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Yuki KATAYAMA, Katsuya KUGAI
Article type: Article
Session ID: 739
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The swimming motion of Tuna type fishes has excellent ability for its speed and efficiency. This paper shows an analysis toward the swimming motion of Blue Fin Tuna with some experimental data. This analysis is based on the simple wing theory, because our primary target is not to know how it works but to decide how to actuate the robot fish. In the 1^<st> report, we assumed that the tale fin angle must be controlled according to the water inflowing angle. So, in this paper, an accurate model of real tuna tale fin is used for experiment to measure the lift and drag force while going forward into the water. By using these data, the relationship between needed actuating force for tale fin and created propulsive force by tale fin.
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Yuuichi IKENAGA, Hidehiko HIGAKI, Yoshitaka NAKANISHI, Atsushi ISHIKAW ...
Article type: Article
Session ID: 740
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Influence of molecular weight of hyaluronic acid on its viscosity was investigated through cone-plate viscometer. Water solution of hyaluronic acid had non-Newtonian flow, and the higher molecular mass showed higher viscosity. Lubricating ablility of hyaluronic acid at start-up motion was investigated by using a reciprocating friction tester, in which polyvinyl formal cylindrical surface slid on glass plate. High molecular mass of hyaluronic acid had an excellent film formation property in boundary lubrication mode at start-up, even if static loading duration was applied for invalid state of squeeze film.
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Yoshitaka NAKANISHI, Eiichi KAMIYAMA, Takayuki UCHINO, Hidehiko HIGAKI ...
Article type: Article
Session ID: 741
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The lubrication mechanism by means of an electric field was proposed to reduce friction for the biomimetic load bearing with the low elastic modulus bearing surface. The friction of a stainless steel ball sliding on a conductive silicone rubber plate dropped rapidly on application of an electric field. The continuous change in polarity on the surface by the electric field appeared to affect the adsorbed film adjacent to the bearing material, so that friction seemed to be varied. Additive molecule which promotes adhesion between bearing surfaces to a lubrication liquid deteriorated ability to control the friction. It is possible the technique will be used for an active-control bearing, which use no electrorheological fuild.
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Kenji NAKAO, Shigenobu OKAZAWA, Koji NISHIGUCHI, Shigeho NODA, Shu TAK ...
Article type: Article
Session ID: 821
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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A solid-fluid interaction scheme is proposed for biomechanics simulation. The scheme is based on full Eulerian formulation, which is familiar with voxel data for medical data. Eulerian formulation can treat large solid deformation in a biomechanical phenomenon because analysis meshes are fixed in space and material moves through them. Both solid and fluid is modeled as an incompressible material and one governing equation treats two equations by using density function.
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Hiroyuki KATAOKA, Shigeho NODA, Hideo YOKOTA, Shu TAKAGI, Ryutaro HIME ...
Article type: Article
Session ID: 822
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Needle insertion is minimally invasive cure, but the precise targeting is difficult by the soft tissue deformation and needle deflection. In this study, we simulated needle insertion using Eulerian hydrocode, which could operate multiple objects and their contact. A needle of 0.5mm diameter with a diagonal tip and a soft tissue were modeled, and the needle was inserted into the tissue at the speed of 5mm/sec. As the results, the needle deflection was observed. However, since the hard material of the needle required extremely small time step for the simulations, we largely reduced the Young's Modulus of both the needle and tissue. We also investigated the change of the time step on the process of the needle insertion, and it was cleared that the large decrease of the time step occurred at the first and last contact between the cutting face of the needle tip and the tissue.
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Daisuke FURUKAWA, Takanori NISHINO, Souichi SAEKI, Takashi SAITO
Article type: Article
Session ID: 823
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Recently, biomedical diagnosis using Near-Infrared light has been highly improved, which is based on the inverse analysis. To compensate the light scattering effect, it is important to simulate light propagation. Therefore, this study reports on simulation of fluorescent emission using optical diffusion equation. And these simulations are validated appropriateness by experimental results. Simulation results obtained by finite difference mathod (FDM). As a result, these simulation results agreed qualitatively with fluorescence intensity obtained from experimental results. And reconstructed images was applied Convolution Back Projection (CBP) for each results, reconstructed image obtained from simulation results agreed qualitatively with reconstructed image obtained from experimental results. Therefore. these simulationa were validated.
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Kohei OKITA, Kenji ONO, Shu TAKAGI, Yoichiro MATSUMOTO
Article type: Article
Session ID: 824
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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High Intensity Focused Ultrasound (HIFU) therapy has been developed for the treatment of deeply-placed tumor such as the liver and brain tumor. Problems are the displacement of focal point due to the reflection and refraction of ultrasound at the interfaces of bones and the attenuation of ultrasound due to the skins, fat and tissues. To minimize the invasive region of tissues by HIFU, the numerical simulation is available for the prediction of the treatment of tissues. The development of the numerical simulation of ultrasound propagation through the voxel modeled body based on the MRI and CT data is reported. The results of the three-dimensional computation show the displacement of focal point for the ultrasound of 1 MHz through the bone.
