Department of Applied Mechanics

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Smart materials integrated with thin walled structures can be used to achieve the desired shape, stiffness, damping and other mechanical properties of structures in response to the induced changes in temperature, electric or magnetic field in these, without causing any significant change in the mass as is required in aerospace applications. In this paper, the effects of surface bonded piezo ceramic (PZT-Lead Zirconate Titanate) actuation patches to enhance the strength of thin composite cylindrical shells have been studied experimentally and numerically under the actuation of PZT. The study reveals that it is feasible to minimize the effects of the local imperfections and increase the strength closer to the theoretical buckling strength. However, it has been found that even with the currently available PZTs with minimum thickness, the strength of the tested shell increases owing to the added stiffness of the PZT than due to the actuation. Furthermore, with thinner PZTs of thickness of the order 0.01 times the thickness of the shell and with high actuation force, improvements in the shell capacity is possible by the application of voltage. In addition, the actuation of PZT can be used to decrease the radial buckling deformation for any given load. Importantly, the effect of PZT actuation would increase if the initial imperfections are large leading to larger reductions in the ultimate strength of the shell. Finally, a numerical procedure is established to corroborate the experimental results and also for arriving at an optimum PZT configuration. © 2021 Elsevier Ltd

World University root node

Thin-Walled Structures

Investigations on axially compressed composite cylindrical shells with surface bonded PZT

Fulltext

Frontiers in Human Neuroscience

A Framework for Sensor-Based Assessment of Upper-Limb Functioning in Hemiparesis

The present paper reports findings of the 3D computational studies of the effect of frontal gusty shear flow on the force patterns of a flapping wing. A rigid wing with semi-elliptical wing planform with asymmetric 1 DoF flapping kinematics was exposed to a gusty shear flow. The shear gradient of the flow was varied from −10 to +10 in steps of 5. Computation studies were carried out for Re = 150 which lies in the typical flight Reynolds number range of natural flyers like a fruit fly and anthropogenic flyers like a Pico Aerial Vehicle. 3D, unsteady, laminar, and incompressible Navier-Stokes equations were solved using finite volume formulation based commercial code ANSYS Fluent. Wing kinematics and gusty inflow conditions were modelled into the solver by User Defined Functions (UDFs). Wing motion was simulated using the dynamic meshing technique. The effect due to variation in the frontal inflow condition was studied quantitatively and qualitatively. Comparisons of the instantaneous and gust cycle averaged forces and moment coefficients about the wing root mid chord point and 3D phase space projections of the forces and moment coefficients was carried out. Qualitative studies were carried out by comparing the static pressure over both the surfaces of the wing and the vortex patterns near the flapping wing using λ2–criteria. It was observed from these studies that negative shear gradient resulted in a rise in the vertical force and moment and a minor reduction in the horizontal force. Positive shear gradient resulted in a minor rise in horizontal force and a significant reduction in vertical force and moment. © 2021, Springer Nature Singapore Pte Ltd.

Lecture Notes in Mechanical Engineering

3D Computational Studies of Flapping Wing in Frontal Gusty Shear Flow

The present paper aims to gain an understanding of the physics associated with the fluid-structure interaction behavior of a flexible filament interacting with the wake of an upstream rigid cylinder situated at a finite distance. The computational framework of the present high fidelity numerical simulations consist of an incompressible Navier-Stokes solver strongly coupled with a chord-wise flexible structural model based on a partitioned approach. The effect of body-wake interactions on the resulting vibrating modes of the chord-wise flexible foil due to its passive flapping is studied in detail. The gap between the cylinder and the flexible filament is seen to play a major role in the vortex impingements on the flexible flapper and the subsequent interactions. Insights are obtained into the dynamics through a parametric study for different values of this finite gap. Moreover, the effect of the length and thickness of the flapper on its dominant mode-shapes is also investigated. The present study shows that higher values of the gap and the length of the filament lead to the loss of periodicity in the body-wake interactions which is of current interest. © 2021, The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Department of Aerospace Engineering

