Nanostructures such as nanorings and nanocoils are proposed, being assembled by carbon nanotubes. The molecular dynamics simulations with the Tersoff type empirical potential are performed to estimate the buckling stresses of the nanorings and the spring constants of the nanocoils. The buckling stresses obtained from the uniform bending moment of the nanorings are lower than those by using the cantilever type model. The Stone-Wales transformation from four hexagon to two pair of pentagons and heptagons only happens when the appropriate heat treatment is given after relaxation. The spring constant of the nanocoil is estimated from the energy change according to the uniaxial deformation.

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In order to understand the atomic level crack propagation of silicon, we have proposed the hybridized molecular dynamics(TB-MD), being coupled with the linearly scaled tight-binding method and the ordinary MD with the empirical Tersoff potential. Double count of energy, caused by the so-called ghost forces in the patched region between the two, has been modified and the exacter total energy description has been given. In this paper, using the proposed hybridized computational method, we discuss the directionality propagations of the silicon (110) plane, which has been observed in the micro testings.

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A concurrent simulation of molecular dynamics (MD) and smoothed particle hydrodynamics (SPH) is proposed by means of a force bridging method. Numerical test is performed on aluminum crystalline model with planar defect. 1980 MD particles with Σ=5 symmetrical tilt grain boundary structure are inserted into two SPH regions composed of 1960 particles. Shear and tensile loadings are applied to the model. In shearing, maximum stress occurring in MD region is comparable to that in full MD simulation. Amount of grain boundary migration also agrees with that obtained in full MD. On the other hand, in tension, fracture unexpectedly occurs in surrounding SPH region. This is supposed to be due to tensile instability which SPH should confront.

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The impact process of a C_<60> molecule on a C_<60> film is studied by using molecular dynamics simulations in order to investigate the ion radiation effects. Single C_<60> molecule impacts on the C_<60> film with an acceleration energy ranging from 0.5 to 4keV/molecule, and the transformation of the film structure and the binding morphology are observed. The volume of the impact-induced hole is proportional to the incident energy while rather few atoms sputter out. The carbon atoms around the hole show amorphous-like binding morphology with the average potential energy lower than that before the impact, and the local hardening due to the irradiation is indicated.

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This paper describes a method to evaluate the fracture property of nano-materials with Acoustic Emission (AE) method. In this study, the nano-material was prepared by Molecular Dynamics (MD) method and its AE were detected as "velocity of atoms at material surface". Several emitted AE of nano-material were measured while tensile testing, and they were compared with the real AE signals. The AE parameters (AE energy, frequency and fractal dimension of AE waveform) of nano-material depended on structure transformation of the nano-material, and the behaviors of "Relation between strain rate and AE energy" and "Transition of the fractal dimension and the frequency" were similar to the real AE signals. From these results, it is shown that a possibility of the evaluation on the fracture property in nano-materials with AE method.

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Pb(Zr,Ti)O_3 (PZT) is widely used because of its remarkable ferroelectricity and piezoelectricity. In order to investigate mechanical properties of PZT at the atomic level, the molecular dynamics simulation is a key-technique. For the simulations, it is necessary to use accurate interatomic potential. However, interatomic potential for PZT has not been proposed yet. This work aims to develop shell model potential which can reproduce mechanical properties of PZT. In our first step, we fit its parameters to the lattice constants and elastic constants of PbTiO_3 and PbZrO_3 which are calculated from Ab initio. Shell model with the optimized parameters can reproduce both structure and properties.

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Amorphous metal has excellent mechanical properties. This work aims to investigate the deformation mechanism. We conducted atomic simulation under tension, and examine many unstable deformations, which brings about plasticity.