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Kazuyasu SUGIYAMA, Mitsuaki KATO, Kohei OKITA, Shu Takagi, Yoichiro MA ...
Article type: Article
Session ID: 825
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Heating effects in High Intensity Focused Ultrasound (HIFU) treatments are numerically addressed. To reduce the computational cost due to the much longer characteristic timescale in the temperature rise than that in the ultrasound wave propagation, a separation-of-timescales approach (Rudenko & Soluyan, 1977) is employed. Coupling with the oscillating motion with the period of sound, which is obtained by means of the direct numerical simulation, the time-averaged equation set is solved to predict the quasi-stationary phenomena. Budgets of kinetic and thermal energy transports are demonstrated.
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Xian CHEN, Seiryo SUGIURA, Kenji SUNAGAWA, Toshiaki HISADA
Article type: Article
Session ID: 826
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In this work, a multiphasic model for coronary circulation system is proposed based on mixture theory by treating the myocardial matrix and the blood in hierarchical coronary system as solid phase and multi-fluid phase respectively. The governing equations and constitutive relations have been derived by applying conservation laws and entropy inequality in the framework of mixture theory. The microscopic properties, such as the viscosity of blood or the compliance of the micro vessel are represented by their macroscopic counterparts. The abilities of representing the characteristic behavior of coronary system have been confirmed by numerical examples.
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Kenrou Matsuda, Kiyoshi Kumahata, Akira Amano, Teruo Matsuzawa
Article type: Article
Session ID: 827
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The cardiomyocyte contracts for the calcium ion concentration changing by action potential. The contractile force of the cardiomyocyte can be calculated with a cell function simulator that had made by Kyoto University. We constructed the left ventricular motion model with the use of this contractile force. And we calculate the displacement of the left ventricle. Then, we calculate the blood flow from the left ventricle to the aorta using this model by fluid-structure interaction. As a result, the blood flow was able to be calculated from the left ventricle, and the flux tendency was able to be obtained. But, it is necessary to improve the heart valve model.
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Satoru NAGASAWA, Fuyou LIANG, Kenichi TSUBOTA, Hao LIU
Article type: Article
Session ID: 828
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Recently, significance of left ventricular-arterial (VA) coupling has been frequently stressed in studies concerning aging and hypertension. In this study, we construct an integrated computational biomechanical model of the left ventricle and the major arteries in terms of the multi-scale computation of the whole-body circulatory system. We have this image-based three-dimensional model coupled with the 0-1-dimension models and a physiological model. Using the coupled model, we offer an integrated investigation on the ventricular-arterial (VA) interaction with a focus on hemodynamic features at bifurcations.
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Fuyou LIANG, Shu TAKAGI, Ryutaro HIMENO, Hao LIU
Article type: Article
Session ID: 829
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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A multi-scale computational model of the cardiovascular system is developed for the purpose of studying the changes in arterial pulses with physiological condition. In this study, we play emphasis on heartbeat rate, one of the parameters most sensitive to physiological condition. Herein, three heartbeat rate cases (40, 60 and 120 beats/minute) are studied. Obtained results show pronounced changes in both the shape and the magnitude of arterial pulses with heartbeat rate. Such changes are attributable to the dependence of systolic wave reflection on systolic duration determined by heartbeat rate. These findings indicate that the effects of heartbeat should be considered carefully when analyzing measured arterial pulses, otherwise, wrong conclusions might be drawn.
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Osamu KUWAZURU, Akane MARUBAYASHI, Nobuhiro YOSHIKAWA
Article type: Article
Session ID: 830
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Fundamental buckling property of human facial skin is addressed to understand the effects of epidermal aging on the formation of prominent wrinkles. We have proposed a new wrinkle formation theory that the prominent wrinkles suddenly appear with aging by the buckling mode switch from the horny buckling to the epidermal buckling. In this theory, the epidermal aging plays an important role in promoting the enlargement of wrinkles. Focused on the epidermal aging, dependency of the buckling property on Young's modulus and thickness of viable epidermis is evaluated through the linear finite element buckling analyses to search for the minimum buckling mode of the infinite-length skin. We found that the change in Young's modulus of viable epidermis more predominantly affects the buckling mode switch than the change in epidermal thickness.
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Chengzhi LI, Genri INAGAKI, Gaku TANAKA, Makoto HISHIDA, Toshihiro SER ...
Article type: Article
Session ID: 831
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Computational fluid dynamics (CFD) simulation was carried out for an oscillatory flow in an expanding and contracting model of small airways. The model of multi-branching airways was prepared from X-ray CT images of mouse. Airway diameter ranges from 55 to 360 gm. The Fluent software package used in this study was applied for calculation of the fluid particle trajectory in the airway model. Performing fluid particle tracking, we discussed the characteristics of fluid mixing and dispersion. The results show that fluid mixing and dispersion are promoted by the expansion and contraction of airways.