Investigating Fluid-Structure Interaction Behavior of a Chord-Wise Flexible Filament in the Wake of a Bluff Body Using Partitioned Strong Coupling Approach

Mesenchymal stem cells (MSCs) are so far the most widely researched stem cells in clinics and used as an experimental cellular therapy module, particularly in cardiac regeneration and repair. Ever since the discovery of cardiomyogenesis induction in MSCs, a wide variety of differentiation protocols have been extensively used in preclinical models. However, pre differentiated MSC-derived cardiomyocytes have not been used in clinical trials; highlighting discrepancies and limitations in its use as a source of derived cardiomyocytes for transplantation to improve the damaged heart function. Therefore, this review article focuses on the strategies used to derive cardiomyocytes-like cells from MSCs isolated from three widely used tissue sources and their differentiation efficiencies. We have further discussed the role of MSCs in inducing angiogenesis as a cellular precursor to endothelial cells and its secretory aspects including exosomes. We have then discussed the strategies used for delivering cells in the damaged heart and how its retention plays a critical role in the overall outcome of the therapy. We have also conversed about the scope of the local and systemic modes of delivery of MSCs and the application of biomaterials to improve the overall delivery efficacy and function. We have finally discussed the advantages and limitations of cell delivery to the heart and the future scope of MSCs in cardiac regenerative therapy. Graphical abstract: [Figure not available: see fulltext.] © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.

Department Of Biotechnology

Stem Cell Reviews and Reports

Mesenchymal Stem Cells for Cardiac Regeneration: from Differentiation to Cell Delivery

We demonstrate the formation of a versatile luminescent organo-inorganic layered hybrid material, composed of bovine serum albumin (BSA)-protected Au30 clusters and aminoclay sheets. X-ray diffraction revealed the intercalation of Au30@BSA in the layered superstructure of aminoclay sheets. Coulombic attraction of the clusters and the clay initiates the interaction, and the appropriate size of the clusters allowed them to intercalate within the lamellar aminoclay galleries. Electron microscopy measurements confirmed the hierarchical structure of the material and also showed the cluster-attached clay sheets. Zeta potential measurement and dynamic light scattering probed the gradual formation of the ordered aggregates in solution. The hybrid material could be stretched up to 300% without fracture. The emergence of a new peak in the luminescence spectrum was observed during the course of mechanical stretching. This peak increased in intensity gradually with the degree of elongation or strain of the material. A mechanochromic luminescence response was further demonstrated with a writing experiment on a luminescent mat of the material, made by electrospinning. © 2021 American Chemical Society.

Department of Metallurgical and Materials Engineering

Department Of Civil Engineering

Department of Computer Science and Engineering

Department Of Chemistry

ACS Applied Materials and Interfaces

Hierarchical Assembly of Atomically Precise Metal Clusters as a Luminescent Strain Sensor

Laser-Induced Breakdown Spectroscopy (LIBS) technique is used to determine the emission intensity of inorganic elements, such as Si, Fe, Mg, Al, Ca, Na, and K in coal samples. The average emission intensity of the inorganic elements increases with the ash content of the coal sample with R2 = 0.82. Using the LIBS data, partial least square regression (PLSR)-based multivariate analysis was performed to determine the coal ash content. The PLS approach combined with the LIBS technique resulted in the coefficient of correlation R2 = 0.93, root-mean-square error RMSE = 3.5%, standard deviation SD = 11.7% and resolution = 3.7% corresponding to the reference ash data. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Department of Engineering Design

Springer Proceedings in Physics

Determination of Ash Content in Coal Using Laser-Induced Breakdown Spectroscopy with Multivariate Analysis

