Papers by Author: Yasunori Nakamura

Abstract: Suspended ceilings consist of ceiling boards, furring channels, channel clips, furring brackets, hangers and ceiling bolts. The ceilings are easy to drop down when the large earthquake occurred. The channel clips deform and disengage from the ceilings or break at that time. Design engineers calculate and evaluate the stress in the clips by using method with mechanics of materials. The evaluation depends on the experiences of the engineers. Mechanics of materials is considered in elastic region, but the channel clips are in plastic deformation. Therefore, after the design, the clips are manufactured and are subjected to verification tests as the design evaluation. Sometimes the prototype tests become multiple times. The purpose of this research is to build a simple method of an efficient design for the channel clips. It is ordinary to use elastic-plastic analysis at strength design in the case of plastic deformation. But software for elastic-plastic analysis is expensive, so the design method of the channel clips depends on the elastic stress analysis function of 3D CAD in this research. Instead, we designed and evaluated the equivalent stress corresponding the tensile strength in plastic deformation as the evaluation criterion. As a result, it was possible to evaluate the design that the channel clips are not broken when assuming earthquake occurrence with a seismic intensity of 7. This evaluation is reliable compared to the verification test conducted in the past.

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.