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Takahito MIKI, Yohsuke IMAI, Shigeo WADA, Takuji ISHIKAWA, Takami YAMA ...
Article type: Article
Session ID: 832
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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We have numerically analyzed inspiratory and expiratory airflow using an image-based pulmonary airway model. As a result, the image-based analysis provided us with some interesting flow features, which is hardly seen in analyses using idealistic airway models. We have examined relationship between flow rate at trachea and pressure drop between trachea and peripheral airways during inspiraotry and expiratory phase. There was difference of pressure drop between inspiratory and expiratory phase even the flow rate was identical, though pressure loss due to fluid viscosity in inspiratory and expiratory phase was almost identical. Generally, pressure drop in a tube is given from summation of dynamic pressure and pressure loss due to fluid viscosity. We conclude that the difference of pressure drop was occurred due to dynamic pressure caused by the difference of cross sectional area between trachea and peripheral airways.
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Kenichiro KOSHIYAMA, Shigeo WADA
Article type: Article
Session ID: 833
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Molecular dynamics simulation of pulmonary surfactant on a water layer is conducted to investigate the effect of the surfactant on gaseous exchange in alveolus. The pulmonary surfactant is modeled by a monolayer comprised by dipalmitoylphosphatidylcholine (DPPC) molecules, which are the major component of human pulmonary surfactant. The constant temperature and volume MD calculation is performed in 10 ns. From the result of density profile of water across the system calculated it is found that the reduction of the water density in the liquid-vapor interface is more gradually than that calculated in the system without surfactant. In addition, the vapor water density is locally decreased in the hydrophobic region of the surfactant monolayer. The results of this water density profile and snapshots obtained here suggest that water exchange across the pulmonary surfactant hardly occurs in the time scale calculated here.
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Xiaobo GONG, Shu TAKAGI, Yoichiro MATSUMOTO
Article type: Article
Session ID: 834
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The deformed behavior of multiple red blood cells in a straight capillary vessel is simulated based on the continuum mechanics. The membrane of red blood cells is modeled as a thin layer with hyper-elastic properties. The in-plane stress is calculated using Skalak's hyper-elastic model; and neo-Hooken model is adopted for the calculation of bending momentum tensor. The coupling of the deformation of the membrane with the flow of surrounding liquid is modeled with the immersed boundary method. The numerical results show that the initial distribution of the red blood cells, symmetrically or asymmetrically to the central line of the flow, does not affect the velocity distribution in the cross section obviously.
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Yuki KAWAGUCHI, Yoshihisa MINAKUCHI, Yasuaki OTAKI, Kenichi KUSHIDA, R ...
Article type: Article
Session ID: 901
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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As one of the matters to get long-term success of treatment of implant curing, it is important that a kinetic load of implant and alveolar bone is reduced or distributed. In this paper, the shape optimization of dental implant was investigated using growth-strain method. At first, we investigated the stress and strain energy density distribution of a dental implant under vertical and inclined forces by using a three dimensional finite element method. Next, growth criterion parameters of fixture and abutment, alveolar bone were defined by mean values of stress of previous three-dimensional finite element method in each total element. And growth strain analysis was performed under the growth criterion parameters of the each analysis model. Then, the optimum shape of the fixture was created. As a result, it was clarified that the created dental implant was able to reduce the concentrated stress in cortical bone and fixture.
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Makoto SAKAMOTO, Keisuke SASAGAWA, Koichi KOBAYASHI, Hideaki ENDO, Hid ...
Article type: Article
Session ID: 902
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Dentin is a natural composite material consisting of three phases: mineral, organic and water. These three phases are not independent each other, but rather work in harmony to determine the viscoelastic property of dentin. Although the viscoelastic properties of root dentin at a macroscopic level have been studied, those of the crown to root dentin at a microscopic level have not. Dynamic nanoindentation is a new promising method of measuring the dynamic viscoelastic properties of biological tissues with a smaller length and using smaller load scales than those allowed by other testing methods. The objective of the present study was to use the dynamic nanoindentation method to determine dynamic viscoelastic properties such as storage modulus and loss tangent of human crown to root dentin at the microscopic level in a tooth direction. The effects of dentin mineral density (DMD) measured by pQCT on viscoelastic properties at a macroscopic level were also studied.
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Hidemi ITOH, Angelo. A. CAPUTO, Tomofumi SASAKI, Mituo SATO, Hiroko NA ...
Article type: Article
Session ID: 903
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The purpose of this study was to photoelastically compare the load transfer characteristics of a distal extension RPD with implant assisted support in the posterior of a mandible with an atrophic edentulous ridge. The model included the anterior teeth and the first premolars bilaterally. Threaded implants, 3.75mm diameter 7mm length, were embedded 20mm distal to the first premolars on the posterior edentulous ridges. I-bar partial dentures with mesial rests were fabricated and physiologically adjusted to the models. The implant support conditions tested were healing abutments and 3mm ball attachments. Simulated vertical and lateral occlusal loads were applied at the first molar position and the stress developed in the abutment teeth were monitored photoelastically. Posterior implants with both healing abutment and ball attachments in the posterior of a mandible tended to assist support of a distal extension RPD and produce only low level stresses in the supporting atrophic edentulous ridge.
