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Hajime KATOU, Ryou MIYAKE
Article type: Article
Pages
95-96
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In this paper, a new mixing method for micro-liquid is proposed. It is well known that the free surface of a liquid is agitated when ultrasound propagating in the liquid reaches that surface. This is due to the radiation pressure of ultrasound. By using this pressure, liquid in a vessel can be mixed without direct contact with the liquid. The mixing system consists of a vessel (3.8×5.6×20mm) that contains the liquid to be mixed and ultrasound sources (1.6MHz, 20Hz On-OFF modulation) that are arranged outside the vessel. The mixing flow was measured by using the Schlieren visualization method. Our results demonstrated that 250μL liquid can be mixed within 1.8 sec when our mixing system is used.
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Yuji ONIMURA, Katsuko FURUKAWA, Takashi USHIDA, Tetsuya TATEISHI, Taka ...
Article type: Article
Pages
97-98
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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When we develop artificial organs, which contact with blood, hemocompatibility of materials should be considered. However, assessing hemocompatibility of materials is difficult, because platelet adhesion, an indicator of hemocompatibility, occurs through lots of factors. Especially, although the effect of shear stress is thought to be most important factor, reports thus far have ignored it. Therefore we developed a system to evaluate test materials by using human blood, under shear flow conditions. Our system could visualize human platelets flowing, rolling, and adhering to opaque materials in real time under shear stress. The number of platelets adhering to "HUVEC on glass" is less than any other materials under a shear stress of 0.05Pa.
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Katsuko FURUKAWA, Takashi USHIDA, Akiko NUMATA, Hideyuki SUENAGA, Tets ...
Article type: Article
Pages
99-100
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Chondrocytes in articular cartilage synthesize collagen type II and large sulfated proteoglycans, whereas the same cells cultured in monolayer (2D) dedifferentiate into fibroblastic cells and express collagen type I and small proteoglycans. On the other hand, a pellet culture system was developed as a method for preventing the phenotypic modulation of chondrocyte, and promoting the redifferentiation of dedifferentiated one. Because the pellet culture system forms only one cell-aggregate each tube by a centrifugator, the aggregate could not be applied to produce a tissue engineered cartilage. Threrefore, we tried to form chondrocytes-aggregates by a rotational culrure, expecting to form large amounts of aggregates at once.
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Michitaka HIGAKI, Hiroshi MIYAZAKI, Kozaburo HAYASHI
Article type: Article
Pages
101-102
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Local stiffness of living endothelial cells in the abdominal aorta and in the medial and lateral wall of aortic bifurcations obtained from rabbits fed 1% cholesterol diet were determined by means of an atomic force microscope (AFM). The stiffness of endothelial cells located apart from atherosclerotic plaques was comparable to control level in normal diet-fed rabbits, at the three locations; it was higher in the medial wall than in the other regions. The stiffness of endothelial cells in the medial wall was lower on atherosclerotic plaques than in the locations away from plaques, although it was not different between the two locations both in the abdominal aorta and the lateral wall. These results are attributable to the disorganization of stress fibers in endothelial cells in the medial wall induced by the development of atherosclerosis.
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Akihide KAWAMURA, Hiroshi MIYAZAKI, Kozaburo HAYASHI
Article type: Article
Pages
103-104
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Local stiffness of vascular smooth muscle cells (VSMCs) isolated from rabbit thoracic aortas using a enzymatic digestion method and then cultured for 3,7,and 14 days were determined by means of atomic force microscopy. The stiffness obtained at the highest points of VSMCs had a tendency of decreasing with culture period. In the cells cultured for 3 days, the stiffness was highest and relatively uniform around highest points over cell nuclei. However, the stiffness over cell nuclei was remarkably variable in the cells cultured for 7 days; it was much larger over fibrous structures than between fibers. The cells cultured for 14 days had relatively low and uniform by distributed stiffness. These results suggest that the local stiffness of VSMCs is greatly affected by dynamic changes in the internal structure of cells which are developed by phenotypic modulation.
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Tomaki KUBO, Yoshiyuki MIWA, Keisuke HATTA, Hideaki MATSUOKA
Article type: Article
Pages
105-106
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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It is necessary for the elucidation of life phenomenon to solve work of cell. Therefore, the elucidation of the reaction mechanism of the chemistry and enzyme reaction analyze in the part level of a cell, or gene discovery attracts attention. The experiment which introduces a substance into the small organ of a cell is conducted. However, in order to perform substance introduction to a detailed domain like cell protoplasm, the high degree of skill is needed. Furthermore, under a microscope, since the position information on the organ in a cell is not acquired, working efficiency is very low. Then, we developed the system which detects the position of the organ in a cell with intracellular potential and introduces a substance to protoplasm and a vacuole to a tobacco cell automatically.
