Papers by Author: Hidetoshi Sakamoto

Abstract: In this research, the bullet-collision test was done in the different velocity. The influence of its velocity on the deformation shape after collision was discussed by comparison with experiment and simulation. The velocity of the bullet was chosen in several kinds of speed ranges at 80m/s-250m/s. The angle of incidence with the collision object is 90 degree (head-on collision). The deformation shape was measured by 3D measurement instrument and reconstructed with 3D-CAD based on the 3D digital data. The deformation mark of the polycarbonate plate and the penetration shape of acrylic plastic plate caused by the bullet's collision with the object were examined. In addition, the collision simulation of the bullet was done by using FE analysis code “LS-DYNA”, and these analytical results were compared with the 3D digital data which is the experimental results.

Abstract: The purpose of this study is development of gun-bullet protect board. The collision test was executed in such a way to launch a bullet and collide to the target by the air gun. The mock bullet made of brass was used as the projectile. The collision behaviors of polycarbonate (PC) target board were clarified. Next, the analysis of gun bullet collision between the bullet and PC board has been practiced by non-liner dynamic FEM commercial software (AUTODYN^TM) and an effective bullet protection board is designed based on this analytical result.

Abstract: In order to promote the recycling of the one way glass bottles, the impact fracture by using the pulse power underwater shock-wave with micro bubble was examined. It is reported that the pressure of underwater shock-wave with micro-bubble increases. From the experimental result, the glass bottle‘s crushed experiment was executed in the water with micro-bubble. As a result, the small glass fragments (Cullet) increased and it was shown that the micro-bubble in the water promoted the bottle fracture.

Abstract: In this study, we conducted a tensile shear test according to JIS K 6850 for a simple superposed adhesive joint, and as a result, it was found that the expected adhesive strength can be obtained only when cohesive failure occurs. The surface enlarged length was measured from a micrograph that observes the surface texture of the boundary between the adhesive and the adherents, and it was found that cohesive failure occurred when the length was longer than a certain length. Surface enlarged length is a new way of thinking. It measures the length of the ridgeline of the unevenness in the microscopic photograph of the surface roughness. By doing so, we can quantitatively determine the effective adhesive length. Effective adhesion length is the length of adhesion of the adhesive as viewed microscopically. We can know the adhesive effect by examining the effective adhesive length. Therefore, we found the relationship between the surface enlarged length (= effective adhesion length) of the bonding interface of the simple superposed adhesive joint and the adhesive strength. Then, it was verified whether adhesion strength could be predicted by setting the standard surface enlarged length as a threshold. As a result, we developed a nondestructive inspection method that can estimate the failure mode after the tensile test.

Abstract: This paper discusses the plastic deformation and fracture development of Ti-alloy under uniaxial tension. The energy dissipation and transfer characteristics in the plastic deformation and fracture processes were analyzed using acoustic emission (AE), thermal infrared (TIR) imaging, and thermocouples. Uniaxial tension tests were carried out, during which TIR images were obtained and the AE energy was observed. The mechanical characteristics of Ti-alloy with I-type cracks were analyzed based on the TIR images, AE energy, and temperature. The plastic work of the Ti-alloy specimen was found to dissipate as thermal energy rather than AE energy. Moreover, the TIR images were correlated well with the AE energy observed during the plastic deformation and fracture processes of the material.

Abstract: This research is the application of new design method for integrating the optimum shape and strength design process. The products is manufactured from product design which can use the advanced characteristic of composite materials obtained by the experiment and the numerical analysis. Here, the collaboration of the design and the strength analysis by using composite materials is carried out. The products, which are made from high strength composite materials, need new product design technology which draws out the characteristic of material's advantage. Existing product developments tend to separate product design from product planning. The process consists of three stages as follows; 1) Planning the shape of the product by designers, 2) Calculating the strength by numerical analysis, 3) Designing the product. It is performed a styling design by requirements from the engineering point of view. By using this design method of high-strength materials, we designed new styling ZIGZAG Chair made of the carbon fiber reinforced plastic with excellent strength and lightweight.

Abstract: The purpose of this study is development of gun-bullet protection board. In this experiment, the air gun’s performance and the effective bullet supporting sabot’s shape were evaluated. The launched gun-bullet velocity was measured by high speed video method.

Abstract: Recently, many countries are promoting the collection, the reproduction and the use of consumer goods；aluminum cans, PET bottles, and so on. On the other hand, the reproduction of the glass bottles is not so active excluding use as a returnable bottle, because the recycle cost is high. The glass bottles are fractured by the small fragment for reproduction. The small crushing fragments are called ‘Cullet’. The cullet is melted and molded again as glassware. The surface area is enlarged by making the bottle cullet, and it is possible to melt these efficiently. As a result, it becomes possible to shorten the time to melt the glass bottle and reduce a consumption of the fuel oil. The reasons with not active recycling of the glass bottle are that large-scale crushing equipment is required and it takes a lot of time and cost. This study proposed a new recycling technique for fracturing the glass bottle by using an underwater shockwave by explosive and electric pulse. The shock wave pressures produced by the explosive and the electric pulse energy were measured and the optimum crushing conditions were discussed.

Abstract: The purpose of this study is to apply a new design method, which integrates both optimum strength and product design. Here, the collaboration of design and strength by using composite materials is administered. Many products, which are made from high strength composite materials, require new product design technology. Existing product developments tend to separate product design from product planning. The process begins from planning the shape of the product, then calculating the strength, and lastly designing the product. In our new design method, we create from an engineering point of view. By using a design method of high-strength materials, we designed a new ZIGZAG CHAIR made of carbon fiber reinforced plastic of excellent strength and light-weight.

Abstract: The purpose of this research is the development of new design method for integrating the optimum strength evaluation and the product design which can make the best use of material's characteristics obtained by the experiment and the analysis. Further we do design using high-strength composite material with this developed concept which is different from conventional design. First, to establish this design method of high-strength materials, we examined these materials characteristics and manufacturing methods and the commercialized products. As this research target material, we focus the fiber reinforced materials such as composite with carbon fiber, glass fiber and aramid fiber. Above all, we marked the carbon fiber which has the high specific tensile strength, wear resistance, heat conductivity and conductance. Here, we introduce the fundamental design concept which makes the best use of the design with enough strength.