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Yasuhiko OSATO, Kazuhiko SASAGAWA, Kotaro YOKOYAMA, Eiichi SAITOH
Article type: Article
Session ID: 904
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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For effective therapy of dysphagia, it is necessary to appropriately evaluate the function of swallowing by measuring contact pressure and fluid pressure in the throat. However, the contact pressure in swallowing has not been measured in detail and accurately. We developed the measurement system of contact pressure between soft tissues of throat and mouth in swallowing using pressure-sensitive conductive rubber (PSCR) sensor. The developed measurement system was applied to normal subject for verification of the system. The distributions of contact pressure between soft tissures in pharynx and oral cavity were measured with swallowing saliva. Measurement result of the contact pressure was obtained as reflecting the function of propelling saliva. From the result, the usefulness of this system was validated.
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Kouhei MURASE
Article type: Article
Session ID: 905
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In this research, as characteristic input support of soft tissue, the prediction system that combines a tactile sense device and finite element analysis was developed. The rubber samples were selected for the soft tissue of the living body, and were touched by the tactile sense device. Based on the information obtained from the samples, the limited element analysis was conducted in order to assess the derivation of Young's modulus that is one of the most important mechanical characteristics of the material. Three different kinds of restricted conditions were given to presume Young's modulus. The result showed that Young's modulus was able to be presumed with an error of about 10%. In the experiment using subjects, all of them distinguished the difference in hardness, and then it is considered that this technique is effective in presuming mechanical characteristics of soft tissue.
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Yuji TANABE, Hiroyoshi IWAKI, Hidetane KATO
Article type: Article
Session ID: 906
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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One of the factors influencing initial fixation of total hip arthroplasty with bone cement is cement pressure° Cement mantle pressure is thought to change with the shape of a stem, the roughness of the stem surface, and the thickness of the bone cement layer. This in vitro study examined cement pressurization during the insertion of femoral stems, namely PERFECTA (PER) and ANCAFIT (AFJ) stems, into seven pairs of human cadaver femorao Cement pressures were measured at proximal and distal stem levels during the insertion of each stemo AFJ with a thin cement layer showed greater cement pressures than PER with a thick cement layer at both proximal and distal stem regions. Distal stem levels appeared to show greater pressures than proximal levels for both AFJ and PER.
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Hidenori YOSHIDA, Makoto SAKAMOTO, Koichi KOBAYASI, Yuji TANABE
Article type: Article
Session ID: 907
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The analysis of joint kinematics aid contact area by MRI has been performed. The determination of contact is important to obtain the contact area This has been performed by visual. However, the quantitative determination of aortal is Nuked for measurement of contact area The purpose of this study was to demonstrate the objective determination of contact using two hog's knee. Simultaneous measurement of contact area was made using both the pressure sensitive film technique and MRI. The contact area was obtained by changing the signal intensity ratio. The validity of the MRI method was assessed, and the optimum signal intensity ratio of MRI was found out Good agreement was found between the MRI and the pressure sensitive film techniques.
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Yosei NODAGUCHI, Hidenori YOSHIDA, Yuji TANABE, Koichi KOBAYASHI, Mako ...
Article type: Article
Session ID: 908
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The purpose of this study is to evaluate contact characteristics of talocrural joint using MRI which enables us to observe contact situation of the joint in vivo. We investigated the change of contact region in normal ankle in plantal and dorsal flexions under compressive and non-compressive conditions. As a result, the contact area appeared to move to anterior surface in plantar flexion, and move to the posterior surface in dorsal flexion, respectively. Both compressed and non-compressed contact area became largest in neutral position and showed a tendency to decrease with an increase of a flexure angle. Furthermore, it showed positive correlation between body height and normalized contact area, while there was negative correlation between talus ratio of flattening and normalized contact area.
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Koichi KOBAYASHI, Nobuaki TANAKA, Ken-ichi ODAGAWA, Makoto SAKAMOTO, Y ...
Article type: Article
Session ID: 909
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The purpose of present study is to examine the accuracy of 2D-3D image registration technique for measuring natural knee kinematics. A human cadaver distal femur was secured to a 6 degree-of-freedom (DOF) mechanical stage that is controllable within ±5 ° and ±5 mm. The stage with the femur was fixed to a camera calibration frame so that the 3D position of the femur can be determined in terms of the camera coordinate system. Single-plane x-ray photographs of the femur were taken using fluoroscopy and plane radiography. Each of 3 rotation parameters was changed from -2° to 2° by 1°, and for each of 3 translation parameters -2 mm to 2 mm by 1 mm. The 3D position of the femur was recovered by matching the digitally reconstructed radiographs generated from its 3D volume model derived from CT scan data. Average errors ± standard deviation and root mean square errors in two out-of-plane rotations were 0.4°±1.6° [1.1° and 0.1°±1.2° [1.2°], and one out-of-plane translation was 0.4 mm±4.3 mm [4.3 mm] by fluoroscopy, and those by plane radiography were 0.8°±0.4° [0.9°], -0.7°±1.4° [1.5°] and 0.6 mm±5.2 mm [5.1 mm].