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Tadashi KOSAWADA, Masashi ENDO, Tomonori ICHIKAWA
Article type: Article
Pages
107-108
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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A novel method for detection of dynamic characteristics of two dimensional minute soft tissue is presented. In this method, using forced vibration of small cantilever beam excited by piezo electric ceramic, elastic properties of tissues are measured directly in wide stable frequency range. A two dimensional minute soft tissue is suspended from a free end of cantilever beam. Displacement of the beam vibrator and load response of the tissue is precisely measured. Mainly elastic properties of the cow's thoracic aortas tissue were measured, and the feasibility of the method was confirmed.
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Tadashi KOSAWADA, Shingo YAMAMURA, Kenichi KONNO, Toshikatsu KANAZAWA
Article type: Article
Pages
109-110
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In this study, a method of sensing is specifically developed to detect dynamic characteristics in three dimensional minute living bodies. Experimental studies have been carried out by using the killifish's egg cell and rabbit's articular cartilage. Micro wire plastic needle was bonded on the tip of the sensor viblator so as to detect dynamic characteristics of the cells and tissues. The sensor was controlled by micromanipulator system, while dimensions and morphologies of the cells were measured by inverted phase-contract microscope system connected to a CCD video camera.
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Maki IHARA, Teruo MURAKAMI, Yoshinori SAWAE
Article type: Article
Pages
111-112
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Articular cartilage has viscoelasticity based on high water content up to 80% and the flow behavior of water concerns the deformation of articular cartilage under compression. In addition, its depth-dependent complicated structure causes complex stress-strain field. It is important to elucidate biomechanical environment of chondrocytes because they play an important role in the mechanism of deformation and degeneration of articular cartilage. The purpose of this study is to investigate the structural response of time-dependent strain behavior under unconfined, axial and static compression using confocal laser scanning microscopy, and the observation can be made using the stained chondrocyte. We could observe the time-dependent interior strain change of compressed articular cartilage.
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Yusuke MORITA, Naohide TOMITA, Hideyuki AOKI, Shigeyuki WAKITANI, Yasu ...
Article type: Article
Pages
113-114
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Change in mechanical properties of regenerated cartilage tissue were measured during cultivation. Dynamic visco-elastic measurement and friction test were carried out for rabbit articular cartilage inoculated in fibroin sponge. The dynamic visco-elastic measurement was performed under compressive loading condition. The E' values increase with cultivation days and the peak value and frequency of tan δ shift to a lower amount. Friction coefficinet decreased with cultivation days. It is suggested that changes in mechanical properties of the regenerated cartilage are caused by synthesis of extracellular matrix and maturation of cultured cartilage tissue.
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Hiroyuki FUJIKI, Michiaki KOBAYASHI, Seiichi OMORI, Yukio NAKATUCHI
Article type: Article
Pages
115-116
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Microcracks in bone are assumed to increase the risk of bone fractures and to stimulate bone remodeling. In order to clarify the process of the insidious micro bone fractures, it may be important to know the biomechanical changes of bone properties surrounding the microdamages. In this paper, a crack whose opening is filled with other tissue was detected in the femur sample of young beagle dog. To distinct the kind of tissue, the comparison of material properties with some tissues and materials in the sample was performed attempted using the scanning acoustic microscope (SAM). As a result, the tissue between the maicrocrack was seemed to be callus. This means that the restoration process of microcracks proceeds in same as the process in general bone fracture with the appearance of callus.
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Osamu MARUYAMA, Takashi YAMANE, Masahiro NISHIDA, Tomio ONOGUCHI, Tats ...
Article type: Article
Pages
117-118
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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We are developing microcapsule suspensions, as model blood for absolute hemolysis evaluation. The microcapsule suspensions showed similar fractural properties to that of bovine red blood cells, under shear flow by rotational shear stressor developed in AIST. Hemolytic properties of four commercial centrifugal blood pumps, BP-80,Sarns, HPM-15 and CAPIOX, were tested using microcapsule suspensions in the mock circulation under 500 mmHg, and results were represented in NIH. The NIH tendencies of BP-80 and Sarns showed similar results between microcapsule suspensions and bovine blood. NIHs of HPM-15 and CAPIOX could not detected due to too low hemolysis levels, and the corresponding NIHs by bovine blood were smaller than those of BP-80 and Sarns. Though it is necessary to improve the capsule membrane stiffness, the microcapsule suspensions can be expected as model blood for a new hemolysis test solution.
