Update equations are important in the field of computational mechanics. In the topology optimization problem, the optimality criteria (OC) method is commonly employed as an update equation. The OC method updates design variables faster than the steepest descent method and was developed for topology optimization based on homogenization method and density method. However, because the OC method has certain arbitrary parameters for updating, the results may depend on the parameters. The modified OC method that we have developed does not require arbitrary parameters. Notably, the penalization parameter, which is a parameter that must be set to represent the material property, had less influence on the density distribution when the modified OC method was employed in static problems. Based on the aforementioned analysis, the purpose of this study was to investigate whether the same trend could be obtained in density-based topology optimization for dynamic oscillation problems. As a result, even when the penalization parameter was varied, the density distribution when using the modified OC method was clearer than that when using the OC method.

The changing colors seen in soap bubbles or oil floating on water are the result of thin-film interference. These are not the actual colors of the substance itself, but are color changes brought about by its structure. They are a familiar sight to children and, as a subject for study, they can excite scientific curiosity while also being fun to observe. In practical science education, there have been reports of thin-film interference in metal oxide films produced by the anodic oxidation of titanium being used for the development of teaching materials or in teacher training seminars. However, anodic oxidation requires high voltages, and there is also a need to dispose of fluid waste (e.g., phosphoric acid aqueous solution). For this reason, there are few reports of this method being used in practical classes. Within the range of our survey, the interference and diffraction of light has been covered in high school physics classes using soap bubbles, but we found no reports of practical experiments using metal oxide films. Here, we show that after an Sn–Zn binary alloy (85:15 mol%) is heated to melting point, it oxidizes upon exposure to air and interference colors can be observed as a result. The melting point of the Sn–Zn binary alloy is low (198.5 ºC), such that the alloy can be melted using a microwave oven. Furthermore, if the oxide film that forms on the surface of the metal is removed by re-heating, the alloy can be used repeatedly for the experiment. Not only does this cut down the required preparation steps and fluid waste disposal, it also reduces the environmental burden, as the experimental material is reusable. It is theoretically possible to reproduce a given target interference color by adjusting the thickness of the metal oxide film. We compare the temperature characteristics of carbon powder and copper (II) oxide as heating media, in order to determine whether an oxide film can be reliably formed. As a result, we confirm that the oxide film could be formed in a shorter time when using copper (II) oxide as the heating medium.

The surface of nanocarbon fiber silicone-matrix composites causes water droplets to be slippery with presence of CNTs (Carbon nanotube). However, the assistance of CNTs in decreasing the resistance of water droplets has not been clarified yet. It was confirmed that further increasing the amount of CNTs promotes fiber orientation on the surface. The aim of this research is to clarify the mechanism by which sliding property of water droplets of composites containing CNTs. In this paper, composites which have different orientations were created and their effects on the sliding property of water droplets are reported. A silicone resin solution containing CNTs was shaped by a bar coater while applying shear stress (called Film). CNTs on surfaces of the film were oriented. Water droplets on the film with higher degree of orientation tended to be slippery. This result means that fiber orientation on surfaces is related to the sliding property of water droplets. And it may help prediction of movement of droplets on surfaces.

Surface textures are significantly related to the geometric specifications of products, and thus, quantitative quality control is required. The material ratio curve (MRC) and MRC parameters, which are methods for evaluating surface textures, are effective methods for evaluating surfaces with excellent lubrication and frictional characteristics. MRC is a curve that shows the ratio of the material and void parts of the surface roughness to the height direction, represented by the height of the surface profile on the vertical axis and the percentage of the material part on the horizontal axis. MRC proposed in ISO 13565-2, ISO 21920-2 and ISO 4287 has long been known and applied in the automotive industry and other industries. MRC and MRC parameters are widely used as effective evaluation methods for the quality control of automotive parts and bearings in the industry. The algorithm for calculating MRC proposed in the ISO standard has the problem that it requires more computing time as the number of slices against the roughness profile increases. In recent years, surface roughness evaluation has increased the demand for the areal surface texture measurements, and the measurement data of the areal surface texture has surface roughness profiles of at least 50 to 300 lines in the depth direction. Therefore, the ISO 13565-2 standard method does not satisfy the realistic time at the production site due to the time required to calculate MRC. Hence, in this study, we propose the sort method as an algorithm for calculating MRC, in which the computing time is reduced. However, it was found that this calculation method had some problems depending on the shape of the profile of the measurement data. Therefore, in this paper, we report a new improved algorithm that improves this problem. In this study, an algorithm for calculating MRC using the sorting algorithm has been researched and developed. The proposed algorithm in this study succeeded in reducing the computing time to derive MRC compared with the calculating algorithm of MRC proposed in the ISO standard. Therefore, we consider that computational algorithms can contribute to the efficiency of quality control in the industry.

