Advances in Science and Technology Vol. 83

Abstract: On 11 March 2011, a moment magnitude 9.0 earthquake and its subsequent tsunami struck the Pacific coastal areas in the north-eastern part of Japan (Tohoku district). Iwate, Miyagi and Fukushima prefectures in particular were severely damaged. Some cities, towns and villages in these three have been entirely destroyed by the tsunami, and have not yet fully recovered from those destructions. With the tsunami flood, one of the nuclear power plants in Fukushima Prefecture was catastrophically damaged, resulting in the release of radioactive materials. In this paper, the impacts of this quake are discussed in regard to tsunami, nuclear power plants, high-rise buildings, and response-controlled buildings. In addition, as a successful example of control and monitoring, an emergency stop operation for the Tohoku Shinkansen trains is presented.

Abstract: In this paper, some smart sensors or material used to make the smart sensors, such as piezoresistance composite, piezoelectric polymer, piezoelectric cement and corrosion monitoring sensor, developed by Harbin Institute of Technology were introduced. Piezoresistance composite is made with carbon nanotube and resin, one character of the work is the carbon nanotube is orientation arranged by magnetic field. Piezoelectric polymer is made with PZT particles and PVDF, in order to improve its performance a few carbon nanotube are also mixed in the composite. Piezoelectric cement is one kind of sensing material whose primary raw materials are cement and piezoelectric ceramic particles (or fiber). The sensing performance of piezoelectric cement is coming from its functional phase, the piezoelectric ceramic. The corrosion monitoring sensor is made with solid-state reference electrode, whose surface is one kind of binary alloy membrane produced with physical vapor deposition technology. The main producing technology, performance and applications of above sensors were introduced in this paper.

Abstract: The application of Shape Memory Alloy (SMA) devices to practical uses need well established performance. The reliable application in some areas, as dampers in engineering, needs a known, relatively long fatigue life (some million oscillations). The thermomechanical properties of SMA, based on their martensitic transformation, made them attractive to use for damping, taking advantage of the pseudoelastic window and hysteresis on transforming-retransforming. Due to size effects and to the fact that fatigue failure in metallic NiTi usually comes from a defect inducing crack growth, fatigue has to be studied for concrete applications, with the correct samples. The present work points out the possibility to apply NiTi to dampers and actuators. Testing machine experiments indicate that the main parameter controlling fatigue life is the effective stress on the NiTi wire. Long wire life (in the million cycle regime) can be achieved under limited stresses (around or under 200 MPa). Also, experiments have been done on thermal actuation of NiTi wire under traction at constant load. The results demonstrate that long actuator life (larger than 300000 cycles) can be achieved at low stresses (around 100 MPa), coherently with the mechanical cycling. From our results, NiTi is useful to effectively damp vibrations even at relatively low stresses and strains. The experimental results from facilities (cable No. 1 in ELSA-JRC, Ispra, Italy, and IFSTTAR test cable, near Nantes, France) confirm that NiTi wire is able to damp stayed cables.

Abstract: Three-dimensional and multilayered packets from plates, simulating base-foundation, base-seismoisolator-foundation of constructions, are considered. A general asymptotic solution of three-dimensional dynamic problem of elasticity theory for n-layered packet is built. It is shown that the solution becomes mathematically exact, when entering in the boundary conditions functions are polynomial. The character of the stress-strain state of a three-dimensional packet, when the contact between the layers is complete, is studied in detail. On the base of the mathematically exact solution it is established that when there is a middle layer made of softer material of rubber type, the amplitudes of vibrations on the upper layer decrease sharply. By the same taken the application of seismoisolators is theoretically justified. The analysis of the exact solution of another class of problems, when the contact between the separate layers is incomplete, brought to the conclusion that the tangential displacements informed to the lower layer practically do not influence on the stress-strain states of the above standing layers with complete contact between the layers. The detected phenomena may be applied in the calculations of bases-foundations of constructions in seismosteady building for diminishing the negative influence of the seismic forces.

Abstract: Model Order Reduction (MOR) denotes the theory by which one tries to catch a model of order lower than that of the real model, in view of the design of an efficient structural control scheme. When the nonlinear response of the reference structural system affects the nature of the reduced model making it dependent on the visited subset of the input-output space, standard MOR techniques do not apply. The mathematical theory offers some specific alternatives. One of them is applied, in this paper, to a case study focused on a multi-bay, multi-storey plane frame with assigned locations for the potential plastic hinges.

Abstract: In this paper, some control strategies to design decentralized controllers are developed and discussed. These strategies are based on the Inclusion Principle, a very useful mathematical framework to obtain decentralized controllers, mainly when the systems are composed by overlapped subsystems sharing common parts. A five-story building model serves as example to show the advantages provided by this approach. Numerical simulations are conducted to assess the performance of the proposed control laws with positive results.

Abstract: Power requirements for microelectronics continue a downward trend and power production from vibrational power harvesting is ever increasing. The result is a convergence of technology that will allow for previously unattainable systems, such as infinite life wireless sensor nodes, health monitoring systems, and environmental monitoring tags, among others. The Laboratory of Intelligent Machine Systems at Cornell University has made many significant contributions to this field, pioneering new applications of piezoelectric energy harvesting, as well as contributing to harvesting circuitry and mechanical design theory. In this work, we present a variety of new applications for energy harvesting technology, including infinite life avian based bio-loggers, flutter induced vibrational wind power, and in-flight energy harvesting in munitions. We also present theoretical contributions to the field including an energy harvester beam design guide and multisource energy harvesting circuitry.

Abstract: A promising harvesting technique, in terms of simplicity and efficiency, is the conversion of ambient kinetic energy through piezoelectric materials. This work aims to design and investigate a piezoelectric converter conform to a fractal-inspired, multi-frequency structure previously presented by the author. A physical prototype of the converter is built and experimentally examined, up to 120 Hz, in terms of modal response and power output. Three eigenfrequencies are registered and the power output is particularly good at the fundamental eigenfrequency. Also the effect of the resistive load applied to the converter is investigated.

Abstract: Vibration control of civil engineering structures using tuned mass dampers (TMD) is a widely accepted control strategy after numerous analytical and experimental verifications. Although the design and application of traditional linear TMD systems are well developed, nonlinear TMD systems that may lead to better control performance are still in the developmental stage. There are two main problems associated with TMD systems, i.e. (1) detuning effect and (2) excessive stroke of TMD. In order to improve the performance of TMD systems, a novel semi-active TMD named resettable variable stiffness TMD (RVS-TMD) is proposed in this study. The RVS-TMD consists of a TMD and a resettable variable stiffness device (RVSD). The RVSD is composed of a resettable element and a controllable stiffness element. By varying the stiffness element of the RVSD, the force produced by the RVSD can be controlled smoothly through a semi-active control law. By resetting the resettable element, the hysteresis loop of the RVSD can cover all four quadrants in the force-deformation diagram and thus results in more energy dissipation. The harmonic and seismic responses of a building equipped with the RVS-TMD are investigated numerically and compared with those by its active control counterpart and an optimal passive TMD system. The results show that the proposed RVS-TMD system has good control performances as its active control counterpart and is able to alleviate detuning effect and reduce TMD’s stroke.