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Shoji MORIMOTO, Yasunori HASHIMOTO, Akio NAKAGAWA, Yasushi AKAZAWA, Ma ...
Article type: Article
Pages
95-96
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A knee joint for medial stem HKAFO (Hip Knee Ankle Foot Orthosis) for paraplegia is developed, in which lock-unlock holding mechanism operated by pulling cable action and knee extension assist mechanism generated by compact gas spring are installed. With this knee joints, a patient who fully lost his lower limb activity can move between sitting and standing position by himself. The mechanisms of lock-unlock-holding and knee extension assist are described. The first trial of product is made of stainless steel and weight is about 800g.
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Yasushi AKAZAWA, Akio NAKAGAWA, Tsuyoshi NOMURA, Masahiro TODOH, Masao ...
Article type: Article
Pages
97-98
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Ankle-foot orthosis (AFO)is an important aid for patients with gait disorder. We have investigated the relationship between hemiplegic ankle joints function and AFO joint characteristics during gait, because mechanical characteristics of AFO joint directly affect the walking function. In this article, we examined an ankle joint device using magneto-rheological fluid that rheological characteristics can be adjusted by changing intensity of magnetic field applied. The device is composed of a rotary cylinder and a short tube with restrictor connecting both cylinder ports, and its closed hydraulic circuit is filled with MR fluid. The moment and angular velocity relationship was measured for the device with a permanent magnet, and the resistant moment was evaluated under different magnet distance from the tube. This device was mounted on an experimental CFRP upright AFO accompanied with a magnet position adjustment mechanism. Gait of a hemiplegic volunteer with this AFO was improved in some time-distance parameters when viscosity was switched to low at initial stance phase and to high immediately before swing phase.
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Shigeaki MATSUO, Takashi MAEDA, Toshinori IWASAKI, Tojiro YANAGI, Yuui ...
Article type: Article
Pages
99-100
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Electrical stimulations such as FES and TES have been widely used in the rehabilitation of paralyzed patients whose natural nervous control of muscular contraction were lost due to a spinal cord injury. Also the stimulation is used for keeping or reinforcing skeletal muscles. We tried to reinforce skeletal muscles based on our new idea on training method. Our idea on stimulation timing is that the timing is adopted for the antagonist muscle to resist the agonist muscle contraction. For comparison, stimulation was applied to the arm while extended. We experimented to clarify whether the triceps brachii could be reinforced by electrical stimulation. We stimulated the triceps brachii and biceps brachii with a FES device. We examined the force and cross section of the muscle of the upper arm by using KIN/COM and MRI after a 12 weeks experiment. We obtained that the muscle and the force were more enlarged and improved, respectively than in the case of electrical simulation on agonist muscle directly. Muscle force can be reinforced by electric stimulation. Especially, agonist muscle will be strengthened by our new idea on training method. We obtained also data about thigh by same as experiment.
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[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
Article type: Article
Pages
101-102
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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We recently developed a hybrid exercise system in which electrically-stimulated antagonist muscles are used to resist volitional contractions of the opposing agonists. This system has already been used successfully to strengthen the upper extremities of healthy men. (Yanagi et al, 2003) Reciprocal limb movements are central to walking and many activities of daily living. Despite their importance, training is usually relatively primitive and typically involves multiple repetitions of the desired activity. This approach permits training of the desired pattern of movements but does not lend itself to increasing the subject's strength much above that needed for the task. Our goal was to combine hybrid exercise and ergometer training and study its potential in strengthening muscle in a functional pattern that matches that of daily life.
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Makoto WATAKABE, Katsumi MITA, Seiji HIRAMATSU, Atsuo KATO
Article type: Article
Pages
103-104
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This study was designed to examine the effects of length changes in ankle dorsiflexor, tibialis anterior, on the activation of the muscle, using the mechanomyogram (MMG) and force relationship during isometric ramp contractions. The relationships between the root mean squared amplitude (RMS) and mean power frequency (MPF) of the MMG and relative force (% MVC) in the dorsiflexed ankle and plantarflexed ankle were markedly different from those in the neutral positioned ankle. It is widely accepted now that the RMS and MPF of the MMG reflect the motor unit activation patterns. Therefore, these differences in MMG suggest that the changes in length of muscle probably influence the muscle activation pattern during isometric ramp contraction.
