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石渡 宏平, 若山 修一
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発行日: 2008/08/02
公開日: 2017/08/01
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Fracture toughness tests of notched bending specimens of alumina ceramics were carried out in air and water. During the test, stable crack propagation was observed, and AE signals emitted from microcracking were detected by piezoelectric transducers. Then AE source function which describes the nature of microcrack nucleation was also determined by inverse calculation using detected signal. Sizes and nucleation velocities of individual microcracks could be determined from the source functions. For tests in air, radius was 7.1-42.6μm, while it was 8.1-43.5μm in water. Cumulative AE event was less in water than in air. Fracture resistance was also lower in water than in air. In addition, The size of coalescing cracks observed on fracture surface by SEM was in good agreement with the result of AE source characterization.
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若林 千智, 松尾 陽太郎, 安田 公一, 塩田 忠
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発行日: 2008/08/02
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In this report, gamma distribution is used for flaw size distribution, and their parameters are estimated by the most likelihood method by using the flaw size data reported by Nakamura et.al. Taking the logarithms of its probability density function, a term in proportion to the flaw size is several orders of magnitude larger than the other terms. Therefore, linearization of flaw size distribution can be made by neglecting the other terms. To compare the experimental data, the gamma distribution parameters are used for the linearization, so this parameter expresses the character of flaw size distribution well. To consider about the relation between the fracture strength and flaw size distribution, the fracture strength and the shape parameter of gamma distribution are discussed.
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董 古, 大滝 英征, 琴坂 信哉, 長坂 保美
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In this research, effective use of the waste of paper was examined. Composite material made with waste paper, raw material of brake pad, and Porietirenteretarart (PET bottle) was developed. And, this product was applied as an adsorption material of the waste gas and the waste fluid. In this report, adsorption characteristic was described.
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北條 恵司, 安藤 柱, 高橋 宏治
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発行日: 2008/08/02
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ZrO_2/SiC composite ceramics were sintered and subjected to three-point bending. A semi-circular surface crack of 100μm in diameter was made on each specimen. We studied crack-healing behavior. The main conclusions are as follows. (1) ZrO_2/SiC composite ceramics could heal a crack. Then the best healing condition is at 800℃×30 h in air. (2) A crack was healed even at 700℃ that was very low temperature compared with other ceramics. (3) The ZrO_2/Y_2O_3/SiC system ceramics caused an extensive oxidation.
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名越 康人, 上野 祐太, 高橋 宏治, 安藤 柱, 斎藤 慎二
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Effects of crack-healing on crack propagation behavior in Si_3N_4/SiC were investigated by in-situ observation. The in-situ observation was conducted for two materials which were sintered with different sintering additives and subjected to raising stress at several temperatures, environment (Air, N_2) and loading rate. As a result, it was revealed that suppression of crack propagation and increase of fracture strength were occurred at high temperature in both Air and N,. These effects in N_2 were caused by release of tensile residual stress at high temperature. Moreover, these effects in Air were affected by crack-healing in addition to release of tensile residual stress. These two factors, crack-healing and release of tensile residual stress were dependent on time. So the effect of these factors on increase of fracture strength was higher, as the loading rate was smaller. From these result, it became clear that release of tensile residual stress as well as crack-healing play an important role in suppression of crack propagation and increase of fracture strength.
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犬塚 隼人, 赤津 隆, 篠田 豊, 若井 史博
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Using Finite Element Method (FEM), elastic indentation behavior with a point-sharp indenter on film/substrate systems is analyzed numerically. Non quadratic relationship between indentation load P and penetration depth h observed in an indentation on the film/substrate systems is well described with an empirical equation ,in which surface deformation such as pile-up and sink-in is taken into account, developed in this study. Using the empirical equations, the elastic modulus of film can be quantified with iterative calculation when the elastic modulus of substrate and the thickness of film are given apriori.
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山田 賢二郎, 若山 修一
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The 4-point bending tests of cermets and cemented carbides were conducted and the fracture processes were evaluated by acoustic emission (AE) technique. The results show that cumulative AE energy rapidly increases before the final fracture, which corresponds to the maincrack formation. In addition, AE wavelet analysis and direct observations were carried out. As a result, two types of signals were detected. One is the burst-type signal with the frequency of 300 ・500 kHz and the other is continuous-type signal with 100〜200 kHz. Considering their natures, the former could be related with microcrack nucleation or propagation, and later with plastic deformation of binder phase.