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Collective dislocation emissions and their dynamic behaviors are observed in the defect-free region of the crystalline materials. In order to describe the nano-plastic deformation in this situation, it is necessary to develop the mesoscopic modeling which deals with both the dislocation nucleation and the collective dislocation behavior as the result of long/short-range interaction. Discrete Dislocation Mechanics (DD) is the most suitable methodology to treat dislocation motion directly. In this paper, we use Molecular Dynamics (MD) to obtain some criteria of dislocation emissions and apply DD combined by Boundary Element Method (BEM) to describe the dislocation motions in the semi-infinite media with traction-free surface. The developed scheme is applied to the inclusion problem embedded into the ductile matrix, where we have captured the dislocation emission and the short-ranged behavior by the full MD atomistic simulation. Stress field of the DD-BEM problem can be obtained by the superposition of the stress field generated by dislocation segments and the free surface image stress calculated by BEM.

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One of the most frequently encountered problems in joint structures is interfacial cracking, sometimes also known as delamination. The stress intensity factors of a crack between dissimilar media are important parameters for evaluating delamination strength. A new method is proposed for the stress intensity factor analysis of a crack between dissimilar anisotropic materials under mechanical and thermal stresses. In the present method, the M-integral method that is an extended J-integral in conjunction with the finite element method was used to calculate individual stress intensity factors, K_I, K_<II> and K_<III>. The present method was applied to some interface crack problems under mechanical and thermal loads. The results are compared with analytical solutions. It is shown that the energy release rate and stress intensity factors obtained by the present method are very accurate.

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Molecular dynamics was applied to the simulation of near-threshold fatigue crack propagation in bcc Fe, which was modeled using the Finnis-Sinclair interatomic potentials. Two different crack geometries and crystal orientations were considered. All cracks were loaded in mode I, using linear elastic fracture mechanics displacement fields. To take the effect of new crack surface into account, the method of crack surface recognition was introduced. The effect of crack advance was also considered in the simulation. The effectiveness of these modification was demonstrated.

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Sound absorbing device for the infrasound is studied, using the mass and the damping. Thin film is used as the mass and neodymium magnets are used as damping. The reflection coefficient and the transmission coefficient of the film with damping in the acoustic duct are calculated, and are compared with experiments. The neodymium magnet can be realized the damping needed for the proposed device. 3 dimension sound fields are also calculated by BEM with and without the proposed device. The successful results suggest that the proposed device is effective to reduce the infrasound.

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In this study the string vibration of the moving silent chain is discussed experimentally. It is found there are two kinds of string vibration occurred in a moving silent chain: one has the same frequency with meshing between chain and sprocket and another has the frequency that equals 1/2 of meshing frequency. The former is the resonant vibration excited by the meshing, but the later is the parametrically-excited vibration caused by the fluctuation of chain tension.

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The purpose of this paper is to show the way to move the frequency of an acoustic cavity resonance using equipped resonator. The resonator works like a dynamic absorber in vibration engineering. We test the effect of an equipped side-branch type resonator. Moreover we propose the way to reduce the influence of an acoustic cavity mode using very simple semi-active control.

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An acoustic material made of exploded bamboo fibers has been newly developed from the viewpoint of environmental protection. The basic acoustical properties such as the sound absorption coefficient of the material were measured. Compared with the acoustic material made of glass wool, it was confirmed that the acoustic material made of exploded bamboo fiber had the same sound absorbing effect. In order to design an optimal arrangement of the material, we tried to find out the best combination of the bulk density of the material. Second, we applied the designed arrangement of material to actual loudspeakers. The basic properties of loudspeakers such as the frequency characteristics and the cumulative decay spectrum were measured. The results show that the material clean more effectively standing wave which exists in loudspeaker than an actual product. Third sensory evaluations for loudspeakers were carried out based on Scheffe's method of paired comparison. From the results, the loudspeakers which were applied the acoustic material made of exploded bamboo fiber had more soft, deep, and delicate sound than an actual product. Consequently, fundamental design criteria have been confirmed for the sound absorption of newly developed bamboo fiber material under the restricted conditions.