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Takashi MAEDA, Yoshihiro NAKASHIMA, Keisuke HIROTA, Yuichi UMEZU, Naot ...
Article type: Article
Pages
105-106
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A gait analysis result has been used as an examination item of rehabilitation for explanation and improvement of a gait state. Thus it was shown about the method in an example of the trans-femoral amputee who did gait analysis regularly really. I thought that understanding of necessity of rehabilitation was easy to be provided as for the subject as for using it for explanation of a gait analysis result and an examination item of rehabilitation because a gait state showed understanding, problems and a solution more objectively.
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Daisuke MIGITA, Yoshihiko TAGAWA, Naoto SHIBA
Article type: Article
Pages
107-108
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Human gait is typically studied with clinical observation or in a gait laboratory. The first approach is rapid but subjective and limited. The second, while it is experimentally rigorous and provides voluminous amounts of quantitative data, is time consuming and expensive. Computer simulation may offer an alternative approach for both the analysis of normal gait as well as in modeling the effects of changes in joint mechanics, muscle strength, and orthotics use. Current simulation techniques, however, are limited in their ability to model the complex analysis necessary to study gait when it is altered by an abnormal joint or the compensatory actions of the body and other joints. Numerical presentations alone do not permit an intuitive understanding of modeling trials. Graphical presentation, on the other hand, has much to offer in that it presents the overall pattern of gait in a manner that is easy to assimilate. We investigated the feasibility of a new approach to the graphical presentation of gait modeling that is sensitive enough to demonstrate the effects of joint abnormalities, changes in muscle strength, or the presence of orthotic devices.
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Hiroshi YAMADA, Iwao FUKUDOME
Article type: Article
Pages
109-110
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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We carried out MR imaging to investigate the positions of the lumber vertebrae and the intervertebral discs as well as their mechanical loading states for four healthy male students. The subjects lie on the bed in a supine position without loading as well as a recumbent and squat position with/without loading as a 20% body weight by pulling rubber tubes by hands. The measurement results show that locations of the vertebrae from T12 to S1 change significantly between the squat position and the supine position. The loading at the squat position had little effect on the positions of the vertebrae. The analysis of the MR images shows that the averaged angle of the upper surface of the vetebra S1 varies S1 varies depending on subjects.
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Kazuto MIYAWAKI, Keiichi KUTSUZAWA, Shinzou Nishimura, Takehiro IWAMI, ...
Article type: Article
Pages
111-112
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In the progress of elderly society, evaluation of equipments for assisting human is getting more important nowadays. People use frequency a Wheelchair. However it does not seem to have been examined how the equipment moderates the generated consumption energy of its helpers. In this paper, we perform mechanical evaluation of a helpers walk using the wheelchair on slope. We estimate the consumption energy based on the Musculo-Skeletal Model. Our evaluation method will be useful for developing practical assisting equipments.
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Yuki NAKAMURA, Toshio TSUTA, Takeshi IWAMOTO
Article type: Article
Pages
113-114
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Kazunori FURUKAWA, Isao WATANABE, Kazuo MIKI, Takashi DEGUCHI, Koji Mi ...
Article type: Article
Pages
115-116
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Six-year-old child FEM Model was developed for the analysis of impact behavior of child. In this paper, impact behavior simulation for 6-year-old child was performed applying the acceleration field at frontal car crash impact to the 6-year-old child model in child restraint system. Head locus, head angle and head angular velocity of child FEM model simulation were compared with those of child cadaver testing.
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Yasuyuki KATO, Youichi SATO
Article type: Article
Pages
117-118
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The catheter is known as a tubular medical instrument which is used to discharge the imputities of abdominal cavity or to inject nutrients into a body. However, the catheter is used not only for the purpose of the discharge or 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 as the material of catheter. Simultaneously, 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 catheter which is made from the nylon resin braided by a thin stainless wire. In this paper, we clarify a viscoelastic response by performing a stress relaxation and creep experiment. Moreover, we try to investigate the relation between the braid-angle and the Young's modulus.
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Naoki YAMADA, Hironobu YONEZAWA, Katsuya KAWAGUCH, Ichiro MASAMORI, To ...
