Synchronous conveyor belts with attachments are widely used in the industrial field. It is able to select the type of attachment by customer's needs. The fatigue failure is often initiated from the heat melting region between attachment and belt. As for the cause of the fatigue failure, there are two types of failure mechanism. One is for the case that the belt is damaged by the cyclic bending deformation around the pulleys. The other is for the case that the belt is damaged by inertia force when the attachment contacts with a product. In this study, the authors focused on the failure mechanism by the inertia force at the heat melting region of the attachment. The finite element analysis (FEA) was carried out to evaluate the maximum principle stress at the melting region.

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V-ribbed belts is a friction transmission belt, and is used as an accessory drive belt, which drives an alternator, compressor and water pump using the power of crankshaft. The V-ribbed belts has some ribs, which comes in contact with the pully grooves. The V-ribbed belts constructs of the top fabric, cords, adhesive rubber and rib rubber. There are three failure mode for the fatigue damage accumulation, namely "Cord Pop-out ", "Rib bottom wear ",and "Rib crack ". Furthermore, a "Rib crack" can be classified into the "Rib top crack" for which the rib top is cracked, and the "Rib bottom crack" for which a rib bottom is cracked. In this study, the failure mechanism of the "Rib top crack" and "Rib bottom crack" was discussed caring out some observations and FEA.

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Recent years, silica-filled rubber has been used in fuel-efficient tires because silica-filled rubber has low rolling resistance and high wet skid performance compared to carbon black-filled rubber. The effects of silica content on wear have not been fully revealed. The purpose of this study is to clarify the wear property of silica-filled styrene-butadiene rubber (SBR). Six types of SBR filled with different contents of silica and carbon black were used as rubber specimens. The experiment was carried out using a pin-on-disk type tribometer. Each specimen was rubbed against metal gauze in silicone oil. As a result, the specific wear rate K and coefficient of friction fx decreased when the silica content was increased. The cross section of worn surface area was observed by atomic force microscopy. The deformation of bound rubbers in specimens was observed after friction test. The shape of the bound rubber looks round. The bound rubber of specimens after friction experiment was elongated and deformed from the round shape. The size of bound rubbers after friction experiments was smaller than before friction experiment.

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According to Persson's statement, the friction coefficient of a rubber is determined by the rubber's viscoelasticity and the surface property on multiscale asperities which can be represented by surface roughness power spectrum. In this study, we conduct friction testing for the two different dry surfaces and evaluate the Persson's mathematical model giving the friction coefficient that depends on sliding velocity and flash temperature. We also measure the rubber friction sliding on surface to which grease is applied and discuss about how the multiscale asperities might make an effect on friction.

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Synchronous conveyor belts are widely used in the industrial field. Rubber conveyor belts have fusion bonded joint which can be flexibly designed for arbitrary belt-length. Since the tension cords are disconnected at the fusion bonded joint, the strength of the joint area are relatively low. In this research, the deformation behavior of the joint area was measured. Then, the FEA and the mechanical analysis using a simplified mechanical model were carried out to discuss the geometric design of the joint area.

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The objective of this study is to develop a new constitutive model, which can precisely reproduce cyclic stress-strain responses of carbon black (CB)-filled SBR vulcanizates under wide ranges of applied strains and strain rates. Dumbbell specimens sampled from the vulcanizates were prepared for uniaxial cyclic tests; then, effects of maximum strain, strain range, strain rate and CB content on the cyclic stress-strain responses were investigated. The comprehensive experimental investigations clarified that the cyclic stress-strain response for pre-strained specimens showed characteristic phenomena (stress softening, and emergences of residual strain and hysteresis loop), and the phenomena were changed with cycles. However, such changed stress-strain response recovered the initial one by relaxation treatment under an unloaded state at room temperature for a specific period; therefore, it was inferred that the characteristic phenomena of the pre-strained specimens were caused by viscoelasticity.