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This study presents experimental and analytical result of squeal vibration in the disk-pad-caliper system which is modeled after an actual disk brake. The frequency of squeal becomes higher as the thrust pressure grows large. To clarify this cause, we measured the dynamic stiffness between the disk and the pad. As a result, the dynamic stiffness in the contact region depends on thrust pressure. Therefore we analyzed the disk-pad-caliper system as a distributed dynamic stiffness model. This model considers the distribution of the thrust pressure and the dynamic stiffness of the contact region.

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This paper describes the vibration control technologies in consumer electronics field. It concretely explains the vibration control method which controls the imbalance of clothes and optimizes the springs/dampers conditions of the drum type washing machine in order to reduce vibration in the dehydration stage.

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Performing seismic experiments, it is very important to excite test specimens precisely with the input seismic waves that are used in earthquake-proof design. However, the actual exciting seismic wave become different from the target wave due to the interaction between the shaking table dynamic characteristics and the test specimen vibrational characteristics. Though there have been several countermeasuring methods, they always require the preexcitation as off-line control. So, in this paper we developed the new control method by using quadratic stabilizer for non-linear test model as on-line control. This method is proved to be effective by numerical parameter studies.

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By using differential algebraic equations (DAE), this paper proposes and analyzes the conditions of constraints between mobile objects. We examine the motion and vibration of the coupled vehicles by using a roller coaster as a model. In the simulation, we investigate difference among the number of coupled vehicles.

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An active dynamic absorber using piezoelectric actuator is proposed. The absorber is made up of a cantilever beam with a weight attached on the free end. The piezoelectric actuator is bonded near the fixed end and a strain gauge also attached near the fixed end is used for feed-back. It is found that the optimal feed-back can be done simply based on the theory of traditional dynamic vibration absorber. Experiments using a cantilever beam as the main system, under different excitation, are carried out, and the effect of vibration reduction has been obviously observed.

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A ladder truck with lift mechanism has played an important role in life-saving and fire-fighting. Although the quicker operation mechanism is requested for these demands, the lift operation generates a lot of vibration at the time of the extending and retracting motions, the ascending and descending motions, and turning motion. In this paper, though an actual ladder truck is composed of five sections, a two-sections ladder model is investigated to make the physical understanding easier. A coupled equation of the model is derived using the differential algebraic equation.

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We examine an intelligent supervisory level control by using a qualitative, physical model of a steam generator in this paper. And the effectiveness is shown by a HIL simulation in the meaning of included a target value adjustment of an expert in a control loop. It is shown that the three elements control has an effect of suppressing pressure changes. If the gain is raised too much, it becomes unstable. However, this instability might be controlled by a target value operation by an expert method. Moreover, the steady state deviation in the case of more high target value can be suppressed by a 4-elements control with a new feedback loop of generation calorie. Then, a basic specification of a simple fuzzy target valued control is shown.

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This paper proposes a estimation method of dynamic forces between 4 wheels and road using strain information of steering nuckle. First, we propose a vehicle-tyre model. It contains nonlinear caracteristics of tyre by Magic Formula function. In addition, we design multi-body dynamics suspension model. And we conduct the coupled simulation to obtain the boundary condition of steering nuckle. Then, in order to decide the optimum positions of strain sensors to estimate the forces, FEM simulations are conducted.

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Multibody dynamics is applied to the vibration analysis of mass-spring system which consists of a car body, suspensions and wheels. When an automobile is running on uneven terrain, displacement of the wheel is determined by contact condition between the wheel and the road. In this paper, rigorous and approximate constraint condition is presented in order to study kinematics of a rolling wheel on a plane curve. It is shown that approximate method is not able to predict the accurate motion when the curvature of the road is not negligible compared with that of the wheel. Analysis of the strut suspension model with rigorous method shows an irregular nonlinear oscillation under the ideal case of no damping.

