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Article type: Cover
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Cover1-
Published: September 20, 2002
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Article type: Appendix
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App1-
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Article type: Index
Pages
Toc1-
Published: September 20, 2002
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Osamu OKUDA
Article type: Article
Pages
1-2
Published: September 20, 2002
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This paper discribes briefly the structured parallel processing algorithm to compute the stress distribution of two-dimensional composite materials using domain decomposition method. The matrix and reinforcement of unit cell of multi-phase polymer are modelled using the quadrilateral finite element discretization for the microstructure. The effects of parallel computation and the arrangement of reinforcement are discussed.
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Shohei HORIUCHI, Seiichiro YATAKE, Hirohisa NOGUCHI
Article type: Article
Pages
3-4
Published: September 20, 2002
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In structural analysis, the so-called multi points constraints are often used for practical boundary conditions. In order to incorporate the multi points constraints into the finite element formulation; the penalty method, the Lagrange multiplier method and the master-slave elimination method have been adopted so far. In this study, the focus is placed on the effectiveness of these methods in iterative solver. A simple contact problem is solved by these method using the multi point constraints. As results, the convergence of the penalty method with conjugate gradient method is very slow, while the Lagrange multiplier method with conjugate projected gradient method and the master-slave elimination method with conjugated gradient method, proposed in this study, show stable convergence.
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Tomonori YAMADA, Kenji NIIYAMA, Yoshikazu ISHIHARA, Toshio NAGASHIMA, ...
Article type: Article
Pages
5-6
Published: September 20, 2002
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In most existing solid CAD systems, boundary representation methods, which express three dimensional geometry regions with surrounding surfaces and with their topological connections, are used. The boundary representation data structures give some difficulties to be used in CAE systems, and hardly import physical data from CAE systems. A new CAD system named Volume CAD (V-CAD) using volume data for geometry expression are developed for avoid these problems. V-CAD deals geometrical data with volume unit called cell defined all over the interested region, and each cell has physical data and simplified surface data. To use V-CAD data structure directly in the analysis, the extended finite element method (X-FEM), which can consider a free surface inside analysis element, are developed. In this paper, results of some example models models are compared to theoretical values, and show an ability of X-FEM to use V-CAD data structure directly.
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Yuichiro AOKI, Hiroshi SUEMASU, Toshio NAGASHIMA
Article type: Article
Pages
7-8
Published: September 20, 2002
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In order to study an impact damage accumulation problem in composite laminates, a special three-dimensional interface element is proposed to simulate the delamination propagation in laminates. The traction at the interface, which is a function of relative displacements of interface, can reduce to zero when the energy stored in element per unit area reaches critical total energy release rate. This element is incorporated in a commercially available finite element code and applied to the DCB and ENF fracture toughness test problems to demonstrate its validity. The solution converges smoothly and numerical results agree well with the theoretical ones when the element is sufficiently small compared to the significantly deformed area. Also, the present method is applied to damage accumulation problem of CFRP laminates subjected to transverse load and the results obtained are reasonable and interesting.
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Ryo SHIRAKASHI
Article type: Article
Pages
9-10
Published: September 20, 2002
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In the present study, effects of iso-osmolar trehalose solutions on intact murine myeloma cells (sp2) during the freezing-thawing process are discussed. Intact sp2 cells suspended in iso-osmolar trehalose were installed in cryomicroscope and frozen at various cooling rates (-1℃/min, -90℃/min, -5℃/min) down to -80℃, followed by rapid thawing, 90℃/min. It was found that extracellular ice grains in trehalose solution did not mechanically suppress cells even at lowest cooling rate, -1℃/min. Further, only a seldom intracellular ice formation were observed in all cooling rate for iso-osmolar trehalose solution. However ice recrystalization was observed for all the conditions even at a fastest warming rate, 90℃/min.
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Hiroshi TAKAMATSU, Takeshi KUROKAWA
Article type: Article
Pages
11-12
Published: September 20, 2002
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Exposure to hypertonic solution during freezing is believed to be one of the major causes of the post-thaw cellular injury after freezing at low cooling rates. We have characterized the post-hypertonic survival at 23℃ as a function of hypertonic NaCl concentration, the time of exposure, and the rate of increase or decrease in NaCl concentration by using a newly developed perfusion technique. In the present report the same experiments are carried out at 0℃ and compared with the previous result at 23℃. The cell membrane permeability to water is also measured to explain the obtained result.
