The thermoelectric generating device can convert the heat flow due to temperature difference into electric energy by the Seebeck effect. In general, electric power can be obtained by alternately arranging N type thermoelectric elements and P type thermoelectric elements and connecting upper and lower staggered electrodes (π type structure).
However, the generation capacity due to Seebeck effect is low, and even bismuth-telluride thermoelectric elements widely used at the present time are at most about 200 μV / K. Therefore, it is necessary to arrange hundreds of π structures, but the π structure is complicated, poor mass productivity, and there is a problem of increasing the internal resistance due to being connected in series.
The nickel material and aluminum material can be directly bonded by applying temperature and pressure . Using this feature, two nickel plates with a thickness of 0.2 mm, a length of 30 mm and a width of 15 mm and three aluminum plates were alternately laminated and directly bonded. An anodized film of 1 μm is formed on the surface of the aluminum plate, and the oxide film is peeled off by 5 mm from the end portion by polishing. Direct bonding was performed by holding for 40 minutes under the conditions of a pressure of 7.6 MPa, a temperature of 600 ° C. and a degree of vacuum of 0.4 Kpa. By selectively forming an anodic oxide film on the surface of aluminum and using it as a mask, it is possible to selectively and directly bond them. Since only the aluminum portion from which the anodized film has been removed is bonded, if it is slightly pulled, it peels off, and five layers accordion type structure can be produced.
It was found that by adding a temperature difference of 73 ° C to this device, electric power of maximum 20 μW can be obtained.
In this research, we propose a new monitoring method of the temperature of the molten pool for stable layered fabrication in the metal wire supply type laser 3D printer. The metal wire to be supplied is melted by the laser during molding and flows into the molten pool of the base metal, so that an electric closed circuit is formed. At that time, since the temperature of the molten pool exceeds 1400 ° C., when the metal wire and the base metal components are different, the Seebeck effect produces an output voltage between the base metal and the molten pool and metal wire. From this output voltage, the temperature of the molten ground can be obtained.
Furthermore, by applying this method, it is also possible to monitor the component ratio of the gradient material from the voltage generated between each metal wire and the base material when a plurality of different wires are supplied and a gradient material is produced .
The thermoelectric power generation device can take out electric energy from thermal energy directly. In order to transform a difference of temperature into electric power efficiently, it is common to make the thermoelement of N-type and P-type into pi structure. Since the thermoelectric power of an element was small, much pi structures needed to be connected with series, but when a large number were connected with series, there was a problem that internal resistance will become large.
In this study, we propose a new multilayer π-type structure sandwiched between an insulating layer using a metal direct bonding technology. By using this technique, significantly lowered layered structure the electrical resistance of the joint portion, because it can be produced by laminating at least one hundred sheets at a time, even when using a metal material having low Seebeck effect, a sufficiently practical level. It can boost the voltage, a possible cost reduction of the device itself. Further, since the laminated π type structure fabricated. Each interface is tightly bonded by eutectic reaction, it is possible to use a structure having a power generation function.
We succeeded in the deposition of piezoelectric thin film on a titanium substrate and on nickel-titanium alloy (shapememory alloy) by employing the hydrothermal synthesis method for the direct deposition of PZT thin film, which is a piezoelectric material, on a titanium substrate. The formed film is quite thin (tens of micrometers), and the density is low (theoretical density of ~70%). As the thin piezoelectric film is formed by the layering of many crystals, it is capable of responding to large deformations (up to 5%), which would have been inconceivable with the existing piezoelectric materials without any structural damages. The hydrothermal synthesis method was used in this research study to form films of PZT piezoelectric films on the surfaces of nickel-titanium shape-memory alloy wires to fabricate and evaluate a new multifunctional device that features a combination of four effects, namely, the shape-memory effect, super-elasticity effect, piezoelectric effect, and pyroelectric effect. The fabricated fiber was subjected to a tensile test in the super-elastic state, and the amount of deformation thereof was read from the piezoelectric effect to show the functioning of both the super-elastic effect and the piezoelectric effect.
We reported some work on flexible tactile sensors based on Flemion ionic polymer metal composites previously. In this
work, we compared the signals in both voltage and current with the signals obtained from a giant nerve fiber reported
previously by other researchers. We found some similarities between the artificial tactile sensor and the nerve fiber, in
both of which ionic movement play a very important role. This bio-inspired Flemion based ionic polymer metal
composites would be a good candidate for bio-related sensors especially for prosthetic limb socket interface applications.