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Keisuke SASAGAWA, Makoto SAKAMOTO, Hidenori YOSHIDA, Koichi KOBAYASHI, ...
Article type: Article
Session ID: 910
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The aim of this study is to investigate in vivo joint contact mechanisms of the human wrist by magnetic resonance imaging (MRI). We analyzed the wrist joint cartilage contact areas and distributions during flexion/extension quantitatively. MR scanning was performed on the wrist of ten subjects by 1.5T-MRI system. The wrist joint was scanned at the 5 positions (palmer flexion -30 deg, neutral 0 deg, and dorsal flexion 30, 60 and 90 deg). The quantitative analysis of wrist joint contact mechanisms was performed for radioscaphoid and radiolunate joint. The mean contact area at radioscaphoid joint was greater than that at radiolunate joint in all wrist positions (40.3 and 7.8 mm^2 for neutral position at radioscaphoid and radiolunate joint, respectively). There were flexion/extension angles that radiolunate joint contact was not confirmed. The contact distributions indicated by 3D models of scaphoid and lunate were shifted during flexion/extension.
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Yoshimasa TAKEZAWA, Isami NITTA, Xuefeng ZHAO, Yoshitaka MAEDA
Article type: Article
Session ID: 911
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The aim of laser therapy is to destroy the target cells without harming the surrounding tissue. Current approaches to the treatment of lesions often use the delivery of high energy with larger spot sizes compared to the target size, and sometimes unnecessary laser exposure to the adjacent tissue leads to collateral damage. So, we had developed a new type of laser apparatus with a fine laser spot size. To treat vascular lesions on skin, a KTP laser (CW) and a video camera were used. The developed system equipped with a collecting lens assembled by a shrink fitter can focus the laser beam well over a wide scanning width. As a result of the observation of the blood vessel in mouse's pinna after laser beam irradiation, the laser pinpoint irradiation was proved to be effective in the vascular lesions therapy.
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Shinya YAMANADA, Shigeru MURATA
Article type: Article
Session ID: 912
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper proposes a noninvasively measuring method for evaluating the state of fractured bone using a time series analysis based on speckle interferometry. In order to know the healing state of fractured bone, the out-of-plane displacement of the skin around fractured part is measured using speckle interferometry and its distribution is obtained as speckle fringes. Then the fine fringes generated at the fractured part are detected with a time series image analysis based on a gradient-based method, and the resulting optical flows are used for constructing the estimator evaluating the state of bone fracture. The performance test using a test phantom shows that there is a detectable difference in the proposed estimator between the cases with cut and without it in an internal hard object of the phantom. The numerical analysis of elastic body using a particle method shows that the numerical results are in agreement with those obtained in the experimental test.
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Shigeo M. Tanaka, Tingshun Cao, Ken-ichi Yamakoshi, Toshiyuki Tsujimot ...
Article type: Article
Session ID: 913
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Non-invasive bone densitometries using X-ray, e.g., DXA give precisely bone mineral densities (BMD), by which osteoporosis can be diagnosed, however, its usage are limited to in medical facilities, meaning inappropriate to routine screening for possible osteoporosis. Optical bone densitometry could be a promising way for osteoporosis screening with compactness and safety. In this study, a novel optical depth-resolved measurement method was proposed and its validity as a bone densitometry was tested by Monte Carlo simulation and model experiments. In this method, coherent light is emitted to a skin layer over bone tissue through an optical scattering modulator (OSM). By changing its thickness, the modulator changes continuously the scattering state of transmittance light between forward scattering able to penetrate deeper and isotropic scattering with a shallow penetration. With this optical penetration control, our method can give the optical information of bone, which correlates to BMD, separately from the interference by skin.
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Fumio NOGATA, Yasunari YOKOTA, Yoko KAWAMURA, Hiroyuki MORITA, Yoshihi ...
Article type: Article
Session ID: 914
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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To establish a noninvasive method for estimating mechanical integrity of artery, we examined arteries of the human aged eighties by tensile and internal pressure tests, as well as sheep and cow as comparative data. It was shown that strength and elongation decreased approximately a half and a quarter respectively than young artery specimens. We found that a relationship between E_<th> and strength has been obtained, which allows the estimation of arteriosclerosis in term of the strength. Then, a system for estimating the stiffness E_<th> has been developed using the ultrasound B-mode image of in vivo artery. The software permits to estimate E_<th> in real time, and a few minutes for the both side of the common carotid artery. Some clinical data were also obtained such as E_<th>-age relation, E_<th>s for both side of the common carotid artery, distribution of E_<th>, and E_<th>-IMT (Intima Media Thickness) relation. The result indicated that the E_<th> and strength are useful symptom indices for arteriosclerosis, especially for finding the beginning sclerosis that would start early twenties.