Article type: Article
Pages
119-120
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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To achieve the operation improvement such as doors of the car, the technique for quantitatively evaluating "Ease of operation" is constructed. Three-dimensional three links and seven joints degree of freedom model expresses the arm muscular-skeletal system and manipulating effort is evaluated by manipulability evaluation technique (manipulating force ellipsoid) in robotics. The joint torque characteristic data of human is measured and combined with manipulability evaluation technique. The manipulability evaluation technique corresponded to human nonlinear joint torque characteristics is developed.
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Megumi TAMENAMI, Satoshi HORIHATA, Tetsuo MIYAKE, Shunsuke ISHIMITU
Article type: Article
Pages
121-122
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The voice communications are important to spend in our daily life smoothly. Patients who remove his or her larynx lose all vocal function. A variety of alternative voices have been designed and made practicable for such a functional disorder person up to now. A functional disorder person who lost the language function uses the uttered esophageal speech method by vibrates the mucous membrane of the vocal tract as a substitute voice. However, there are problems which tone quality is bad and difficult to hear it. Vocal chords vibration signal is necessary to correct because it is does not make a plain voice. In this study, we try to make the speech production by correcting the vocal chords vibration signal by using of the voice tract filter characteristics.
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Mami TANAKA, Jiyon CHO, Yoshikatsu TANAHASHI, Seiji CHONAN
Article type: Article
Pages
123-124
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This paper is a study on the optimum design of a palpation sensor for the diagnosis of prostate abnormalities. The palpation sensor is configured as a polyvinylidene fluoride (PVDF) film placed on a sponge rubber base. Thus, the stiffness of the sponge rubber base of the sensor is of great importance for the best discrimination of normality and abnormality. First, the elastic characteristics of real organ tissues, both normal and abnormal, are investigated. Then, FEM analysis is introduced for the optimal design of sensor and the best fit stiffness of the sponge rubber base is determined.
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Junichi SHIBANO, Shigeru TADANO, Manabu MORIKAWA, Yukio NAKATSUCHI
Article type: Article
Pages
125-126
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A fall in walking on snowy road often causes sever hip fracture. For especially elderly person, thus hip fracture has high risk for bedridden. The purpose of this study is to investigate the gait characteristics on snowy road. In this experiment, eight healthy subjects walked onto snowy and asphalt roads. Gait accelerations were recorded at 20Hz by micro-accelerators equipped with the head, hip, knee and ankle of them. As a result, it was confirmed that the gate acceleration of each body segment showed different patterns with road conditions. Slipping during gait on snowy road could be detected from the change of acceleration of ankle.
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Samjin CHOI, Takashi KAKIMOTO, Takumi KUBARA, Yoshiaki MATSUMOTO, Daij ...
Article type: Article
Pages
127-128
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The objective of this paper is to present the development of a LonWorks network based cardiorespiratory monitoring system for twenty-four hours vital sign measurement. A belt sensor is developed, which could be worn by the patients without or few restraint so that their health conditions can be monitored twenty-four hours a day. The belt sensor consists of conductive fibers, a Polyvinylidene Fluoride (PVDF) and a condenser mike so that the signals of ECG, pulse, breathing, cardiorespiratory sound can be measured. The sensors' outputs are filtered, amplified and converted to digital signals by a telemedicine device. The recorded signals can be also transmitted to a computer through RS232,the digital wireless communication link, and the LonWorks Network. Therefore the patient state can be analyzed continuously and remotely. Any trait of abnormal health state and possible accidents is promptly detected by analyzing the data. This telemetry system is particularly useful as a telemedicine device for the elderly care of neonates or infants. Detailed descriptions of the hardware and the software of system were presented in the paper.
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Daiji YOSHIKI, Yoshiaki MATSUMOTO, Zhongwei JIANG
Article type: Article
Pages
129-130
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In recent announcement, the number of households with elderly people exceeded about 7 million for the first time in Japan. As it, the number of elderly people living alone is on the increase. Therefore, the system which can monitor the living status of them is desired. From such background, we propose the system which can monitor the living status of elderly people living alone from the use situation of plural home electric appliances. This system can detect a use situation of them, without remodeling the existing home appliances. The result of the field experimented, it was possible to monitor the living status accurately from the use situation of plural home electric appliances.
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Koji MORI, Koji HATTORI, Naoya Takahasi, Keiichiro Yamamoto, Takatomo ...
