Shinichi Enoki

Formability evaluation of carbon fiber NCF by a non-contact 3D strain measurement system and the effects of blank folder force on its formability

Non-Crimp Fabric (NCF) consists of unidirectional plies, which are kept together by stitching yarns arranged in a number of different orientations relative to the fabric production direction. Since NCF has no crimp, NCF can take full advantage of the continuous carbon fibers. As NCF is deformed mainly due to shear deformation, it is difficult to form 3D shapes from it. Therefore, formability improvement of NCF by slitting a textile preform has been attempted; however, problems such as strength degradation at a notch and cost increase due to the increase of working process have occurred. So, it is necessary to improve formability of NCF without slitting. One of the methods of formability improvement is to use blank holder force. In previous studies, though the influence of blank holder force on formability of woven fabrics has been clarified, that on formability of NCF is uncertain. In this study, the hemisphere geometry punch drape test was conducted to evaluate the influence of blank holder force on the formability of NCF. Meanwhile, deformation of NCF during the drape test was measured by a non-contact 3D strain measurement system.

The Effects of Trabecular Bone Microstructure on Compression Property of Bovine Cancellous Bone

To establish clinical bone assessment for osteoporosis, it is necessary to evaluate not only bone density but also trabecular bone microstructure and mechanical properties of bone. Therefore relationship between the micro-structural parameters and the mechanical properties of the cancellous bone of bovine distal femur was investigated. Compression test was carried out using universal testing machine to measure Young’s modulus and the ultimate strength. X-ray CT was used to obtain 3D image of specimens. Bone trabecular orientation was obtained from fabric ellipse by the MIL (Mean Intercept Length) analysis. Young’s modulus and ultimate strength had a high correlation with bone density respectively; furthermore ultimate strength had a high correlation with Young’s modulus.

FEM analysis of the temperature distribution of CFRTP pipe mold with direct resistance heating

In the automobile industry, from the point of preventing global warming, the mass reduction of automotive bodies has become more important than ever. Especially automotive weight lightening by using Carbon Fiber Reinforced Thermoplastics (CFRTP), which has advantage of high-specific strength and high-specific modulus, has received much attention. A lot of pipe-shaped materials are used for a car. For CFRTP pipe molding, a low-cost and high-speed molding method is required. Using high-frequency electric resistance heating allows heating the mold surface rapidly. Rapid heating of the mold can reduce production cycle time. The electrical energy of this heating method is less than that of traditional heating methods, and therefore the reduction in production cost is expected. In molding of CFRTP, uniformity of temperature distribution is one of the important issues to be solved. In this study, temperature distribution of CFRTP pipe molding by direct resistance heating was evaluated by FEM analysis. In direct resistance heating, the temperature distribution of the mold depends on the shape of electrodes and electric frequency. Influence of the shape of electrodes and electric frequency on the temperature distribution of the mold is revealed by using FEM analysis.

Heating Properties Of Carbon Fibers By UsingDirect Resistance Heating

In the automobile industry, reduction of car weight is needed to deal with environmental issues. Recently, Carbon Fiber Reinforced Plastics (CFRP) is expected to be used for lightweight component parts. The application of CFRP will become possible to reduce car weights, because CFRP has higher specific strength and specific rigidity. However the cost of CFRP is so high that the use of CFRP does not increase. In addition, it is expected to use thermoplastics as a matrix of CFRP in consideration of recyclability. To mold Carbon Fiber Reinforced Thermoplastics (CFRTP), it is necessary to impregnate carbon fiber with thermoplastic resin by heating the materials. There are electromagnetic induction heating and direct resistance heating for heating method. The electromagnetic induction heating has a high production cost because of complicated equipment. On the other hand the direct resistance heating is performed with a simple piece of equipment and low consumed power. It is better to use direct resistance heating for low-cost CFRTP molding. We propose a method of CFRTP molding process using direct resistance heating of carbon fibers in n on crimp fabric (NCF). In this paper, the resistance heating characteristic of NCF and the influence of resistance heating upon mechanical properties of carbon fiber were discussed. The temperature distribution of 0° and 90° layer were sufficient and it took 70s to reach to 250°C on temperature history when heat is applied to the NCF [0°/90°] using direct resistance heating. From the results of tensile tests of single carbon fiber, tensile strength was not decreased by resistance heating at 300°C for 300s.

Formability Evaluation of Non-Crimp Carbon Fabric by Non-Contact 3D Deformation Measurement System

Non-Crimp Carbon Fabric (NCF) consists of unidirectional plies which are kept together by stitching yarns arranged in a number of different orientations relative to the fabric production direction. It is reported that NCF possesses excellent drape performance compared to woven fabrics. However there is not a clear criterion of a drape evaluation on the drape characteristic of the NCF. In addition, it is not clarify that stitch pattern and stitch tension influence on the drape characteristic of the NCF. Moreover, in existing bias extension test, measurement of shear angle is based on the pin-jointed net (PJN) approximation. The PJN approximation doesnt takes into consideration the fiber sliding and the effect of the stitched parameters of the NCF. In this study, the bias extension test based on the measurement of shear angle by non-contact 3D deformation measurement system was conducted to evaluate the drape performance of the NCF. We made a proposal of the formability evaluation index based on the measurement results. Moreover, the 3D draping tests were conducted onto hemisphere geometry and regular tetrahedron, in order to verify availability of the formability evaluation index. The availability of the formability evaluation index was verified.

