Hidetoshi Sakamoto

Development of Multi‐Scale Finite Element Analysis Codes for High Formability Sheet Metal Generation

In this study, the dynamic‐ and static‐explicit multi‐scale finite element (F.E.) codes are developed by employing the homogenization method, the crystalplasticity constitutive equation and SEM‐EBSD measurement based polycrystal model. These can predict the crystal morphological change and the hardening evolution at the micro level, and the macroscopic plastic anisotropy evolution. These codes are applied to analyze the asymmetrical rolling process, which is introduced to control the crystal texture of the sheet metal for generating a high formability sheet metal. These codes can predict the yield surface and the sheet formability by analyzing the strain path dependent yield, the simple sheet forming process, such as the limit dome height test and the cylindrical deep drawing problems. It shows that the shear dominant rolling process, such as the asymmetric rolling, generates “high formability” textures and eventually the high formability sheet. The texture evolution and the high formability of the newly ...

Development of dielectrophoresis MEMS device for PC12 cell patterning to elucidate nerve-network generation

We developed a PC12 cell trapping and patterning device by combining the dielectrophoresis (DEP) methodology and the micro electro mechanical systems (MEMS) technology for time-lapse observation of morphological change of nerve network to elucidate the generation mechanism of neural network. We succeeded a neural network generation, which consisted of cell body, axon and dendrites by using tetragonal and hexagonal cell patterning. Further, the time laps observations was carried out to evaluate the axonal extension rate. The axon extended in the channel and reached to the target cell body. We found that the shorter the PC12 cell distance, the less the axonal connection time in both tetragonal and hexagonal structures. After 48 hours culture, a maximum success rate of network formation was 85% in the case of 40 μm distance tetragonal structure.

Development and Evaluation of Protect-board in High Speed Collision

In various fields, the high velocity flight object protection board is demanded in order to defend the person and the device from the collision damage. Recently, the gun shooting incident has happened in Japan. Therefore, the shield that defends the person from the bullet is required. The purpose of this study is development of gun-bullet protection board. The polycarbonate is selected to the material of protect-board. The reason is that the polycarbonate is high transparency and lighter than the metals. In this experiment, the bullet model is launched by the air gun, and it is collided with the polycarbonate plate. As a result of experiment, the performance of the air gun was evaluated, and the influence by the bullet model collision of the polycarbonate plate was examined. The launched bullet model velocity was measured and the bullet model collision image was taken by high speed video method.

Study on deformation conditions of epoxy compounds for semiconductor integrated circuits

The constitutive equations for epoxy compounds used for Integrated Circuits (ICs) were examined in a small viscoplastic strain region of approximately 0.01 in the temperature range from room temperature to the glass transition temperature. The specimens that were moulded and cured were subjected to tensile testing to examine their constitutive equations. Various characteristics obtained in the tensile test were reasonably represented using a simple model in which a three-element viscoelastic model, which changes depending on viscoplastic strain, is connected in series with conventionally used viscoplastic elements. The loading and unloading characteristics of specimens were also evaluated with satisfactory accuracy using the model.