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Hiroshi ISHIGURO, Hirokazu IMAI, Noriaki SUZUKI
Article type: Article
Pages
13-14
Published: September 20, 2002
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Behavior of ice crystals and cells in the biological tissues during the warming after rapid-cooling was investigated microscopically in time-series using a confocal laser scanning microscope with a fluorescent dye. Attention was paid on the recrystallization of intracellular ice crystals to increase the mechanical damage of the tissues. Size and number of the ice crystals were measured from the image-date of ice crystals and statistically analyzed to obtain frequency, average, and standard deviation of the size of ice crystals, total amount and number density of ice crystals, etc. in time-series during the warming. Influence of the warming rates on these characteristics was made clear.
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Manabu TAKAHASHI, XHA Zhu, Nagatoshi OKABE, Shinfuku NOMURA, Kenji AND ...
Article type: Article
Pages
15-16
Published: September 20, 2002
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To execute surgical operations on livers in a short time and to reduce the stress on the patients, we propose a soft freezing method for liver surgical procedures. In this surgical procedure, a tumor surrounding the liver is frozen in order to ease the ease the excision and prevent hemorrhage. The effects of cooling velocity and freezing temperature on the excision force by the scalpel on the liver are carried out experimentally as a basic research into partial freezing surgical procedures. In this study, to excise a cancer using free excision curve, the development of the cooling needle and the investigation of the cooling function were carried out using a liver of a big. The physical properties value was reversely analyzed by using the finite element method based on the heat transfer characteristic data of a mock liver. In addition, the proposed estimation equation can express the relation between arbitrary cooling time and distance and temperature.
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Hisashi NISHIYAMA, Yoshiaki KONISHI, Masato FUJIWARA, Yoshiaki NAONO, ...
Article type: Article
Pages
17-18
Published: September 20, 2002
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The flow rate of insulin from insulin pumps for diabetic patients is less than 3.0 μl/min, and the average flow velocity in a tube with a diameter of 0.4 mm becomes less than 0.4 mm/s resulting in the maximum Reynolds number of about 0.2. A thermo-trace type flow meter is employed for a low meter in this very small range of flow rate and velocity. A theoretical analysis and preliminary experiment were conducted for the flow meter. It was found that the influence of heat conduction in the direction of the tube axis must be included which is usually ignored in the boundary flow analyses.
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Katsufumi UCHIYAMA, Yugo NAGAE, Masanobu UJIHIRA, Kaori NISHI, Kiyoshi ...
Article type: Article
Pages
19-20
Published: September 20, 2002
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Internal temperature equalization of the bovine metatarsal with cortical and cancellous bone during microwave irradiation was investigated. In our previous study, bovine bone more rapidly than methods of conventional thermal process, because the bone was heated from deep part during microwave irradiation. Moreover, humidifying the surface of the bone reduced distribution in the internal bone temperature. Internal temperature equalization in bovine metatarsal bone by microwave irradiation was not successful, but in bovine femoral head (cancellous bone) and diaphysis (cortical bone), a temperature of 80±10℃. So in this study, industrial microwave oven was used. After refining the system using an industrial microwave oven, an internal temperature of the bovine metatarsals (containing both cancellous bone and cortical bone) could be maintained at 82±3℃ and processing time. These results suggest that thermal processing for disinfection using microwave irradiation can heat the bone more quickly by equalizing the internal temperature.
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Isao Shimosaki, Akira Takeuchi
Article type: Article
Pages
21-22
Published: September 20, 2002
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We have developed a method of heating and control body temperature in Whole Body Hyperthermia (WBH). Tumor cells can be demaged at high temperature and it is also efficient to prevent metastasis of advanced cancer. It is important for the advanced WBH to control a vasoconstriction that the deteriorate of heat transfer efficiency in human body and to reduce the stimulus of skin by heating. As the basic verifications, we identified the reaction of body temperature under WBH as five phases and we tried the reduction of WBH-period by pre heating and cyclic heating by adjustment of the combination of heat conductive and radiant.
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Yuko SHOJI, Toshikazu TAKEMORI
Article type: Article
Pages
23-24
Published: September 20, 2002
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We have developed a clothed human thermal model to predict physiological response in thermal environment. In this paper, the model was applied to an unsteady thermal environment as the local cold exposure of the right hand. Then the AVA vasomotor response equation of the hands in the model was improved by the experimental data. The model predictions were compared to the experimental data in the skin temperature of the hands and the forearms and the skin blood flow rate of the hands. These results show that the clothed human thermal model was able to predict the physiological response in the local cold exposure, such as the vasoconstriction response and the contralateral response of the hands and the skin temperature of the forearms affected by the venous return from the hands.