MECHANICAL PROPERTIES OF A SINGLE CANCELLOUS BONE TRABECULAE TAKEN FROM BOVINE FEMUR

The increase of patients with osteoporosis is becoming a social problem, thus it is an urgent issue to find its prevention and treatment methods. Since cancellous bone is metabolically more active than cortical bone, cancellous bone is often used for diagnosis of osteoporosis and has received much attention within the study of bone. Bone is a hierarchically structured material and its mechanical properties vary at different structural levels, therefore it is important to break down the mechanical testing of bone according to the various levels within bone material. Mechanical properties of cancellous bone is said to be depended on quantities and orientation of trabecular bone. It is supposed that mechanical properties of trabecular bone are constant without depending on any structural arrangement and parts. However, such assumption has not been established in studies of trabecular bone. Furthermore test results have a large margin of error caused by insufficient shape assessment. In this study, three point bending tests of single cancellous bone trabeculae extracted from bovine femur were conducted to evaluate the effects of directions to the femur major axis direction on the mechanical properties. X-ray μCT was used to obtain shape of trabecular bone specimens. Furthermore compression tests of cancellous bone specimens, which were extracted in 10mm cubic geometry, were conducted for evaluation of directional properties.There were small difference in the elastic modulus of the trabecular bones which were extracted in parallel and in perpendicular to the major axis of femur. Considering from the results that the cancellous bone specimens, which were extracted in 10mm cubic geometry, have different elastic properties depending on the tested directions; the bone structure has larger influence than bone material property on the mechanical properties of cancellous bone.

Observation of Supersonic Jet Using Small Volume High-Pressure Shock Tube

The unsteady supersonic jet and the shock wave injected by the small volume shock tube are experimentally studied in this paper. The experimental was performed by the background oriented schlieren method. The main parameters for the jet are the pressure ratio by the high pressure chamber/ a back pressure 10.9-53.0 and the length of high pressure chamber/diameter ratio 1 and 10. The velocity of the shock wave and supersonic jet were estimated by using the principle of the background oriented schlieren method. The results showed that the influence of the length of the high pressure chamber on the velocity of the jet.

A baseball game analysis by an extraction of characteristic play sequence

In baseball games, a term of momentum affecting the flow of the game is used as a mental concept. A team can feel positive momentum during a game when the first batter in an inning gets a base; the following batters get runs more easily. Regarding psychological momentum, many folk theories are widely believed among baseball people. A more quantitative approach to folk theories on baseball games is required because these are qualitatively explained without any clear basis. In this article, we statistically analyze the plays on 31 games by National Institute of Technology, Nara College (NIT-Nara) team in Japan high school baseball tournament. The verification of typical folk theories associated with some specific plays shows that these theories are not statistically significant. The playing-style is checked by means of bias on the play frequency. It is found that negative plays occurred more often than those by the opponent teams. The evaluation for the plays with «-gram frequency extracts some characteristic play sequences. These analyses revealed that NIT-Nara team is rather emotionally unstable to keep their positive momentum. Furthermore, a method for detailed investigation of the key plays driving momentum on the game is mentioned as the future problem.

Heat transfer analysis of two wavelengths laser microprocessing inside glass

We investigated the relationship between size of melting marks formed inside glass and irradiation time and absorptivity of femtosecond laser beam. For this investigation the absorptivities for static exposure in fs-laser processing (femtosecond laser microprocessing inside glass) was estimated to approximately 4.5 [%]. Also the size of melting marks formed by fs-laser processing was measured with two irradiation times (1/125 [s] and 1/4 [s]). The sizes were much the same. Thus, in this time scale, the size was nearly independent of the irradiation time. Furthermore, luminescence phenomenon that occurred in fs-laser processing was observed. The duration of this luminescence was less than 2/1000 [s]. With the above experimental results, we demonstrated numerical heat transfer analysis during the fs-laser processing. From the experimental and numerical results it thought that the most process in fs-laser processing finishes within 2/1000 [s].

Heating properties of carbon fibers subjected to direct resistance heating

To mold carbon fiber reinforced thermoplastics (CFRTP), it is necessary to impregnate carbon fiber with thermoplastic resin by heating the materials. Electromagnetic induction heating and direct resistance heating are available heating methods. The electromagnetic induction heating has a high production cost because of the complex equipment used. In contrast, the direct resistance heating is performed with a simple piece of equipment and low power consumption. It is thus better to use direct resistance heating for low-cost CFRTP molding. A process of CFRTP molding is here proposed using direct resistance heating of carbon fibers in non-crimp fabric (NCF). The resistance heating characteristics of NCF and the influence of resistance heating upon mechanical properties of carbon fibers are discussed. The temperature distribution in 0° and 90° layers were found sufficient and it took 70 s to reach 250°C in the temperature history when heat is applied to the NCF [0°/90°] using direct resistance heating. From the results of tensile tests of a single carbon fiber, the tensile strength did not decrease by resistance heating at 300°C for 300 s.