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The authors propose a new basic suspension model which isolates longitudinal shocks and vibrations. In the new model, the wheel is supported by a crankshaft and has a degree of freedom of circular motion. Application of this new basic model to aircrafts, automobiles, trains, and motorcycles overcomes the limitation of the performance against longitudinal impact. This study focused on the as-yet-unresolved problem of aircraft landing gears, which is acceleration impact on the wheels.

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This paper describes a mechanical energy recovery system with flywheel and CVT. In recent years, greenhouse effect is brought to international attention, which is closely related to cars. Improvement of the car which discharges greenhouse gas is desired. And so, in order to achieve hybrid vehicle we studied energy recovery system, which used the flywheel and CVT. We studied the effectiveness of energy recovery experiment using a real vehicle, but it's energy efficiency was smaller than assumed one. In this study, in order to achieve the efficiency improvement, we clear up the cause of low efficiency. Especially to examination Flywheel Energy Recovery System only, we built the testing system. By the experiment we revealed the characteristic of system and the problem of CVT.

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Recently, various types of high damping materials are widely used for suppressing vibrations in order to develop quit machines and create comfortable life spaces. However, those damping characteristics are generally evaluated experimentally. In this paper, the damping characteristics of a metal are investigated analytically. A dynamical analytical model of steel molecules is established and the molecule behaviors of a metal are investigated in order to study the viblation damping mechanism. Iron is treated here. As a first step, fundamental vibration characteristics and the energy dissipating characteristics are studied in an adiabatic condition for the initial offset condition.

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This paper describe the base isolation characteristics of a newly developed 3-dimensional base isolation system using a verocity reduction mechanism. In the previous studies, it is confirmed analytically that this system has very effective base isolation characteristics and the rocking suppression characteristics for the horizontal and vertical simultaneous excitations. In this study, a scale model of the 3-demensional base isolation system is fabricated and the excitation test is carried out in order to confirm the base isolation characteristics of this system experimentally.

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A novel application of nanotechnology in the field of mechanical engineering, called colloidal damper, is investigated. This device is complementary to the hydraulic damper, having a cylinder-piston construction, but the hydraulic oil is replaced by a colloidal suspension, consisted of a mesoporous matrix and a lyophobic liquid. Here the porous matrix is composed from hydrophobized silica gel and water is considered as associated liquid. The colloidal damper test rig has only one room inside of the cylinder, but due to the pre-pressure applied, it is able to dissipate energy for both positive and negative displacement of the piston. Variation of the damper's dissipated energy and efficiency versus working parameters (frequency, displacement, pressure, pre-pressure) is illustrated.

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Floor heavy impact sound caused by children's jumping in condominiums is a serious problem because there is no effective device to reduce it. In this study, a momentum exchanging damper was presented to reduce the impulsive vibration of the floor. This damper was composed of a spring, a dashpot and a mass, whose mass was in contact with the floor surface. When a heavy impact source falls on the floor, the momentum of that source is transmitted to the damper through the floor, so the momentum of the floor could be absorbed. Calculations and experiments were achieved to verify the effectiveness of the damper. It can be concluded that the damper significantly reduces the first vibration mode of the floor and reduces the sound pressure at the downstairs room.

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In this paper, we develop a damage identification method for beam stractures based on the measurement of bending wave excited by ambient noise. First the ambient noise data acquire by arrayed sensor and separate it into the forward-going and the backward-going wave components in freqency domein due to dispersibility of wave. Then we put the transfer function into above-referenced two wave conponents. Finally we can get information about damege existance and position by estimate impulse response which acquired by inverse Fourie-transform of transfer function.

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The thermal expansion coefficient of rectangular specimens at low temperatures was measured by Electronic Speckle Pattern Interferometry(ESPI). Since ESPI is a non-contact measurement method, ESPI system doesn't receive the influence of temperature change. The thermal expansion coefficient was obtained from the thermal strain acquired by ESPI and the temperature measurement for specimens of Poly tetra fluoro ethylene(PTFE) and Stainless steel(SUS316). The thermal expansion coefficients of SUS316 and PTFE were obtained in the temperature range from 130K to 300K, 150K to 330, respectively. These data agree well with the published ones.