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小柳 潤, 小谷 政規, 八田 博志, 川田 宏之
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発行日: 2008/08/02
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A comprehensive model that determines tensile strengths for various systems of unidirectional composites is presented. The model derives the strength of unidirectional composites as a function of single-fiber strength distribution, interfacial shear strength and matrix strength. The point of this model is to consider that a fiber group considered to be experiencing simultaneous fiber failures triggered by neighboring fiber failure is assumed to fail when the weakest fiber in the fiber group fails. A method to determine the magnitude of the fiber group for various systems of composites is discussed based on whether a crack located near a bi-materials interface penetrates into another material or deflects along the interface. The comprehensive model is established by integrating the magnitude of the simultaneous fiber failure into the conventional Global Load Sharing model.
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安野 拓也, 坂本 直道, 向後 保雄
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セッションID: 1451
発行日: 2008/08/02
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The effects of heat treatment on fiber/matrix interface microstructure of carbon-carbon (C/C) composites were examined. The fiber/matrix interface morphology was observed by optical microscope, scanning electron microscope and atomic force microscope. The microstructures were observed by transmission electron microscope in detail. In samples heat-treated at more than 1273K, the matrix with changed morphology was observed between fibers. In addition, in samples heat-treated at more than 1873K, the grain structures were observed between fibers, and the grains grew with increasing heat treatment temperature. This matrix with changed morphology had turbostratic structure,while the matrix without changed morphology had amorphous structure.
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音田 友三, 若山 修一, 赤津 隆
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発行日: 2008/08/02
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Thermal shock fracture behaviors of SiC-whisker-reinforced alumina composites were investigated. Composites containing up to 60vol% SiC whisker were fabricated by SPS. Disc-on-Rod test was employed to characterize thermal shock fracture behavior. Futhermore,4-point bending tests with AE measurement were conducted. These experimental results showed that thermal shock fracture took place when thermal stress reached critical stress of maincrack formation and the value of the stress increased with whisker volume fraction in composites. SEM observations reveal the evidence of whisker bridging and few pullout, which suggests that the modification of interface properties will result in further toughening.
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多々見 純一, 吉尾 紗良, 高橋 賢司, 脇原 徹, 米屋 勝利, 日黒 竹司, 小豆島 明
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発行日: 2008/08/02
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CNT dispersed Si_3N_4 ceramics were fabricated by adding HfO_2 and TiO_2 to Si_3N_4Y_2O_3Al_2O_3-AIN system. As a result, dense sintered body was obtained; especially the relative density of the 5HOT sample was 98.7% after hot isostatic pressing process. It was found that a large amount of CNT existed in Si_3N_4 ceramics. Consequently, HfO_2 and TiO_2 addition was effective in fabrication of dense CNT dispersed Si_3N_4 ceramics at lower temperature.
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橋本 義之, 渡瀬 直樹
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Cast iron parts such as casing and piping of the pump the running water plane is a corrosive environment, and the graphitization corrosion is secularly generated. Then, The technology which judged these corrosion conditions using characteristics of the ultrasonic echo was developed, and the practical application was attempted.
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大谷 俊博, 井上 邦夫, 河村 翔太, 殷 福星, 鎌田 康寛
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発行日: 2008/08/02
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We studied the evolution of microstructure in a Cr-Mo-V steel (JIS-SNB16) during creep by monitoring internal friction. After obtaining a series of creep samples with various strains under a tensile stress of 25 and 35 MPa at 923K, we removed small samples from the creep samples and measured free vibration resonance frequencies and internal friction with electromagnetic acoustic resonance (EMAR). EMAR is a combination of the resonant acoustic technique with a non-contact electromagnetic acoustic transducer (EMAT). The measurement of internal friction is inherently free from any energy loss, resulting in pure attenuation in a metal sample. Furthermore, we observed the evolution of microstructure with electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). The result from the small samples shows the same trend as our previous result from larger sample. We propose a non-destructive method using EMAR to evaluate creep damage in small specimens sampled from structural metals in-service.
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高橋 学, 井原 郁夫
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発行日: 2008/08/02
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An effective ultrasonic method for measuring the internal temperature distribution of heated materials is presented. The principle of the method is based on temperature dependence of the velocity of the ultrasonic wave propagating through the material. An inverse analysis method coupled with a finite difference model is employed to determine one-dimensional temperature distribution in a heated plate. To improve the accuracy in the determination, the relation between the temperature and the velocity is approximated by a quadratic function. A steel plate of 30 mm thickness is heated by contacting with a heater of 200℃ and subsequently cooled down by water. The ultrasonic measurements are performed for the steel during the heating and cooling. The internal temperature distribution and its transit variation determined ultrasonically agree well with those obtained using thermocouples installed in the steel.