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We present a new constitutive equation which enables to simulate experimental cyclic stress-strain responses in a carbon-black filled SBR rubber. The constitutive model for the basic elasticity is based on the Yeoh model, and the theory of finite viscoelasticity with an intermediate configuration is used to describe the rate dependent behavior. The simulated results were approximately consistent with the experimental ones; therefore, the proposed model reproduced the experimental cyclic stress-strain responses of the vulcanizates under wide ranges of applied strain and strain rates with satisfactory accuracy.

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This paper presents mechanical simulation of resin foam with the self-centered cells under the unidirectional compression load. Sports shoes mainly have various resin foams as midsoles, which produce the shock attenuation. The stress-strain curves under compression are really complex, which are classified into 3stages, elastic, plateau and densification. It's said that these stages are derived from cell wall deformations and included gas in the cells. In order to design the shock attenuation, the control of the above complex behavior is necessary. In this study, we constructed a numerical model of resin foam considering the micro structure based on the CT images. For checking the validity of this model, a stress-strain curve under quasi-static compression is compared with an experimental result. Through these results, it reveals that the cell wall deformations are the trigger to the complex mechanical behavior and the effect of gas in the cells can be ignored.

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Foamable resin is used for the purpose of improving the mechanical characteristics of industrial products by elastic and damping. SEBS of foamable resin is Thermoplastic Elastomer, and its behavior represents the rubber elasticity at room temperature. When foamable resin is analysed by Abaqus, the analysis is performed using the elastomeric foam material model obtained by extending the hyperelastic material model, because features is rubber elasticity at room temperature. In This paper, we went to a tensile tests, compression tests, and viscoelastic measurement of SEBS with different expansion ratio. And we developed a material model combined the viscoelastic material and elastomeric foam material for using Abaqus.

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In this paper, the residual strain of the fiber-reinforced rubber (FRR) in a cyclic tensile test was investigated. The FRR is used in seal materials, tires, and so on. This material is a composite material made of rubber matrix reinforced with fibers. So, it shows higher stiffness along the reinforced fiber. Products listed above are used under cyclic deformation. So, stress softening and the residual strain of the FRR should be considered for design. Therefore, the cyclic tensile test was discussed at each tensile direction. The result showed anisotropic behavior, stress softening, and the residual strain at each tensile direction.

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When analyzing incompressible rubber material with explicit method, the Courant condition is very important. The bulk modulus will become infinite number when solving the incompressible material. Then the critical time step becomes tremendous small number, so the analysis CPU time is not realistic. We report the relationship between incompressibility and numerical time step under the explicit method.

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In this paper, a computational prediction method of the compression set of EP-rubber O-rings was proposed. As the prediction method, the finite element analysis code using thermo-mechanical viscoelastic model was developed. The material model consisted of viscoelastic elements connected in parallel. A viscoelastic element consisted of a hyper elastic spring and a viscous damper, which were connected in series. The relationship between relaxation times and temperature for the viscous characteristics of this model were calculated using the Arrhenius equation. This model is possible to perform the elastic strain which is generated by stress reduction. The boundary conditions of the FEM simulation were supposed that rubber O-rings were in the two flat plates and in the groove and lid. Surface contact algorithm with penalty function was applied to the FEM code.

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The micro-sphere model which is a physically motivated constitutive model for the description of the material behavior of rubbery and glassy polymers has been proposed in Miehe et al(2004). The main focus of this paper is to investigate the mathematical relationship between micro sphere model and common hyper-elastic model. The implementation and the accuracy of these approaches are demonstrated with a simple Mooney-Rivlin model.

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Lithium ion battery is generally used in mobile devices for its advantages such as easy downsizing and weight saving due to high energy density. If there were short circuit points in the battery, the abnormal heating occurred for higher energy density than conventional batteries. It is necessary to identify the short circuit parts in Lithium ion battery. However, it is difficult to clarify the micro abnormal part in the battery by diagnosis imaging such as X-ray inspection. Therefore, a new technique of localization of short circuit part has been developed by using inverse analysis of the electromagnetic field around the battery. This method can inspect the short circuit part in the battery by estimating the electric current value at the arbitrary point from data of the magnetic field around the battery. Because the technique is nondestructive inspection and able to quantitatively evaluate, it can be expected to reduce the inspection cost and to improve the detection accuracy of short circuit in the battery. In this report, the effectiveness of this method was demonstrated through the analytical results in which the short circuit parts was identified from the magnetic flux density measured around the specimen that simulated the battery with short circuit by using the magnetic sensor.