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Tomoko NEGISHI, Kazuto MASAMOTO, Tetsuro OMURA, Naosada TAKIZAWA, Hiro ...
Article type: Article
Pages
25-26
Published: September 20, 2002
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There are many papers that discussed precapillary oxygen loss. It means arterioles play an important part in oxygen supply to tissues. The purpose of this study was to investigate the role of arteriole in oxygen transport and the effect of its geometry on oxygen distribution in tissue. We used confocal laser scanning microscope to visualize microvasculature and determined vascular geometry. For mathematical simplification, oxyhemoglobin dissociation curve were assumed to follow Hill's equation and facilitated diffusion coefficient was incorporated. The model, which excluded capillary networks shows that one arteriole seems to supply to tissue to the extent of 200-300 um long in the radial direction. When oxygen consumption rate (CMRO_2) is bigger than 2 (cm)^3-O_2/100g/min, the tissue hypoxia (Po_2<1mm Hg) was largely shown beneath surface in spite of high blood velocity (15mm/s). Actually, CMRO_2 at surface layer is smaller than other layers. Accordingly, these indicate that capillary networks between arterioles and the heterogeneity of CMRO_2 in cortex are important in oxygen distribution in tissue.
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Kiyoshi OINUMA, Hirofumi HASHIMOTO
Article type: Article
Pages
27-28
Published: September 20, 2002
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In order to apply the thermal effect by plant to air conditioning in a room, the differences between of the temperatures in the boxes with and without plants were measured and were analyzed about ten kinds of plant. Tendency of those differences between the two temperatures shows two patterns. The one is a pattern in species of Basil, Begonia, Chingensai, Fuyushirazu Habotan, Marigold, Minitomato and Oxicardium; the higher temperature is, the more difference between the two temperatures is. In species of Chingensai, Fuyushirazu Habotan and Marigold, the plants drop the temperature with effect. In species of Chingensai and Oxicardium, the plants control the temperature with effect. The other is a pattern in species of Asparagus and Pothos; the difference between the two temperatures does not depend on environment temperature.
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Daigo KAWAHARA, Teruo MURAKAMI
Article type: Article
Pages
29-30
Published: September 20, 2002
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At cortical bone, "diffuse damage" -pre-linear microcrack level damage, was observed as flame-like area of fluorescence image. We assumed that the diffuse damage was a signal of start of bone remodeling, and tried quantification of relationship between strain and diffuse damage of cortical bone. Specimens for this study were prepared from tibial diaphyses of adult porcine. The zone of diffuse damage in static 3-point bending test, was stained and observed by conforcal laser scanning microscope (CLSM). Then the changes in diffuse damage were evaluated from their histogram. We found that diffuse damage started from macro-level yield point, and had kept their density constant. So, it is suggested that the diffuse damage exists at grain boundary of hydroxyapatite.
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Kenji MIYAZAKI, Taiji ADACHI, Yoshihiro TOMITA
Article type: Article
Pages
31-32
Published: September 20, 2002
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For a bone regeneration using a biodegradable scaffold, design of its external shape and geometry of porous microstructure is a key issue to control the structural properties of regenerated bone tissue as well as the regeneration process. During and after the regeneration process, in which degradation of the scaffold and formation of the new bone occurs in the same time frame, bone-scaffold system is required to keep and obtain a desired mechanical function such as the stiffness as a structural system. Scaffold need to have porous structure to expect cell ingrowth and migration, and flow transport of nutrient and metabolic materials. In this study, three-dimensional computational simulation method for a bone-scaffold system in the bone tissue regeneration process using a porous scaffold was newly proposed, and the effects of porous scaffold structure on bone tissue regeneration process were discussed.
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Takeshi MATSUMOTO, Masahiro TODOH, Masao TANAKA
Article type: Article
Pages
33-34
Published: September 20, 2002
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Bone has hierachical and complex structure and multiscale viewpoint is important for bone mechanics because the mechanical property is dependent on the scale factor of bone structure. Macroscopically, some relation is known between the mechanical property and bulk morphology. On the other hand, limited attention has been paid for such structural and mechanical consideration in mesoscopic and microscopic scale. In this article, the macroscopic elastic modulus of cancellous bone is examined by means of the elastic modulus of trabeculae, its orientation and volume fraction. Mean intercept length and fablic ellipsoid analysis and conventional compression test were used for the brick specimen harvested from bovine femoral head, and three point bending test was used for mechanical property of trabeculae specimen obtained from brick specimen. Some dependency of elastic modulus of trabeculae was suggested on the trabeculae orientation, and the complex relation was expected between the elastic moduli of trabeculae and cancellous bone.