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川崎 智則, 高橋 学, 徐 晨艶, 井原 郁夫
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発行日: 2008/08/02
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A simple ultrasonic method for measuring the temperature distribution of heated materials is presented. The principle of the method is based on temperature dependence of the velocity of the ultrasonic wave propagating through the material. In this work, a long steel rod whose end surface is being heated, is used as a specimen. Considering the temperature gradient during the heating, five slits are machined at certain locations on the side wall of the steel rod. In order to obtain the temperature distribution along the long axis of the rod, ultrasonic pulse echoes from each slit are measured and the mean velocities of ultrasonic waves propagating through the distance between two slits are calculated. The velocity is then used to determine the mean temperature between the two slits, using a simple relation of the temperature dependence of the velocity of the steel. An experiment with a steel rod of 60 mm length and 10 mm diameter has been performed. The temperature distribution of the rod determined ultrasonically agree well with those obtained using thermocouples and an infrared camera.
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舎川 知広, 荻 博次, 小高 秀文, 木原 直人, 平尾 雅彦
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セッションID: 1505
発行日: 2008/08/02
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We studied the acoustic properties at sub-THz frequencies of SiO_2 amorphous thin films. SiO_2 amorphous thin films were prepared by reactive sputtering of Si target in argon/oxygen mixture with various conditions. We measured Brillouin oscillation frequency using a femtosecond pump-probe method. We determined the longitudinal sound velocity from measured frequency and refractive index measured by ellipsometry. The results show that the velocities of SiO_2 amorphous thin films highly depend on the microstructure such as microcracks and texture. Thus, this indicates that Brillouin oscillation technique is an effective tool of evaluation for not only acoustic properties but also reliability for transparent materials.
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加計 陽介, 多根井 寛志, 中村 暢伴, 荻 博次, 平尾 雅彦
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セッションID: 1506
発行日: 2008/08/02
公開日: 2017/08/01
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We studied the elastic constant of the epitaxial Pt ultrathin films deposited using RF magnetron sputtering on MgO(001) monocrystal substrates heated at 500℃. We measured the film thickness by the X-ray reflectivity technique (XRR), and determined the normal elastic constant C_<33> of the films by the picosecond-laser ultrasounds (PSLU). The elastic constant depends on the film thickness, and the value of 20 nm films is larger than that of 90 nm by 50 %. The normal strain determined by X-ray diffraction(XRD) measurement is less than 0.1 %, which fails to explaine the elastic behavoir. Thus, we observed extraordinary increase of the elastic constant of epitaxial ultrathin Pt films.
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渡辺 一実
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セッションID: 1507
発行日: 2008/08/02
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The Doppler effect in a reflected wave is discussed based on the exact 1D theory of wave mechanics. The motion of a reflector is non-uniform and arbitrary, but an exact expression for the Doppler frequency shift is obtained in the closed form. The Doppler frequency shift for the four types of reflector motions are presented; (1) uniform, (2) back & forth, (3) acceleration, (4) deceleration.
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宇都宮 登雄, 齋藤 敦史, 佐伯 弥, 佐藤 裕
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発行日: 2008/08/02
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The safety of structures and mechanical instruments can be evaluated quantitatively by monitoring the damage level of the composition elements. In this study, we propose the oscillation circuit method for measuring local strain in the elements. The fatigue tests of the specimen with a center hole are carried out under tension-compression axial loading, and the change of local strain is measured by using the oscillation circuit method and the usual instrument. The results are summarized as follows; (1) when the frequency of cyclic load is low, the strain measured by the oscillation circuit method agrees well with that by the usual measurement. (2) the crack initiation and propagation can be monitored based on the mean value of sampling time of stain measured by the oscillation circuit method.
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劉 臨生, 石川 昌治, 巨 陽
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発行日: 2008/08/02
公開日: 2017/08/01
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In this paper, a method to measure the pipe wall thinning in a large scale by microwaves was demonstrated. In the experiment, a microwave network analyzer was used to generate microwave signals propagating in the pipe where the frequency was swept from 47.38 to 47.47 GHz. A copper pipe having 16.26 mm inner diameter, 1 mm wall thickness, 900 mm length and with joints of thickness reductions having the length of 17 mm and thinning values of 3 to 80% wall thickness were detected significantly. By building up a resonance model, a quantitative evaluation method was established. By comparing the experimental results with those derived by the theoretical analysis, it is shown that the errors of the evaluated results are less than ± 0.5% of the pipe diameter. It indicates that high precision for remote detection and evaluation can be achieved by using this nondestructive method.