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Toshikazu ISHIHARA, Yuko Nakahira, Isao Watanabe, Chiharu Kato
Article type: Article
Pages
119-120
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Impact biomechanics of the pig liver and the spleen were measured in "free-fall" direct impact test. Test pieces of the liver and the spleen were obtained from edible pigs in order to examine the injury criteria and tolerances. Impact speed, relative compression and maximum impact force are reviewed as explanatory variables for injury severity. Relative compression of organ shows high correlation coefficient in all cases of the liver and the spleen test. The tolerances of the organ with artificial blood perfusion in the physiological blood pressure are little smaller than that of without perfusion.
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Toshiro OHASHI, Syukei SUGITA, Takeo MATSUMOTO, Kiichiro KUMAGAI, Hiro ...
Article type: Article
Pages
121-122
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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A newly designed experimental setup was fabricated to measure rupture properties of aortic aneurysms. Square specimen obtained from human thoracic aortic aneurysms was inflated by air pressure at a rate of 10 mmHg/s until rupture occurs. Deformation process was observed through two CCD cameras and a high-speed camera. Mean breaking stress and strain were estimated from the specimen geometry considering incompressibility, resulting in 0.97±0.39Mpa (mean±SD) and 0.64±0.10,respectively. Moreover, significant difference was found between mean breaking stress and area fraction of collagen fibers. It should provide clinically useful information to know mechanical properties of human aortic aneurysms in assessing potential for aneurysm rupture.
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Osamu OSHIRO, Mikio SUGA, Kotaro MINATO, Kunihiro CHIHARA
Article type: Article
Pages
123-124
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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This paper describes the method to estimate the shear modulus and the viscosity of an elastic material with MRE (magnetic resonance elastography), which is one of MRI (magnetic resonance imaging) sequences and enables to measure elastic information of a biomedical organ in vivo with giving vibration to a measurement object. The shear modulus could be calculated from the phase change of the observed MRE signal and the viscosity from the amplitude attenuation. Here, we estimated elastic values of phantoms with PVA (polyvinyl alcohol) and agarose gel. Simultaneously, the elastic values were measured invasively using the dynamic test that is the typical measurement method for elastic information. The elastic values obtained from both methods show the good correlation, which indicates that MRE has the useful methodology to obtain the elastic information non-invasively.
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Yutaka SAWAKI, Hidenori HIGASHI, Masataka TOKUDA, Tadashi INABA, Kiyos ...
Article type: Article
Pages
125-126
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The regional work per unit volume is evaluated based on the stress and strain distribution in a cardiac wall calculated by using 3-dimensional finite element method. The total work of left ventricular wall is compared with the external work evaluated from the pressure-volume relationships of left ventricle. It is recognized as a result that the efficiency of the left ventricle is around 20%. In conclusion we examine a possibility of using the regional work of myocardial muscle fiber as an universal index of cardiac function.
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Tatsushi TOKUYASU, Kenichi ASAMI, Tadashi KITAMURA, Genichi SAKAGUCHI, ...
Article type: Article
Pages
127-128
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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For the cardiac plastic surgery, cardiac muscle palpation is certainly needed to determine the surgical plan. The opportunity to palpate the cardiac muscle is limited in the operative scene, so that the cardiac surgeons desire the training systems for cardiac muscle palpation. For building the cardiac muscle palpation training system, the virtual heart model which enables to give its mechanical elasticities to the trainees in real-time is necessary. The virtual heart is composed of cine CT imaging data for human beating heart, a simple systemic circulation system, and a set of the low dimension dynamic model for real-time processing. In order to identity the mechanical parameters of cardiac muscle, we measured the cardiac characteristics from animals' heart. The large deformation model will make our virtual heart more practical. The proposed virtual heart took a good evaluation from the cardiac surgeons.
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Takuji KOIKE, Hiroshi WADA, Yu YUASA, Ryou YUASA, Tetsuaki KAWASE, Tos ...