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Recently, it is necessary to prevent accidents of infrastructures and industrial structures that were caused by poor maintenance and aging. Especially it is important to decide the time to replace the pipe for management of the pipe wall thinning. However, conventional methods to identify the pipe wall thickness such as ultrasonic and radiation are influenced by surface conditions of the pipe wall, size of the equipment and radiation leak. Therefore a new technique of identification of the pipe wall thickness has been developed by using an inverse problem for a distribution of magnetic flux density around the pipe wall. This technique is superior to the conventional method at the view points of no influence of surface conditions, safety for the radiation leak and potential of downsizing because of using only an electrode and magnetic sensor. This paper demonstrates the validity of the proposed technique. Moreover it is attempted to improve sensitivity for identification of the pipe wall thickness by using high magnetic permeability material.

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For seismic damage evaluation for important structures, such as nuclear power plants, additional plastic deformation under the earthquake should be estimated. However, most of nondestructive tests, such as hardness test, can only approximate accumulated plastic deformation under all processes. In this study, we show change of residual magnetic distribution can indicate additional plastic deformation in ferromagnetic metals. Since magnetic walls are pinned with dislocations, plastic deformation makes the dislocations unpin the walls to move into steady anhysteresis curves. All magnetized ferromagnetic metals were demagnetized after tensile tests. Since magnetization is affected from dislocation density, evaluation of the additional plastic deformation has not been realized yet.

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In recent years, thermoplastic CFRP attracts considerable attention especially in aviation and automobile industries due to weldability of thermoplastic CFRP. Ultrasonic testing (UT) is commonly adopted as a testing method for inspecting weld parts although time and cost on UT is thought to be problematic. Since eddy current testing (ET) is used for rapid and non-contact inspection on electrically conductive materials, this paper presents an eddy current based approach for detecting defects in thermoplastic CFRP welded zones. However, it is difficult for conventional ET to detect delamination which is parallel to eddy current although delamination is one of the common forms of weld defect. To detect delamination in thermoplastic CFRP welded zones, new eddy current based approach which utilizes temperature characteristic of electrical conductivity is proposed. The proposal consists of two steps. Firstly, temperature difference between intact zones and defective zones is caused by heating the one side of the weld part. Secondly, the temperature difference is detected by ET utilizing temperature dependency of electrical conductivity.

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The influence of the distribution of the elastic-plastic strains in the irradiated area of the polychromatic X-rays on diffraction profiles was investigated by using a numerical simulation. The value of FWHM increases with increasing strain range. On the other hand, the weight coefficient of Lorentzian decreased. The effect of the elastic strain on the increase of FWHM is much larger than that of the plastic strain near the crack-tip. The elastic strain distribution can be evaluated by the averaged elastic strain using the optimization technique.

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In order to assess structural integrity for operating welding structures, it is important to evaluate three-dimensional welding residual stresses non-destructively. Then the bead flush method has been proposed. In this method, welding residual stress distributions for whole structure are calculated by an elastic FEM (Finite Element Method) analysis from eigen-strains those can be evaluated quantitatively by the inverse analysis from released strains measured by strain gauges in the removal of the reinforcement of the weld. However, the estimation accuracy of this method becomes poor if inelastic strains are newly created during the removal process. In this study, a calculation technique to assess eigen-strains included processing strains estimated by X-ray diffraction is shown, and estimation accuracy of welding residual stress on the rear surface calculated from residual strains on the front surface with measurement errors is evaluated numerically. If this method is established, the reinforcement of the weld can be machined easily and accurately in the measurement process.