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西野 秀郎, 高橋 雅和, 星野 秀和, 小倉 幸夫, 北川 秀昭, 楠元 淳一, 金谷 章宏
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発行日: 2008/08/02
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A novel method for defect detection of a pipe using the circumferential Lamb wave was proposed. In this method, wave-packets of multiple-turnaround Lamb waves are overlapped when the number of tone-burst cycle takes so large. The amplitudes of the overlapped signals are determined by the relative differences of phases of all the wave-packets overlapped. When a defect is existed in the propagation path of the Lamb wave, the phase of the wave is changed in general. The phase change induces the amplitude change of the overlapped portions. The principle depending on above mechanism and experimental verifications was described.
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近藤 浩徳, 吉田 憲一, 西野 秀郎
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発行日: 2008/08/02
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Our research group proposed the efficient transduction method of a guided wave in a pipe using reflectors located at near the sensors. The reflection phenomena both at the magneto-strictive sensor and the reflector were important role in the propose method for efficient transduction. In this paper, the nature of the phenomena was minutely discussed. Experimental verifications of the discussion were also carried out.
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小倉 圭二, 近藤 浩徳, 吉田 憲一, 西野 秀郎
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セッションID: 1512
発行日: 2008/08/02
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The authors have been recently shown a novel method of an efficient generation and detection method using the wave reflector located near the sensors. The maximum efficiency have reached three times the larger than the normal method without the reflector. In this paper, experiments with and without the reflector were carried out to evaluate the two methods. The sensitivity of the method with the reflector was two times the larger than that without the reflector when the cross-sectional loss was larger than 1%. Conversely, when the loss was smaller than 1%, it was not confirmed obvious differences between the two methods.
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田中 康浩, 近藤 浩徳, 吉田 憲一, 西野 秀郎
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発行日: 2008/08/02
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Our research group has proposed a novel method of efficient generation of a guided wave in a pipe utilizing a reflector located near a transmitter. In this report, more efficient generation of a guided wave was proposed using two synchronized transmitters as well as the reflector. The two synchronized transmitters and the reflector were also utilized to enhance the amplitude of the guided wave due to their interference effects. The simple mechanism of the method and experimental verifications were shown.
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林 高弘, 村瀬 守正, 川嶋 紘一郎, 琵琶 志朗
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発行日: 2008/08/02
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堀川 紀孝, 李 成墨, 鮫島 大湖, 内一 哲哉, 池 浩之, 高川 貫仁
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セッションID: 1515
発行日: 2008/08/02
公開日: 2017/08/01
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Tensile properties of thin wall ductile cast iron containing chill structure were evaluated, and eddy current measurements were carried out to detect the chill structure which affect the tensile properties. Ten cast iron samples with six specimens were prepared. Tensile tests were performed on the four specimen of each sample and the eddy current measurement and the microstructure observation were carried out for one specimen. Tensile test results showed that chill structure shortens the elongation at break when the size or amount of the chill is large enough. Although the values of the elongation are different among samples that were cast in same mold, there is no difference on stress-strain diagram until braking. Eddy current signal indicates the difference of matrix and tensile strength. Chill structure can be distinguished with the signal distribution when the chill structure clusters, but it is difficult to find the small chill spread homogeneously. Sensitivity or resolution should be improved to evaluate various thin wall ductile cast iron samples.
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安岡 崇博, 上田 政人, 轟 章, 松崎 亮介, 平野 義鎭
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発行日: 2008/08/02
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Carbon fiber reinforced plastic (CFRP) laminates are very sensitive to an impact which causes delaminations in the laminate. Since delamination reduces the mechanical property of the laminate, nondestructive inspection is required to maintain the structural reliability of the CFRP structure. Eddy current test (ECT) has been studied to be applied to CFRP laminate. Strong electric anisotropy, however, makes application of the method difficult. Since delamination is in-plane damage in the laminate, conventional ECT has a problem for making current-loop which should be impeded by the damage to be detected. In the present paper, rectangular twin probe for electrically anisotropic CFRP laminate is introduced to resolve the problems. The probe is made of two rectangular coils put side-by-side to induce strong uniform electric current. Delamination was made in CFRP cross-ply laminates by means of the indentation test; the applicability of the ECT with rectangular twin probe is examined experimentally.