Article type: Article
Pages
129-130
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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It is important to evaluate stapes mobility in tympanoplasty surgery, because it affects the prognosis of improvement of the hearing level. In this study, a new hand-guided apparatus was developed by assembling a small-sized force sensor and a hydraulic micromanipulator. Then, the mobility of stapes in humans was measured. In addition, the nobilities of incus and malleus in guinea pigs are also measured under the condition that the stapes was artificially fixed with glue being applied to the annular ligament to simulate otosclerosis. The load-displacement curve obtained from the normal stapes was different from that obtained from the fixed stapes. This result suggests that a surgeon can quantitatively analyze stapes mobility with this apparatus during surgery.
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Kenichi SUZUKI, Takeo MATSUMOTO, Masaaki SATO
Article type: Article
Pages
131-132
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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We have been developing a system for the measurement of human skin elasticity by applying a pipette aspiration method. In this study, we have integrated the system to develop a portable device. We reduced the number and the volume of the parts by utilizing a compact laser displacement meter, an electronic vacuum regulator, and a pressure transducer with an amplifier, and successfully packed the whole system except a computer in a box of W250×H150×D210mm. By using this device with a notebook PC, we measured the elastic modulus of human skin to find that it reduced with corny layer removal. It can be said that the device is not only portable but also sensitive enough for the measurement of subtle changes in the corny layer.
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Takehito KEMURIYAMA, Hiroyuki KOYAMA, Takashi KOMEDA, Shinichiroh YAMA ...
Article type: Article
Pages
133-134
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Recently, dermatosis represented for atopic dermatitis has increased, it has required that characteristic of the skin are quantitatively evaluated. The purpose of this study was quantitatively evaluated the dynamic characteristic of the skin, and to measure the indentation load and the frequency shifts that required from the difference between material acoustic impedance, and to compare the dynamic characteristic of the healthy skin and the atopic skin. As a results, the indentation load was different in the every individual, and it showed the difference the frequency shifts in the healthy male skin and the healthy female skin and the atopic skin. In comparison with the water contents of horny layer measuring the capacitance, the frequency shifts became decreased when the water contents was increased.
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Hiroshi Matsumura, Youichi Matsuhisa, Youichi Tsuboi, Ikuya Miyamoto
Article type: Article
Pages
135-136
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Distraction osteogenesis (D. O) is one of the promising bone lengthening technique. After osteotomy, the callus will change from soft bone to hard bone with healing time. Usually operated bone situation is diagnosed by X-ray photograph. However, it is difficult to know the detail condition of distracted bone only by X-ray procedure. In this study, a new method to detect bone situation with measuring vibration was developed. Theoretical analysis of the bending vibration of distracted bone and animal experiment in the rabbit tibia were carried out. The natural frequencies of tibia's bending vibration were measured for four weeks by accelerometer. The results indicate that the natural frequency can be good index of the healing in distracted bone.
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Takashi IRIE, Hisao Oka
Article type: Article
Pages
137-138
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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This paper examines the relationship between muscle fatigue and its biomechanical characteristics by using biomechanical impedance. Visco-elasticity was calculated from biomechanical impedance. In our experiment, isometric contraction was applied to a subject's forearm with 10 and 15% of maximum voluntary contraction (MVC) for a certain constant period until one got fatigued. The change of visco-elasticity in unloaded and under contraction was observed, and the change under contraction was not mo notonous at most of the subjects. The magnitude of load affected advancing speed of fatigue but did not the tendency of visco-elasticity.
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Noritaka YAMAMOTO, Masahiro NEGISHI
Article type: Article
Pages
139-140
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Nine subjects taking various exercises were evaluated. The anterior drawer test of tibia was performed and from the result the stiffness of anterior cruciate ligament (ACL) was estimated. Quadriceps and hamstrings strengths were estimated from the maximum weight lifted by knee extension and flexion. There was no significant correlation between the anterior displacement and muscle strength. These results indicate that exercises increase the muscle strength but do not increase the stiffness of ACL.
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Yoichi NAKAMOTO, Osamu KUWAZURU, Nobuhiro YOSHIKAWA
Article type: Article
Pages
141-142
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The in vitro mechanical test has been adopted to measure the mechanical property of organic tissue. A legitimate question arises about how plausible the result of in vitro test is for the material model of the in vivo tissue which is indispensable to finite element analysis of human body. So that, in vivo and non-invasive test is necessary, and we investigate a new measurement methodology of the three dimensional displacement field by means of the material test system combined with X-ray computed tomography to identify mechanical state of the in vivo tissue. Two voxel images of the initial and deformed states are obtained by the material test system. Representing displacement field by a mapping function from the initial voxel image to the deformed one, we pose an identification problem of the unknown variables in the mapping function. Use is made of the Genetic Algorithm to solve the problem. The proposed methodology is demonstrated through an example using chicken.
