A formulation method of arbitrary shaped curvilinear fibers for laminated fibrous composites is proposed and applied to the multi-objective optimization problem. Two conflicting objectives employed here are the maximum principal strain around circular hole as a mechanical property and throughput of productivity relating to fiber curvatures. As an optimizer, both improved non-dominated sorting genetic algorithm (NSGA2) and multi-objective particle swarm optimization (MOPSO) are used. Obtained solutions from the MOPSO are distributed in the wide range of objective function space compared with the NSGA2, and the solutions with curvilinear fibers indicate lower maximum strains than the solution with straight fibers. This reveals the possibility of composites with curvilinear fibers as an effective component of wing structure.

View full abstract

Due to the rapid growth of aging society, it demands for mechanical system to support human motion in several area, such as heavy labor in industries, nursing care in medical field, and so on. Pneumatic actuator has feature of flexibility owing to the air compressibility, which works as safe function absolutely required for human support mechanical systems. In this study, we introduce some mechanical system using pneumatic actuators to support human motion and the effectiveness through some experiments.

View full abstract

A novel micro-vibration actuator using a shape-memory alloy (SMA) for the presentation of various tactile sensations to human skin will be introduced in this paper. A tactile actuator consists of a thin SMA wire with the diameter of 50μm, and generates micro-vibrations with various frequencies and amplitudes synchronizing with a driving pulse signal. By coupling the actuators as a pair, an information transmission system is created for presenting higher-level tactile perceptions such as the phantom sensation and the apparent movement to transmit novel tactile sensations to human skin. The apparent movement was especially well perceived by users as a sensation of something running across their fingers, or as being tapped by an object, according to well-determined signals given to the devices. The actuator features compactness and low energy consumption, and is applied to tactile displays and tactile interaction systems.

View full abstract

Tactile sense is one of the most important sensory channels for us to perceive the surrounding environment as well as visual and auditory senses; however, tactile sense is not fully understood/used at present. According to the physiological understandings, tactile sense is perceived through mechanoreceptors located just under our glabrous skin. There are four types of mechanoreceptors sharing the frequency range against vibration stimuli. This paper introduces a tactile sensor and a tactile display operated based on the physiological knowledge. The tactile sensor acquires vibration data using a piezoelectric element when tracing on a sample with a tracer. Then the data is conducted with fast Fourier transform to compare with the characteristics of mechanoreceptors. As a result of this comparison, we can estimate the response of each mechanoreceptor which may help us quantify the tactile sensation of the sample. On the other hand, the tactile display mainly consists of a disk-shaped ultrasonic vibrator. The resonance frequency of vibrator is 24 kHz, which is not discriminable by the mechanoreceptors, however, by using the amplitude modulation technique, it can display a tactile sensation. Since the configuration of vibrator is simple, the tactile display is a promising candidate for future tactile applications.

View full abstract

Large capacity oil-free screw compressors are mainly used in petrochemical plants such as styrenemonomer, and linear alkyl benzene plants, where suction and discharge pressures are relatively low and large capacity is needed. Recently, these plants have tended to become larger and the requested capacity to the compressor also has tended to become larger. To satisfy such a market needs, we have developed the world's largest capacity oil-free screw compressor "Model KS80" by using the design technology and manufacturing technique of the large screw compressor. In this paper, the design concepts and features of "Model KS80" are introduced.

View full abstract

Gear transmission is used in a wide field of general industries. In among them, reduction gear unit for a gas turbine - generator is a large capacity and high- speed rotation. With the increase in the size of the gas turbine, the reduction gear also required a large capacity. Hitachi Nico Transmission Co., Ltd. (herein, Hitachi Nico) is providing a reduction gear unit to the domestic gas turbine companies. The uses of the gas turbine are for power of power generator, for general industrial and oil & gas field etc. Therefore, the reduction gear unit has been required high reliability and high efficiency. In this paper, large capacity gear unit for gas turbine is described.

View full abstract

In the history of ships, steam turbine has been adopted as the main engine for many years. Ships to be mounted steam turbine as a main engine have been decreasing due to economic problems such as fuel efficiency in today. That though, the Liquefied Natural Gas Carriers (LNGC) only adopts steam turbine as the main engine. This presentation introduces the main steam turbine engine for LNGC, and explains machining technology of large high-precision reduction gear such as 5m diameter.