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長 秀雄, 早野 智晴, 松尾 卓摩
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発行日: 2008/08/02
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This study aims to study in-situ evaluation of bond quality of brazing in vacuum using an optical fiber acoustic emission monitoring system with a highly heat resistant optical fiber. The heat resistant fiber was fabricated by plating Ni-P on a commercially available metal coated fiber. This fiber enables us to monitor AE at elevated temperature up to 1150℃ We monitored AE using the system during blazing at appropriate and lower temperature at pressure of 2 Pa. We detected two types of AE signals classified by frequency analysis during brazing. One was the AE with low frequency components which was detected during heating and cooling process and were identified as friction noises of the sample and jig or fastening bolts. Another was the AE with broad band frequency of 20 kHz to 120 kHz which was detected only cooling process for the sample brazing at lower temperature and was caused by poor bond quality.
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大曽根 龍次, Ahmed Bucheeri, 栗下 裕明, 加藤 昌宏, 二川 正敏, 直江 崇, 前川 克廣, 山崎 和彦
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セッションID: 1518
発行日: 2008/08/02
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Liquid mercury target system for high power spallation neutron sources is being developed. When high intensity proton beams are injected into the target, pressure waves are generated by thermal shock in mercury and cavitation damage will be imposed inside the target vessel. Injection of micro bubbles into the mercury is effective to mitigate the pressure waves. In the previous report, we proposed a method of fabricating a micro nozzle using powder metallurgy method. SUS316L and molybdenum powders were used as the nozzle matrix material. In a combination of molybdenum and quartz fiber, we had produced a straight hole with a circular cross-section, in which the diameter is approximately 100μm. In this work, experiment was carried out to observe the shape change of glass fiber against temperature. Quartz's phase changed from liquid to gas when heating between 1030℃ and 1875℃. This result shows that change of glass phase is an important factor for fabricating a hole.
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高野 直樹, 西籔 和明
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発行日: 2008/08/02
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One of the authors has developed a novel manufacturing method of micro mechanical parts made of porous metals named powder space holder metal injection molding (SPH-MIM). This study presents an original numerical analysis of inner local stress considering the microstructure architecture by the finite element mesh superposition method, which aims at proposing the strength evaluation and design methodology for those micro parts. Fracture test, digital image-based measurement of macroscopic surface strain distribution and numerical results are presented in this paper.
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小原 雅生, 平井 雅人, 品川 一成, 三原 豊
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発行日: 2008/08/02
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To develop a method of producing straight channels in metal bodies by hot extrusion of billets containing metallic powder with resin inserts, the influence of extrusion conditions on the extruded profiles is examined for the combination of aramid fiber and aluminum powder. The reduction in diameter of the aramid inserts varies in a certain extent, but its average is almost stable under the test conditions. Material tests of the single aramid fiber are also conducted to compare its mechanical properties with those of the aluminum matrix. The strength level and the ductility of the aramid fiber are similar to those of the aluminum powder matrix during hot extrusion.
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田中 千尋, 尾田 十八, 坂本 二郎
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It is thought that the content and placement of inclusion in composite materials have a great influence on the mechanical characteristic such as strength. However there is no an effective technique to estimate characteristic of all models. In this research, a technique to obtain an optimum composite material under a constant content cavity rate is proposed by using Cellular Automaton (CA), Genetic Algorithm (GA) and Finite Element Method (FEM).
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山崎 和彦, 斉藤 大介, 本橋 嘉信, 前川 克廣
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セッションID: 1522
発行日: 2008/08/02
公開日: 2017/08/01
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An attempt has been made to manufacture electrode films for the solid oxide fuel cells, by utilizing the green tape laser sintering (GTLS) method. The films for both fuel and air electrodes were fabricated on a ceramics substrate. First, two kinds of green tapes were prepared from Ni cermet powder for the fuel electrode, and lanthanum strontium manganite (LSM) powder for the air electrode. These tapes were glued on an 8 mol% yttrium-stabilized zirconia substrate for an electrolyte. Then, they were dried at 373 K for 60 min in a controlled electrical furnace. Finally, laser sintering was carried out in a row by scanning a pulsed Nd:YAG laser of 1.06μm wavelength and around 1.0 ms pulse width. As a result, a suitable porous structure of both electrode films, Ni cermet and LSM, were obtained.
