Indian Institute of Technology Hyderabad (IITH) is a premier institute of science and technology established in 2008. IITH has been consistently ranked in the&nbsp;<a href="https://iith.ac.in/reports/" rel="noopener noreferrer">top 10 institutes</a>&nbsp;in India for Engineering&nbsp;<a href="https://www.nirfindia.org/2021/EngineeringRanking.html" rel="noopener noreferrer" target="_blank">according to NIRF</a>&nbsp;making it one of the most coveted schools for science and technology in the country.

IITH offers&nbsp;<a href="https://iith.ac.in/academics/under-graduate/">undergraduate programs</a>&nbsp;in all the classical engineering disciplines, applied sciences, design, as well as several modern interdisciplinary areas. Students are given a flexibility to explore a broad set of areas, and potentially pursue a minor or double major in a discipline that is not their own. Students who wish to seek a deeper understanding of their own discipline are strongly encouraged to get involved in cutting-edge research with the help of a faculty to mentor them, and earn an Honors in their own field.

The very foundation of IIT Hyderabad is based on&nbsp;<a href="https://iith.ac.in/research/">research and innovation</a>. The vibrant research culture is evident from the number of patents and publications that IITH produces consistently every year. IITH offers&nbsp;<a href="https://iith.ac.in/academics/programmes-offered/">graduate programs</a>&nbsp;at both a masters, and a doctoral level, in several diverse areas. There are separate programs for technology, design, science, and liberal arts. The&nbsp;<a href="https://iith.ac.in/academics/post-graduate/">MTech program</a>&nbsp;is offered in various modes and durations to cater to the ever-growing need of postgraduate level professionals in the country.

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IITH enjoys a very special relationship with Japanese universities and industries that goes beyond academic and research collaborations. In fact, some of the iconic buildings in IITH campus will carry the signature of Japanese architecture.

IITH creates a unique holistic ecosystem for education that offers interactive learning, a very flexible academic structure, cutting-edge research, strong industry collaboration, and entrepreneurship. This is an environment which enables students and faculty to translate their dreams into realities.

IIT Hyderabad

In this article, the size-dependent mechanical response of an isotropic functionally graded (FG) microbeam has been investigated. The size-effects over the elastic response have been modeled by the Mindlin-Toupin strain gradient theory, with the coefficients evaluated from the generalized first strain gradient theory of elasticity. In order to facilitate the derivation of the exact solutions to the governing differential equations of equilibrium, an exponentially graded FG beam is chosen. These exact solutions are derived for a simply supported beam subjected to a sinusoidally distributed mechanical load. Following this, an element-free Galerkin (EFG) model involving moving least squares interpolations across the domain is also developed here. The EFG model is validated with the exact solutions for the exponentially graded beam. Finally, the EFG model is extended to the more general case of a power law-graded beam. The mechanical responses for the power law-graded beams under various loading and boundary conditions are presented here. These results may serve as benchmark for further studies over size-effects in FG beams. © 2019 The Author(s). Published by Oxford University Press; all rights reserved.

Department of Mechanical and Aerospace Engineering

World University root node

Quarterly Journal of Mechanics and Applied Mathematics

Size-Dependent elastic response in functionally graded microbeams considering generalized first strain gradient elasticity

In this paper, exact solutions for the static bending response of laminated composite beams have been derived considering the effect of strain gradient elasticity. Separate solutions for the laminate comprising of isotropic and orthotropic laminae have been presented here. The sixth-order tensor for the higher order elastic coefficients has been evaluated using the generalized first strain gradient elasticity model with three independent material length constants. The significance of the gradient elasticity in low-dimensional structures has been established employing numerical examples of micro and nano-beams, and comparing the current results with the classical elasticity results. A parametric study over the variation of the axial, transverse Cauchy and physical stresses across the thickness of the beam has been conducted. Also, the discontinuity of the inter-laminar transverse Cauchy stresses and higher order stresses across the thickness has been studied in the current framework. The exact solutions developed in this paper may be used as benchmark results for validating further research involving the strain gradient elastic response of low-dimensional laminated composite beams. © 2018 Elsevier Ltd

Composite Structures

Exact solution for size-dependent elastic response in laminated beams considering generalized first strain gradient elasticity

The effective flexoelectric coefficients of a multifunctional flexoelectric fiber reinforced composite (FLFRC) have been estimated using an analytical micromechanics based model. The analytical estimation carried out here has been validated with the effective piezoelectric and the fourth-order elastic constants of the composite available in literature. The effective flexoelectric coefficients of the composite show a size-dependent effect, not seen in similar calculations for piezoelectric composites. Also, above a critical fiber volume fraction with a suitable choice of matrix, the effective flexoelectric properties of the FLFRC can be tailored to be significantly superior to those of the monolithic dielectric solid. It is noted that, the FLFRC can be customized to have negative axial flexoelectric coefficients. This study opens new avenues for further research on developing smart nanocomposites characterized with enhanced functional properties. © 2018 Elsevier Ltd