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Daisuke MORI, Takami Yamaguchi
Article type: Article
Pages
143-144
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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We devised a method that combines the differential geometrical technique and overset grid formation to construct an aortic arch model for computational fluid dynamics (CFD) simulations. The simulations incorporate both non-planarity and the major branches at the top of the arch, using a set of magnetic resonance (MR) images, and we discuss their combined effects on blood flow. The results show that flow along the arch consists of a large right-handed rotational flow in the descending part of the arch, and a large left-handed rotational flow at the end of the arch. Although these characteristics of the global flow were similar to the results obtained using our previous arch model without branches, backwards flow was found near the inner wall at the top of the arch due to the flow into the branches.
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Yukio TADA, Mie TOGAWA, Yoshinobu SATO, Takashi NISHII, Toshihiko SASA ...
Article type: Article
Pages
145-146
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The project "in silico Human" is one for constructing a model of "each patient" in a virtual space (in silico). "in silico" hip joint is one part of this project and has already been adopted clinically as "Computer Navigation System for Surgery" for supporting geometrically the surgical operation in the orthopedics. In this paper, we aim to introduce the function for mechanical analysis in this system so that we may have more detailed plan to THA (Total Hip Arthroplasty) from the viewpoint of biomechanics and can expect situations after the operation for the long term. In order to create a finite-element-model for each patient, we develop a system that constructs voxel finite element models from CT-images by combining with the Navigation System. By the use of the present system, we can implant prostheses in femur at arbitrary position and angle automatically. We examined and compared the computational time for analysis and the analysis results by the difference of voxel sizes. Moreover, we examined the stress distribution by the difference of the prostheses' angle implanted.
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Daisuke TAWARA, Jiro SAKAMOTO, Juhachi ODA
Article type: Article
Pages
147-148
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Mechanical property of bone is inhomogeneous especially between cortical and cancellous bone, and it also varies individual. So mechanical analysis considering inhomogeneous property of bone is necessary for patients oriented evaluation of bone in clinic. If the finite element method is used, mechanical analysis considering the bone inhomogenity is possible by giving a material property to an element one by one. So that, extreme fine meshing of finite elements is required. In this study, we improved the "ADVENTURE system", which had developed as a large-scale finite element analysis system, to be applicable to stress analysis of inhomogeneous bone problems. We applied the improved program to a composite beam model with graded material property and ensured its validity by comparing between the theoretical and calculated results. Furthermore, it was applied to stress analysis of proximal femur based on CT images and its efficiency was discussed.
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Norio INOU, Michihiko KOSEKI, Yusuke KITAGAWA, Koutarou MAKI
Article type: Article
Pages
149-150
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Reliable stress analysis of a bone requires not only precision in shape of the finite element model but also proper setting of material constants for the model. This study proposes two methods to recognize proper shape and to evaluate mechanical properties from X-ray CT images. The former method corrects CT values considering influence of partial volume effect. The latter interpolates outlines of an object in muti-sliced CT images. This paper shows that these methods perform a proper correction and a clear interpolation using CT images of an acrylic cylindrical specimen.
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Rina SAKAI, Kimiaki AMAO, Moritoshi ITOMAN, Kiyoshi MABUCHI
Article type: Article
Pages
151-152
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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A commonly-accepted concept about the fixation method for joint prostheses is that a wide contact area between bone and artificial materials results in lower pressure that is better for biological tissues. Another concept is that the load should be applied to the proximal femur together with the distal femur because proximal and distal fitting can avoid stress shielding of bone. However, these two concepts appear to contradict each other because the exact contact point cannot be determined in an apparent and wide contact area. We postulated that limited fixation with a narrow contact area could be better for the initial fixation of a stem.
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Yukiko KURODA, Masahiro TODOH, Eiji TANAKA, Masao TANAKA
Article type: Article
Pages
153-154
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Temporomandibular joint (TMJ) disorder relates to the mechanical irregularity of the structual joint components, and disc behevior is considered as a key to understand the biomechanical condition in the TMJ. Permanent anterior disc displacement and derangement are typical finding in TMJ disorder. The mouth opening motion naturally induces the anterior disc displacement tentatively even in normal TMJ, and the condyle motion is considered as the key to understand the disc displacement and stress. This study examined the influence of condyle trajectory on the disc displacement and stress of irregular TMJs with anterior disc displacement (ADD) in the context of finite element analysis with individual modeling.