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前川 克廣, 堤 研介, 山崎 和彦
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セッションID: 1523
発行日: 2008/08/02
公開日: 2017/08/01
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A novel 3-D modeling method that combines rapid prototyping with spark plasma sintering (SPS) is proposed, which enables us to control internal porous structures. Titanium sheet or powder-tape is cut by a pulsed Nd: YAG laser to form a 2-D fractal cross-section. These 2-D layers are temporarily laminated in a carbon mold, and then jointed by the SPS method, so that an internal porous structure is maintained. Process parameters for the sheet lamination method have extensively been investigated. A variety of porestructure characteristics are measured in the porous component for a biotechnological use. In addition, this method can be utilized to form a 2.5-D structure with negative Poisson's ratio.
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熊谷 誠治, 石沢 浩隆, 武田 紘一, 戸井田 康宏
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セッションID: 1524
発行日: 2008/08/02
公開日: 2017/08/01
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Micro and mesoporous carbon/silica composite (CSC) materials were fabricated from rice husk and beet sugar. The pore structure of CSC activated at 875℃ in CO_2 for 0.5-2.5 h was analyzed in relation to bulk density. The activation time of 2.0 h provided the largest total pore volume and BET specific surface area (0.68 cm^3/g and 1027 m^3/g), but low bulk density (0.54 g/cm^3). CSC of which activation time was 1 h was once again immersed in the beet sugar syrup and then activated in CO_2 for 1 h. This two-steps activation provided high bulk density (0.69 g/cm^3) and high micro and mesoporous structure (BET specific surface area: 943 m^2/g, total pore volume: 0.56 cm^3/g, micropore volume: 0.32 cm^3/g, mesopore volume: 0.19 cm^3/g).
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大北 一也, 高木 均
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セッションID: 1534
発行日: 2008/08/02
公開日: 2017/08/01
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This paper describes flexural properties of bamboo/PBS(polybutylene succinate) composites prepared by injection molding. The bending modulus was improved with increasing the bamboo powder content. However the bending strength had the reverse tendency to be decreased with increasing the bamboo powder content. The SEM photomicrograph of the fracture surface for bamboo/PBS composites showed the typical fracture behavior of pull-out fibers without fiber fracture and the sticking of PBS resin on the surface of the pull-out bamboo fibers. Moreover, the effects of water absorption about flexural properties of bamboo/PBS composites were examined.
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李 承桓, ThiThi Nge, 遠藤 貴士, 寺本 好邦
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セッションID: 1535
発行日: 2008/08/02
公開日: 2017/08/01
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Nano-scale fibrillation of pulp fibers and purified cellulose was successfully conducted by batch-type kneader with twin-screw elements, specially designed disk mill, and high-pressure homogenizer (more than 200 MPa). The screws in batch-type kneader were coordinated to give a maximum shearing force and thus obtained results are introduced with the final purpose to utilize twin-screw extruder. This presentation mainly summarizes the morphological characteristics of thus obtained nanofibers and its application for nanocomposite.
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東海林 成嘉, 柴田 信一, 町田 マガリー, 福本 功
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セッションID: 1536
発行日: 2008/08/02
公開日: 2017/08/01
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Bagasse fiber composites were fabricated to improve the formability and quality. To archive this objective, MFI, surface roughness and odor were studied. The MFI in the composites was increased by using high-flow polypropylene to improve the formability. The surface roughness was most smooth when the injection conditions were in range of high injection speed and high temperature in mould. This was due to the skin layer formed in the composites. The odors in the composites were found as cyclopentenelones and guaiacols by gas chromatography analysis. These odors were caused by thermal pyrolysis of a hemicellulose with water. To avoid the odors, the effect of the thermal drying were investigated.
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久保田 秀典, 藤井 透, 大窪 和也, 田中 達也, 藤浦 貴保, 長谷 朝博
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セッションID: 1537
発行日: 2008/08/02
公開日: 2017/08/01
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A technique for preventing fiber breakage was studied during fabrication of PP-based green composite pellets with bamboo short fibers. The residual fiber length in BFRPP pellets fabricated by using the side feeder on a twin-screw extruder was longer than that of conventional products. Improvement of residual fiber length in BFRPP did not affect the tensile properties of injection-molded samples. However, high tensile strength was observed when the fiber aspect ratio was improved. The residual fiber length and fiber aspect ratio in BFRPP pellets were strongly affected by feed position of the materials. This paper shows that the appropriate feed position of both materials significantly increases the residual fiber length and aspect ratio in BFRPP pellets.