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Junichirou SUENAGA, Yoshihito KUROSHIMA
Article type: Article
Session ID: 1033
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Fatigue crack consists of crack initiation region of Stage I, Stage II a and crack propagation region after Stage II b. Crack propagation region is effected by mechanics factor greatly and can evaluate quantitatively. But quantitative evaluation in crack initiation region is difficult, because of two rule factors coexist of a mechanics and metallurgical. This study described fatigue crack in three dimensions and examined fatigue crack growth behavior in fatigue crack initiation region. The material investigated was the low carbon steel S10C. As a result, as number of cycle is increased, crack depth is increased. When crack depth reach certain degree of depth, angle between crack growth direction scatter near 45°, 90°. This means that crack transit Stage I, Stage II b at each degree.
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Mina WAKITA, Tetsuro SHOJI, Takashi NAKAMURA, Hiroyuki OGUMA
Article type: Article
Session ID: 1034
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In order to specify the exposure environment of interior-originating cracks in very high cycle fatigue, crack growth tests with CT specimens were conducted in air, high vacuum (HV) and ultra high vacuum (UHV). Influence of vacuum environment on characteristics of fatigue crack propagation and fracture surfaces was investigated. As a result, the following were obtained. (1) difference of fatigue crack growth rate between HV and UHV was accounted for by ΔKeff, although difference between air and vacuum was not explained only by the crack closure, (2) Kop became larger when vacuum pressure decreased, (3) a few micrometer size granular region was observed on the fracture surface only in HV and UHV.
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Shinji SEKIGUCHI, Takuya HIRASAWA, Keisuke TANAKA, Kazunari FUJIYAMA
Article type: Article
Session ID: 1035
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The crack propagation behavior of lead-free solder was investigated using pp, cp, cc, tension-hold loading at ambient temperature and analyzed by J-integral range. Tension-hold and cp type crack propagation rate showed higher crack propagation rate. SEM and EBSD observation of fatigue cracks showed intergranular path between β-Sn phase as well as transgranular path.
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Kaname MORI, Akira UCHIYAMA, Sinpei NISHIUCHI
Article type: Article
Session ID: 1036
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The effects of heat treatment and anisotropy on fatigue crack growth characteristics of a bearing steel (JIS SUJ2) were studied by the stroke controlled fatigue testing with special crack measuring system. The da/dN-ΔK relations of LR- and RL-oriented CT-specimen in bearing steel (spheroidizing annealing, HV250) were corresponding well. On the other hand, the crack growth rates of RL-oriented in quench-tempered bearing steel (hardened, HV750〜840) were higher clearly than those of LR-oriented, under same ΔK conditions. The crack growth rates of RL-oriented in quench-tempered bearing steel were higher markedly than those of annealed bearing steel, under same ΔK conditions.
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Makoto AKAMA, Akira KIUCHI
Article type: Article
Session ID: 1037
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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To investigate the influence of the load ratio ΔK_<III>/ΔK_I, degree of overlap and material on the fatigue crack growth, mixed mode I and III tests were carried out on the normal rail steel and head hardened rail (HH340) steel. It was found that the growth rates became higher when the ratio ΔK_<III>/ΔK_I was decreased. It was also shown that the growth rate of HH340 steel was lower than that of normal rail steel. A non-linear weighting between ΔK_I and ΔK_<III> was used to fit the data empirically to the Paris type growth laws.
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Yasuhiro TOHODA, Hiroyuki AKEBONO, Masahiko KATO, Atsushi SUGETA
Article type: Article
Session ID: 1038
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Fatigue crack growth test was carried out on α-brass. Successive observation of small fatigue crack growth behavior was performed by means of an Atomic Force Microscope (AFM) equipped with small in-plane bending fatigue testing machine. The fatigue crack almost propagates by using preferred slip system. Occasionally, the crack propagates by using other slip systems. So, the fatigue crack propagates with deflections repeatedly. The fatigue crack deflection behavior was investigated by the crystallographic orientation analysis based on the Electron Backscatter Diffraction (EBSD). Furthermore, in order to examine internal crack surface feature, the crack pass of specimen that was etched by Focused Ion Beam (FIB) was observed by SEM. It is possible to explain the mechanism of fatigue crack behavior mentioned above by using Slip factor and examining the relationship between the inclination of internal fatigue crack plane and the crystal orientation.
