Department of Mechanical Engineering

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

The primary objective of this project is to increase the fatigue life of aluminium wheels and to prevent the fatigue failure of the wheel above the bolt hole region. In the testing and validation of wheels, the cornering fatigue test (CFT) plays an important role in deciding the stiffness of the wheel. In CFT testing, the wheel will be fixed in the bottom flange, and the bending moment will be applied, according to the load rating of the wheel multiplied by its corresponding test factor. CFT testing results of aluminium wheels showed crack above the bolt hole region in most of the cases. To prevent this mode of failure, and also to improve the fatigue life of the wheel further, it has been found that increasing the localized hardness above the bolt hole region will improve the fatigue life in CFT. Laser peening is a surface hardening technique by which the surface hardness of the material will be enhanced, along with which hardness and compressive residual stresses will be imparted on the surface in which the treatment is done. The depth of the high magnitude compressive stresses will greatly improve the material’s resistance to fatigue failure. In aluminium wheels, laser peening was done circumferentially around the bolt hole region to induce localized compressive stress and increase the hardness in that area. The wheel in which laser peening was done was tested on CFT and showed a significant improvement in life. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd 2021.

World University root node

Department Of Chemical Engineering

Lecture Notes in Mechanical Engineering

An innovative method of preventing bolt hole crack in aluminium wheels by using laser peening technique

Carbon fiber reinforced polymer (CFRP) composites are preferred for their specific strength and toughness. As fibers are the main load-bearing constituent of composites, fiber breakage has a significant effect on their strength and stiffness. The complex nature of damage involving oriented fiber breakages across multiple layers has posed a challenge to manufacturers and end-users alike. While detailed investigations of the damage have been carried out using micro-CT scans, assessment of oriented fiber breakages with field-deployable non-destructive techniques would facilitate our understanding significantly. A new scheme deploying induction thermography to detect fiber breakage and identify its orientation is proposed. It is experimentally demonstrated on samples with realistic fiber breakage produced in a controlled manner. Further, a numerical model capturing the proposed inspection mechanism is described. © 2021

NDT and E International

Identification of the fiber breakage orientation in carbon fiber reinforced polymer composites using induction thermography

Majority of the industrial and domestic fire accidents occur due to electric short circuits. Hence, it is imperative to monitor the condition of electric power box to facilitate preventive maintenance. The key reasons for power box failure are overheating, tripping, and arcing/sparking at the electric joints. This paper reports on the online condition monitoring of electric power box using the waveguide sensing technology. The critical components of the power box are monitored, namely; Miniature Circuit Breaker (MCB), Solid State Relay (SSR), and Contactor. A pair of wire waveguides is designed to monitor overheating as well as the occurrence of tripping in the MCB. While one waveguide functions as an active ultrasound temperature sensor, the other acts as a passive acoustic emission based arcing sensor. During the overheating experiments, the ultrasound sensor precisely measures the temperature gradient along multiple points on the sub-components, with a minimum gauge length of 10-15mm. The perturbation caused due to MCB tripping is successfully captured by the passive acoustic emission sensor and the location of tripping is determined. Both the overheating temperature and tripping signature are detected by the waveguide transducer system. This work has potential application in industrial and commercial establishments to ensure improved reliability and workplace safety. © 2021 by ASME

Proceedings of 2021 48th Annual Review of Progress in Quantitative Nondestructive Evaluation, QNDE 2021

ONLINE MONITORING OF ELECTRIC POWER BOX USING WAVEGUIDE SENSORS

The spatial variation in the wettability of a surface can have a significant effect on the spreading and retraction behavior of an impacting droplet and hence the overall impact dynamics. Although composite surfaces have proven applications, there is a lack of understanding of droplet impact on surfaces with a sudden jump in wettability. Here, we study the behavior of a liquid drop impacting a composite surface having a superhydrophilic (SHL) spot surrounded by a superhydrophobic (SHB) region. We find that the droplet exhibits different regimes: no-splitting, jetting, and splashing, depending upon the spot size (βs) and the Weber number (We). At a smaller βs, the behavior shifts from the stable to jetting regime and then to the splashing regime, with increasing We. We find that by increasing the value of βs, one can avoid the undesirable splashing and jetting regimes and attain a stable regime even at a higher We. Our study reveals that βs has a significant influence on the maximum spreading diameter βmax at a smaller We but a negligible effect at a higher We. We show that the dominance of capillary energy at a smaller We and viscous energy at a higher We underpins the phenomena. We employ an energy conservation approach to develop an analytical model to predict βmax on a composite SHL-SHB surface by considering the total energy of the system before the impact and at the maximum spread position. We find K = (Re1/2/We) emerges as a key parameter in the model that accurately predicts the experimentally measured βmax. Our study reveals the existence of an inertia-viscous dominated regime at a smaller K and an inertia-capillary dominated regime at a larger K. The outcome of our study may find applications in stable and precise positioning of impacting droplets. ©

Langmuir

Drop impact on a superhydrophilic spot surrounded by a superhydrophobic surface

Handling and manipulation of particle-encapsulating droplets (PED) have profound applications in biochemical assays. Herein we report encapsulation of microparticles in aqueous ferrofluid droplets in a primary continuous phase (CP) and sorting of PED from empty droplets (ED) at the interface of the CP in coflow with a second continuous phase using a magnetic field. We find that the encapsulation process results in a size contrast between the PED and ED that depends on the flow regime - squeezing, dripping, or jetting - which in turn is governed by the ratio of the discrete phase to the continuous phase capillary number, Car. The difference between the volume fractions of ferrofluid in the PED and ED, ΔαPED, is utilized for sorting, and is found to depend on the ratio of the capillary numbers, Car. The difference ΔαPEDis found to be maximum in the jetting regime, suggesting that the jetting regime is most suitable for encapsulation and sorting. The sorting criterion is represented in terms of a parameterξ, which is a function of the ratios of the magnetic force to the interfacial force experienced by the PED and ED. Our study revealed that sorting is possible forξ&lt; 0, which corresponds to ΔαPED&gt; 0.25. The maximum sorting efficiency of our system is found to be ∼95% at a throughput of ∼100 drops per s. © The Royal Society of Chemistry 2021.