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Kenji SASAKI, Yoshihisa MINAKUCHI
Article type: Article
Pages
35-36
Published: September 20, 2002
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We investigated the stress conditions and growth deformation behaviors in the vertebral body using the growth strain method. The growth criterion parameters of the 3,4,5th lumbar vertebras were determined by applying two-dimensional finite element method. Next, growth-strain analysis of the 3,4,5th lumbar vertebras was performed for various loading conditions under the growth criterion parameters of each lumbar vertebra. Our findings showed that the shape of the intervertebral disc markedly changed according to the loading conditions and the hernia occurred.
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Yoshihisa MINAKUCHI, Tamiyuki NAKANE, Yukinori SATO, Sinji KAWASKI, Ta ...
Article type: Article
Pages
37-38
Published: September 20, 2002
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The X-ray and magnetic resonance imaging methods has been difficult to grasp the small loosening between hip prosthesis stem and human femur. The sectional form in the front of the human femur is investigated using an ultrasonic pulse echo method. An ultrasonic wave is emitted toward the femur using a focused probe attached to the thigh surface. The echo waveform reflected from the outside of femur, and the inside of femur is measured. The sectional form in the front of the human femur by the ultrasonic wave is compared with that of the X-ray CT. Consequently, the sectional form in the front of the human femur can be obtained an accurately using the focused probe.
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Kazuhiro FUJISAKI, Shigeru TADANO, Junichi SHIBANO
Article type: Article
Pages
39-40
Published: September 20, 2002
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Bone tissue is a composite material composed of hydroxyapatite (HAp) and collagen. In the X-ray diffraction method using characteristic X-ray with a unique wavelength, HAp in compact bone has much lower crystallization than metal as steel. The peak position of diffracted intensity is not easy to determine from the gradual intensity-angle profile. This work proposes a method to calculate the lattice strain from the information of a whole diffracted profile without a peak position. In this experiment, strip specimens of 28×8×2 mm in size with their long axis aligned to the bone axial or the circumferential direction were cut from cortical bone in a shaft of bovine femur. To confirm the relationship between applied macroscopic strain and lattice strain in bone tissue, a four-point bending device was developed to apply bending load to the specimen during the X-ray irradiation. As a result, the accuracy of measurement by this method was better improved.
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Jun SAKAI, Fumikazu KOUDA, Makoto SAKAMOTO, Hidehiro MORIKAWA, Hidemi ...
Article type: Article
Pages
41-42
Published: September 20, 2002
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The enamel is considerably hard and brittle in the human tissues. Fracture toughness K_<IC> is used to evaluate brittle materials. In addition, K_<IC> reflects the resistibility of a material to crack initiation and unstable propagation. In this study, we investigated fracture toughness and Vickers hardness number through an indentation microfracture method with a Vickers microhardness testing machine.
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Shuichi WAKAYAMA, Teppei KAWAKAMI, Satoshi KOBAYASHI, Mamoru AIWAWA, A ...
Article type: Article
Pages
43-44
Published: September 20, 2002
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The effect of simulated body environment on mechanical properties and fracture behavior of bioceramics were investigated. Alumina ceramics, which are a typical bioinert ceramics, were used. Four-point bending tests were carried out in air, refined water and a simulated body fluid (SBF) in order to investigate the dependence of microfracture process on environments. The microfracture process during the bending tests was evaluated by an acoustic emission (AE) technique. Rapidly increasing point of cumulative AE energy was observed before the final unstable fracture and it was understood that the stress at AE increasing point, σc, corresponds to the maincrack formation in the previous work. The test environments affected σc more strongly than bending strength, σ_B, from the fracture process. Consequently, it was suggested that the critical stress, σc, is available for an evaluation parameter, which is essential as the yield strength in metals, for bioceramics materials.
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Jiro SAKAMOTO, Ryunosuke SAKODA
Article type: Article
Pages
45-46
Published: September 20, 2002
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It is necessary to control of absorption time of drug capsule made of bio-absorbable material in drug delivery system (DDS), in order to release the drug concentrated at an affected part. Drug capsule with non-uniform thickness is useful to control the absorption time because capsule break and drug release occur at a thinnest part of the capsule. Mechanical stress occurred in bio-absorbable material also affect to its absorption ratio, so it is possible to control the absorption time by varying residual stress value if residual stress is given for the drug capsule of DDS. We investigated effect of the non-uniform shape and residual stress to the absorption time in two-dimensional ring made of bio-absorbable material. Variable cross-sectional ring with residual stress was made of PLLA, and absorption examination was carried out in HCOOH solution. From the results, possibility of control absorption time of drug capsule in DDS was considered.