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A COPV (Composite Overwrapped Pressure Vessel) is consisting of a thin metallic liner wrapped with a fiber composite. The outer side CFRP layers bear the load due to internal pressure, and the inside liner provides a barrier between the fluid and the composite. Because of its high specific strength compared to metal pressure vessel, COPV have been applied to the field of aerospace. If it suffers impact load such as by falling tools, both CFRP and liner cause the impact failure, and a dent remains in liner by metal plastic deformation. Usually, the liner deforms elastically in MEOP (Maximum Expected Operating Pressure), but in the part of liner dent, there is a possibility of plastic deformation by adding the bending moment as well as the load due to internal pressure. If tensile and compressive plastic deformation repeats by pressurizing and depressurizing, the ratchetting plastic deformation occurs and plastic strain is accumulated in liner dent. This study discusses the ratchettig defomation of the COPV liner, and investigates the presence of ratcheting by FEM.

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Temperature of a specimen subjected to repeated stress under high temperature was measured using infrared thermometer. The temperature of specimen was raised to 200°C in an electric furnace. After the temperature reached predetermined temperature, repeated stress was applied to the specimen. And the door of the electric furnace was opened to measure the temperature of the specimen. The temperature fell continuously with small temperature change caused by repeated stresses. The temperature change was caused by three factors as follows; 1) thermal radiation, 2) heat conduction, and 3) thermo elastic effect. By evaluating their influences, repeated stress was measured under temperature change from 200°C to room temperature.

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The effect of surface coating on the accuracy of thermoelastic stress analysis (TSA) under uniaxial tension is studied. In TSA, the surface of sample is usually coated with matt black paint to improve the infrared emissivity. However, this coating may reduce the accuracy of stress measurement due to the heat conduction in the thickness direction. In this study, a theoretical solution describing the effect of heat conduction in the coating has been derived and compared to the experimental results for several specimens of different coating thicknesses. It has been verified that the present solution fits to the experimental results better than that obtained in the previous study. In addition, it has been shown that the solution can be used for compensating for the effect of coating in TSA.

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It is desirable to evaluate the fatigue limit of real products to verify the appropriateness of fatigue design. However, fatigue testing of real products requires huge cost, namely a large number of loading cycles and a large number of specimens. In order to reduce the cost, a technique of rapid evaluation of fatigue limit using infrared thermography is developed and paid attention recently. However, the reliability of the technique has not been verified well yet, especially for application to specimens with stress concentration. In this study, the applicability of the technique to notched specimen of SUS304 is examined experimentally. By comparison with the numerical simulation conducted previously, it is shown that care must be taken about the spatial resolution of infrared thermography in order to evaluate the fatigue limit correctly.

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Recently, fatigue limit estimation based on the dissipated energy measurement using infrared thermography has attracted attention in various industries. In this study, fatigue limit estimation based on dissipated energy measurement was applied to the evaluation of shot peening treatment. Shot peening treatment is used for fatigue limit improvement by applying work hardening layer and compressive residual stress. The strength of material is affected strongly by shot peening treatment condition. Therefore, it is useful to evaluate the effect of shot peening condition by fatigue limit estimation. The fatigue limit estimation by energy dissipation was applied to shot peened 316L stainless steel specimen. It is found that estimated fatigue limit of the shot peened material obtained by dissipated energy is conservative value compared with that obtained by conventional fatigue test. After the fatigue test, micro cracks were observed in the unbroken specimen of shot peened materials. Therefore, dissipated energy for shot peened materials subjected to the stress amplitude below fatigue limit was affected by non-propagation cracks. It was considered that the estimated fatigue limit indicated crack initiation stress level.

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For the design of mechanical structures, the fatigue limit is indispensable. Therefore, it has been developed the simple evaluation method utilize the dissipated energy. In this method, the temperature change can be measured for the specimen under cyclic load, and the fatigue limit is corresponding to the inflection point the temperature starts to rise rapidly. It is unclear the mechanism of the between fatigue limit and temperature rise, though this method has been studied widely. In this study, we perform the fatigue limit estimation considering influence of mean stress, and aim to clarify these mechanisms.