View full abstract

Against the declining birthrate and super-old society, a non-manufacturer robot keeps high social expectation though, there are few robots on the market so far. Author thinks the lower back support muscle suit (Exo-muscle^[○!R]) author developed is the only mass product which can stand up to use. In this paper, history of Exo-muscle and business strategy of university-originated venture INNOPHYS co. Ltd. are described.

View full abstract

KEIROKA[○!R] assistive system is assistive technology which can reduce fatigue or load of human workers and also can keep their physical performance. In this paper, the author describes the concept of KEIROKA assistive system and Smart Suit [○!R] as a concrete example of KEIROKA system. The assistive mechanism of Smart Suit and its design based on information and robot technology (IRT), biomechanics and ergonomics will be mentioned. Usage examples of Smart Suit will be also shown. The application of IRT on KEIROKA assistive system and its future prospects will be remarked.

View full abstract

We apply a passive walking technology to the support and the rehabilitation of walking to improve QOL. ACSIVE is an ecological assistance device based on a principle of the passive walking. Its main characteristic is non-powered without motor and battery, more safety, low cost, easy-fitting, and quiet. The commercial model is approximately 500g in the case of a single leg, and is ultra light weight and slenderness. Hip cam-spring mechanism is equipped in order to assist swinging of the leg. This mechanism can regard as redistribution of the energy.

View full abstract

There is tradition which expresses the opinion each other and argues freely by everyone in Honda. We call this traditional argument WAIGAYA discussion. This Honda WAIGAYA is a place of the arguments to let us concentrate personal experience and ability. The place gives us "flashes" and "notices". As a result, we can create a new thing and a new concept. However, unfortunately I do not seem to be known too much when it is thought how this "WAIGAYA" is known in the world. Therefore I introduce arts in the promotion how it was carried out in the summary and the history of the birth, the real scene about WAIGAYA which an author experienced in the spot of research and development.

View full abstract

As the aeroastronautic industory has been innovated and matured, it is necessary for the space development and utilizing organization or company to make and operate those satellite that can provide more variety of services. The purpose of Systems Engineering in early stage was to reduce malfunction, but in late years the Systems Engineering has been innovated as a technique to create new ideas. For an example, "Waigaya" processed in automobile company in Japan, is expected to be useful for space application as design thinking methodology.

View full abstract

The conventional development required much experience, intuition and a lot of trial and error. In contrast, by using the latest design tools can realize efficient development by simulation based discussion. Particularly, the capability of the developer can be improved using "designer CAE" which can use "CAE tool" and "3D CAD" seamlessly. Moreover, the development efficiency of the team can be dramatically improved by combining "WAI-GAYA" which is free technical discussion with discussion which use this "designer CAE". This paper introduces F1 transmission development as an example of this development methodology.

View full abstract

The Japanese techniques, such as "Waigaya" of Honda, attract attention in recent years as "co-creation work considered from zero in a group. "Although the characteristic cultural technique of Japan is seemed, it is systematized about the group creation at the university etc. which are located in North America West Coast. Moreover, "group creation" work is introduced into the Disney animated film for several years, and that effect is becoming clear. If it looks back upon how the desire which people desire has been embodied conventionally, having depended on a certain specific individual "flashing" can call it the actual condition. In order to create in a group an individual "flashes", examination about "group creation" has been advanced in various fields. It seems that the common thing for which it has an on-site experience has a big role in "group creation" for evoking "flashing" with "noticing" with a participating member. The trial ride was performed when this common environmental offer that has an on-site experience was vehicle development. However, sharing of experience and thinking serves as only the fellow passenger, and it seems that there is a limit in a spread common to the thinking. Now, the Virtual Engineering environment progressed greatly and it became a time utilizable simple. Therefore, more participants can understand now the "spot", the "actual thing", and "realistic" experience. This has enabled many participants to carry out "common in thinking" effectively. Here, the possibilities of the conditions which brew "flashing" with "noticing", and the Virtual Engineering environment are introduced.

View full abstract

Because a person will be able to carry out a more intellectual activity, it will be necessary to relieve the human of complicated work. The engineering have been developing for relaxing people as one subject until now. However, to be able to do something easily may take pleasure and a motivation from them. The system have to understand the relationship between the user and the system and the situation to motivate the person, and it is necessary to have the function that can change its' service for adaptation to circumstances. In this article, An ideea is suggested to design the system to achieve the motivation of the person.