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The shock wave in water generated by laser focusing was observed by shadowgraph method and real-time holography interferometry. For the laser focusing, YAG laser beam of output 4mJ, pulse duration 10ns was used. By the irradiation of argon laser beam of 100ns pulse duration made by acoustooptic modulator, the generating phenomenon was recorded in the CCD camera. A series of behavior of shock wave and bubble was observed by the shadowgraph method, and the shock wave velocity was measured by double pulse exposure recording. By the real-time holographic interferometry, the interference fringe pattern was recorded and the refractive index variation of the water by shock wave was analyzed by using Fourier fringe analysis. The pressure distribution of front and rear region of shock wave was calculated from the refractive index variation.

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This study treats the dynamic stability of mechanical systems subjected to multi-directional excitations, such as dynamic buckling behavior, etc.. A steel cylindrical pier is treated and modeled analytically as a thin cylindrical structure with an attached mass on its tip. The analysis is carried out by numerical simulations, where the horizontal and the vertical seismic loads are applied simultaneously. From the previous study, it is known that the seismic responses of the thin cylindrical shell structure tend to increase due to the coupling effects between the horizontal and vertical excitations, and that flattening phenomena occurs. In this study, the deformation behavior is investigated for very large external force.

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This paper shows vibration behavior of a circular cylinder subjected to jet-flow from a narrow gap in the vicinity of wall by using computational fluid dynamics (CFD) simulation. We investigated the effects of the distance between the centerline of jet-flow and the cylinder center. And these CFD simulation results are comparred with the experiments in published paper. As a result, the vortex shedding vibration phenomena and the fluid elastic vibration phenomena can be confirmed in a circular cylinder subjected to jet-flow from a narrow gap as well as in the case of the experiment.

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Many researchers have studied the impact phenomenon in ball games, such as golf, tennis, baseball, soccer and so on. Although it is very important to understand the dynamic characteristics of a ball on the impact phenomenon, the sufficient theoretical understanding of the characteristics has not been obtained. In this paper, normal impact of hollow balls on flat surfaces is theoretically analysed and the dynamic deformation of hollow balls is derived as an axisymmetric motion of an elastic spherical shell by using modal expansion method, where variation of contact area is took into account. Numerical calculation has conducted and the dynamic characteristics are discussed.

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There are some troubles which are caused by self-excited vibration of pipes conveying fluid, used in some plants. The target is the cooling pipes which has a large diameter and a thin wall, used in special nuclear reactors. The purpose of this study is calculating static and dynamic of the pipes. On this paper, calculations for a straight pipe, a semi-circuler pipe, a pipe with an elbow, and experiments for out-of- plane motion of the pipes are described.

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Recently, the importance of development of clean and reproducible natural energy has been taken notice, for solving global environment problems and energy scarcity problems. Japan is one of the richest countries from the viewpoint of wave energy. However, the most of the energy is not efficient used. Then we studied on new wave power generation system using the gyro moment, In this paper, the background of this study, the generating principle of this system, the first prototype model test and the second prototype model test are described.

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When thin cylindrical shells having freely supported end as labyrinth air seals and thermal shielding annular structures in large diameter piping are subjected to axial annular flows, an unstable vibration is apt to be occurred. The unstable vibration of thin cylindrical shells is investigated considering the fluid structure interaction between shells and flowing fluids. The coupled equation between shells and fluids is derived using the Flugge's shell theory and the Navier-Stokes equation. The unstable phenomenon is clarified by root locus based on the complex eigenvalue analysis. The influence of shell-dimensions on the threshold of the instability of the coupled vibration shells and flowing fluids is investigated. Especially, in this paper, the analysis is carried out by using two types of shell that have different length and water as a fluid.