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Toshia FUJISATO, Seiichi FUNAMOTO, Masamitsu HASEGAWA, Satoshi NUMATA, ...
Article type: Article
Pages
47-48
Published: September 20, 2002
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Decellularized tissues and those recellularization are widely studied to give more durability and invisible immunogenicity to the conventional bioprostheses. We are investigating efficient processes of decellularization and recellularization of biological tissues. Our recent studies on biomechanical properties of decellularized tissues were reported. Porcine pulmonary valves and aortas were excised and treated by a newly developed method using ultrahigh pressure. They were then subjected to the histological and biomechanical studies. The results were compared with those by the decellularization using Triton X-100. The leaflet and aorta were completely cell free when new method was applied. There were no significant changes in biomechanical properties. However, the cells were still remaining inside the tissue and both of the breaking strength and elastic modulus were increased when the tissue was immersed 1% Triton X-100. Biological tissues decellularized by our new method having intact biomechanical properties may provide more durable bioprostheses.
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Mitsugu TODO, Nobuyuki SHINOHARA, Kazuo ARAKAWA
Article type: Article
Pages
49-50
Published: September 20, 2002
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PLA, poly (lactic acid), was molded under different conditions to fabricate PLA samples of different crystallized structures. Mode I fracture toughness was then evaluated at five different loading-rates using two kinds of testing systems. It is interesting to see that for the materials molded at 130℃, the fracture toughness dramatically increased as loading-rate increased up to (10)^3mm/min, and rapidly decreased at 1m/s. It should be noted that the toughness obtained at 1m/s was almost equivalent to that evaluated at 1mm/min. Microstructures of the molded samples and fracture surfaces created at different loading-rates were also observed using optical microscopes. Dependence of loading-rate and microstructure on the fracture toughness was discussed on the basis of those experimental results.
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Kenichi HAMADA, Fumiaki KAWANO, Kenzo ASAOKA
Article type: Article
Pages
51-52
Published: September 20, 2002
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Shape change of shape memory alloy (SMA) fiber embedded denture base resin matrix composite after crack healing was discussed. Two types of rectangular composite specimen were prepared : one is a sandwich type specimen with well-aligned SMA fibers and the other is single layer specimen with less-aligned SMA fibers. Specimens were broken by 3 point bending test and heated for shape recovery. They were repaired by a conventional brush up method, and the flexion was measured. The flexions of both types of specimen were approximately 0.1 to 0.2 mm, which indicated this process was expected to be applicable for denture repair. Since the effect of fiber alignment on the flexion after repair was not significant, the process of fiber embedding by hands, a conventional technique in dental field, was not expected to have serious problems for the repair.
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Toshimasa Ishida, Ikuya Nishimura, Masaru Higa, Yoshinori Mitamura
Article type: Article
Pages
53-54
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The long-term success of total hip arthroplasty (THA) depends on the chance of acrylic cement failure and interface disruption. This chance can be diminished by an optimal long-transfer mechanism, whereby stress concentrations are avoided. Implant design is decisive for success or failure. This paper introduces an optimum design of the hip prosthesis. A generic three-dimensional FEM model of the proximal femur containing a cemented femoral stem of a total hip arthroplasty was developed. The design objective was to minimize the largest maximum principal stress in the cement. To verify validity of this design, fatigue analysis according to Miner's Rule was introduced.
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Jiro SAKAMOTO, Juhachi ODA, Atsushi KAKUUCHI, Tomoyuki AKAMARU, Norio ...
Article type: Article
Pages
55-56
Published: September 20, 2002
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In total en bloc spondylectomy, a tumorous vertebra is totally removed and replaced by a titanium mesh cage filled bone graft, and spinal instrumentation is carried out by using pedicle screw system. Two types of reconstruction method are available. One is the multilevel posterior instrumentation (MLP), and another is the short posterior and anterior instrumentation (SPA). MLP has posterior fixations using pedicle screws system at four or more vertebrae. SPA has anterior and posterior fixations in left side at two vertebrae. It is considered that bone fusion and remodeling of the grafting depend on mechanical stress condition. Although mechanical stress condition has not been sufficiently investigated. In this study, analysis of the reconstructed structure were carried out and stress condition around the titianium mesh cage was discussed.