Article type: Article
Pages
131-132
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The quantitative estimation of articular cartilage is needed by orthopeadic clincians to make comparative study of various treatments for joint damage. We have proposed the ultrasonic method using wavelet transform. Clinical and animal studies showed that the proposed method was effective for the cartilage estimation. The aim of this report was to investigate morphological effects of cartilage, for example the curvature or angle between cartilage and subchondral bone. The numerical analysis is adapted for the study, because various models that are not obtained from clinical or animal study can be considered. The ultrasonic echo from subchondral bone was founded to consist of two echoes. This suggests that the duration time of the echo from subchondral bone relates to the thickness of subchondral bone. Using numerical and experimental study, much information may be obtained from ultrasonic echo.
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Sota YAMAMOTO, Atsushi HAYAKAWA, Tsuyoshi TANIGUCHI, Tomohiro KONDO, E ...
Article type: Article
Pages
133-134
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A new experimental system for injury evaluation of strain-injury and contusion of skeletal muscle was developed. This system equips a linear actuator which can move in high velocity with high acceleration to make strain-injury and perform tensile tests. It also has a pendulum-impactor system for evaluation of contusion. Some preliminary tests were performed to validate the functions of the developed system. The results of both the strain-injury and contusion experiments indicated that mechanical properties of skeletal muscle change by damage caused by external loading. The developed system can be useful for quantitative evaluation of injury criteria and clarification of injury mechanism of skeletal muscle.
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Toshihiko YASUDA, Shougo KUWABARA, Toshiyuki TANAKA, Katsuyuki TANAKA
Article type: Article
Pages
135-136
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In this paper, a power assist mechanism for one hand drive wheelchair developed in our research group is investigated. Based on observation data of the torque given by wheelchair user and the velocity of wheelchair, a nonlinear power assist rule described by piece-wise linear function is proposed. Usefulness of proposed assist rule is demonstrated by slope drive experiments.
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Kensaku SAKAI, Masaaki MOCHIMARU, Kazunori YOKOYAMA
Article type: Article
Pages
137-138
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The endoscopic paranasal sinus surgery is conducted under local anesthesia. The patient keeps consciousness. So, they feel pain and fear of surgical procedures. Pain and fear put a lot of stress on patient and affect the physiological variability such as increasing heart rate, elevating blood pressure and so on. To evaluate effects of surgical procedures on patient mental strain, the heart rate variability of 7 patients were measured. As results of analysis, characteristic fluctuations in heart rate caused by differences among types of surgical sections (wait, break, bone and mucosa cutting, blood aspirating, insertion and removing a piece of styptic cotton) were found.
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Makoto SUGAHARA, Masayuki ITO, Kunihiko TOKUNAGA, Toshiaki HARA
Article type: Article
Pages
139-140
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The transtrochanteric surgical approach to th e hip is commonly used, especially for revision hip surgery. Failure of greater trochanter osteotomy leads to hardware failure, persistent pain, and limp. The major cause of failure to heal is inadequate fixation of the greater trochanter. The objective of this study was to consider primary fixation characteristic by the tension of wire, pressure of cut surface of 2 fixation location. In this experiment, the model bone was used for the sample. As a result, when tension is the near 90 N, approximately 10 N decreased 60 minutes later. In addition, cut surface pressure decreases at greater trochanter top.
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Ryota SHIMIZU, Ikuya NISHIMURA, Toshiki NAKAMURA, Takeo MATSUNO, Yoshi ...
Article type: Article
Pages
141-142
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A high prevalence of thigh pain has been reported after cementless total hip arthroplasty. But it is still unknown about the in-depth mechanism. To study the relevance between the occurrence of thigh pain and the stress in femur, we made animal experiment and actually put pressure on rabbit thigh from the medullary cavity using balloon catheter. The results of the experiments are reported here.
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Goh YAMAKO, Hiroki IIYOSHI, Naoto ENDO, Toshiaki HARA
Article type: Article
Pages
143-144
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A three dimensional computer model of the hip joint with a newly special designed device which is applicable to avascular necrosis was formulated to study the load bearing function of the device during a daily life. Finite element analysis showed that the new orthopaedic device seem to have significant load bearing function and endurability.
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Takako UCHIDA, Akiko MORI, Koichi KURAMOTO, Noriyuki NAGAYAMA, Takaaki ...