This work aims to reveal the shear deformation of stacked three pieces of 0.31mm thickness non-coated paperboard (based on virgin pulps for printing) subjected to a two-dimensional punch’s indentation against dies when changing the adhesive strength of the interlayers of the three pieces. Some generation of pull-out wastes from the sheared zone in the punching process was empirically reported. That seemed to be related to the releasing resistance of tangled fibers and sandwiched waste chips with the upper and lower layers. In this study, the effect of the adhesive resistance on the shear behavior and the generation of pull-out waste were investigated using two-dimensional punching shear test. The transient state of the fracture phenomenon of the three layers was observed by a high speed digital microscope. The difference of de-lamination behavior was detected with respect to the several adhesion states, and the breaking state of the lower and upper layers was revealed, while the middle layer was pull-out during the shearing process. Furthermore, the secondary cut of a small chip pulled out from the middle layer was detected when the adhesive strength of glued interlayers was relatively weak.

A porous bone filling material of Hydroxyapatite (HA)-β-Tricalcium Phosphate (β-TCP) composite with bioabsorbability and biocompatibility was synthesized by the Hydrothermal Hot-Pressing (HHP) method. The porous bone filling material was produced through HHP method, drying, and sintering processes. But, it had low porosity of about 59 %. The porosity of more than 70 % and initial strength of more than 10 MPa were required to speed up the remodeling of bone defects. To improve the porosity, we tried new preparation method by increasing the water content in HHP method and adding pore-forming material (Polymethyl Methacrylate: PMMA). Furthermore, the drying method was changed from heat drying to freeze-drying to try to improve the strength. When the triple of water content in HHP method, the porosity increased to 56.2 %. According to the thermogravimetric analysis, the cause was increase in the sample's water content after HHP method. The strength was improved by adding water content suitable. Because the hydrothermal reaction in HHP method was promoted and particles were strongly bonded. At a Ca / P ratio of 1.50, 20 wt.% was the optimum value. When the PMMA was added, adding the amount of 30 vol.%, the porosity improved by 14.1% to 55.9 %. And the compressive strength was improved to 29.7 MPa, about triple when the amount added 15 vol.%. Up to 15 vol.%, the porosity increased, and the pore diameter and pore distribution decreased. It suppressed layer cracking and led to an improvement in strength. When the PMMA was much, the porosity increased, but the strength decreased due to the expansion of the pore diameter. In freeze-drying, maximum pore diameter and average pore diameter were the smallest. The strength doubled to 15.0 MPa while maintaining the porosity. From the above results, increasing the water content in HHP synthesis and adding PMMA was effective in improving the porosity. If the strength was to be improved, freeze-drying was effective. This study suggested conditions which strength and porosity can be increased in HHP method.

This paper descrives the mold releasability evaluation of MAX pahse ceramics. MAX phase ceramics has excellent machinability, wear resistance and corrosion resistance. Therefore, it is considered to be suitable as a mold material in plastic molding. In this study, in order to clarify the applicability of MAX phase ceramics to mold materials, the mold release force between max-phase ceramics and resin was measured. Furthermore, the effect of the surface roughness of the electrical discharge machined surface on the mold release force was investigated. A thermosetting phenol resin was compression-molded on the die-sinking surface of the MAX phase ceramics used as a mold, and the mold release force was measured. For comparison, the mold release force with SKD11 was also measured. The MAX phase ceramics had a smaller mold release force than SKD11. In addition, the mold release force tended to increase as the surface roughness increased in both mold materials. From these results, MAX phase ceramics can be compression-molded with the same transferability as SKD11.