KEYWORDS: Structural health monitoring, Sensors, Data storage, Polarization, Telecommunications, Ferroelectric materials, Data communications, Reliability, Energy harvesting, Electric field sensors
Vehicle's components experience a variety of small to large strains during its operations. Monitoring a set of only large
strains of the components is preferable for critical analysis of structural health of the vehicle. For data of all strain history
including smaller amplitudes as a function of time require huge data storage system which in turn requires large power
and communication equipment. Therefore, development of more energy efficient structure health monitoring (SHM) system is increasingly important for assessment of its long-term reliability. SHM has two components, one is to record history of large straining during vehicle's operation, and the other is to detect any larger damages hidden in a vehicle during or when it is at rest. This study is aimed at the first SHM issue.
The concept of this new SHM is to measure the fatigue properties of piezoelectric sensors that are subjected to a set of
loading. In this research, we used cantilever beam made of steel plate on which a piezoelectric thin plate is mounted. The
cantilever beam is subjected to a set of known vibrations by electro-magnetic induction apparatus. Then we measured
residual P-E curves of the piezo-sensor at a number of fatigue cycles. It is found that the residual polarization (Pr) of the
P-E curves of fatigued piezo-sensor exhibit continuous reduction, which provides a useful data set to assess what level of
loading that the cantilever beam has experienced.
The shape-memory alloy, for example NiTi (Nickel Titanium), is used for an actuator and frame by the shape- memory effect and the
super-elasticity effect. And piezoelectric material, for example
PZT (Lead Zirconate Titanate), is used for an actuator and sensor by the piezoelectric effect and the pyroelectric effect. However, each of the materials has been used for the sensor and the actuator
independently because the principle of the function of each of materials is different. In this research, a new multi functional device combines these four functions is developed by coating the PZT thin film of 20μm to the surface of the NiTi wire by the chemical reaction by using the hydrothermal crystallization method. We succeeded in the detection of the displacement at a super-elastic deformation of this multi functional device from the piezoelectric effect of the PZT film on the surface. By combining each effects, the multifunctional device can be used for a self-sensing actuator, wherein the transformation by the shape-memory effect is detected by the piezoelectric effect or the pyroelectric effect, and the rough and precision actuator performs the rough movement by the shape memory effect and performs the precise movement by the piezoelectric effect.
Perovskite-related layered multicomponent oxide films with strongly correlated electrons such as (La, Sr)MnO3 and HTS are promissing candidates for advanced MRAM, Josephson devices and others. These devices have usually sandwich-type structure with an ultra-thin intermediate layer. Formation of the impurity-precipitates on the surface during the growth of the multicomponent oxide films is a fatal problem working against high-performance of devices. In this study, high quality and surface-clean thin films of multicomponent oxides have been grown by MOCVD on substrates with artificial steps of predefined height and width. The surface of the films grown on the steps having width equal to the 'double of the migration length' of the atomic species depositing on the substrate is totally free of precipitates: precipitates are gathered at the step edges where the free energy is lowest. The method has several advantages: it is simple, universal (it is independent of the materials, substrates, deposition technique or application) and allows control of precipitates segregates so that the quality and growth conditions of the films are the same as for the films grown on conventional substrates. The method is expected to result in new opportunities for the device fabrication, integration, design and performance. As an example we present successful fabrication of a mesa structure showing intrinsic Josephson effect. We have used completely precipitate-free thin films of Bi-2212/Bi-2223 superstructure grown on (001) SrTiO3 single crystal substrates with artificial steps.
This paper reports damage detection and vibration control of a new smart board designed by mounting piezoelectric fibers with metal cores on the surface of a CFRP composite. Damage to the board is identified on the assumption that the piezoelectric fibers used as sensors and actuators are broken simultaneously at the damaged location. When such damage-induced breakage occurs, the piezoelectric fibers expand and contract between the root and the damaged position on the cantilever beam. Damaged positions are detected by focusing attention on this property. Furthermore, this deterioration of sensors and actuators caused by breaks in the piezoelectric fibers is a consideration in the design of the gain-scheduled controller. First, the length of the piezoelectric fibers is measured to derive a finite-element method (FEM) model of the cantilever beam. If the fiber length is shortened due to a break, there is a decrease not only in actuator performance but also in the sensor output. Thus, peak gain of the FEM model is calculated for the length of every piezoelectric fiber. Damage detection is based on the computed relation between peak gain and the damage position. Furthermore, a reduced-order model that considers only the first mode is derived for the controller design and transformed into a linear fractional transformation (LFT) representation for the gain-scheduled controller design. The position of the damage is the contributing parameter in the variation. Next, the gain-scheduled controller is designed using LFT representation. Finally, the simulation and experimental results of the damage detection and the gain-scheduled control are presented. These results show that our gain-scheduled controller can improve control performance when damage cause a break in the piezoelectric fiber.