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小林 大将, 合田 公一, 野田 淳二, 大木 順司
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セッションID: 1538
発行日: 2008/08/02
公開日: 2017/08/01
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The purpose of this study is to develop a green composite with high strength and stiffness, using long bamboo fibers, in order to apply biomass resources for practical use. A biodegradable resin was used as a matrix of the composite, and hot-pressed with 60 to 70vol% bamboo fibers. Then, bamboo fibers were dyed to create a good interfacial bonding between the fiber and matrix, and compared with untreated fiber reinforcement. The composites reinforced with dyed bamboo fibers indicate a relatively large tensile strength, similarly to ramie fiber and Manila hemp fiber reinforced green composites, reported elsewhere. In addition, commercially available micro fibrillated celluloses (MFC), nano-sized natural fibers, were added into the matrix to make a better interface, and the green composites were fabricated in the same way. In this study, furthermore, the effect of the interfacial shear strength on the composite strength was explored through a strength reliability model.
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斎藤 淳仁, 竹村 兼一, 加藤木 秀章
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セッションID: 1539
発行日: 2008/08/02
公開日: 2017/08/01
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In this study, effect of heat treatment on mechanical properties of JGC (Jute fiber reinforced Green Composite) were examined. PLA (Poly Lactic Acid) resin was used as matrix. Jute fiber cloth was used as reinforcement. Heat treatment and heat compression treatment on JGC laminates after molding were conducted. As a result, tensile strength of heat treated JGC increased about 24%. Tensile strength of heat compression treated JGC increased about 19%. Young's modulus of heat treated and heat compression treated JGC increased about 1% and 11% respectively. Tensile creep strain of heat treated and heat compression treated JGC decreased. Therefore, there is an effect of heat treatment and heat compression treatment to tensile strength, Young's modulus and creep strain for JGC.
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原口 慶樹, 合田 公一, 野田 淳二, 大木 順司
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セッションID: 1540
発行日: 2008/08/02
公開日: 2017/08/01
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To clarify the effect of alkali-treatment on the mechanical properties of plant-based natural fibers, ramie plied yarns were treated using NaOH solution. The alkali-treated yarns decrease in strength if the concentration of the solution is more than 15wt%. It was proved from X-ray analysis that this decrease was closely related with the change in crystallinity index of the yarns. Such change in strength properties was similarly seen in green composites reinforced with the same yarns. Furthermore, in this study, the effects of liquid ammonia treatment on the mechanical properties of ramie plied yarns and their green composites were investigated.
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高橋 明宏, 山元 直行, 榮徳 幸祐
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セッションID: 1541
発行日: 2008/08/02
公開日: 2017/08/01
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The deformation and fracture characterizations of natural fibers under high temperature are useful in product the degradable composites. Elastic responses and tensile properties of bamboo fibers prepared by steam explosion method were investigated at elevated temperatures. Fiber strength and fiber ductility distinctly decreases with increasing temperature. Additional material's tendency to brittle failure at elevated temperature is caused by heat decomposition for cellulose. Tortional deformation of bamboo fibers were found out at high temperature above 160℃. Once a fiber was plastically deformed under high temperature, it couldn't recover its original fiber shape at room temperature.
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佐々木 惇也, 熊谷 誠治, 武田 紘一
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セッションID: 1542
発行日: 2008/08/02
公開日: 2017/08/01
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Agricultural waste of rice husk (RH) was converted into a densified carbon/silica composite with superior mechanical properties. A powder of RH produced by using a planet ball mill was carbonized and molded into the precursor, by means of binderless hot-pressing with a specialized procedure. The precursor of which bulk density was 1.36 g/cm^3 was sintered for the further densification up to 1400 ℃ without compression in nitrogen gas. The sintering at 800 ℃ provided the maximum bulk density of 1.52 g/cm^3. The maximum compressive strength and the maximum Vickers hardness at the surface were measured to be 55.7 MPa and 343 HV at the sintering temperature of 1200 ℃ and 800 ℃, respectively.
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峰野 友幸, 澤井 徹, 速水 尚, 加治 増夫
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セッションID: 1543
発行日: 2008/08/02
公開日: 2017/08/01
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Extrusion experiments for pruned branches from fruit tree were conducted at a uniform press speed. The results obtained in the present study are as follows. Molding defects were observed for all experimental conditions. The size of cracks on the molding increases with an increase in press speed. The dynamic equilibrium load in the range of press speed between 0.1 and 10mm/min. was denoted as a power function with press speed. In the case of capillary diameter of 2mm, bursts in extrusion processes occurred due to production of thermal decomposition gas.
