PROPOSAL OF A NEW NATURAL DISASTER MITIGATION BASED ON SMART MATERIALS AND STRUCTURAL SYSTEMS
Prof. Asanuma, Chiba University, Japan
August 7, 2014, 2:00 pm, NASA Langley, Bldg 1293A, Rm 222
Abstract:
Recently, more and more serious disasters occur around the world and a large number of people are lost in spite of rapid advancement of science and technology. In this situation, disaster mitigation to be realized by novel ideas and technologies is of increasing importance. In order to solve the above mentioned problems, we will build a platform to be able to create novel technologies and products by involving enthusiastic people from various fields based on advanced science and technology such as smart structures, materials, devices, systems, processing and related technologies especially from aerospace fields. Asanuma et al. have been proposing the new concept “Disaster Mitigation and Sustainable Engineering” which enables sustainable human life as well as disaster mitigation, effectively and economically.
The new concept can be briefly explained as below. Serious disasters may occur today, or may not occur for a long period of time. Devices and structures necessary for disaster mitigation consume vast amount of money for their constructions and maintenances. So, we have to utilize them for our daily lives to produce something useful such as energy. The generated energy can be used for their monitoring, maintenance, self-repair, and many other purposes such as lighting, charging useful devices (MAVs etc.) and so on. The devices and structures have to be available even if disaster occurs once for hundred years. For the overwhelming days without disasters, they are not necessary from disaster mitigating point of view, so their compactness is very effective to be friendly for people’s daily life because it can refrain from becoming obstacles, and to be useful from aesthetic point of view due to their stealth function by refraining from damaging beautiful scenery.
In this seminar, two examples having been done by Asanuma et al. are introduced and discussed in addition to the above mentioned content.
In the first project, artificial and multifunctional forests have been developing, which are intended to have better capability of tsunami mitigation than actual ones by optimization of various parameters such as configuration, density, material, combination of materials. There exist many problems, that is, low fraction of trees, low visibility of ocean waves, low strength, long period necessary to grow, and so on. The first two experimental parameters have been tried to be examined by preparing a water channel set-up. By changing them, that is, arrangement of square or triangular, number of rows and spacing of stainless steel rods, apparent effects of mitigation and possibility of optimization are found. In addition, experiment concerning the effect of material/material system and employment of smart functions such as energy harvesting to make them be available even when without disasters to satisfy the concept of Disaster Mitigation and Sustainable Engineering are planned. The harvested energy will be useful to light-up, activate sensors, charge MAVs, and so on.
In the second project, new smart structures based on honeycomb like structures have been developed. They are under development for having multiple functions to satisfy the concept, for example, autonomously deployable up to the height of tsunami, compact enough to remain in sea water for energy harvesting, residentially and environmentally friendly due to flexibility in addition to high specific strength. This stealth/multifunctional smart materials and structural system will be the key to realize our dream hopefully in the nearest future. In order to cope with tsunami, rigid and fragile structures are not suitable, and rather strong, light and flexible structures are preferred. So, Asanuma et al. have started to develop the flexible and deployable materials and structural system to diminish the force of tsunami and dissipate its energy by microscopically separating the flow and letting them conflict with each other. A multilayer type structure is designed to optimize the effect. In addition, similar developments against flooding (smart banks), and also some others to protect valuable things from falling from shelves at the time of earthquake (smart furniture), which are much easier to realize and very useful, have been tried to be done by designing and fabricating honeycomb type structures using thin aluminum layers and/or composite/aluminum laminate layers. A corrosion testing of the laminates have been also undergoing in collaboration with Hihara.
Asanuma et al. are establishing a research committee on Disaster Mitigation and Sustainable Engineering with several active members from Chiba University and Hirosaki University, and also extending it to an international one.