Polyamide (PA) resin is anticipated to be a beneficial matrix of carbon fiber reinforced thermoplastics (CFRTP) because of its low cost and good bonding property to the carbon fiber. However, the well-known highly hygroscopic nature of PA demands that the influence of water absorption on the mechanical properties of carbon fiber/polyamide composites (CF/PA) be clarified. In this study, to evaluate the influence of water absorption on the mechanical properties of CF/PA composites, single fiber pull-out test for CF/PA model composites and tensile test for CF/PA composite were performed. For CF/PA6, and CF/PA66 model composites, water absorption at 80 ˚C caused significant reductions in interfacial shear strength. CF/PA12 model composites also showed a decrease in interfacial shear strength due to water absorption, but to a smaller degree compared with that of the other model composites tested. Oven drying was able to completely reverse the deleterious effect of water absorption on the interfacial shear strength in CF/PA6 and CF/PA12 model composites, but full restoration was not possible in CF/PA66 model composites. Oven drying was able to restore tensile strength in CF/PA6, CF/PA12 and CF/PA66 composites.

Recently, Carbon Fiber Reinforced Thermoplastics (CFRTP) are expected to be used for lightweight component parts. To mold CFRTP, it is necessary to impregnate carbon fiber bundles with thermoplastic resin by heating the materials. We have been developing a low cost CFRTP molding technique in which direct resistance heating was applied to carbon fiber itself. When electrical current runs through the materials, they are heated by joule heat. Therefore this method can run with simple equipment and low consumed power. In our previous studies, flat plates and pipes of CFRTP have been molded by using direct resistance heating and the molding abilities have been evaluated. To use this molding method for automobile components, it is necessary to apply this method to three-dimensional molding. However, the temperature distribution of carbon fiber NCF has not been clarified when a direct resistance heating method is applied to three-dimensional molding. In this study, the heating properties of carbon fiber NCF formed at 90º and 120º by using direct resistance heating were evaluated, and angle plates were molded. By using direct heating to carbon fiber NCF the angle plates of CF/PA6 have been successfully molded in the condition for the holding time of 1 minute, the pressure of 2 MPa and heating temperature of 290°C.

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.

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 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.