator in the wide frequency region around the natural frequency using multiple dynamic absorbers. The iron stator of motor is modeled by circular ring, and a pair of dynamic absorbers or two pair of them are installed on the outside of the circular ring to quench the forced vibration caused by the rotating distributed electromagnetic force. The solutions of forced vibration are obtained by the theoretical analysis. Following was made clear: (1) By installing two dynamic absorbers those have the same appropriate natural frequency ratios and damping ratio, the iron stator is quenched well. (2) By installing the same two dynamic absorbers leaving an angle that is equals to the one between loop and node of the mode to be quenched, the iron stator is quenched best. (3) By installing the two dynamic absorbers those have different natural frequency ratios and damping ratios each other, the quenching effect become a little better than the case mentioned above. (4) By installing the multiple pair of dynamic absorbers, the quenching effect become much more better than the cases using a pair of dynamic absorbers.
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  • Xiaolan ZHENG, Muneharu SAIGO
    Volume 80 (2014) Issue 818 Pages DR0306
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    This paper treats the wave control of suspended ropes by a control law based on the finite difference model. The control is acted on one finite difference interval inside of the upper fixed end. The control input is the distributed force equivalent to the difference between the boundary node equations and the interior node one. This control compensation of the boundary condition with use of the wave propagating solution of the interior node equation makes the boundary state as if it were the interior nodes. The wave propagating solution of the finite difference model of suspended rope is obtained as the transfer function between adjacent node displacements in the frequency domain that gives the convolution integral kernel function in the time domain. The simulation of the suspended rope systems with or without load mass at the free lower end boundary and with load mass at the fixed lower end boundary have been conducted. The frequency response analysis and numerical time simulation have confirmed the presented wave control effectiveness. The lower end boundary condition of a suspended rope has been also discussed.
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Design, Systems, and Manufacturing
  • Masatoshi SHIMODA, Tomoki OKADA
    Volume 80 (2014) Issue 818 Pages DSM0307
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    This paper presents a free-form optimization method for maximizing the elastic buckling load of a shell structure. A shell structure is assumed to be movable in the normal or the tangent direction to the surface for the shape optimization. The 1st buckling load factor is maximized under a volume constraint. The 1st eigenvalue constraint is employed to avoid the repeated eigenvalues problem in this max-min problem. This problem is formulated as a distributed-parameter shape optimization problem, and the shape gradient function for this problem is theoretically derived using the Lagrange multiplier method, the adjoint variable method and the formulae of the material derivative. The shape gradient function derived is applied to the free-form optimization method for shells, a gradient method in the Hilbert space, where the optimal shape variation is calculated as the displacement field of the linear elastic analysis of the fictitious shell model. With this method, the optimal free-form surface or boundary is determined without shape parameterization. The effectiveness of the 1st eigenvalue constraint is also studied. The results show the validity of this method to determine the optimal free-form of shell structures for the elastic buckling design problem.
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  • Yoshitaka MORIMOTO, Katsuhiro NAKAGAKI, Takayuki MORIYAMA, Hiroshi SAI ...
    Volume 80 (2014) Issue 818 Pages DSM0308
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    A new NC tandem table unit driven by linear motor has been developed for machining curved surfaces by turning. This turning method enables to machine the non-axisymmetric curved surfaces with high speed motion synchronizing with the spindle rotation. The key factor for this turning method is to realize precise tool trajectories on a designed workpiece's surface. Therefore, the dynamic response of NC table is required so that the tool post can move with the rapid motion and with high acceleration. In this study, we propose a new NC table unit that has achieved the acceleration and the deceleration of over 100m/s2 by the use of the tandem linear motor driving system. Each table is controlled in opposite direction to cancel the inertia force during machining motion. In this report, the fundamental dynamic performance of the table developed is evaluated. The effectiveness of canceling the vibration transmission by the NC tandem table system while the motion control is executed for the curved surfaces is also reported.
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  • Toshiki HIROGAKI, Eiichi AOYAMA, Keiji OGAWA, Showgo NISHIDA, Akihiro ...
    Volume 80 (2014) Issue 818 Pages DSM0309
    Released: October 25, 2014
    JOURNALS FREE ACCESS
    We look at a growing-up force from bamboo to construct a sustainable manufacturing system and have developed the green products made from the sustained reproducible natural materials. Thus, we devised a novel method to extract bamboo fiber which is high-quality with high-accuracy with a machining center. Meanwhile, we also developed the hot press method of bamboo fibers with green mold technology. As a result, the simple shape products could be molded with these technologies as self-bonding bamboo fiber green products. In the present report, we attempt to produce a self-bonding bamboo fiber spur gear, which is a machine element with a complicated shape. First, the molding die is designed and fabricated, and then the molding process is performed to develop a green spur gear. Second, its strength performance is estimated to find out a proper fiber shape. Finally, its driving test is performed to evaluate its dynamic performance. It is demonstrated that the developed bamboo fiber gear is considered to be effective as one of green products.
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