Department of Mechanical Engineering

Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

In the recent past, intervention-class autonomous underwater vehicles (AUVs) have gained the ocean/marine research community's attention due to their multidisciplinary operational capabilities. This article discusses a detailed comparative-performance study of an underwater vehicle (UV) with two different actuator configurations based on fixed-thrusters and vectored thrusters. The fixed-thruster configuration consists of eight thrusters. Four thrusters generate thrust in the horizontal plane and the remaining thrusters produce thrust in heave direction. The vectored thruster configuration has four thrusters placed at diagonal corners of a rectangular vehicle, and four independent internal servomotors rotate these thrusters. The classification terminology in this article identifies the underwater vehicle without vectoring capability as Fixed-Thruster Underwater Vehicle (FTUV) and the one with vectoring capability as Vectored-Thruster Underwater Vehicle (VTUV). Furthermore, a nonlinear controller is designed, based on a backstepping scheme for tracking a given spatial profile in a three-dimensional space. An underwater robot's control for a trajectory tracking problem is useful for any real-time multidisciplinary autonomous applications. The comparative simulation results are summarized to validate both the vehicle variants’ performance differences. © 2021 Elsevier Ltd

World University root node

Ocean Engineering

Simulation-based semi-empirical comparative study of fixed and vectored thruster configurations for an underwater vehicle

The current work aims to improve the sustainability of wire electric discharge machining by predicting the wire breakages. Wire breakages are process interruptions which increase the machining time, energy wastage and material consumption. The study is a novel approach to predict process continuity by binomial classification of machining outcomes using kernel-based naive Bayes algorithm. The two classes are labelled as wire breakages and continuous machining. Training dataset consists of 31 experiments according to central composite design of response surface methodology, and wire breakage instances are recorded as response. The input dataset contains four machining parameters, namely pulse on time, pulse off time, servo voltage and wire feed rate, whereas mean gap voltage variation is derived from in-process data. The trained model was 96.7% accurate in wire breakage predictions. Further, nine confirmation tests were conducted to check model adequacy in real-world situations. The model predicted all instances of wire breakages accurately. The stages of wire wear up to wire rupture were studied by conducting microstructural analysis. © 2021, The Brazilian Society of Mechanical Sciences and Engineering.

Journal of the Brazilian Society of Mechanical Sciences and Engineering

Sustainability improvement of WEDM process by analysing and classifying wire rupture using kernel-based naive Bayes classifier

Abstract: Mathematical models are among the new approaches employed to predict the properties of any material under various conditions. Mathematical models are essential for not only understanding the material properties but also estimating the cost of design, product life, and failure criteria of the product. Therefore, in the current investigation, the hot deformation (HD) behaviour and microstructure alteration of deformed AA7150-5 wt% B4C composite was studied through a mathematical model. The new AA7150-5 wt% B4C composite was fabricated through an ultrasonic-probe assisted (20 KHz, 1000 W) stir casting process. The hot compression test was performed on a hydraulic press for various deformation temperatures (623–773 K) and strain rates (0.01–1 s− 1). Based on the outcome, it is inferred that the flow stresses and microstructures of AA7150-5 wt% B4C composite was significantly altered during the hot compression test under various deformation conditions. The constitutive and dynamically recrystallized grain (DRXed) models were developed as a function of various deformation conditions of deformed AA7150-5 wt% B4C composite, which was then applied to forecast the flow stress and grain size behaviour for different deformation conditions. The flow stress and DRXed grain size were obtained through the proposed constitutive and DRXed models are correlated with experimental results, with excellent accuracy. The models developed are reliable to predict the AA7150-5 wt% B4C properties for various conditions. Graphic abstract: [Figure not available: see fulltext.]. © 2021, The Korean Institute of Metals and Materials.

Metals and Materials International

Mathematical Models to Predict Flow Stress and Dynamically Recrystallized Grain Size of Deformed AA7150-5 wt% B4C Composite Fabricated Using Ultrasonic-Probe Assisted Stir Casting Process

The study of high viscosity liquid atomization is of interest especially in agricultural food processing and pharmaceutical industries, where the viscosity of the liquid increases with an increase in the dry matter content. Effervescent atomizer is one kind of twin-fluid atomizer used for effective atomization of high viscosity liquids. The present study focuses on correlating internal two-phase flow characteristics of an effervescent atomizer with the external spray characteristics. Spray structure images covering a distance of 80 mm downstream of the exit orifice and images of the entire two-phase flow mixing region were captured by diffuse backlit imaging using a high-speed camera. The spray cone angle was estimated at different gas-to-liquid ratios (GLRs), when operated at a liquid injection pressure of 0.5±0.01 MPa. Spray unsteadiness was studied by estimating the variation in the moving average of the spray cone angle (taken over 50 images). The study shows that the internal two-phase flow governs the external spray characteristics in effervescent atomization. Annular flow regime formed at higher GLRs gives a stable spray while slug flow regimes formed at reduced GLRs leads to a larger variation in spray structure. Though the bubbly flow regime for higher viscosity liquid shows smaller variation in spray cone angle, the atomization was observed to be inferior with an intact liquid jet. © 2021 ICLASS 2021 - 15th Triennial International Conference on Liquid Atomization and Spray Systems. All Rights Reserved.