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Kazuya HANAORI, Koji TAKAHASHI, Kotoji ANDO, Fumio TAKAHASHI
Article type: Article
Session ID: 1039
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Effects of shot peening on the bending fatigue limit of steel specimens (SUP9A) containing an artificial small slit which are simulated as surface crack were investigated. Shot peening (SP) and stress shot peening (SSP) were conducted on the specimens containing a semi-circular slit whose depth is 0.1,0.2 and 0.3mm. Then, bending fatigue tests were conducted on the specimens. The fatigue limits of specimens containing a semi-circular were increased by SP SSP. The shot peened specimens containing a semi-circular slit whose depth is under 0.2 mm fractured outside the slit, and they had considerably high fatigue strengths almost equal to those of the shot peened smooth specimens. It was found that the fatigue limit of specimens having a semi-circular slit whose depth is under 0.2 mm determined by the threshold condition for non-propagation of fatigue cracks emanated outside the slit. From these results, it was clear that a semi-circular slit under 0.2 mm could be made acceptable by SP and SSP.
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Fumio TAKAHASHI, Akira TANGE, Kotoji ANDO
Article type: Article
Session ID: 1040
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The effects of shot peening on the fatigue limit of specimens having a semicircular slit-like artificial surface defect of varied surface length, 2a, are investigated. The fatigue limit of specimens with a slit were increased by shot peening. The fatigue limit improvement ratio of the specimen having a slit were larger than that of the slitless specimen. Shot peening is useful for materials with a surface flaw. Multiple non-propagating cracks were observed on the fracture surface. The stress intensity factor of the maximum non-propagating crack size of 470HV and 570HV specimen corresponded to that of 2a=0.52mm and 2a=0.32mm semicircular crack respectively. This result shows that semicircular cracks less than the value described above will likely to have no significant effects on the fatigue limit by shot peening and the fracture limit will be determined based on the growth limit of non-propagating cracks from the surface.
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Hideyuki Ishigami, Katsuyuki Matsui, Shinsaku Fukuda, Kotoji Ando
Article type: Article
Session ID: 1041
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Shot peening is a commonly employed technique to improve the fatigue strength of nitrocarburized components. However, the compound layer of the component can be broken by this technique. Cavitation peening (CP) is an alternative shotress technique, which can increase the fatigue strength of the component without separation of the compound layer. To evaluate the potential of CP as a means for improving fatigue strength, nitrocarburaized carbon steel (JIS S50C) has been analyzed in the non-peened and CP conditions. The fatigue strength of CP specimen was achieved by the increase in the maximum hardness and compressive residual stress within the diffusion zone.
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Shinsaku FUKUDA, Toshihiko AMANO, Koji TAKAHASHI, Katsuyuki MATSUI, Hi ...
Article type: Article
Session ID: 1042
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The cavitation peening is a new possible surface refining method, which is a shot-less peening method and increases compressive residual stress without changing roughness of specimens surface. Therefore, the authors conducted an experiment using the smooth specimen with an artificial semi-circular slit and evaluated its refined surface characteristics and fatigue limits. The results obtained are: By cavitation peening, a) fatigue limit was increased more than 30%, b) slit depth of the acceptable defect with the smooth specimen was 0.055mm.
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Yuji SUZUKI, Suyalatu, Kiyotaka MASAKI, Yasuo OCHI, Takashi MATSUMURA ...
Article type: Article
Session ID: 1043
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Rotating bending fatigue tests were conducted in order to investigate effects of laser peening (LP) treatment on fatigue property of wrought aluminum alloys A7050-T7452 for aircraft structures. As the results, the LP treatment was effective for the fatigue property improvement of A7050-T7452 alloys, and the fatigue strength at 107 cycles of the LP treated alloys increased 40-50 MPa for the non-treated alloys. It is assumed that the reason of the fatigue property improvement is the work hardening. And the fatigue life of the LT material tended to be higher than that of the ST material.
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Keiro TOKAJI, Yoshihiko UEMATSU, Kazuma FUJIWARA, Yasunari TOZAKI, Hid ...
Article type: Article
Session ID: 1044
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The fatigue behaviour of friction stir processed (FSPed) cast magnesium alloy AZ91 was studied. Fully reversed axial fatigue tests have been performed using as-cast, T5-aged and their FSPed specimens (as-cast/FSP and T5/FSP). Both FSPed specimens showed considerably higher fatigue strength than the as-cast and T5-aged specimens. By applying FSP, β-phases with irregular shape from which cracks initiated in the as-cast and T5-aged specimens were finely dispersed and grain refinement was achieved, thereby the crack initiation resistance and the crack growth resistance were significantly improved, resulting in the higher fatigue strengths of the FSPed specimens.
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Yoshihiko UEMATSU, Keiro TOKAJI, Masahiro MATSUMOTO
Article type: Article
Session ID: 1045
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The effect of aging treatment on fatigue behaviour in extruded Mg alloy AZ80 was investigated. Rotating bending fatigue tests have been performed using as-received, T5 and T6 treated specimens. Due to the aging treatments, Mg_<17>Al_<12> precipitated near grain boundaries and within grains. Both aging treatments could improve the static strengths, but fatigue strength was considerably lowered in T6 condition, while slightly improved in T5 condition. It was indicated that the effect of aging treatment on fatigue strength was mainly attributed to the change in fatigue crack initiation mechanism.