View full abstract

This paper describes a new mass production system of high functional plastic films, and an application to guide new technology named "Roll-to-Roll Printed Electronics". The primary advantages of this approach are that (1) the use of a web means that the material is extremely thin and large area, (2) formation of three-dimensional wiring with high precision is possible, (3) ultra-high speed mass production is possible, (4) the liquid process eliminates the need for vacuum processing and allows for production at low-temperatures, (5) the freedom to select the web materials is high, and (6) scaling from the nano to the meter size is possible. Although there are many such advantages to this type of roll-to-roll printed electronics, there are still problems that need to be overcome before this technology can be generally applied. In particular, the materials are becoming ever thinner, and the processing precision is higher than in the past, so it is necessary to completely prevent defects such as slip and wrinkles. In addition, it is necessary to reduce stretching as much as possible, making low tension transport essential. As such, significantly progressing the web handling technology accumulated thus far has become an issue for the future.

View full abstract

There have been many kinds of high functional film used for our common goods, such as photo graphic film, magnetic tape, optical film for liquid crystal displays and battery separator for hybrid motor car etc. These kinds of long and flexible film, so called 'web', are manufactured by roll to roll process. Web handling process among roll to roll process is the significant key technology to avoid production loss caused by defects such as wrinkling and scratch. In the viewpoint of production, web handling technology was developed by increasing productivity in the past and will acquire high precise technology to create high functional film in the future.

View full abstract

Three typical types of control used by facilities that handle webs and steel plates are edge position control, tension control, and register control. Edge position control systems prevent products from deviating from their proper path as they travel, and ensure that the edges of rolls of webs are uniform. Edge position control systems control the edge or center position of a web when it is being unwound from a roll into the processing machine and during rewinding. Edge position control is the most important technology and has the longest history in the web control. The root of edge position control system has been the jet-pipe hydraulic control system., but now many technologies are applied for the recent control systems. The new image sensing technology will be applied to the web control.

View full abstract

Carbonaceous hard coatings as DLC and CNx coatings keep attention for low friction and high wear resistance. Transformed layer which is graphite like layer induced by cyclic friction generated ultralow friction coefficient in dry condition. However the transformed layer in oil lubrication has not been observed yet because this transformed layer could be too thin to measure quantitatively. The spectroscopic reflectometry has been applied to measure the thickness of transformed layer of wear scar of DLC and CNx after friction under oil boundary lubrication and dry nitrogen blowing, respectively. After measurement of thickness and hardness of transformed layer from optical properties of transformed layer, we found that thickness and roughness of transformed layer affected friction so much. Therefore we appied solid thin film lubrication theory to explain the effect of transformed layer on friction for both of DLC and CNx under oil boundary lubrication and dry nitrogen blowing, respectively.

View full abstract

We have performed molecular design to achieve both low and high friction systems from the nanoscale standpoint of view. In the low friction limit, superlubric fullerene molecular bearings comprised of graphene/C_<60>/graphene interface have been developed. Furthermore theories of nanomechanical measurement such as friction force microscopy and dynamic force microscopy have been developed in order to understand the mechanism of friction. As one example, nanoscale friction appeared in MEMS-in-TEM measurement is discussed.

View full abstract

A molecular simulation method was adopted to theoretically investigate the mechanism by which a transfer film, which strongly contributes to reducing friction and wear of a resin material, of polytetrafluoroethylene (PTFE) forms. The influence of ambient water and nitrogen molecules on the transfer film formation was studied by using a molecular dynamics (MD) method. The degree of PTFE transfer to an aluminum surface in a dry gas atmosphere was less abundant than that in water vapor because the non-polar gaseous molecule shielded the adhesive ionic interaction, which is a key factor in forming the transfer film. It is inferred that enhancing interfacial interaction between metal and PTFE is one of the ways to improving the tribological performance of PTFE. On the basis of the theoretical findings, a surface treatment of aluminum was then studied experimentally. A friction test showed that a nickel-based surface treatment enables to reduce a wear of PTFE even in a dry condition since abundant transfer film can be formed. It is worth suggesting that a chemical nature of metallic surface plays an important role to lowering wear of PTFE.