International Conference on Liquid Atomization and Spray Systems (ICLASS)

Effervescent atomization of viscous liquids

Background: Membrane-bound intracellular organelles have characteristic shapes attributed to different local membrane curvatures, and these attributes are conserved across species. Over the past decade, it has been confirmed that specific proteins control the large curvatures of the membrane, whereas many others due to their specific structural features can sense the curvatures and bind to the specific geometrical cues. Elucidating the interplay between sensing and induction is indispensable to understand the mechanisms behind various biological processes such as vesicular trafficking and budding. Scope of review: We provide an overview of major classes of membrane proteins and the mechanisms of curvature sensing and induction. We then discuss the importance of membrane elastic characteristics to induce the membrane shapes similar to intracellular organelles. Finally, we survey recently available assays developed for studying the curvature sensing and induction by many proteins. Major conclusions: Recent theoretical/computational modeling along with experimental studies have uncovered fascinating connections between lipid membrane and protein interactions. However, the phenomena of protein localization and synchronization to generate spatiotemporal dynamics in membrane morphology are yet to be fully understood. General significance: The understanding of protein-membrane interactions is essential to shed light on various biological processes. This further enables the technological applications of many natural proteins/peptides in therapeutic treatments. The studies of membrane dynamic shapes help to understand the fundamental functions of membranes, while the medicinal roles of various macromolecules (such as proteins, peptides, etc.) are being increasingly investigated. © 2021 Elsevier B.V.

Biochimica et Biophysica Acta - General Subjects

Recent developments in membrane curvature sensing and induction by proteins

The current work demonstrates a novel multi-criteria decision-making (MCDM) technique to optimize the process parameters during the wire electric discharge machining of Inconel 718. A hybrid GRA-TOPSIS algorithm using entropy weights is developed to optimize wire electric discharge machining processes parameters for maximizing the cutting speed and simultaneously minimizing the surface roughness and flatness error. Experiments were conducted according to Taguchi L18 orthogonal array considering pulse on time, pulse off time, servo voltage, wire feed rate, and wire electrode types as the input parameters. The weights of each responses were calculated by entropy weights method. The different alternatives were ranked using the hybrid technique, and an optimum parameter combination is found that maximizes the process outcome. The analysis of variance (ANOVA) was performed to study the relative significance of process parameters on the performance index. The results were finally validated by performing confirmation tests. The entropy weighted GRA-TOPSIS method was observed to improve the overall process performance compared to conventional TOPSIS. Microstructural analysis, morphological studies, and EDS analysis were conducted to study the surface integrity of the machined surface under optimal parameter settings. © 2021, The Author(s), under exclusive licence to Springer Nature Singapore Pte Ltd.

Process Integration and Optimization for Sustainability

Multi-response Optimization of Wire EDM of Inconel 718 Using a Hybrid Entropy Weighted GRA-TOPSIS Method

A modern control approach for a submerged robot with tiltable thrusters is explored in this paper. The rotatable action capability of the four thrusters makes the system framework as over-actuated with only six degrees of freedom (DOF) to be carried out. The dynamic model of the submerged robot on account of rotatable angles results in highly nonlinear thrust vector mapping, where linearization of the model leads to the rejection of possibly advantageous nonlinearities. This issue can be abstained by utilizing model-based nonlinear control schemes such as backstepping in the presence of continuous rotatable action resulting in a better control action. The stability of the system is ensured by the Lyapunov stability criterion by tuning the control gain constants with the RMS values of tracking error. Finally, the numerical simulations demonstrate the cascaded nature of the derived tracking control, where the tracking errors asymptotically reduce to close vicinity of zero. © 2021, The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Lecture Notes in Mechanical Engineering

A Robust Motion Control Scheme of an Underwater Robot with Tiltable Thrusters

This work focuses on determining the link interference-free workspace of a Cartesian (3-PRRR) parallel manipulator. An algorithm for obtaining the largest volume cuboid that inscribes the interference-free workspace is proposed, which can be used as a performance index for the mechanism under investigation. The effect of link dimensions and the size of the moving platform on the interference-free workspace is also analysed in this work. © 2021, The Author(s), under exclusive license to Springer Nature Switzerland AG.

Mechanisms and Machine Science

Investigation of Interference-Free Workspace of a Cartesian (3-PRRR) Parallel Manipulator

Rapid tool degradation poses a critical challenge for joining of high carbon steels using friction stir welding (FSW) despite its ability to provide sound and defect-free welded joints. Tools of tungsten carbide with nickel binder phase (WC-Ni) are potential alternatives as they exhibit good strength and toughness. A detailed examination on the wear and consequent damage of WC-Ni tools for FSW of steels is reported in this work. The results show that the longevity of the WC-Ni tools is improved at relatively higher welding speed and lower tool rotational speed during FSW of high carbon steels. In contrast, higher tool rotational speeds and lower welding speeds result in higher rate of heat generation and elevated temperature leading to adhesion wear and oxidation of the tools. In FSW of typical 3-mm-thick high carbon steel plates, a tool rotational speed of 300 rpm and welding speed of 150 mm min−1 resulted in the minimum tool wear and allowed the use of a single tool up to 1000 mm without any significant damage. © 2021, The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.