The aim of our study is to investigate the effect of boron with different ratios in Ti-Cu-Pd-Zr metallic glass (MG) matrix (Ti-Cu-Pd-Zr:B) fabricated by Pulsed Laser Deposition (PLD) for biomedical implants. The Ti based Thin Film Metallic Glasses (TFMGs) in combination with boron (in different atomic %) was assessed in attaining the combined properties, like outstanding corrosion resistant properties and good biocompatibility in this work. The disordered structure and amorphous nature of the Ti-Cu-Pd-Zr:B thin films systems were achieved by the PLD process and affirmed by XRD and transmission electron microscopy. The boron incorporation in the TFMG has been elucidated by XPS analysis. The boron containing films displays distribution of boron protuberances interleaved in the amorphous matrix was stated from SEM analysis. It is found that increase in atomic percentage of boron contents in TFMG results in the improvement in glass transition temperatures. The electrochemical parameters suggest better corrosion resistance and capabilities of passivity when boron percentage was increased in the film thereby preventing adverse biological reactions. TFMGs exhibited excellent hemocompatibility by preventing the platelet activation. MTT assay manifests increase in cell concentration with culture period on the TFMGs for the MC3T3-E1 preosteoblasts cells. Cell morphology was also studied which confirmed the viable state of the cells on the TFMG surfaces. The combination of such distinctive properties marks these TFMG systems as prospective aspirants for biomedical implants. © 2021

Colloids and Surfaces B: Biointerfaces

Biological performance of metal metalloid (TiCuZrPd:B) TFMG fabricated by pulsed laser deposition

Analysis of uterine contractions using electromyography signals is gaining importance due to its capability to measure the dynamics of uterus. Uterine electromyography (uEMG) provides information on the nature of uterine contractions non-invasively. In this study, the fluctuations in uEMG signals associated with Term pregnancies are analyzed. For this, Term uEMG signals corresponding to second (T1) and third (T2) trimesters are considered. The signals are subjected to Adaptive Fractal Analysis (AFA), wherein a global trend is obtained by using overlapping windows of three orders namely, 25%, 50% and 75%. The signals are detrended and the fluctuation function is estimated. Two Hurst exponent features computed at short range (Hs) and long range (Hl) are extracted and statistically analyzed. Results show that AFA is able to characterize variations in the fluctuations of Term delivery signals. The feature values are observed to vary significantly during different weeks of gestation. It is found that features of T2 signals are higher than that of T1 signals for all the considered overlaps, indicating that T2 signals possess smoother characteristics than T1 signals. Further, coefficient of variation is observed to be low, indicating that these features are able to handle the inter-subject variations in Term signals. Therefore, it appears that the proposed approach could aid in investigation of progressive changes in uterine contractions during Term pregnancies. © 2021 IPEM

Medical Engineering and Physics

Differentiation of fluctuations in uterine contractions associated with Term pregnancies using adaptive fractal features of electromyography signals

In this paper, the potential of superelastic shape memory alloy (SE-SMA) wire embedded architectures to increase the quasi-static indentation properties of a laminated glass/epoxy composite material was evaluated. Three types of SE-SMA configurations namely straight independent, meshed and anchored wires were embedded in the glass/epoxy composite laminates via a vacuum bag resin infusion technique. Throughout this investigation, the changes in the quasi-static indentation behavior and allied damage mechanisms due to these embedments were compared with the homogenous glass/epoxy laminates. Real time acoustic emission (AE) monitoring technique was employed to characterize the damage profile of the different glass/epoxy specimens during the quasi-static indentation tests. The experimental results showed that SE-SMA embedments play a vital role in increasing the penetration resistance by enhancing redistribution of the indentation load all across the laminates. In particular, the meshed specimens restricted penetration of an indenter and delayed the critical fiber fracture unlike homogeneous and straight wired ones, whereas the anchored specimens further restricted extensive SMA/matrix pull-out, unlike meshed ones and provided the most excellent balance among rigidity, rear face fiber breakage, and SMA/matrix pull-out. Straight, meshed and anchored SE-SMA wires increased the load-carrying capacity approximately by 31%, 79%, and 100%, respectively, in comparison to the homogeneous ones. © 2020 The Authors