View full abstract

The friction coefficients of different metal pairs are determined by the difference in the interatomic distance between each metal material under low load conditions. Here, eight types of metal pins were rubbed against Si (111) substrates that were covered with a native oxide film. Results showed that the friction coefficient increased when the interatomic distance of the metal approached 3.1 Å, which corresponds to the interatomic distance of SiO_2. The same eight types of metal pins were rubbed against bare Si (111), and the friction coefficient increased with the smaller difference in the interatomic distance between the pin and Si (2.35 Å). A similar relationship was found between pairs of Ag/Cu/Ni and Au/Pt/Si (100).

View full abstract

Hydraulic power has been used with the watermills since ancient times. In and after the 19th century, hydraulic power came to be used for generating electricity with the developed turbines. This lecture gives the fundamentals of hydropower generation. Specific energy, power of water and typical turbine types for hydroelectric power are introduced. The hydraulic power given at the inlet of the turbine is reduced due to the energy loss at each component of the flow passage and the leakage flow between the runner and stationary parts of the system, etc.. Therefore, the turbine efficiency is given by the efficiencies related to specific energy loss, leakage flowrate, disk friction loss and mechanical loss.

View full abstract

The Japanese electric power system has been facing to a big turning point after the outbreak of the unprecedented Great East Japan Earthquake and tsunami on March 11th 2011. New Electricity system reform is discussed by means of recent years' social requests. The hydropower generation, that is purely domestic renewable energy, plays a key role in the Japanese power system as both the peak power generation and the power system stabilizer. In addition, the pumped-storage power generation contributes to the power system with its unique characteristics. This report will introduce a key role of the hydropower generation in the Japanese power system.

View full abstract

The background of the performance test using homologous model turbines as well as the necessity of performance conversion from model to prototype is briefly described. The major standards for the performance conversion commonly used are overviewed. Finally, 3D boundary layer calculation, which is applied for the validation of scalable losses in turbines, and its major results are described.

View full abstract

In this paper, the mass flow induced by a reciprocating paddle in the electroplating cell is studied by the finite element analysis software-COMSOL multiphysics. The reciprocation of the paddle is simulated by moving mesh (Arbitrary Lagrangian Eulerian: ALE method) and the solution of paddle agitating fluid dynamics is coupled into the calculation of tertiary current distributions. The reciprocating frequencies are 0.5, 1, and 2 Hz. An acid copper sulfate electrolyte composed of 50 mM CU_2SO_4 and 0.5 M Na_2SO_4 is taken into account. The results shows that the reciprocation of the paddle could effectively improve the concentration distribution of cupric ions and the current density distribution on the cathode surface.

View full abstract

In this paper, we present the application of the particle-based simulation to complicated fluid flow problem with free surfaces. The particle approach is based on the SPH (Smoothed Particle Hydrodynamics) method using hyperbolic-type kernel function. The hyperbolic-type kernel function is constructed by differentiating the characteristic function (i.e., sigmoid function) based on neural network framework. The function which has the property of Dirac delta function is concomitantly applied to the smoothing kernel function in the SPH-framework. Numerical results demonstrate the workability and validity of the present approach through the dam-breaking flow problem.

View full abstract

Evaluation of human thermal comfort needs to consider the thermal effect of actual clothing which has wrinkle on its surface. However, it is quite difficult to calculate the geometrical modeling of clothing shape because it requires huge number of meshes in order to simulate the complicated flow behavior on and in the clothing. The final purpose of this study is to develop the simple prediction model to be able to estimate the amount of the heat transfer from the human skin surface to the environment without the geometrical clothing model. In this report, the impact of the height of the clothing wrinkle to the thickness boundary layer has been investigated.

View full abstract

Kink deformation bands appearing in compressed specimens of Mg alloy with long-period stacking ordered structure (LPSO) are thought to contribute to improving their mechanical properties. Accordion kink (AK) is considered as the main body of ridge-shaped kink structure (RSKS) which has been observed in layered solids such as metal alloy, muscovite aggregate, geological strata and so on. In this work, we will build mechanical analysis model of AK in finite body based on disclination dipoles in simply-supported boundary condition, and solve the boundary value problem using the approach. The influence of the interval of AK to the stress field in finite body will be discussed in details. The relationship between energy (including strain energy and boundary energy) and intervals of AK will be calculated. The simulation results show that with the extending of intervals of AK, the strain energy increases monotonically. Meanwhile the total area of kink boundary decreases, which effect the variety of boundary energy obviously.