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To detect the clack of boiler pipes or turbine casings of thermal power plants, ultrasonic testing is used. To improve the reliability for these equipments, we are developing high temperature ultrasonic sensor using oscillating heat pipe. In this paper, we made an experimental sensor, and checked the cooling performance and the ultrasonic sensitivity of this sensor.

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Numerical and experimental study of the ultrasonic reflection characteristics of porosity-containing CFRP laminates immersed in water was carried out. Using two different kinds of incident frequency, the influence of porosity on the bottom echo as well as the reflected waves from interlayer interfaces was investigated respectively. It was observed from the lower-frequency incidence (2.25 MHz) that the bottom echo was gradually attenuated with the increasing porosity fraction. On the other hand, it was found from the higher-frequency incidence (10 MHz) that the duration of the reverberation behind the surface echo, due to the reflection at different interlayer interfaces, was reduced with the increasing porosity fraction.

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The surface roughness is an important parameter for examining the quality of material surfaces. The stylus profiling technique or laser microscopy are widely used for measurement of surface roughness, though these techniques are not applicable to measure the back surface roughness. In this study, back surface roughness evaluation technique using ultrasonic testing is proposed. The effectiveness of the proposed method is investigated by numerical simulation and experiment. Based on a Kirchhoff model, the root-mean-square roughness can be evaluated by measuring the intensity of coherent component. For accurate measurement, the incident angle of ultrasonic beam should be small in order to reduce the effect of mode conversion.

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Ultrasonic wave propagation behavior in the corner section of CFRP (carbon-fiber-reinforced plastics) laminates is investigated by finite element analysis. The analysis is performed to examine the influence of the wave incidence direction and the stacking sequence of CFRP (unidirectional or quasi-isotropic) on the reflection waveforms. As a result, when the wave is incident from the inner side of the corner, the observed waveform for the unidirectional laminate is featured by distinguishable surface and bottom echoes, while the waveform for the quasi-isotropic laminate does not show clear bottom echo due to multiple reflection by interlayer interfaces. On the other hand, when the wave is incident from the outer side of the corner, the waveforms for both types of laminates are fairly similar, and featured by clearly distinguishable bottom echoes.

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It is essential for the nondestructive ultrasonic testing to predict the wave propagation mode in a long object such as pipe, plate, among others. To obtain the propagation mode in long objects with complicated cross section and local inhomogeneity, the semi-analytical finite element method (SAFE) has been proposed previously. In this study, the validity of the SAFE is checked with ultrasonic signals. Instead of using measured signals, we here use numerical signals which are calculated with the elastodynamic finite integration technique (FIT). The propagation mode and dispersion curves obtained from the SAFE and the FIT show a good agreement.

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Flexural properties of injection molded hydroxyapatite (HAp)/ P-tricalcium phosphate (TCP)/ poly lactic acid (PLA) ternary composites with different mixing ratio of HAp and TCP particles were investigated. Flexural properties such as flexural strength and the modulus depended on the mixing ratio of HAp and TCP particles, and the ternary composites with 3:7 of mixing ratio showed the highest flexural strength. In addition, hydrolysis degradation effect on the flexural properties was also investigated using phosphate buffer solution at 37°C. The results showed that flexural properties were degraded by hydrolysis degradation, and degradations of flexural modulus depended on the mixing ratio of HAp and TCP particles.

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In this study, immersion tests on poly(L-lactic acid) (PLLA) and their composite with β-tricalcium phosphate (β-TCP) to phosphate buffered solution (PBS) at 37℃ is carried out to investigate the effect of immersion in PBS on tensile mechanical properties. A simple phenomenological model to predict tensile elastic properties of hydrolyzed biodegradable polymer and their composites is also constructed by assuming voids generation in the hydrolyzed sites of the polymer. The model of relationship between number average molecular weight and immersion time is in a good agreement in any specimens, and it seems to be the evidence of autocatalytic hydrolysis of PLLA. Furthermore, the model shows that the hydrolytic degradation rate constant is decrease withβ-TCP contents. It means thatβ-TCP particle has inhibitive effect on hydrolytic degradation of PLLA. Although the predicted value has large error on the later scheme of hydrolysis, the model describes tensile elastic modulus trend of degraded PLLA and β-TCP/PLLA composites reasonably.