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高木 均, 高田 善弘, 興津 嘉人
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セッションID: 1544
発行日: 2008/08/02
公開日: 2017/08/01
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Raw bamboo was hot-pressed in order to increase its mechanical properties, such as flexural strength, flexural modulus and impact strength. The hot-pressing conditions were varied in the following range: temperature, room temperature to 220℃: pressure, 5 to 100 MPa. The flexural strength, compressive strength and Izod impact strength increased with increasing molding temperature, showing the maximum peak values at 160℃, but thereafter decreased. Densification at both vascular bundles and parenchyma cells region was achieved by hot-pressing, resulting in the improved mechanical properties.
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西田 政弘, 伊藤 紀臣, 川瀬 祐之, 田中 皓一
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セッションID: 1545
発行日: 2008/08/02
公開日: 2017/08/01
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The effect of strain rate and temperature on compressive properties of starch-based biodegradable plastics (Nihon Cornstarch Co., CPR-M2) was examined. Dynamic stress-strain curves of starch-based biodegradable plastics were measured over a wide range of strain rates from 10^<-5> s^<-1> to 10^4 s^<-1>, using a quasi-static compression testing machine and a split Hopkinson pressure bar (SHPB) method. A master curve of 7% flow stress, reduced to 297 K, was made. The values of activation energies related to the α and β relaxation processes were respectively estimated from the master curve of 7 % flow stress and from the best fit of equations based on Ree-Eyring theory and Bauwens' treatment.
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平良 公太郎, 柴田 信一, 町田 マガリー, 神田 康行
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セッションID: 1546
発行日: 2008/08/02
公開日: 2017/08/01
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Poly L-lactic acid was synthesized by ROP (ring opening polymerization). The effects of polymerization time, contents of Tin 2-ethylhexanoate as a catalyst, polymerization temperature on Molecular and mechanical properties weight were investigated. The Molecular weight was determined at 30 degrees with Ubelode viscometer. The optical purity of L-lactide, monomer, was measured by a polarimeter. The L-lactide was obtained through pyrolysis and purified. The maximum molecular weight reached 245000 at 160 degrees at polymerization temperature, 0.05 catalyst weight % and 6 hour polymerization time. Conversion rate of L-lactide to PLLA was increased after crystallization starting from 94% to 99.8%. Furthermore, the tensile strength and elongation in the PLLA were 27-47MPa, 2.5-3.5%. These results shows the hard and brittleness in PLLAs compared to other polymers.
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中島 樹之, 堀田 篤, 宗宮 詮
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セッションID: 1547
発行日: 2008/08/02
公開日: 2017/08/01
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The effect of material recycling on the mechanical properties of biodegradable poly-(butylenes-succinate) (PBS) is discussed as one of the environmental pollution-controlling methods using biodegradable plastics. To analyze the relationship between reprocessing and the mechanical properties of PBS, the number of reprocessing cycles was varied, followed by the measurements of the bending strength and the bending modulus of PBS. It was found that even after the fifth cycle of reprocessing, there was no significant change in the mechanical properties of the material. The influence of the cumulative damage caused by hot water on the mechanical properties was also discussed. It was found that the material degraded under non-hydrolysis conditions has recovered its original characteristics by reprocessing. For example, the material degradation caused by absorption of water was slightly healed, partially regaining its original mechanical properties owing to the removal of water during reprocessing. Moreover, the bending strength remained constant after reprocessing of the material degraded by hydrolysis. From the results, it was concluded that the cumulative damage due to the hydrolysis remained unchanged in the material even after reprocessing.
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今野 武志, 江頭 満, 小林 幹彦
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セッションID: 1548
発行日: 2008/08/02
公開日: 2017/08/01
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We have developed a microwelding technique using micro electric discharge, and reported that gold particles of 60-80μm in diameter can be welded to a gold substrate. Here, two thin wires, an alumel wire and a chromel wire, were welded to make fine thermocouple by the above microwelding method. The two wires were fixed to cross their tips. A Tungsten needle was placed about 200μm above the cross, and 2kV or more was applied to the needle. The cross was melted and a junction was formed by the electric discharge. The size of the junction is less than 2 times of the wire diameter, while that of common thermocouple is more than 3 times of the wires diameter. Output of the thermocouple fabricated is almost the same with that of thermocouples on the market up to 650℃.
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