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Akinori IWABU, Toshiro MATSUMOTO, Nobuhiro KATO, Hiroshi UOZATO
Article type: Article
Pages
155-156
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Glasses and contact lenses are popular solutions for many individuals with refractive disorders. Although many techniques have been proposed and tested by the laser eye surgery, photorefractive keratectomy (PRK), and laser in situ keratomileusis (LASIK) are the most widely practiced by using excimer laser. A difficult problem for all refractive surgical procedures is to predict the final refraction because the intraocular pressure (IOP) applies inside the eyes. In this paper, mechanical analysis of cornea was carried out by using finite element method (FEM) and the optical performance of these models was calculated by ray tracng.
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Hiroaki KATORI
Article type: Article
Pages
157-158
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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A higher-order shear deformation theory is used to analyse plates for natural frequencies. The theory accounts for parabolic distribution of the transverse shear stresses. A displacement finite element of model the theory is developed.
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Hitoshi IMAMURA, Kohei SUZUKI
Article type: Article
Pages
159-160
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In this paper, we propose the exact derivation method of all stationary solutions for an zero stiffness impact oscillator system, and clarified its mathematical structure. First, deriving process and functional structure of stationary solution for linear system are reconsidered, and extend to stationary solution for zero stiffness impact oscillator. Second, we gave a rigorous proof that the global representation of stationary solution which had been derived formerly by authors intuitive manner is actualy stationary solution. The derived representations are natural extension of stationary solution for linear system for nonlineary system globaly. Besides, this representation perfectly prescribes all mathematical forms of the stationary solution include chaotic case.
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Hiroyuki KUMANO, Yutaka TATSUMI, Shinichi HARA, Katsuhiro TEMMA
Article type: Article
Pages
161-162
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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This paper deals with the analysis of collision vibration in continuous system excited by periodic force with arbitrary function. The analytical model is steady collision vibration of cantilever which collides at arbitrary position from fixed end to free end in cantilever. Then, the cantilever excited by forced displacement vibration collides elastically to symmetrical face. In order to analyze the response of main resonance, the Fourier series method is applied to the system, and an exact solution is proposed. Following these theoretical analyses, the numerical calculation is performed and the resonance curves are made from resulting vibration. Effects of stiffness of clamped spring and amplitude of excitation on resonance curve are shown by numerical results. For verification of the analytical method, experiments are performed. Analytical results are in a fairly good agreement with experimental ones.
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Shigehiko Kaneko, Tatsuo Watanabe, Shigeyoshi Maeda, Etsunori Fujita, ...
Article type: Article
Pages
163-164
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In order to reduce the noise level emitted from home use automatic washing machines with vertical axis of rotation, it is important to identify the mechanism how vibrations are converted into noise. We assumed that the vibration of the drum suspended by four suspension dampers is one of the exciting sources to the outer panel of the washing machine. In this paper, first experimental results of damping characteristics of single suspension damper is introduced and then results of measurement of drum vibration together with noise level of an automatic washing machine are summarized. In addition, modeling procedure for analyzing the vibration of a drum is introduced and resonant characteristics are calculated.
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Tomohiko Harada, Shigehiko Kaneko, Hiroki Honda, Tatsuo Watanabe, Etsu ...
Article type: Article
Pages
165-166
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Present suspension damper for washing machine mainly generates damping forces by coulomb friction. Therefore, the performance of damper lowers by the aging degradation. We propose noncontact damping mechanism using permanent magnet. In this paper, we call newly developed damper which consists of coil spring, magnetic spring and magnetic damper "Composite Damper". In order to realize high-performance damper, we examined the relationship between displacement and damping coefficient of dampers by excitation tests. Then, we expanded the simulation method in the previous report to the case where Composite Damper is installed. Finally, we succeeded in constructing the calculation method for describing the behavior of the drum only from the result of the excitation test.
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Yasuhisa OKANO, Kenichiro OHMATA, Taichi MATSUOKA
Article type: Article
Pages
167-168
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In this paper, a new type of arm-type damper with two links, two joints and a rotary damper has been developed. The damper is able to suppress six modes of vibration of a machine. The trial damper was made and the resisting force characteristics in the three translational directions were discussed theoretically and experimentally. The seismic responses of a three-degree-of-freedom system consisting of a mass and four coil springs and supported by the damper were measured using a two-dimensional electrohydraulic type shaking table. The experimental results are compared with the calculated ones, and the effects of vibration suppression of the damper are discussed.