Article type: Article
Pages
145-146
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In cement-less artificial hip joint arthroplasty, stress distribution in the femur was evaluated by finite element method. In cement-less type, strong fixation with femur is performed by the bone ingrowth of porous structure. Increasing porous area, stress shielding effect in femur increases. But decreasing porous area, fixation ability of artificial hip joint decreases. Therefore influence of porous structure area/position on stress distribution in the femur was studied, and the optimum design in the cement-less artificial hip joint stem was discussed.
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Takeshi SANO, Toshiaki HARA
Article type: Article
Pages
147-148
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The mathematical model of the human lower extremities was used to study and predict the musculo-tendinous load in ankle joint. In this study Genetic Algorithm was applied to the mathematical model to estimate the precisely musculo-tedinous load in ankle joint. However, the solutions show that there are some differences between the solutions obtained by the typical optimization method and those for major muscles developed here. It means that modifying the value of some parameters would be necessary in order to find the optimal load.
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Ko KITAHARA, Ko TAKANO, Kazuhiro HASEGAWA, Toshiaki HARA
Article type: Article
Pages
149-150
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Using a special spinal-testing device, five functional spinal units obtained from pig spinal column were subjected to flexion-extension analysis in the intact state and after spinal motion segment failure/resection. Instant center of rotation under lumber FSU motion were found to study the motion characteristics at the extent of ligament damage and disc injury. The experimental results showed that the instant center of rotation seems to move as an increasing of motion segment damage.
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Kenichi TEZUKA, Akiyuki TAKAHASHI, Yoshitaka WADA, Takahiro YOSHIDA, M ...
Article type: Article
Pages
151-152
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Bone is a complex system with functions including those of adaptation and repair. To understand how bone cells can create a structure adapted to the mechanical environment, we proposed a simple bone remodeling model based on a reaction-diffusion system influenced by mechanical stress. When an external mechanical stress was applied, stimulated bone formation and subsequent activation of bone resorption produced an efficient adaptation of the internal shape of the model bone to a given stress, and demonstrated major structures of trabecular bone seen in the human femoral neck. By modulation of a single parameter affecting the balance between formation and resorption, deformation of bone structure during osteoporosis was also demonstrated. This simple model gives us an insight into how bone cells create a sophisticated architecture, and will serve as a useful tool to understand both physiological and pathological states of bone based on structural information.
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Taiji ADACHI, Hideto KIMURA, Yoshihiro TOMITA
Article type: Article
Pages
153-154
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This study proposes a mathematical model and simulation method for trabecular pattern formation in regeneration process using reaction-diffusion system with consideration of activation due to mechanical stimulation. The trabecular bone regeneration process in the defect was simulated using a voxel finite element method for stress analysis and a finite difference method for the reaction-diffusion analysis. For the defect subjected to macroscopic principal stresses, the formation and the evolution of three-dimensional trabecular pattern was simulate. The results demonstrated that the new trabecular island-like pattern was primarily emerged from the randomly distributed initial marrow condition, followed by the growth into the trabecular-like structures by connecting each other that depended on the macroscopic stress conditions.
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Hiromichi KOJIMA, Michihiko KOSEKI, Norio INOU, Koutarou MAKI
Article type: Article
Pages
155-156
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This paper deals with a simulation method of adaptive structural formation including anisotropic properties. The proposed method is based on a cellular automaton model which consists of isotropic cells. We propose the concrete method that generates an orthotropic structure considering nine kinds of elastic modulus and principal axes of elastic anisotropy under multiple loading conditions. The method renews the moduli and the axes of each cell according to the principal stresses. For validity of the method, three-dimensional simulation is performed under three loading conditions and the computed anisotropic structure is presented.
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Kenichi TSUBOTA, Taiji ADACHI
Article type: Article
Pages
157-158
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Distribution function of mechanical quantities at single trabecular level as remodeling stimuli was obtained by using digital image-based finite element models of normal vertebral body of rat. When a linear rate equation was assumed, integration of strain energy density (SED), von Mises equivalent stress, and local stress nonuniformity were more candidate stimuli of trabecular bone remodeling near remodeling equilibrium than SED. The sensitivity of distribution function of stress nonuniformity to change in physiological loading condition was the smallest in the four mechanical quantities.
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Naoki TAKANO, Masaru ZAKO, Kouji Tsujimura
Article type: Article
Pages
159-160
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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To understand the correlation between the microstructure and macroscopic poperties and behaviors for porous media, a novel digital image-based analysis technique is presented. It consists of digital image-based modeling, morphology analysis, and multi-scale stress analysis. This paper focuses on the morphology analysis that studies statistically the heterogeneity and variety in pore sizes, shape and dispersion. The analysis of dispersion of a vast number of pores has led to the quick prediction of stress concentration, which is of help to the multi-scale stress analysis. An application to porous alumina with spherical pores is shown.