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Yasuyuki KATO, Youichi SATO, Yasuo AOYAGI
Article type: Article
Pages
57-58
Published: September 20, 2002
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The catheter is known as a tubular medical instrument which is used to discharge the impurities of abdominal cavity or to inject nutrients into a body. Recently, however, the catheter is used not only for the purpose of the discharge or the injection alone but also for the removal of the imperforation in the blood vessel without receiving a large damage by surgical operations. Therefore, a soft characteristic is necessary for the material of the catheter so as to reduce the damage in the vascular wall. Simultaneously, in the case of the operation such as the myocardial infarction, the responsiveness and the operationality are required in order to carry out the remote operation smoothly. The purpose of this study is to investigate the deformational behavior and strength of the catheter made of the nylon resin braid by a thin stainless wire. And, we reveal how the braid has effects on the reinforcement and the responsiveness under uniaxial tensile tests.
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Tsunetoshi Masuda, Toshio WATANABE, Kazunori UEKI, Yoshinori SHIBATA, ...
Article type: Article
Pages
59-60
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The sports of teeth and jawbone might be connected directly with an eating disorder, a speech trouble, and appreciation of the beautiful injury. It may be not sufficient for preventing sports injury while the mouth guard is defense apparatus to prevent the injuries. Therefore, it is necessary to analyze the injury mechanism of the sports player with the mouse guard which is designed based on the experience of dentists and players. In this research, the functional effect of mouth guard to protect teeth under static loading condition was analyzed by FEM. Some results were shown to discuss the clinical and dental applicability.
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Sota YAMAMOTO, Daisuke NAKANE, Eiichi TANAKA
Article type: Article
Pages
61-62
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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This study is concerned with the mechanical instability of isthmic spondylolisthesis. The effects of isthmic defect on the structural stiffness of lower lumbar spine are discussed by using finite element analyses. The structural stiffness of lower lumbar spine was examined by the load-deformation relations in vertical direction using an intact, L4-defect and L5-defect lumbar spine models. The results showed that the structural stiffness of L4-defect lumber spine was lower than those of intact and L5-defect lumbar spines. There was no significant difference between the stiffness of intact and L5-defect lumbar spines. The decrease of the structural stiffness may be attributable to the mechanism of isthmic spondylolisthesis.
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Toshikatsu WASHIO
Article type: Article
Pages
63-64
Published: September 20, 2002
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This article describes methods on measurement and analysis of spinal mobility during surgical operation for appropriate medical treatment. Because intraoperative spinal mobility is one of most useful concepts for definition of spinal instability which is not defined clearly. In this experiment, several porcine spines were used. Stiffness, neutral zone and residual load were derived from load-deformation curve. Spinal mobility is evaluated by Fourier descriptor from load-deformation curve, too. Fourier descriptor is useful for analysis of contour of hysteresis loop. 3D Movement of spine was analyzed by DLT from biplane video images. Both three parameters and Fourier descriptor were available for evaluation of spinal mobility.
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Akihisa SHIMIZU, Shigeru AOMURA, Takayuki IKOMA, Satoshi FUJIWARA
Article type: Article
Pages
65-66
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In this paper an experimental study of the impact response of a physical human head-neck model is described. The midoccipital region of the model was hit by steel block impacter, then the intracranial pressure of frontal region and the acceleration of the head were measured. The intracranial pressure curve showed a sharp negative pulse. The peak of intracraial pressure pulse appeared right after the peak of acceleration pulse and the difference was 0.8 msec. The influence of the rigidity, the speed and the shape of the steel block on the intracranial pressure and the acceleration was investigated.
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Takaaki SARAI, Hiroyuki HASHIZUME
Article type: Article
Pages
67-68
Published: September 20, 2002
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Fracture-dislocation of proximal interphalangeal (PIP) joints caused by impact loadings is one of common injuries in finger joints. It seems that the propagation of stress wave in the joints is strongly affected by the thickness of articular cartilage. The influence of thickness of cartilage on the impulsive stress in PIP joints is therefore studied using the dynamic finite element method in the present paper. The thin cartilage layer causes the stress concentration in the subchondral bone. The influence becomes remarkable when the thickness is less than a quarter of normal thickness, indicating that the risk of fracture is high when the cartilage has worn out.
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Jun HOUDA, Masao KAMATAKI, Atushi NISHIDA, Masaki NEGAMI, Hitoshi MIYA ...