In the previous conference, we produced a new metal core-containing piezoelectric ceramics fiber by the hydrothermal method and extrusion method. The insertion of metal core is significant in view of its greater strength than ceramics materials, and electrodes are not required in the fiber's sensor and actuator applications. A new smart board was designed by mounting these piezoelectric fibers onto the surface of a CFRP composite. After that, this board is able to use this board to a sensor, actuator and vibration suppression. In this paper, we measured s mechanical properties of metal core piezoelectric fiber. We examined the tension test of a piezo-electric fiber, and measured the Young's modulus and breaking strength. Moreover, the expansion in the fiber unit was measured, and the displacement of the direction of d31 was measured. In addition, a piezo-electric fiber that used lead free material (BNT-BT-BKT) to correspond to environmental problems in recent years was made.
We produced a new piezoelectric fiber with metal core by the hydrothermal method. The insertion of metal core was significant in view that the fragility of ceramics can be overcome and electrodes are not required in the use as sensors and actuators. And new smart board was designed by mounting these piezoelectric fibers on the surface of the CFRP composite. It was shown that these complex fibers function as sensor and actuator in the CFRP board. In order to evaluate the sensor and actuator. However, by the hydrothermal method, piezoelectric layer can be uniformly formed with about 20μm thickness on the titanium wire surface, the PZT clad is insufficient in thickness for the actuator use. In this paper, we solve this problem using extrusion method. We developed the metal core further thicker PZT clad fiber by the extrusion method. 31 piezoelectric fibers were embedded under CFRP composite materials, and the sensor and the actuator function were evaluated. We showed that self sensing was possible using this smart board.
This paper addresses the active vibration control of a new smart board designed by mounting piezoelectric fibers with a metal core on the surface of the CFRP composite. These complex fibers function as sensors and actuators in the CFRP board. A finite element model of a cantilever and a reduced order model for controller design were established. The piezoelectric fibers are uneven in the actuator outputs.Therefore, the linear fractional transformation (LFT) is formulated considering the unevenness of the actuator outputs as the perturbation. Next, the controller is designed by using mu synthesis, considering the perturbation and robust stability. The control performance of the proposed method is verified by experiment and demonstrates that piezoelectric fibers can be effectively used in vibration control.
In an attempt to develop piezoelectric sensor and actuator for smart board, complex piezoelectric fibers with metal core were fabricated by both hydrothermal method and extrusion method. The insertion of metal core was significant in view that the fragility of ceramics is overcome and electrodes are not required in the use as sensor and actuator. In order to evaluate the sensor and actuator abilities of these new-type fibers, a cantilever structure was constructed by embedding them into the surface of CFRP composite board. As a result of vibration of this CFRP board by electromagnetic vibrometer, it was found that the fiber has an obvious sensor function, since electric charge was output from the fiber in proportion to the vibration amplitude. On the contrary, it became also evident that the fiber functions as actuator, since the CFRP board was vibrated by applying an AC voltage between the metal core and CFRP matrix. It seemed likely that the hydrothermal fiber is adequate to sensor use, while the extruded fiber is suitable for actuator use because of the higher actuator power.
In an attempt to develop piezoelectric sensor and actuator for smart board, complex piezoelectric fibers with metal core were fabricated by both hydrothermal method and extrusion method. The insertion of metal core was significant in view that the fragility of ceramics can be overcome and electrodes are not required in the use as sensor and actuator. In order to evaluate the sensor and actuator abilities of these new-type fibers, a cantilever structure was constructed by embedding them into the surface of CFRP composite board. As a result of vibration test of this CFRP board by electromagnetic vibrator, it was found that the fiber has an obvious sensor function, since electric charge was output from the fiber in proportion to the vibration amplitude. On the contrary, it is also evident that the fiber can function as actuator, since the CFRP board was vibrated by applying an AC voltage between the metal core and CFRP matrix. By connecting the shunt circuit with the piezoelectricity fiber, it was proven that the vibration in the smart board could be suppressed.
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