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Naoki TAKANO, Yasuo NAGANO, Hiroshi KAWAMOTO, Masaru ZAKO
Article type: Article
Pages
161-162
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Thanks to the intensive research works on the multi-scale computational methods for heterogeneous materials in the last decade, the theoretical and numerical issues in the multi-scale analysis have been matured. In this study, a novel practical software V-SEM has been developed so that many engineers in the materials science and bio-mechanics fields, for instance, can use the multi-scale evaluation in their daily research works. The homogenization method is employed to bridge the micro- and macroscopic properties and phenomena. The developed software provides the users, who are not familiar with the homogenization method, an accurate analysis and visualization environment. In this paper, the outline of the developed software is presented with a demonstrative example.
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Naoki TAKANO, Masaru ZAKO, Yoshihiro OKUNO
Article type: Article
Pages
163-164
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In the analysis of heterogeneous materials and components, it is essential to consider not only the microstructures but also the fracture origin such as crack, interface etc. Considering the dimensions of the microstructures, fracture origin and components, a novel multi-scale computational method is proposed that employs the enhanced mesh superposition method and the homogenization method. Emphasis is put on the microscopic stress analysis near crack tip with high gradient of macroscopic stress, and the 3D large-scale analysis using renumbering by RCM method and out-of-core skyline equation solver.
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Yuki OSAKO, Taiji ADACHI, Mototsugu TANAKA, Masaki HOJO
Article type: Article
Pages
165-166
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The establishment of the designing method for the initial scaffold structure is required for the appropriate property of bone-scaffold system in bone regeneration process using scaffold. In this study, the optimization method of the microscopic structure of scaffold was investigated by 3D computational simulation of bone regeneration. Two types f initial structures with lattice and spherical cavity and different volume fraction were simulated. Simulation results were evaluated quantitatively using the proposed evaluation functions. The optimum structure and the validity of this method were discussed from the viewpoint of mechanical functions of bone-scaffold system.
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Keisuke HAYASHI, Fumio NARITA, Yasuhide SHINDO
Article type: Article
Pages
167-168
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The displacement and polarization switching properties of piezoelectric laminated actuators have been investigated theoretically, numerically and experimentally. A laminated beam theory solution is developed for the piezoceramic/metal/piezoceramic actuator, and the effects of electric fields on the displacements of the actuators are analyzed. A nonlinear three-dimensional finite element analysis is also employed. Bending tests are used to validate the numerical predictions, using laminated actuators made with PZT piezoelectric layers and Fe-48%Ni host material. Good agreement is obtained between the tests and predictions.
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Kenichi HAMADA, Fumiaki KAWANO, Kenzo ASAOKA
Article type: Article
Pages
169-170
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Shape memory alloy fibers were embedded into a denture base resin to produce a smart composite for "smart denture". The effects of fiber prestrain and heat treatment (HT) for curing were discussed. Although the fiber without prestrain deformed randomly in the matrix during embedding, the fiber with prestrain could keep straight after embedding. Fiber prestrain was, therefore, effective for denture esthetics. Small pores were observed at the end of embedded fibers with prestrain in some specimens. They were formed with fiber shrinkage in the matrix before curing. Such specimens with pores showed small shape change after repair of the composite. In contrast, other specimens of the same HT did not include any pores and showed large change. The HT affected the frequency of the pore formation and, thus, affected the average shape change. Optimization of HT was necessary to minimize the shape change after repair.
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Takaya KATOH, Yuichi KASAI, Hiroshi KACHI, Yosuke WATANABE, Tadashi IN ...
Article type: Article
Pages
171-172
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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We proposed a new method for femur fracture using shape memory alloy. The proposed method is a quite simple operation as follows; Ti-Ni alloy wire memorized to linear shape bent into a U-shape and the ends are inserted into the intramedullary cavity of the fractured portions. In the present paper, a usefulness of this method is discussed by animal experiments using a rat femoral fracture model.