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Taisuke Nosaka, Katsuhisa Fujita
Article type: Article
Pages
169-170
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The purpose of the study is the stability analysis of dynamic buckling behavior of mechanical systems subjected to multi-directional excitation wave. Elastic beams are used for the analysis. The analysis is carried out by numerical simulation, where the vertical and the rotational loads are applied simultaneously. The combination of two loads are changed and the effects to the dynamical stability is investigated.
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Yoshiaki ITOH, Yusuke IMAI, Akihiko MURATA, Masatsugu YOSHIZAWA
Article type: Article
Pages
171-172
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The outbreak mechanism of self-excited oscillation of the wire electrode due to corona discharge has not been necessarily given yet. In this paper, the string oscillation placed in the corona discharge field is examined to give some useful information on the outbreak mechanism of the wire oscillation. Some experiments axe made to observe the string oscillation. As a result, the string oscillation is self-excited with the fundamental natural frequency of the string oscillation in the beneath and vicinity of the wire electrode, even though there is no self-excited wire oscillation. It is confirmed that the outbreak mechanism of the string oscillation is excited through the effect of the fluid force, and close relation to that of the wire oscillation.
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Junichi HINO, Masayuki SAKAGUCHI, Toshio YOSHIMURA
Article type: Article
Pages
173-174
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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This paper is concerned with study for chatter prediction in high-speed end milling operations. Chatter vibration occurring in mechanical machining gives rise to poor surface finish and dimensional accuracy in machined part, reduction of tool life, and even damages machine tools. It is various kinds of researchers concerning its prediction and avoidance have been carried out over the last several decades. The purpose of this study is to develop an expert system for predicting chatter vibrations in high-speed end milling using wavelet transform and a fuzzy neural network model with pruning process. The proposed method is applied to a jig griding machine, and the results demonstrate the effectiveness of the chatter prediction procedure.
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Takaaki MAEHARA, Mitsuru KAMIYABU, Mikio NAKAI
Article type: Article
Pages
175-176
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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This paper describes chaos and hyperchaos occurring in two degrees of freedom system using numerical simulations. Hyperchaos occurs only in more than two degrees of freedom systems. And these motions are more complicated than chaos. Poincare maps, Lyapunov spectra and KS Entropy provide the differences between chaos and hyperchaos. It is shown that potential function of the system affects the occurrence of hyperchaos and chaos.
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Zhi xiang XU, Kunisato SETO, Hideyuki TAMURA
Article type: Article
Pages
177-178
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In this paper, we introduce a numerical calculation technique, named as model-based OGY chaos control method by the authors, to get a target unstable orbit on which the controlled system will settle down and the approximately linearized subsystem around it of a continuous chaotic system for applying the OGY chaos control method. This numerical technique will give you a strong tool to use OGY method to solve chaos control problems in engineering that can be modeled as continuous dynamic systems.
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Masahiko ITOH
Article type: Article
Pages
179-180
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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This paper deals with a control technique of eliminating the transient vibration of a geared mechanical system. This technique is based on a model-based control in order to establish the damping effect. The control model is composed of reduced-order electrical and mechanical parts. This model estimates a load speed converted to the motor shaft. The difference between the estimated load speed and the motor speed is calculated dynamically and is added to the velocity command to suppress the transient vibration of the load. This control technique is applied to a twin-drive geared system. The performance of this control technique is investigated by simulations. The effectiveness is confirmed even if the parameter error of torque constant and the modeling error of the 1st natural frequency exist.
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Tsunehiro MUNAKATA, Kamil SULAYMAN
Article type: Article
Pages
181-182
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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In this paper, the results of a fuzzy control with personal computer control program in the handstand pendulum typed by the movement on an arc by its arm is reported. Used by the handstand pendulum modeling equipment (i.e. the small scaled handstand pendulum mechanics controlled by the swing-up pendulum in the program control of Windows version), the authors make the pendulum pointed below swing gradually, and receive the pendulum in the state of swing-up and keep a balance of the pendulum at about central upper position lest it should fall down. In this control process, the fuzzy control method by the personal computer is used : it is tried that a linear fuzzy reasoning method based on the algebraic multiplier-addition gravity method which is evolved the MIN・MAX gravity method is adopted so the numbers of input and fuzzy rules may be the least. The kinds of the membership function are used the types of triangle, trapezoid and singleton, etc., moderately. In consequence, taking care of the following three mentions in the arm of the handstand pendulum : (l) the motion of pendulum swing-up, (2) the motion of the pendulum received, and (3) the motion of the pendulum's keeping the balance condition of a handstand, the fuzzy control is realized by a three inputs and single output and its fuzzy rules shown in this paper. Photos etc. which are visual results will be given within the volume of this script.
