An attempt has been made in this work to develop a simple yet efficient sun tracking mechanism (SSTM) using smart shape memory alloy (SMA). This mechanism is directly activated by the sun dispensing with the requirement of an additional external source to power it. The SMA element incorporated in the SSTM device performs the dual functions of sensing and actuating in such a way as to position the solar receptor tilted appropriately to face the sun directly at all times during the day. The mechanism has been designed such that the thermal stimulus needed to activate the SMA element is provided by the concentration and direct focusing of the incident sun rays on to the SMA element. This paper presents, in detail, the design and construction adopted to develop the functional model that was fabricated and tested for performance.

Magnetorheological (MR) gels are a new class of soft polymers whose properties can be controlled using a magnetic field. The functional effectiveness of these gels depends on their magnetic controllability. In this paper, an experimental investigation on the functional behavior of a particular type of magnetorheological gels under dynamic and static shear conditions in the presence of a magnetic field is studied. MR gels are prepared with micron sized polarizable carbonyl iron particles interspersed in a polymer matrix gel. The compliance of this magnetic gel can be varied under the influence of an external magnetic field. Since dynamical mechanical analysis tests are difficult to conduct in the presence of large deformations of the order of 50% and strong magnetic fields, a free decay test apparatus is designed and fabricated for obtaining the magnetic field dependent shearing response under dynamic conditions at room temperature. It is observed that a significant change in the elastic modulus occurs in the gels under a magnetic field in the range of 0.1-0.4 T. However, no significant change in the damping ratio is observed under various magnitudes of magnetic field. It is shown that the increase in shear modulus of this kind of magnetic composite gel could be as high as 59% of the zero field value for a gel prepared with 50% by weight of carbonyl iron particles.

Composite structures exhibiting magnetoelectric (ME) coupling behavior have applications in various fields such as energy harvesting, sensors and actuators. ME coupling behavior is considered to occur by transfer of strain through bonding of the constituent phases of the ME composite. Here, the influence of thermal environment on the constitutive behavior of ferroic phases was examined, firstly by conducting experiments at various temperatures. To mimic the constitutive behavior of ferroic phases, constitutive models were built based on a thermodynamic framework. In order to account for thermal effects, appropriate functions were introduced to the formulation. Model parameters were chosen based on experimental data and simulation studies were performed. The obtained results were found to be in agreement with the experiments. Additionally, an attempt was made to capture the mechanical, electrical, magnetic and ME coupling behavior of composites. To capture the response of ME composites, a homogenization technique was employed along with the proposed constitutive relation for the constituent phases of an ME composite.

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This work is aimed at the development of a finite element formulation for the analysis of unsymmetric magneto-electric (ME) laminated structures. While analytical solutions are readily available for symmetric structures, the coupling between axial and bending deformations in unsymmetric structures impedes such an analytical solution thus motivating the search for a numerical solution. The proposed finite element model includes this coupling under Euler-Bernoulli assumptions and further includes the material nonlinearity exhibited by the ferromagnetic phase. The enhancement of the ME coefficient under resonant conditions has also been studied under bending and axial resonant regimes. Resonant ME coefficients of magnitude at least 30 times higher than the quasi-static values were estimated. A parametric study has also been performed with the aim of optimizing the ME coefficient with respect to the applied DC bias field, operating frequency, volume fraction and the modulus ratio of the constituents and the different boundary conditions. The boundary conditions yielding a cantilever configuration were found to offer the least bending resonant frequency and the highest axial resonant ME coefficient, thus proving to be the most viable in practice.

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