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Juhachi ODA, Jiro Sakamoto, Kenichi Sakano
Article type: Article
Pages
173-174
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A woodpecker strikes its beak toward a tree repeatedly. But, the damage of brain or the brain concussion don't occur by this action. Human cannot strike the head without the damage of a brain strongly. Therefore, Itis predicted that the brain of a woodpecker is protected from the shock by some methods and it turns out that the woodpecker has the original mechanism which absorbs a shock. In this study, the endoskeltal structure, especialy head part structure, of woodpecker is investigated by dissecting in a point of view of impactproof.
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Noritaka YAMAMOTO, Motoya SASAKI, Eiji IKAWA, Yosuke KANKE
Article type: Article
Pages
175-176
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The fascicles obtained from mouse tail tendons were stirred in saline solution, and interfibrous matrices were removed from the fascicles. Other fascicles were immersed in 37℃ collagenase solution for 1 or 2 hours, and collagen molecules in the fascicles were decomposed. These specimens were stretched to failure. Removal of interfibrous matrices decreased the tensile strength of fascicles but did not change the strain at failure. On the other hand, decomposition of collagen molecules decreased the tensile strength and strain at failure.
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Yuan CHEN, Xian CHEN, Toshiaki HISADA
Article type: Article
Pages
177-178
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Hydrated soft tissues such as articular cartilage and intervertebral disc consist of a fluid phase composed of water and movable electrolytes and a solid phase composed of primarily collagen fibrils and negative changed proteoglycans. Understanding the etiology of degenerative disease of the hydrated soft tissues needs to elucidate the coupling mechanisms between mechanical, chemical and electrical phenomena. In this research, a finite element formulation for the hydrated soft tissues with large deformation was carried out based on triphasic theory. Numerical results are presented to demonstrate the mechanical behavior of triphasic structures. The effect of ion concentration on the mechanical behavior is also exemplified.
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Toshia FUJISATO, Hiroshi Nishioka, Takuro KOGOSHI, Yusuke SUGA, Akio K ...
Article type: Article
Pages
179-180
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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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 for 10 min by a newly developed method using ultrahigh pressure of 10,000 atm. They were then washed by PBS under microwave irradiation for 2 days. The vascular cells isolated from the future minipig recipient were injected into the aortic tissue by a dispenser and the endothelial cells were seed onto the surface of the decellularized tissue by a roller culture bioreactor. The cusps and aorta were completely cell free when new method was applied. There were no significant changes in biomechanical properties. The endothelial cells were seeded uniformly and the vascular cells were well injected to the decellularized scaffold. Biological tissues decellularized and recellularized in vitro by our new methods may provide more durable and safe bioprostheses.
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Shintaro KANOKO, Joonwan KIM, Bumhwan LEE, Yutaka YAMAGATA, Hiroyoshi ...
Article type: Article
Pages
181-182
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This paper describes a new method of protein deposition using surface acoustic wave atomizer and electrostatic force, named as SAW-ED. This method mainly consists of two parts, one is to make fine micro droplets from charged solution of protein by using surface acoustic wave atomizer (SAW), and the other is to deposit them with any shape on the substrate by using electrostatic force and insulating mask. As the atomization of SAW uses high resonant frequency, we can generate fine droplets whose diameter is very small compared with regular ultrasonic devices. These micro droplets are dehydrated immediately, and it is possible to generate droplets even in high conductive solutions, so it is possible to decrease the particles that are not activated.
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Mitsugu TODO, Nobuyuki SHINOHARA, Kazuo ARAKAWA
Article type: Article
Pages
183-184
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Fracture toughness, K_<IC>, of poly (L-lactide) (PLLA) samples having different crystalline structures were evaluated at a quasi-static and impact loading-rate. Static K_<IC> tends to decrease as crystallinity increases, whereas dynamic K_<IC> tends to increase with increase of crystallinity. As a result, for amorphous sample, Static K_<IC> is greater than dynamic one; on the other hand, for highly crystallized sample, the relation is reversed. Effect of hydrolysis on K_<IC> was also examined by hydrolyzing the specimens in phosphate-buffered solution. For both amorphous and crystallized samples, K_<IC> decreases as hydrolysis time increase. SEM and optical micrography were performed to characterize fracture micromechanism. The results of micrographies were when correlated with fracture toughness test result.
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Shuichi WAKAYAMA, Toyokatsu Ohshima, Teppei KAWAKAMI, Satoshi KOBAYASH ...