Materials Today Communications

Effective properties of flexoelectric fiber-reinforced nanocomposite

This paper treats an inclusion problem in the framework of a generalized strain gradient theory (GSGT) of elasticity. The GSGT used here consists of three material characteristic length scales for the evaluation of the elastic response. The Green’s function for the governing differential equations, involving stresses and higher-order stresses, is obtained considering the strain gradient model mentioned above. Then, Eshelby’s tensor is derived in the current framework for an inclusion of any arbitrary shape, under uniform eigenfields. This general form of the Eshelby’s tensor is used to derive closed-form expressions for a spherical inclusion and an infinitely long cylindrical inclusion, each embedded in an unbounded matrix to ignore the boundary effects. To determine the homogenized properties of the composites considering size-effects, the volume averages of the position-dependent Eshelby’s tensor are evaluated for both the inclusions. All the results from the current study match the corresponding results from classical elasticity, when the strain gradient effects are ignored. The homogenized properties of composites with either of the inclusions are strongly influenced by the gradient effects when the dimensions of the inclusions are comparable to the characteristic length scales. They approach the volume averages evaluated using classical elasticity, when the dimensions of the inclusion are very high in comparison with the characteristic lengths. The current study presents the importance of considering the size-effects using GSGT, without any assumption, for the evaluation of the effective properties of the micro- and nano-composites. © 2018, Springer-Verlag GmbH Austria, part of Springer Nature.

Acta Mechanica

Inclusion problem for a generalized strain gradient elastic continuum

This paper presents the constitutive modeling of the flexomagnetic (FM) effect in structures involving a non-zero magnetic field generated in the presence of inhomogeneous strain across the domain. In order to evaluate the magneto-elastic (ME) structural response, the tensorial governing equations and associated boundary conditions for the mechanical and magnetic variables are derived here using the variational principle. Following this, these differential equations are solved to determine the effect of FM over the bending response of a cantilever piezomagnetic nanobeam. Different magnetic boundary conditions are analyzed to study the effect of direct and converse FM couplings over the ME response. The significant influence of FM coupling over the ME response has been noted for thin beams with low-dimensions, which wanes as the geometric dimensions are increased. Given the significance of this size-dependent FM response in nano-structures, the theory for flexomagnetism proposed here may be utilized in the development of smart ME nano-structures with the potential for wide applications. © 2018 Author(s).

Fulltext

Journal of Applied Physics

Flexomagnetic response of nanostructures

This paper deals with the investigation of the static bending response of nano-beams upon application of a mechanical load, considering the effect of gradient elasticity. The gradient elasticity is modelled using the strain gradient elasticity model with three independent material length constants. For the numerical modelling of the structural response, the higher-order displacement theory is used. The element-free Galerkin method is employed to interpolate the displacement field in the continuum in terms of the nodal displacements. Thereafter, using the variational principle, the governing equations of motion in terms of the nodal displacements are derived in the algebraic form. The model developed in this paper is validated by comparison with the exact solutions available in the literature, for the specific case of a simply supported beam under a sinusoidally distributed load. Following this, the numerical model is solved for various other boundary conditions and loading functions. The effect of the strain gradient elasticity is studied for different aspect ratios, and the results are compared. The reduction of the bending response due to the strain gradient effect is compared for each case. A comparison of the effects of each of the material length scales, corresponding to different forms of the higher-order gradients, over the structural response is performed. The present study reveals that the strain gradient elasticity must be considered for an accurate analysis of nanostructures. © 2018, Springer-Verlag GmbH Austria, part of Springer Nature.

Element-free Galerkin model of nano-beams considering strain gradient elasticity

The paper is concerned with the development of finite element model for the static analysis of smart nanobeams integrated with a flexoelectric layer on its top surface, using nonlocal elastic theory. The flexoelectric layer acts as a distributed actuator of the nanobeam. A layerwise displacement theory has been used to derive the element stiffness matrices from variational principles incorporating nonlocal effects. The finite element model for nonlocal response of the beams has been validated with the exact solution for the case of a simply supported standalone flexoelectric layer. Also, the finite element model of the simply supported smart beam has been validated with exact solutions and numerical models for the local elastic case. The performance of the flexoelectric actuator has been compared for different values of nonlocal parameters and different combinations of nonlocal and local elastic substrate and flexoelectric layer. Further, the model developed has been utlized for investigating the performance of the active flexoelectric layer in case of cantilever beam, for which the exact solutions are not available. © 2017, Springer Science+Business Media Dordrecht.

International Journal of Mechanics and Materials in Design

Effect of nonlocal elasticity on the performance of a flexoelectric layer as a distributed actuator of nanobeams

This paper deals with the derivation of the exact solutions for the static electro-mechanical response of a simply-supported doubly curved (DC) smart shell, composed of a piezoelectric fiber reinforced composite (PFRC) placed over a laminated substrate. These responses are evaluated when the system is subjected to distributed electrical and mechanical loads. The electro-mechanical governing equations and the associated boundary conditions have been derived here for the curvilinear coordinate system using the variational principle. Closed-form expressions for the mechanical displacement and the electrical potential have been obtained by solving these governing differential equations and simultaneously satisfying the derived boundary conditions. Numerical results have been presented for different shell geometries. The effect of the curvature and the geometric parameters of the PFRC layer over its performance as an actuator are studied and compared for these shells. Also, the effect of varying geometric parameters of the PFRC over its performance as a sensor is studied. Optimal dimensions of the PFRC for use as an actuator and sensor/harvester have been proposed. This study may be considered as a benchmark for use in the numerical and experimental studies involving smart shells. © 2018