There is a considerable excitement in the space community about the possibility of performing useful missions in space using vehicles that are much smaller in size than current spacecrafts. Lower cost and new type of missions made of this small satellite very attractive for future missions. Spacecraft in the mass range of 1 to 10 kilograms are often referred to as “nanosatellites”. However, the suite of useful missions for nanosatellite is limited by the dearth of space components of suitable scale. Present day nanosatellites are often drifting, uncontrolled packages of instrumentation of very limited capability. The vital subsystem functions of propulsion, power conversion and storage, attitude control, attitude sensing, data storage, command and data handling, and telemetry, tracking and control, are not well supported by these components availability of a number of small, low-cost nanosatellite components in these subsystem areas. This paper introduces the advances on applications based on piezoelectric transformers for nanosatellites.

An attempt was made to fabricate composite material of an Al alloy matrix reinforced by TiNi shape memory fiber using a hot-press method and to investigate its microstructures and mechanical properties. The analysis of SEM and EDS showed that the composite material had good interface bonding. The stress-strain behavior of the composite material was evaluated at room temperature and 363 K as a function of pre-strain, and it showed that the yield stress at 363 K is higher than that at room temperature. It is also found that the yield stress of the composite material increased with increasing the amount of pre-strain and depended on the volume fraction of the fiber and heat treatment. The smartness of the composite could be given due to the shape memory effect of the TiNi fiber, which generated compressive residual stress in the matrix material when heated after being pre-strained. Microstructural observation revealed that interfacial reactions occurred between the matrix and fiber, creating two intermetallic layers.

We study the effect of stress on the behavior of magnetostrictive films. Our approach is different from the conventional one which neglects the strain compatibility. Here, we include the kinematic constraint in our micromagnetic model and proposed to use the average to calculate the stress-induced magnetic field. The analytic formulation of magnetostrictive energy is derived which enables us to perform simulation at a large scale with few iteration steps. The simulation results show that the conventional approach is insufficient to predict magnetic domain patterns for materials with large magnetostriction, and the effect of intrinsic stress cannot be neglected.

The Ti-Ni-Cu shape memory alloy by elemental powders was fabricated by means of a pulse-current pressure sintering method that can produce high-density sintered compacts in a very short sintering time. The fabrication conditions of Ti-Ni-Cu alloy and the influence of Cu content in Ti-Ni-Cu alloy on the tensile properties and thermo-mechanical characteristics were investigated. The relative density of the as-sintered compacts was around 97% at any Cu content. The microstructure, tensile properties and thermo-mechanical characteristics of the as-sintered compacts were improved greatly by performing a solid solution heat-treatment. The yielding behavior due to the stress-induced martensite in stress-strain curves of the alloy took place after elastic deformation at any Cu content. The deformation resistance of the alloys changed with Cu content, and it was lowest around 9at% in Cu content. The tensile strength and elongation of the alloy with Cu content around 9at% were more than 400 MPa and 6%, respectively. It was found that the thermo-mechanical behavior of the alloy becomes stable by performing cyclic deformation.

A combination of the preparation techniques for the ferroelectric films and the micro machining of Si is considered to be an effective way to fabricate microelectromechanical systems (MEMS), such as piezoelectric micro-transducer devices for the electrical and medical fields. In this study, 10-μm-thick disk shape lead zirconate titanate (PZT) thick films were successfully fabricated using a chemical solution deposition (CSD) process. Pt top electrode and PZT layer were etched by reactive ion etching (RIE) process, and 100 to 500-μm-diameter PZT micro disks were fabricated on Pt/SiO2/Si substrate. The relative dielectric constant, dissipation factor, remnant polarization and coercive field were εr = 1130, tanδ = 0.02, Pr = 14 μC/cm2 and Ec = 25 kV/cm, respectively. This means that the ferroelectric and dielectric properties of the PZT micro disks were comparable with that of the bulk PZT ceramics. The PZT micro disk showed the butterfly-shaped displacement curve, related with piezoelectric response, in the case of bipolar measurement. The piezoelectric constant of the PZT disks poled at 80Vfor 10 min was estimated to be AFM d33 = 221 pm/V. A resonance frequency of the radial oscillation was evaluated to apply for micro transducer devices.

The development of lightweight low power consumption actuators is critical to the development of micro-robotics. Electroactive Polymers (EAP), i.e. Nafion N-117, meet these requirements. In the actuation of an EAP, the current does not remain constant over time. The development of a circuit model of current draw over time to best predict a current dynamic has been explored. While the material mimics a parallel plate capacitor, it has been found that capacitance plays no role in achieving steady state current levels. This development is critical to understanding and developing the material as an actuator.

A non-linear constitutive model was formulated for ionic electroactive polymers (EAP) to describe the energetic coupling between electrical and mechanical domains. The polymer was modeled as a multi-port energy storage element with inputs from the electrical and mechanical domain. Using energy conservation methods, general relationships between stress, strain, voltage, and charge were determined. A solution to the uniaxial loading boundary condition was developed fully and compared to a linear model published by Madden and an electrochemical model published by Mazzoldi et al. Experimental results from a conducting polymer actuator composed of polypyrrole were used to validate the electro-mechanical coupling model. It was found that the correlation between the model and experimental data was very good for strains up to 3% and applied voltages up to 1 Volt; these are within the typical operating range of polypyrrole. The model is sufficiently simply to allow real-time control while also exceeding the linear coupling models in its ability to predict polymer behavior in normal operating ranges.

Single crystals of Co48Ni22Ga30 have been synthesized using a modified Bridgman method. The ability to solidify and retain single phase B2 austenite was found to depend not only on the starting composition and growth rate, but also the ability to maintain sufficiently high cooling rates to avoid the precipitation of a Co-rich FCC phase during post-solidification cooling. DSC measurements on the single crystal found the Ms, Mf, As, and Af to be 35.7°C, -1.8°C, 34.1°C and 72.2°C, respectively. On subsequent heating the B2 phase was found to partially decompose into the Co-rich phase at temperatures exceeding 380°C. Decomposition of the single phase B2 phase was tracked by microstructural observation, DSC, powder diffraction and low temperature heat capacity measurement. Restoration of the crystal to single phase B2 austenite required annealing of the crystal at temperatures above 1125°C followed by rapid cooling.

For tetragonal barium titanate (BaTiO3) single crystals, an electric field (E-field) applied along [111]c direction can induce an engineered domain configuration. In this study, the engineered domain structures with different domain sizes were induced into BaTiO3 single crystals, and their piezoelectric properties were investigated as a function of a domain size. Prior to this study, the dependence of domain configuration on the temperature and the E-field was investigated using a polarizing microscope in order to understand the optimum condition for fine and coarse domain structures. As a result, above Curie temperature (Tc) of 132.2 °C, when the E-field over 6 kV/cm was applied along [111]c direction, the engineered domain configuration with fine domain structure appeared. Moreover, it was also found that this fine domain structure was still stable at room temperature without E-field. On the other hand, the coarse domain structure was obtained by poling at just below Tc. Finally, the piezoelectric properties were measured using the 31 resonators with different kinds of domain sizes. As the result, it was found that the piezoelectric properties such as d31 and k31 increased significantly with decreasing domain sizes.

We determined the optical constants of a vanadium dioxide (VO2) thermochromic film deposited on glass substrate by ellipsometry in wavelength range from 380 nm to 1700 nm. The optical constants were employed to design the optimal stacked thin film structure for smart windows which control the solar radiation and heat transmission from the viewpoint of high luminous transmission.