View full abstract

In recent years, there is a need for new space use and design freedom of the building. To achieve this goal, the membrane structure using a film material is capable of a free-form has attracted attention. In this structural design, in order to ensure safety, the verification of the characteristics and safety of the film material with the role of the tension members is required. In this study, we used a Peridynamics of interest as a new failure theory, in order to investigate the tearing behavior of the film material, performing a numerical analysis by particle model. Using numerical analysis results, with the aim to reproduce the phenomenon tear as a property of interest should be of the membrane material, to analyze the qualitative phenomenon. Further, with respect to tear phenomenon of the membrane material, to assess the qualitative nature. Additionally, the numerical analysis by particle models for tearing phenomena of various materials, by performing the analysis of the qualitative phenomena, to verify the possibility of analysis by particle model.

View full abstract

PZT is widely used for actuators and sensors of electromechanical devices and it has multiple crystal systems. Although PZT outputs large piezoelectricity, it shows a complicated hysteresis behavior caused by domain switching and structural phase transition at morphotropic phase boundary (MPB). It is important for development and improvement of lead-free piezoelectric materials to understand the mechanism of huge piezoelectricity in PZT. In this study, a multiscale nonlinear finite element method was developed to estimate ferroelectric material properties. The homogenization theory was employed for scale-bridging between macrostructure and microstructure. We utilized an incremental form of fundamental constitutive law in consideration with physical property change caused by domain switching and structural phase transition. Crystal morphologies, which are characterized as an inhomogeneous structure composed of many grains and domains with individual orientations, are modeled at a micro scale. Then the homogenized physical properties of macrostructure can be estimated with perfect correlation to microstructural changes such as domain switching and structural phase transition. The proposed multiscale finite element method was applied to a polycrystalline PZT, and the relation between the macroscopic properties and microscopic domain switching and structural phase transition were investigated. Especially the difference among tetragonal single phase, rhombohedral single phase and their dual phases were discussed.

View full abstract

Biocompatible piezoelectric thin films are becoming increasingly important for actuators and sensors in medical devices. In our previous study, novel biocompatible lead-free piezoelectric materials, which have perovskite-type structure and include 6 solitary crystals ABO_3 15 complex crystals (A,A')BO_3 and A(B,B')O_3, were discovered through first principles calculations based on density functional theory (DFT). In this paper, the phase diagram of their novel lead-free piezoelectric materials was predicted by employing first principles calculations. Firstly, the stable asymmetry structure of perovskite-type oxide was evaluated. And then, the thermodynamic function with consideration of misfit strain was approximated from total energy and spontaneous polarization of asymmetry structure. Finally, the stable phase with minimum energy was investigated for various misfit strain conditions by employing the approximated function. The proposed method was applied to an existing piezoelectric material PZT (Pb(Zr,Ti)O_3) and verified by comparison with experiment results. Additionally the relation between crystal growth and misfit strain was presented for a novel lead-free piezoelectric material (Mg,Ca)GeO_3.

View full abstract

Stone-Wales defects which often exist in carbon nanotubes (CNTs) and graphene sheets (GSs) can be broke down into pentagon-heptagon (5-7) defect pairs. Using the lattice mechanical model (Peierls-Nabarro model) which considering the effect of periodicity of defects, we will analyze the interaction of 5-7 defect pairs in CNTs. Compare the computational results in this work with the interaction between dislocations according to dislocation theory, and discuss the dependence of radials of CNTs in details. The results show that we can consider 5-7 defect pair as a dislocation and use dislocation theory to solve the problem of interaction between 5-7 defect pairs. The dislocation theory can simplify the simulation of defect pairs in CNTs, and give exactly solution at atomic scale. Based on one slip layer model, we will analyze the distribution of relative displacement on the slip plane and minimizing energy as a function of relative displacement. The minimum energy path will be found by nudged elastic band method. Meanwhile, we find that the interaction of defects plays an important role in the theoretical analysis of defect transformations which strongly effect the stability of CNTs.

View full abstract

Advanced semiconductor products have structures with thickness and width in nanoscale. As the size of the structures reduces to a nanometer level, a ratio of their surface to volume increase. In the present study, the singular stress at the comer in an anisotropic two-dimensional multi-wedge joint made of three materials is analyzed using molecular dynamic method and the anisotropic elasticity theory. The joints is composed of Ni, Au and Cu. Here, the wedge angles are 4π/9 for Ni, π/2 for Au and 17π/18 for Au, respectively. The atomic stress distribution in a circumferential direction in the molecular dynamics calculation is compared with that obtained from Stroh's formalism and eigen analysis with interface properties.