Article type: Article
Pages
69-70
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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We created the simple composition image using computer graphics to investigate the influence of Equilibrium, comparing with the video camera images, which have many indefinite factors. All Point Reaching Time of the Tracking Method was used for evaluation. The influence of horizontal rotation image was larger than that of the vertical rotation image. The influence increased according with changing contrast and color. The influence of 3D effect image was larger than that of 2D image.
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Tadashi KOSAWADA, Takuma SATO, Koji INOUE
Article type: Article
Pages
71-72
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The vascular endothelial cell is the only interface between blood and tissue, where the metabolisc activity is very active. The large deformation of the vesicles is considered to be involved in these transport process. In this study, vesicular mechanics in cells is theoretically investigated. A system of nonlinear differential equations is derived according to the variational principle and is reduced to a two point boundary value problem. The equations are solved through the Shooting method along with Newton-Raphson and Runge-Kutta method. The computed shape suggests that the effect of various parameters and outer cytoplasmic membrane are significant and these should be taken into account in numerical simulation.
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Tadashi KOSAWADA, Hiroshi MATSUKAWA
Article type: Article
Pages
73-74
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The existence of a transendothelial channel, which is considered to be involved in specific of macromolecules, is reported. In this study, the generation mechanism of vascular endothelial chained vesicles and the transendothelial channel is theoretically investigated based on minimization of bending and in-plane shear strain energy of the membrane. A system of nonlinear differential equations is derived according to the variational principle and is reduced to a two point boundary value problem. The equations are solved through the Shooting method along with Newton-Raphson and Runge-Kutta method. The computed shape suggests that the effect of in-plane shear elasticity and outer cytoplasmic membrane are significant and these should be taken into account in numerical simulation.
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Toshiro OHASHI, Takeshi IKEDA, Takeo MATSUMOTO, Masaaki SATO
Article type: Article
Pages
75-76
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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To determine the effect of extracellular matrix on chondrocytes, mechanical properties and production of type II collagen of chondrocytes were measured. Isolated bovine articular chondrocytes were cultured on a culture dish for 3 weeks and then embedded in a type I collagen gels. After 3-4 weeks, the chondrocytes were excised from the constructs and a pipette aspiration test was performed. The Young's modulus significantly increased when the chondrocytes were embedded in the collagen gels, which corresponded to the development in cytoskeletal structure. In addition, type II collagen was observed by immunofluorescence microscopy, showing that the production of type II collagen was less detected with time in culture on the culture dish. This result indicates that the mechanical environment may influence the differentiated state from chondrocytes to fibroblast. The mechanical properties and physiological functions of chondrocytes are very important to provide more quantitative information about the regulation of the cartilage metabolism.
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Takahiro NAKANO, Tadashi INABA, Masataka TOKUDA, Yutaka SAWAKI, Shingo ...
Article type: Article
Pages
77-78
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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It is considered that to evaluate the cardiac contractility from a mechanical point of view is useful for a quantitative evaluation of the extent of heart disease or the effect of treatment. From the above-mentioned point of view, we have tried to investigate mechanically the cardiac contractility by using the magnetic resonance tagging technique, which is a noninvasive measurement technique of regional wall motion. In the present paper, the deformation of the left ventricular wall in normal humans and patients with CABG surgery is analyzed, and the cardiac contractility in the ischemic heart disease is discussed.
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Tomohiro KANAYA, Katuyosi NAGAOKA, Shigeo TANAKA, Kouzou IKEGAMI, Hiro ...
Article type: Article
Pages
79-80
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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There are only a few examinations techniques on loading function of knee after anterior cruciate ligament rupture. We have noticed that the rupture of anterior cruciate ligament significantly affects to the tension of Achilles tendon, as a result of the destruction of the biomechanical structure in hind limb. Hence we developed measurement device for tensile state of Achilles tendon as a new assessment method for the anterior cruciate ligament rupture. The results obtained proved that assessment of ACL rupture with push-in test of Achilles tendon is reliable and may be utilized as the standard in the clinical diagnosis.
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Masakazu KUME, Takeshi IWAMOTO, Toshio TSUTA
Article type: Article
Pages
81-82
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Since a growth of a wrinkle gives a severe change in appearance of face, women have a tremendous interest in wrinkles. In past studies, it was clarified that collagen and elastin fibres are concentrated on dermal tissue along the wrinkle on skin in comparison with normal tissue of dermis. This result is one of the biochemical reactions of the dermal tissue toward an extrinsic factor or local mechanical stimulus acting on the skin. It is possible that mechanical stimulus which returns this tissue to the normal condition contributes to the reduction of the wrinkle. This study presents a modeling of the formation of the dermal tissue under mechanical stimulus. Then, computational simulation is performed along with proposed model.