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Hideaki TAKEKAWA, Yoshihiko UEMATSU, Keiro TOKAJI
Article type: Article
Session ID: 1046
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Rotary bending fatigue tests were performed in laboratory air and demineralized water using DLC-coated wrought magnesium (Mg) alloy, AZ80. Two film thicknesses, 3.5μm and 25μm, were evaluated in order to investigate the effect of DLC coating on fatigue and corrosion fatigue behaviour. In laboratory air, the fatigue strengths of the DLC-coated specimens were higher than those of the bare ones and increased with increasing film thickness. This was because hard DLC film with high coating adhesion suppressed slip deformation on the specimen surface. In demineralized water, fatigue strengths were considerably decreased due to the formation of corrosion pits in the bare specimens. Thin DLC film could not improve corrosion fatigue strength due to the penetration of the solution through the pre-existed hole defects in the film, while thick DLC film could improve corrosion fatigue strength because penetrating paths were eliminated.
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Md. Shahnewaz Bhuiyan, Youshiharu Mutoh, Tsutomu Murai, Shinpei Iwakam ...
Article type: Article
Session ID: 1047
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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It has been observed that under corrosive environments such as high humidity and sprayed 5 wt.% NaCl environment, the fatigue strength of extruded AZ61 magnesium alloys drastically reduces and the reduction rates of fatigue limit under high humidity, NaCl environments were 0.22, 0.85, respectively. However, one of the most effective ways to prevent corrosion is to coat the base material. In the present study, the fatigue performance of the non-chromium conversion coating on extruded AZ61 magnesium alloys has been evaluated under corrosive environments. The results indicated that, the non-chromium conversion coating alone can protect the substrate material from the attack of high humidity environment but cannot protect the substrate material under 5% NaCl environment. Therefore, it is suggested that the non-chromium coating can work to a certain degree of corrosive attack but it is not enough to prevent the attack of 5%NaCI environment.
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Yozo MURATA, Osamu KUWAZURU, Takao UTSUNOMIYA, Yoshihiko HANGAI, Nobuh ...
Article type: Article
Session ID: 1048
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Aluminum alloy die casting products are extensively used in the industries of vehicle from the advantage of lightweight, near-net shaping and high productivity rate. However, disadvantages of such die castings are the presence of casting defects and the reduction of fatigue strength properties by the defects. In this study, observation of casting defects by X-ray CT and fatigue tests of ADC12 aluminum alloy die casting under tension-compression axial loading were carried out and the relationships between stress amplitude and fatigue life was derived. The fatigue life of ADC12 was greatly influenced by the situation and the amount of casting defects. However, the presence of casting skin did not affect the fatigue life and the inner large pores were not the source of fatigue crack.
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Kiyotaka MASAKI, Yuji SANO, Yasuo OCHI, Koichi AKITA, Kentaro KAJIWARA
Article type: Article
Session ID: 1049
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The coalescence behavior of two surface fatigue cracks on A7050-T7451 aluminum alloy was investigated by replication technique and micro computed tomography (μCT) with synchrotron radiation of SPring-8. The results showed that the shape of a macro fatigue crack inside the specimen should be different whether the two surface fatigue cracks being combined or overlapped. In addition, it was suggested that the fatigue crack propagation behavior varied depending on the machining and/or rolling direction of the material.
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Hiroshi NAKAMURA, Yoichi YAMASHITA, Hiroshi KUROKI, Masaharu SHINOZAKI ...
Article type: Article
Session ID: 1050
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper deals with the assessment of low cycle fatigue life under intermittent strain amplitude for Incone1718. Several combinations of intermittent strain fatigue tests were conducted. Intermittent waveform includes not only major cycle but also minor cycle with mean stress. The Walker equation based on virtual elastic stress was used in this study to consider the mean stress effect on minor cycle. The shortest fatigue life was about 1/10 of estimated one without using Walker stress. On the other hand, the predicted lives based on Walker stress were within a factor of 3 scatter band. Therefore, fatigue life estimation for intermittent cycle should be considered mean stress effect on minor cycle damage.
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Yasuaki Hashikura, Keiji Houjou, Yuji Miyazaki, Koji Takahashi, Kotoji ...
Article type: Article
Session ID: 1051
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The effects of overload on the ΔK_<th>, of SUS316 were studied in this study. Tensile overload was applied to a compact tension (CT) specimen. Then, fatigue tests were carried out to determine the resultantΔK_<th>. It was found that the value of ΔK_<th> increases as increasing the overload. The results were discussed from the viewpoint of fracture mechanics. The size of compressive residual stress is the key factor controlling the value of ΔK_<th>. Fractgraphic observation of fracture surface after fatigue tests were also carried out.
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