Article type: Article
Pages
185-186
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Microfracture process during bending tests of alumina, which is the typical bioceramics used for artificial joints, was evaluated by AE technique. 4 point bending tests were carried out in air, refined water, physiological saline and simulated body fluid. It was recognized in the AE generation behavior that the AE activity increased remarkably before the final failure. It was understood that the bending stress at those points, σ_c, corresponds to the critical stress for maincrack formation. The static fatigue behavior in physiological saline was also investigated. The time to failure under the stress higher than σ_c was smaller than that lower than σ_c. Consequently, it was demonstrated that the evaluation of σ_c is significant for the assessment of long-term-reliability of bioceramics.
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Katsufumi UCHIYAMA, Kaori NISHI, Yugo NAGAE, Masanobu UJIHIRA, Kiyoshi ...
Article type: Article
Pages
187-188
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The inactivation of bacteria and viruses by heating is currently an effective method for the disinfection of bone allografts. The condition as the relation between temperature and processing time, such as 80℃ for 10 minute is recommended for heat treatment in the Japanese Orthopaedics Association. We already investigated to measure bone thermal characteristic and response to microwave heating. Our experimental results suggest that thermal processing for disinfection using microwave irradiation will heat the bone from inside more and with a more homogeneous temperature. The purpose of this study was to investigate on biomechanical properties of microwave-irradiated bovine cortical bone. The bone which irradiated microwave did not accept a statistical significant difference in compressive strength, maximum strain and Yang's modulus as compared with control. The bone fell 4.1% by the Vickers hardness number. The biomechanical properties of the bone are maintained and it is possible to use it as bone allografts.
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Yoshikatsu TERAMURA, Kunio FUNAMI, Hiroshi MIYATA, Masakazu KOBAYASHI
Article type: Article
Pages
189-190
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This study is to enhance the bonding strength of the hydroxyapatite powder on titanium alloy bulk surface by the sintering due to advance the characteristic as biomaterial of titanium alloy. It is necessary to find out concretely the clue to the solution about following two problems. One is improvement in sintering properties and the strength of hydroxyapatite itself. Improvement in the properties and strength of hydoroxyapatite sintering sample was realized by addition of binders. In especial, sintered sample added in Na_2CO_3 was more effective for fracture toughness. Other one is to obtain the good bonding condition of titanium alloy bulk and hydroxyapatite powder. In order to obtain high bonding strength, the pre-treatment to titanium alloy bulk. As a result, titanium alloy bulk with maceration pre-treatment into 1M-HaOH showed high bonding property. Moreover, the specimen of titanium alloy bulk with the maceration SBF treatment showed a little better bonding property than only NaOH treatment.
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Kazuhiko ENDO, Makoto TAMURA, Hiroki OHNO
Article type: Article
Pages
191-192
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In the present study, liquid phase deposition method was employed to produce a dense crystalline HA film on titanium substrate in metastable calcium phosphate solution. A 100x10x0.02(mm)^3 titanium foil was employed as a substrate. Prior to HA coating, the substrate was immersed in 5M NaOH solution at 60℃ for 24h. The temperature of the substrate was kept constant at 50,60,and 70℃ by electrically heated with DC power source in metastable calcium phosphate solution. The X-ray diffractogram indicated that the film deposited on the titanium substrate was composed of HA. The amount of HA deposited during 3h-treatment increased with an increase in the substrate temperature from 50 to 70℃. These results suggests that the dense HA film can be formed by a simple chemical and thermal treatments. This technique is useful especially to produce uniform HA coatings onto complex-shaped and porous dental implants.
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Kazuhiro FUJISAKI, Shigeru TADANO, Junichi SHIBANO, Naoki SASAKI
Article type: Article
Pages
193-194
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Bone tissue is a composite material composed of hydroxyapatite (HAp) and collagen. Because HAp particles in bone tissue are crystalline structure, an X-ray diffraction method is available to measure the strain of HAp. This work shows, the relationship between lattice strain of HAp crystals and macroscopic strain. In this experiment, strip specimens of 45×6×0.8mm in size with their long axis aligned to the bone axial 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 tensile device was developed to apply tensile load to the specimen during the X-ray irradiation. Macroscopic strain was measured by a strain-gauge glued on the surface of the specimen. Lattice strain of HAp in the specimen was measured by the X-ray diffraction method. It was found that the lattice strain was generally smaller than the strain macroscopically determined.
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