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Ryuhei Yamaguchi, Susumu Kudo, Hideaki Amagai, Toshiyuki Hayase
Article type: Article
Pages
83-84
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In the present study, the wall shear stress and flow structure in the right angle branch have been studied experimentally in laminar steady flow using a laser Doppler velocimeter. The side branch, 14 mm in diameter, bifurcates at a right angle from the trunk, 24.5 mm in diameter, and both upstream and downstream corners at the entrance of the side branch are square edged. There is a periodical change of velocity in the side branch, and the Strouhal number based on the variables of the side branch is constant to be St_S=1.03. This phenomenon is a characteristic flow structure in the right angle branch.
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Hiroyoshi OMURA, Taku MORINO, Takatsugu YAMAUCHI, Kazuo TANISHITA, Sat ...
Article type: Article
Pages
85-86
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In our study, we made realistic model of aneurysm and analyzed precise flow profile in patients' aneurysms. A clear acrylic internal calotid artery (ICA) lateral aneurysm model was made by using 3D CT angiogram and flow profile during one cardiac cycle in aneurysm was analyzed. Flow profile within the aneurysm model were obtained from velocity measurements by using laser Doppler velocimetry and Particle Image velocimetry. The flow from the parent artery was divided into the daughter artery and the aneurysm along proximal side of the neck. The inflow zoon changed dynamically in cross section of the neck. The highest shear stress was marked at the neck of the aneurysm. The result can show that the characteristic flow change gives controversy relating to coiling.
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Nobuhiko NAKAZAWA, Susumu KUDO, Ryuhei YAMAGUCHI, Hiroshi UJIIE
Article type: Article
Pages
87-88
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In the present paper, the change of flow structure such as the wall shear stress at the apex of the anterior communicating artery with the initiation of aneurysm is described in steady flow. The anterior communicating artery composing the circle of Willis is one of the predilection sites where the cerebral aneurysm occurs frequently. The flow field around the anterior communicating artery is simulated by two confluent tubes joining at the angle of 60 degrees, two parallel bifurcating tubes, and the junctional tube, bypass, connecting four tubes. The velocity profile is clarified around the apex where the cerebral aneurysm is apt to initiate. In particular, the gradient of wall shear stress around the apex at one confluent tube with much flow rate is estimated, and the relation between the change of wall shear stress and the initiation of aneurysm is discussed physiologically.
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Kenta SHINOZAKI, Marie OSHIMA, Toshio KOBAYASHI, Kiyoshi TAKAGI
Article type: Article
Pages
89-90
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Subarachnoid Hemorrhage is a fatal disorder resulting from rupture of cerebral aneurysms. It is considered that aneurismal generation and rupture is closely associated with the blood flow pattern influenced by the arterial geometry such as bifurcation and rupture is closely associated with the blood flow pattern influenced by the arterial geometry such as bifurcation and curvature. To get the knowledge of dominant geometry factor causing the intra-aneurysmal flow pattern and wall shear stress, we carried out the Finite Element Simulation of intra-aneurysmal flow based on real medical CT images . We confirmed two facts; 1) when the Aspect Ratio (AR) of aneurysm is larger than 1.1,a weak vortex appears near the Dome and it forms a lower shear stress area compared with the surrounding area, and; 2) the Tilt Angle α of aneurysm is a factor that dominates the position of higher wall shear stress areas, namely as α increases, the position of high shear stress area migrates from the top of the Dome to the Posterior Neck.
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Nami MATSUNAGA, Hao LIU, Ryutaro HIMENO
Article type: Article
Pages
91-92
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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We have developed a method to solve pulsatile blood flow in a Cartesian coordinate system by directly utilizing voxel data of medical images in a manner of VOF (fractional Volume Of Fluid). The purpose of this paper is to make an application of this method in analysis of blood flow in a realistic carotid artery by using the ultrasonic images.
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Takuji ISIKAWA, Nobuyoshi KAWABATA, Motoyoshi TACHIBANA
Article type: Article
Pages
93-94
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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We have proposed a new method to model an erythrocyte by using drag points and springs as an altanative way to analyze a blood flow. In this paper, a blood flow in a small artery with stenosis is simulated by means of DEM. It is found that erythrocyte is strongly deformed around the stenosis and that the vortex downstream of stenosis weakened by erythrocytes.
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