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Importance of bone fracture treatments has been increasing with the number of bone fracture patients with arrival of the aging society. Bioabsorbable bone fixation devices are required to improve quality of life of patients. Poly(lactic acid) which has high biocompatibility is expected as a material for the device. However, applications of PLA bone fixation device are limited to low loaded region, because of their lower mechanical characteristics. As a method to improve mechanical properties of PLA, drawing has much attention. In this study, molding conditions are investigated to improve mechanical properties of PLA. Deformation behavior of PLA rods in drawing was numerically investigated by finite element method. Orientation for the rods was estimated from principal strain caused calculated. Effects of extrusion ratio on orientation for the rods were investigated by comparison of computed principal strain in extrusion ratio 4 and 8. As a result, the magnitude of principal strain along drawing direction in the drawing ratio 4 and 8 was comparable, which suggested that degree of orientation in extrusion ratio 4 and 8 was comparable.

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Coefficients of Cowper-Symonds constitutive equation for PLLA/PCL = 80/20 at 36℃ were determined using the results of compressive tests. The simulation of split Hopkinson pressure bar using the coefficients was carried out under the same condition as the experiments. The stress-strain curves of specimens, the thickness and the diameter in the simulation at high strain rate were compared with those in the experiments.

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In this study, the change in sintering condition and the surface improvement by ion irradiation method was used to change the microstructure of hydroxyapatite (HA) to control the apatite formation on the HA surface, that is bioactivity of HA. Bioactivity of hydroxyapatite was investigated by soaking in simulated body fluid (SBF). The HA sintered at two different conditions showed similar apatite formation behavior after soaking in SBF. The HA irradiated with Ca ion at different ion dose and depth showed fibrous apatite formation on the surface at all ion irradiation condition. However, apatite formation rate was different. Apatite formation on the HA irradiated with Mg ion became lower with increasing Mg ion dose. Thus, the apatite formation of HA surface can be controlled by changing ion species, dose and depth. This means that the change in microstructure of HA can controll the bioactivity appropriate for use site.

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Continuous porous structure of hydroxy apatite (HA) was fabricated by the template method as a scaffold for bone tissue engineering. Secondary polymer phase of bioabsorbable poly(s-caprolactone) (PCL) was introduced into the HA porous structure through two different methods in order to improve the mechanical properties. Two types of HA/PCL composite scaffolds, namely PCL-coated HA scaffold and HA/PCL dual-phase scaffold, were developed and the compressive properties were compared. Their microstructures were also observed by FE-SEM. It was found that the PCL-coated possesses better mechanical properties than the dual-phase. It is considered that the PCL phase coated onto HA surfaces reinforces effectively the brittle HA frame structure. The dual-phase structure can hold the porous structure after HA frame collapses, resulting in the improvement of mechanical properties. However, the freeze-dry process for the dual-phase fabrication tends to degrade the HA frames, resulting in the lower properties than the PCL-coated.

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Recently, the osteoporosis victims increase in the senior people. Therefore, the danger of the stress fracture due to the decrease in bone strength is pointed out. Especially, the damage accumulation behavior of the bone in the cyclic load becomes a problem for the fatigue of the bone. Moreover, it is necessary to consider the viscoelastic property for the prediction of the fatigue behavior, because the bone is a viscoelastic material. In this study, our objective is to estimate the fatigue behavior that considers the viscoelasticity behavior and the damage accumulation behavior as damage mechanics. The viscoelastic properties were revealed with the strain rate tests, and we calculated the 3-mode Maxwell parameters with these results. The damage accumulation behaviors were measured with the Acoustic Emission method. Using these results, we could estimate the fatigue behavior of cortical bone with the viscoelastic parameter and cumulative AE energy.