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Masahiko ITOH, Hiroto KITAURA
Article type: Article
Pages
183-184
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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This paper deals with a control technique of eliminating the transient vibration of an waist axis of an articulated robot. This technique is based on a model-based control in order to establish the damping effect. The control model is composed of reduced-order electrical and mechanical parts. This model estimates a load speed converted to the motor shaft. The difference between the estimated load speed and the motor speed is calculated dynamically and is added to the velocity command to suppress the transient vibration of the end-effector. The performance of this control technique is investigated by simulations. The effectiveness is confirmed even if the modeling error of the 1st natural frequency exists.
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Yoshihiro TAKITA, Shigenobu ARAI
Article type: Article
Pages
185-186
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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Previous paper shows the realization of single salto backward using a self-standing type horizontal bar exercise robot. Developed robot has three links which are connected with two rotational joints and driven by two DC motors. It is assumed that each actuator is controled by PD control method. As a result, the control system is modeled by a rotational damper and a torsion spring of which the setting angle is able to change during the motion. In order to find the target values of the control system, an animation program is developed by using the integration of derived equations of motion. Finally, a self-standing robot was realized a salto backward after the dismount by simulated target values. This paper shows the realization of double salto backward which is more difficult and challenging than a single one. At the first simulation, the double salto backward needs at least 7.3rad/s over the horizontal bar. This anguler velocity is able to get by two times of forward giant swing. An experimental result demonstrates double salto backward which is conformable with the simulated result.
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Toru TSUMUGIWA, Ryuichi YOKOGAWA, Kei HARA
Article type: Article
Pages
187-188
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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This paper presents a novel variable impedance control for a human-robot cooperative task. There is a problem that a cooperative positioning task could not be performed easy and precisely using a conventional position based impedance control. A proposed control has a virtual stiffness term in order to make the cooperative positioning task easy and precise. A proposed impedance controller generates virtual force in the positioning task using the virtual stiffness term. The virtual force helps a human operator to perform the positioning task precisely. In order to confirm the usefulness of the proposed control, a cooperative peg-in-hole task was performed. Experimental results illustrate that the proposed control is effective for the human-robot cooperative task.
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Yoshiyuki ISHIKAWA, Kimihiro SUZUKI, Junichi KURATA, Hironobu UCHIYAMA ...
Article type: Article
Pages
189-190
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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The haptic interface, which has the function to present the force sense, has been proposed in order to let an operator to know the unknowable information. This kind of interface would be efficient as a controller for person of advanced age, because their five senses tend to be weak than younger people. Some information obtained by the sensor fusion are presented to the operator through the control rod as the force making up for the unknowable information. The amount of force should be concerned not to occur the contradiction for the operators, in order to give them the good fitness. In this report, some psychological experiments were described to adjust the amount of force to be present.
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Toshihiko YASUDA, Shougo KUWABARA, Takeshi NAKANISHI, Hajime KITAGAWA, ...
Article type: Article
Pages
191-192
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
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In order to improve a power assist mechanism for one hand use wheelchair developed in our research group, a wheelchair with some sensors has been constructed. By using this wheelchair, torques given by human through handrims and the velocity of wheelchair have been observed on flat course and on slope. Observed data shows that human's body weight shift in wheelchair running is related to the movement of wheelchair. We consider that attention to this fact is useful for investigating effective power assist scheme.
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Shinichi MATSUDA, Manabu ONO, Shigeo KATO
Article type: Article
Pages
193-194
Published: September 20, 2002
Released on J-STAGE: August 01, 2017
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This paper describes a basic study of gas-liquid phase-change actuator for high-force characteristics. A fablicated actuator was structured by stainless steel bellows, which were contained C_5F_<ll>N0 as operating liquid. For the high pressure and high axial force, the bellows was made from many coned disc springs, which were welded each other for an inner edge and an outer edge by YAG laser. The actuator has a lO Ω heater, a V-shield and a thermistor for measuring operating liquid. We confirmed two kinds of results, which were a force of l00N at 1mm displacement and 20N at 7mm under pulse controlling on 353K with 12W. We also confirmed a quickly arising motion by the V-shield.
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