View full abstract

CFD is an important tool to shed light on cerebral aneurysm. Vascular wall shear stress play an important role in the initiated and developed cerebral aneurysm. In this study, fluid dynamics were analyzed throughout cerebral artery using 3D-CAD technology and CFD software. High wall shear stress was occurred in the area connected communicating artery to cerebral artery. This area was in accordance with clinical information.

View full abstract

Airflow in a realistic nasal model was numerically simulated in order to investigate the transitional nature of flow. Computed tomography scans were used to reconstruct 3D realistic model of nasal airways. Voxel-based simulation of quiet restful inspiratory flow was performed using meshes with voxel pitches of 0.15 mm. Resultant velocity profiles and fluctuations were discussed in comparison to our previous experimental study. As a result, good agreement was observed between the velocity profiles and those measured experimentally, whereas the velocity fluctuations were much smaller than those observed experimentally.

View full abstract

In vitro ventilation experiment by the tandem piston type respirator through the separated pipes for inspiration and expiration has been carried out with several lengths of the connecting pipes on the condition of several frequencies and tidal volumes of oscillatory flow. A smooth pipe and a pipe with circumferential grooves were tested as the connecting pipes between the respirator and the lung model chamber. The half life of the tandem piston type respirator was half of the high frequency oscillatory ventilation respirator in the market on the similar condition. The half life of the carbon dioxide in the chamber as a lung model with the separated connecting pipes for inspiration and expiration was smaller than a single pipe. The half life with the separated connecting pipes was not varied with the increase of the length of the connecting pipes. The inner surface was less affect on the half life. The half life with the separated connecting pipes is inverse proportional against the increase of the product of frequency and tidal volume fV.

View full abstract

Recently, cell patterning that enables to make the cell chip has been under study. And in the existing study, two-dimensional cell patterning by transferring cell adhesion solution with inkjet device or photolithography mainly has been studied. On the other hand, to simulate condition in vivo, the three-dimensional cell patterning technique is essential and this enables the construction of more complicated organization in vitro. However the technique to locate nerve cells at the specific position in the three-dimensional gel is not developed. In this study, to develop three-dimensional cell drawing technique and apply it to neural cell chip, we focus on micro injection which can control the three-dimensional position in gel solutions. The three-dimensional cell drawing technology was consisted of micro injector and automatic positioning stage. Polystyrene beads and PC12 cells were located and patterned three-dimensionally in hydrogel. As the results, our drawing system showed possibility of applying the neuronal cell chip.

View full abstract

In this study, an experimental system is developed to detect three-dimensional shape and local mechanical properties. The three-dimensional shape is detected by a contact sensor and sequentially controlled three stepping motors for x, y and z axis displacement. A motor-controller circuit for the stepping motor is newly designed and controlled by a microcontroller device. From coordinate data of contact points between the sensor tip and a sample, the three-dimensional shape is reconstructed with a computer. From results of some experiments, it is confirmed that the system passably detects cartilage tissue's three-dimensional shape. On the other hand, the system has another sensor to evaluate mechanical properties based on the principle of electrostatic capacitance. Mechanical properties are estimate by amount of cantilever's deflection, and the amount of deflection was measured by the capacitance meter. The experimental result shows that the developed system can detect difference in mechanical properties between fatty white part and red lean part on a sliced meat.

View full abstract

Many elder persons suffer from osteoarthritis. Degeneration of the knee cartilage causes this disease. We have developed the diagnostic equipment for cartilage using an ultrasonic wave. The measurement using the proposed ultrasonic equipment is effected by operators skill and skin on cartilage. These factors leads to low reproducibility of acquisition results. Our goal is to achieve the ultrasonic diagnostic equipment with high reproducibility. In this study, we investigated three dimensional movement of the ultrasonic probe. The movement of the tip and end part of the probe was measured using two cameras. From the two photos, three dimensional position (X, Y, Z) of these parts was calculated from the theory of stereocamera. Ideal operation of probe is that the probe the end part is straightly moved and the tip part is fixed. Displacement of the tip part on X-axis, which is defined as the direction to incline the probe, were 3.44±1.82 mm (T=0 h) and 5.36±1.30 mm (T=4 h). The X-axis displacement gradually increased with cartilage degeneration. From this result, the ideal operation could not be performed, especially, in the case of deeply degenerated specimen. We had often felt that degeneration of specimen related to difficulty of measurement. This result coincided with our experience. This study suggests that some support devices to properly operate the probe is necessary.

