S. Sudersan

Bio: S. Sudersan is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Nonlinear system & Magnetoelectric effect. The author has an hindex of 2, co-authored 6 publications receiving 23 citations.

Bipolar magnetostriction in CoFe2O4: Effect of sintering, measurement temperature, and prestress

Abstract: Magnetostrictive materials are potential candidates for many applications such as sensors, actuators, transducers, and other magnetoelectric applications. Cobalt ferrite ( CoFe 2 O 4) has proven to be favorable in comparison with commonly used magnetostrictive materials due to its high magnetostriction coefficient and low cost. This work deals with the synthesis of CoFe 2 O 4 and subsequent characterization of its magnetostrictive properties. Hydrothermal route was adopted for the synthesis, and the effect of sintering and measurement temperatures on the magnetostrictive response of the synthesized samples was also established. Bipolar magnetostriction has been observed in pure CoFe 2 O 4 for the first time, and its control by means of the sintering temperature has been elucidated. The results thus reveal that the temperature is an important parameter in determining the magnetostrictive characteristics of CoFe 2 O 4. The switching from bipolar to unipolar magnetostriction under elevated sintering and measurement temperatures was also observed, and this was owed to the crystal anisotropy of the material. The effect of prestress on the magnetostriction was also studied, wherein it was observed that the application of a compressive prestress resulted in broadening of the magnetostriction loops. The reported bipolar magnetostrictive characteristics are quite interesting and hence can prove to be cost-effective in comparison with existing magnetostrictive materials.

Stress-dependent nonlinear magnetoelectric effect in press-fit composites: A numerical and experimental study

Abstract: Magnetoelectric (ME) composites have posed an immense research interest over the past few decades. Their multifunctional capabilities enable a wide array of applications like field and pressure sensors, energy harvesters, gyrators, etc. The voltage developed under applied magnetic fields in these composites is governed strongly by the stress and magnetization state of the magnetostrictive phase, which needs to be characterized effectively. Towards this end, magnetostriction measurements are carried out under applied stresses in Nickel to understand its magnetomechanical response. A three-dimensional magnetostrictive constitutive model is used to predict the magnetostrictive behavior, which is later implemented in COMSOL Multiphysics® using the external material module. The FE solutions obtained are validated against analytical solutions. The model is subsequently used to obtain FE solutions for the magnetoelectric response of press-fit composites subjected to general magneto-thermo-mechanical loading. Experiments are performed on the press-fit composite to validate the voltage response predicted by the developed model, which shows a good agreement. The developed FE model is used to conduct a parametric study to quantify the effect of external loading conditions, the shape of inclusion, and the field orientation with an effort to optimize the ME response in press-fit ME composites.

Finite element formulation for implicit magnetostrictive constitutive relations

Abstract: Magnetostrictive materials that couple mechanical and magnetic domains have been widely explored for use in sensors and actuators. These materials often exhibit a nonlinear material response under applied magnetic fields, which limits the use of linear constitutive models. Furthermore, the nonlinear constitutive relations tend to be implicit in nature. Hence, a finite element scheme that can handle the implicit relationship between the mechanical (stresses and strains) and magnetic (magnetic flux density and magnetic field) quantities is proposed in order to arrive at solutions to boundary value problems. In the proposed scheme, while the physical requirements of equilibrium and strain–displacement relation are satisfied point-wise, the constitutive relations hold in a weak integral sense. A fully coupled magnetostrictive plane stress rectangular element is developed based on the proposed scheme and its efficacy in arriving at solutions to coupled field boundary value problems is illustrated by subjecting the element to standard loading conditions.

RESEARCH ARTICLE Finite element simulation of the magneto-mechanical response of a magnetic shape memory alloy sample

Abstract: In this paper, the stress- and magnetic field-induced variant reorientation in a magnetic shape memory alloy (MSMA) sample is simulated by using the finite element method. This model is set up based on a three-dimensional setting with the whole sample and the surrounding space taken into account.Atypical loading pattern is proposed on the sample. The unknowns of the model governing system include the spatial displacement vector, the scalar magnetic potential and some internal variables related to the effective magnetization vector. By considering the different properties of the unknowns, an iterative computational scheme is proposed to derive the numerical solutions. With the obtained solutions, the magneto-mechanical response of the MSMA sample under different field and stress levels can be predicted. The distributions of the variant state and the effective magnetization in the sample can also be determined. By comparing with the experimental results, it is found that the numerical solutions obtained in this model can predict the response of the MSMA sample at a quantitative level.

Modeling of resonant magnetoelectric response in press-fit embedded ring composite

Abstract: Magnetoelectric (ME) effect is a product property arising out of the interactions between the piezoelectric and the magnetostrictive phase. Multi-phase ME composites being multifunctional materials find use in myriad of applications. In this work, epoxy free two phase and three phase embedded ring ME composites have been fabricated by the press-fit technique. For a comparative study, three phase conventional epoxy bonded ring shaped composite of same dimensions have also been fabricated. Dynamic ME experiment has been conducted at room and elevated temperatures on all the prepared composites. It is shown that the epoxy free composite by virtue of the absence of epoxy shows a better resonant ME response at all temperatures. The significance of the Electromechanical Resonance (EMR) in the resonance behavior of the composites has also been highlighted. An analytical model in cylindrical coordinate system incorporating the temperature effects on the individual composite constituents and their interface coupling has been developed based on the concentric ring approach to predict the dynamic ME behavior of the epoxy free ring composite at different temperatures. The model has been further used to study the effect of volume fraction of the constituents on the ME response.