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In this study, component analysis as mechanical evaluation was performed by Raman spectroscopy for cartilage consisted by macromolecule (such as collagen fiber and proteoglycan). Raman spectroscopy is a vibrational spectroscopy by Raman scattering, and allows simultaneous measurement of organic and inorganic components. The spectroscopy is suitable for measurement of biological samples because of little effect on water. The cartilage specimens ware cut out from rabbit knee joint and their Raman spectrum were analyzed. In addition, load response to cartilage by the spectroscopy. The result of Raman shift for hydroxyproline and pyranose shows mechanical response. Therefore, this study indicated the possibility of stress analysis for cartilage with Raman spectroscopy.

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We carried out uniaxial stretching test, strain analysis by digital image correlation (DIC) and histological observation of collagens for aortic specimens dissected from autopsy. Specimens, which were fibrous or fatty, were prepared by dissecting an inner layer of the aorta. Load and grip-to-grip displacement were measured simultaneously using a 5N load cell and laser displacement sensor. Longitudinal deformation of a specimen was measured by using a pair of markers on the surface and distribution of strain was obtained by DIC method. Specimens for histological use were stained and observed by light microscopy and the amount of collagens and the type I were estimated. Stress-strain relationships show that fibrous or fatty regions were much stiffer than normal. Stiffening is correlated with the amount of collagen especially type I. Strain analysis by DIC method shows nonuniform deformation of the specimen which may be due to the heterogeneity of the vascular wall.

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Coronary artery disease is the most prevalent form of cardiovascular disease and is the largest subset of this mortality. Stent implantation becomes a common interventional procedure for treatment of coronary artery disease. In this study, fluid dynamics factors in patient specific three dimensional coronary artery models before and after stenting were studied. The three dimensional models of the coronary artery were constructed from CT image of the patient. Commercial software Adina was used for computational fluid dynamics simulation. The wall shear stress was greater at the region of stenosis before stenting. The fluid dynamics values have come back near to normal values in the coronary artery model fitted with stent. The technique can be employed to estimate the relevant quantities and to optimize the design of intravsacular stents.

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Cell migration plays an important role in many physiological and pathological events, however, the mechanism of collective cell migration has not been well understood. This study performs traction force microscopy on migrating NIH 3T3 fibroblasts using a multichanel device. The device consists of a reservoir for cell culture and 24 microchannels with arrays of micropillars for traction force microscopy. Here, the effect of anisotropic properties in stiffness of substrate on collective cell migration is tested with ellipsoidal cross section of micropillars. The results showed that cells migrated into the microchannels and produced higher traction forces in the direction of major axis of micropillars. This finding suggests that cell can sense the stiffness of substrate and produce traction forces depending on the stiffness, resulting in difference in cell migration rate.

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In this study, we investigate the morphological change of the biological tissue from the mechanical viewpoint and try to elucidate its mechanism by numerical simulation. To this end we formulate a model based on solid mechanics and treat it as an initial boundary value problem. As one example, we focus on a process of invaginate structure of vascular sheet and analyze it within the framework of the finite element method. Diversity in the pattern of invagination was observed, if the material anisotropy of hyperelasticity was taken into account. The consideration of material anisotropy is important, when modeling the morphogenesis.

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In this study, we aimed to develop a method of brain stress analysis to support the treatment of craniosynostosis. Currently, craniosynostosis has been fixed up by surgeiy. It is necessary to develop to predict the effect of surgery during the growth of patients. Previously, we developed a simple head model, where the growth of brain is expressed by thermal expansion of brain elements. Here, we analyzed the effect of meninges on stress distribution of brain constrained by skull under growing. In addition, the boundary condition considering the existence of brain stem was discussed.

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In this study, we investigate thermal stress problem of a hollow circular truncated cone, which is simulated such as a body of space-plane and a tapered tube. First, the coordinate system and element for the analytical model is defined, and heat condition problem for the analytical model is considered. By applying the defined element, the analytical solution of temperature fields in a hollow circular truncated cone is obtained easily using analytical solutions of temperature field for cylindrical coordinate system. Example calculations for the temperature fields are carried out. Also, an analytical approach for thermoelastic stress analysis using the defined element and coordinate system in this study is discussed.