View full abstract

This study aimed to measure a viscoelastic property of porcine liver specimens by the magnetic resonance elastography using micro-magnetic resonance imaging system (micro-MRE). In the experiments, the viscoelastic modulus of gelatin gels was measured. Furthermore, the viscoelastic modulus of a liver specimen obtained from a porcine liver and a liver specimen embedded in a gelatin gel were measured. The specimens were vibrated with longitudinal waves in a micro-MRI with excitation frequency of 50-250 Hz and amplitude of 0.5 mm transmitted by an elastic-bar from a vibration generator. The viscoelastic modulus was calculated as storage shear modulus G' and loss shear modulus G". As a result, G' of the gelatin specimens increased with the excitation frequency, and G" was much smaller than G'. The liver specimen embedded in the gelatin gel was vibrated deeply and G' of the porcine liver increased with the excitation frequency as well as gelatin specimens. The G' of the gelatin gel surrounded the porcine liver specimen corresponded to the value of the gelatin specimens. These results suggest that the viscoelastic modulus of the porcine liver is measured by using the micro-MRE and surrounding the liver with gelatin gel under the excitation conditions.

View full abstract

Mechanical properties of bone are essential to understand the changes in bone fracture risk with aging and/or osteoporosis and to evaluate the effects of osteoporotic medicines as well as bone volume fraction and bone mineral density. The relationship between mechanical properties and hierarchical structure of cortical bone has been investigated using the bone samples taken from an inner region of the diaphysis. According to an optical microscopic observation, different microstructure was observed between cortical surface and inner region of the diaphysis. Hence, the study aimed to investigate the distributions of elastic modulus, microstructure, hydroxyapatite (HAp) crystal orientation, and mineral contents from the cortical surface to the inner region of the bovine femoral diaphysis. In the experiments, strip bone specimens were taken from the surface and the inner region of bovine femoral diaphyses. As a result, elastic modulus at the surface region was significantly lower than that in the inner region (73%). Osteon area fraction at the surface region was significantly lager than that in the inner region (141%). On the other hand, HAp crystal orientation showed no significant difference. Mineral contents at the surface were slightly lower than that in the inner region (98%). It suggests that elastic modulus of osteon region is lower than that of non-osteon region and that the difference of elastic modulus between surface and inner region may depend on the osteon area fraction as well as mineral contents.

View full abstract

Cancellous bone has a three-dimensional network of single trabecula. It has been reported that the apparent elastic modulus of cancellous bone is much smaller than that of cortical bone and that the elastic modulus depends on the trabecular network. However, the mechanical properties of single trabecula are still unclear, because mechanical tests of single trabecula are challenging. This study aimed to develop an experimental method to measure the elastic properties of single trabecula that was 1 mm in length by micro cantilever bending. In the experiments, 10 single-trabecula specimens taken from the proximal epiphysis of a 2-year-old bovine femur were used. The tests were conducted using a small testing device that consisted of an acrylic plate for applying load to the specimen, a linear stage, and a load cell. The specimen was in contact with the edge of a taper bore drilled in the acrylic plate and was deformed by applying the displacement with the stage. The deflection of the specimen was observed by optical microscopy. A finite element model of the specimen was constructed from a micro-CT observation. The elastic modulus of the specimen was calculated from the force-deflection relation by finite element analysis. As a result, elastic modulus of single trabecula was 8.2 ± 3.3 GPa. There was no correlation between the elastic modulus and trabecular orientation in the femur. The study showed that the elastic modulus of single trabecula was much smaller than that of the cortical bone in bovine femoral diaphyses by proposed method.

View full abstract

We previously reported that the output force distribution at the wrist demonstrated in the hexagonal shape, and the characteristic of the hexagonal output force distribution was suggested by the theoretical analysis of the two joint link model with the muscle coordinate system. The muscle coordinate system is composed of the three pairs of antagonistic muscles consist of mono- and bi- articular antagonistic muscles. The difference between distribution calculated muscle coordinate system and distribution calculated joint coordinate system consists of two joint torques was clarified. The individual functional effective muscular strengths could be evaluated from the hexagonal output force distribution. In this study, the relationship between output distribution and muscular strengths under approach by muscle coordinate system was more clarified. Proposal method may be of use when prescribing the portable measuring system of the functional effective muscular strengths.

View full abstract