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An improved Digital Correlation Method (DCM) was developed to measure a small displacement and strain with a high accuracy. One additional technique was incorporated into the conventional DCM system. The Lagrange interpolation technique was newly developed in order to determine the value of the intensity at an arbitrary position. This technique was developed to raise a precision in determination of an identical position between two image planes; the sample surface images before/after deformation. The results obtained using various methods were compared. The modified DCM method with both the Lagrange interpolation and nonlinear strain distribution in subset was found to be good technique for detecting the two dimensional deformation. The DCM system was found to be effective method to strain measurement in the vicinity of notch root.

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This paper describes the development of an improved speckle strain/displacement gauge technique (SSDG). In the conventional SSDG technique, an arbitrary incident angle of laser beam is needed to monitor both various surface strains and displacements. The influence of an irradiation angle and a measurement angle of laser beam on in-plane measurement has already reported in the previous paper. In this study, an application to the out of plane measurement was developed.

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When the capsule type strain gage is used for strain measurement of cast iron, the shearing force in the spot weld is produced from the difference of the amount of the deformation of the capsule gage and cast iron. And, the actual strain caused in cast iron cannot be accurately measured because this shearing force deforms the spot weld. In this research, the shearing force caused in the spot weld was analyzed taking this deformation into consideration. As a result, it was clarified that a constant ratio existed between the measured strain by gage and the actual strain caused in cast iron. Therefore, the actual strain in cast iron can be estimated from the capsule gage output value and a constant ratio.

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In adhesive wear, it is widely known that the mechanism of the transition from severe to mild wear is the wear phenomenon from severe wear with high wear rate to mild wear with low wear late. In this paper, severe to mild wear transform was observed using acoustic emission (AE) technique. And the detected AE waveforms were classified into the burst type, the continuous type and the type which is mixed the burst and the continuous type. The behaviors on the incidence of this three types have characteristics. The wear modes (i.e. the transition from severe to mild wear) were regarded with wavelet transform, fractal dimensions and image analyzing of the contact surface.

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The laser welding is easier to automate than the other welding method, so it is expected as the high quality and accuracy welding. The stainless steels were irradiated using YAG laser for examining the penetrating conditions during the laser irradiation. And the detected AE signals during laser irradiation were analyzed with "Weighted Mean Frequency Distribution Analysis Method" and "Wavelet Transform". In this paper, relevancy between the analysis results of the signals during laser irradiation and the penetrating condition of the specimen are reported.

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A simulation model for three dimensional finite element method (3D FEM) of thread rolling is presented to investigate the deformation behavior for material, the stress and strain distributions during the thread rolling, and also the residual stress distribution after rolling. In the simulation, metal rod is used 2-roller dies thread rolling machine. Because of the large deformation of thread roots, fine meshes should be used these positions. The simulation results of thread rolling show the similar deformation behavior observed in the practical thread rolling and provide residual stress and plastic strain distribution.

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The loading frequency dependence of fatigue crack growth in the near-threshold region in SUS304 steel were investigated using constant K_<max> test method at 350℃, 550℃ and 650℃ in a vacuum. Loading frequency was changed from 30 Hz to 3 Hz and vice versa 30 Hz, and crack growth rates at f=30 and 3 Hz were compared. It was found that crack growth behavior in the region below the conventional threshold value was dependent on the loading frequency. Investigations of the fractal properties of their fatigue fracture surfaces were performed. It was found that the measured values of fractal dimensions of fracture surface tested at 650℃ in a vacuum were larger than those of fracture surface tested at 350℃ and 550℃ in a vacuum.

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In the present study, fatigue test system for thin films was developed, and fatigue tests of aluminum and α-brass thin film was conducted. The surfaces of the specimen were observed by using optical microscopy and atomic forced microscopy to elucidate the mechanisms of fatigue crack initiation of metallic thin films.

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