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This paper deals with an adaptable stress control problem in a multilayer composite disk consisting of a transversely isotropic structural layer onto which piezoelectric layers are bonded. The piezoelectric layer next to the structural layer serves as a sensor and the other piezoelectric layers serve as actuators. It is assumed that a transient electric potential distribution is measured on the sensor layer when an unknown transient heating temperature distribution acts on the structural layer. The inverse thermoelastic problem is analyzed by employing the potential function methods as well as the finite difference method, so that the unknown heating temperature is determined from a knowledge of the electric potential distribution induced on the sensor layer. The transient maximum thermal stress in the structural layer can be suppressed by applying appropriate transient voltages to electrodes arranged on each actuator layer. The applied voltages are determined by optimization in order to minimize the maximum thermal stress at arbitrary time.

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When an isotropic and homogeneous solid sphere and/or infinitely long solid cylinder are suddenly subjected to an instantaneous uniform heating, a stress wave occurs at the moment thermal impact is applied. The stress wave proceeds radially inward to the center of a sphere and/or cylinder. The wave may accumulate at the center and give rise to very large stress magnitudes, even though the initial thermal stress is relatively small. This phenomenon is called the stress-focusing effect. In this study, the stress focusing effect in a solid sphere and solid cylinder under instantaneous uniform heating at the free surface is studied on the basis of the generalized thermoelastic theories, that is, the Lord-Shulman's and the Green-Lindsay's theories. The combined governing equations of both theories are solved by the Laplace transform technique. The effects of the thermomechanical coupling and the relaxation time on the stress focusing phenomena as well as the singularity of stresses are discussed.

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The deterioration in the quality of fresh concrete, which is mixed, agitated and transported in hot weather period has become a problem due to global warming in the concrete industry. It is well known that the quality of fresh concrete transported by a truck agitator in hot weather deteriorates since fresh concrete temperature is increased by the solar heat and outside temperature. Coating a truck agitator drum with high-reflectivity paint which is referred to as heat insulating paint attracts an attention as a measure against hot weather during transport of fresh concrete. Our study on an attempt to improve suppressing effect of increased surface temperature of the drum by heat insulating painting in combination of cooling with water spray and air flow developed by wing-tip vortex is introduced. The water spray is carried to the drum via downwash generated by a wing. A method of water cooling of a truck agitator drum coated with heat insulating paint is suggested, and the improvement of an effect on the suppression of surface temperature rise is examined.

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The purpose of this study is to improve and extend a method to estimate the friction coefficient in equal channel angular extrusion (ECAE) including cases with back pressure. Employing three dimensional finite element analysis (FEA) and Coulomb friction model with truncated shear stress, the relationship between the friction coefficient and the reaction force is investigated in ECAE with back pressure. Additionally, the deformation state of the billet after ECAE and the pressing load are compared between the experiment and the simulation results with the same friction coefficient for validation of the numerical model.

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Multiferroic materials, which have ferroelectricity and ferromagneticity, attract the attention of many researchers since discovery of huge electricity magnetic effect for TbMnO_3. Because their magnetic permeability and electric permittivity can be controlled by external magnetic field and electric field, they are expected to apply to various advanced electromechanical devices. Their macroscopic material property depends on microscopic heterogeneous crystalline structure. The objective of this study is to develop a crystal morphological controlled multiferroic composite materials with high performance. BaTiO_3 was employed for a ferroelectric material, Ni_<0.15>Cu_<0.3>Zn_<0.55>Fe_2O_4 was used for a ferromagnetic phase, then a multiferroic composite materials was fabricated by wet mixing method.

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In recent years, the locomotorium disorders accompanying aging is increasing as aging society extends quickly. For that reason, the prevention medical treatment and rehabilitation have been becoming important at the medical. This research performs the design of the shoes suitable for an individual walking pattern which may cause locomotorium disorders such as gonarthrosis. It is necessary to measure the three dimensional ground reaction force distribution over supporting surface of shoes sole. We have developed pressure measurement device of the sole by using a strain gauge at the first stage of the research, and measured the sole pressure in walking.

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