Soft Matter

Particle encapsulation in aqueous ferrofluid drops and sorting of particle-encapsulating drops from empty drops using a magnetic field

Invasive alien plant species Prosopis juliflora is materialized into valuable biomass-derived carbon for sensing application. In the present work, biomass-derived carbon with decorated SnO2 nanoparticles is synthesized by the sol-gel process and tested for hazardous NO2 gas sensing applications. The uniformly decorated SnO2 nanoparticles and biomass carbon support facilitated the adsorption/desorption of target gas on the surface of the sample. The biomass-SnO2 nanocomposite has shown a very good response and a maximum sensitivity of 31.1% towards highly toxic NO2 gas of 90 ppm at 50° C. The gas sensor's performance is evaluated over a range of NO2 concentrations of 10-90 ppm. Therefore, the invasive species is shown as an alternative carbon support material and successfully demonstrated for NO2 gas sensing applications. © 2021 IEEE.

Proceedings of IEEE Sensors

Invasive Species Prosopis juliflora Derived Carbon Biomass/SnO2based Hazardous NO2Gas Sensor

The dynamical motion of a pair of microparticles exposed to acoustic standing waves and located at the pressure nodal plane is studied using numerical simulations and experiments. The insight into their dynamical behavior along the pressure nodal plane due to the competition between the axial primary radiation and interparticle forces is elucidated. An expression for axial primary radiation force acting on a particle is derived, and the particle dynamics is simulated using fluid-structure interaction model based on the arbitrary Lagrangian-Eulerian method. Considering the total radiation force acting on a particle is the sum of the axial primary radiation force and the interparticle force, three distinct dynamical regimes are observed depending upon the relative magnitudes of the acoustic forces which in turn depend on the gradient of the acoustic energy density. Acceleration, deceleration, and constant velocity motion of the pair of approaching particles are observed, which are explained by the interplay of the acoustic and non-acoustic forces. The dynamical motion of the pair of particles predicted using the model is in very good agreement with the experimental observations. © 2021 Acoustical Society of America.

Journal of the Acoustical Society of America

Dynamical motion of a pair of microparticles at the acoustic pressure nodal plane under the combined effect of axial primary radiation and interparticle forces

This two-part article examines the distribution of metallic layers through the thickness of fiber metal laminates (FMLs) on their response and damage when subjected to high-velocity projectile impact. Glass fiber/epoxy and Ti-6Al-4V titanium alloy sheets are used to obtain four different layups of FMLs fabricating by the hand layup process and exhibiting the same thickness of the total metal layer. Part I deals with experimental investigations of fully clamped square FMLs normally impacting at the center by hemispherical steel projectile using compressed air gun set up. Different parameters are considered to evaluate the FMLs’ performance, which includes damage degree, first cracking energy, crack length, deformation profile, and damage developed on the surface and inside the laminate. The results indicate that the highest permanent deformation and cracking are exhibited by FML 4/3-0.3, exhibiting separation of composite layers with different orientations by the metallic layer. The other FMLs exhibit lower and approximately similar permanent deformations. However, lower cracking and a relatively higher lateral delamination spread and opening of the interlayer are exhibited by FML 2/1-0.6 in which composite layers are arranged together than FML 4/3-0.3, signifying that the damage spreading laterally can be reduced by dispensing titanium layers. The ballistic resistance is found to be similar for FMLs. The levels of permanent deformation, cracking, and delamination with their opening and spreading are lesser for titanium-based FMLs than aluminium-based FMLs. The ballistic response of FMLs will be evaluated using analytical modeling in an accompanying study (Part II). © 2021 Elsevier Ltd

Department of Aerospace Engineering

International Journal of Impact Engineering

High-velocity impact response of titanium-based fiber metal laminates. Part I: experimental investigations

Numerical modeling of the thermo-elastic fracture using a hybrid phase-field method is presented. The model’s capability to simulate complex thermo-elastic crack propagation paths under the temperature and mechanical loads’ influence is demonstrated through a few example problems. The evolution of complex crack patterns in a ceramic plate subjected to quenching are simulated. Further, the behavior of functionally graded specimens with a spatial variation of material properties when subjected to thermal shock is investigated. A staggered solution scheme is used to solve the coupled system of multi-field partial differential equations using an open-source finite element software FEniCS. © 2021 Taylor & Francis Group, LLC.

International Journal for Computational Methods in Engineering Science and Mechanics

Hybrid phase-field modeling of thermo-elastic crack propagation

In process industries, the study of granular mixing can substantially optimize energy costs and the quality of final products. In this work, we study the mixing of binary granular systems assisted by fluid flow through the assembly. The granular system is exposed to continuous fluid flow from the bottom to the top. Particle mixing is simulated by the coupling of Computational Fluid Dynamics (CFD) and the Discrete Element Method (DEM). Parameters like particle stacking order, density ratio, and size ratio show a significant influence on mixing. The presence of tilted plates as a geometric intervention with different configurations plays a critical role in mixing efficiency. A new mixing index which captures the nature of contact creation, and the degree of mixing is proposed. The present work helps develop efficient strategies for particle mixing in fluidized beds. © 2021 Elsevier B.V.