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

<a href="https://www.sciencedirect.com/topics/engineering/additive-manufacturing">Additive manufacturing</a> can produce complex shapes with minimum material waste. This advantage has made metal additive manufacturing attractive, and efforts are being made to make it more technically promising than <a href="https://www.sciencedirect.com/topics/engineering/conventional-manufacturing-process">conventional manufacturing processes</a>. However, due to the layer-by-layer deposition, one of the main issues of the additively manufactured metal parts is the dimensional deviation and highly rough surfaces. This makes it difficult to use the parts in as-built condition and necessities post-processing to meet the required surface finish and tolerances. Hence, this study reports the underlying insights into the <a href="https://www.sciencedirect.com/topics/engineering/grinding-machining">grinding</a> of <a href="https://www.sciencedirect.com/topics/materials-science/selective-laser-melting">selective laser melting</a> (SLM) printed <a href="https://www.sciencedirect.com/topics/materials-science/inconel-718">Inconel 718</a>. Experiments were conducted considering the wide range of equivalent chip thickness values and built directions of as-built workpieces. Specific grinding forces revealed the <a href="https://www.sciencedirect.com/topics/engineering/grindability">grindability</a> of SLM-printed Inconel 718 with the number of passes and depth of cut compared to wrought Inconel 718. SEM images revealed the influence of the inherent pores on the metal additive manufactured samples in frequent abrasive grits fracturing and minor burn marks over the work surface, supported by the <a href="https://www.sciencedirect.com/topics/materials-science/energy-dispersive-x-ray-spectroscopy">EDS analysis</a>. The experiments conducted on porous structured samples also confirm the influence of pores on grit fracturing. The observed micro grit fracturing in SLM-printed as-built Inconel 718 mitigated the effect of strain-hardening on specific energy despite an increased hardness, unlike wrought Inconel 718.

Journal of Manufacturing Processes

Grindability of additively manufactured Inconel 718

The performance of interacting metal surfaces having sliding motion is enhanced by fabricating microfeatures on-top of the surfaces. Laser powder bed fusion (LPBF) is used to fabricate the microfeatures of IN625 on-top of a flat surface. In LPBF, geometrical characteristics of microfeatures are based on the energy supplied and the volume of material melted (layer thickness) at that instant of time. There is very few research reported in open literature on the effect of layer thickness on microfeatures geometry during LPBF. In this work, a series of single tracks is fabricated with different combinations of laser power and scanning speed for 75 μm, 100 μm and 125 μm layer thickness and its effect on single track geometrical characteristics and microstructure was evaluated. It has been found that laser power and scanning speed have a significant influence on the track geometry irrespective of layer thickness. The minimum linear energy density of 2.5 J/mm is considered to fabricate the continuous track formation for investigated layer thickness. From statistical analysis, it is observed that the laser power and scanning speed shows higher contribution on track width and remelting depth, respectively. Whereas, layer thickness shows a higher influence on track height and contact angle of single track as compared to laser power and scanning speed. In 125 μm layer thickness, the volume of material melting is increased which encourages the gravity effect to deform the melt pool and produces larger track width compare to 100 μm layer thickness. Further, the cell spacing is gradually increased with layer thickness resulting increase in the solidification period. The shape controllability of the single track is significantly increased with layer thickness, but as keeps on increasing layer thickness due to the larger volume of molten metal, the melt pool losses ability to maintain convex shapes. An Artificial Neural Network (ANN) model is developed to understand the relationship between the LPBF process parameters and single track geometrical characteristics to predict the responses for a wide range of process parameters. The multiple response neural network model shows excellent agreement with experimental results with R2 value greater than 0.95. © 2024 Elsevier Ltd

World University root node

Optics and Laser Technology

Experimental study and neural network model based prediction of layer thickness influence on LPBF IN625 single track geometry

Indian Journal of Thoracic and Cardiovascular Surgery

Sanal flow choking in cardiovascular systems: A scientific fallacy

The demand for robots capable of performing collaborative tasks requiring interactions with the environment is on the rise. Safe interactions with the environment require attributes such as high dexterity and compliance around obstacles, while still maintaining the requisite stiffness levels for payload manipulation. Such attributes are inherent to biological musculoskeletal systems. Motivated by this realization, this paper proposes a cable-actuated spatial joint with variable stiffness, inspired by the tensegrity principles found in biological musculoskeletal systems. The paper provides a detailed analysis of the joint's mobility and mechanism kinematics. Based on the limits of the actuation forces, the paper also presents the wrench-feasible workspace of the joint. The paper also outlines the conditions that the cable actuation forces must satisfy to maintain the static equilibrium of the joint. The stiffness modeling presented in this work demonstrates the modulation of stiffness bounds as a function of cable actuation forces. Furthermore, the stiffness modulation as a function of the geometrical parameters is also presented. © 2024 by ASME.

Journal of Mechanisms and Robotics

Kinetostatic Analysis of a Spatial Cable-Actuated Variable Stiffness Joint

Modern farmers face several challenges in meeting the food needs of the increasing population growth. In order to meet the growing demand without compromising on the quality and quantity within available constraint spaces of farming, they must transform from conventional methods to precision agriculture, reducing direct human intervention. The advancements in agricultural operations from traditional to technological methods improve efficiency and offer a safer work environment. This paper focuses on the preliminary conceptual design and working of a low-cost all-terrain agricultural robot suitable for small/medium-scale farmers. The robot is designed to perform two individual operations—transplanting and weed removal. A brief description of the various components used to perform the two operations is highlighted in this paper. © 2024, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Smart Innovation, Systems and Technologies

Conceptual Design and Structural Analysis of a Multipurpose Agricultural Robot

This work presents a technique to estimate the spatially varying thermal contact conductance (TCC) over the contact zone of non-conformal bolted joints, which are common in satellite structures for mounting of the electronic packages, through a coupled thermal and structural analysis. The heat flow across an interface occurs only through the actual regions of contact rather than the apparent contact area and is governed by the TCC at the interface. Due to its multi scale nature, accurate estimation of TCC is very challenging. In this work, the TCC between two plates, which are joined using a single bolt at the center is determined for four prescribed bolt torques viz. 1.5, 3.0, 4.5 and 6.0 Nm, using non-intrusive temperature measurements performed at locations away from the actual interface. TCC depends upon micro contact conductance of surface asperities and also on the macroscopic deflection of plates occurring due to the application of bolt torque. The effect of micro contact conductance due to surface asperities are modelled by making the TCC a linear function of applied torque. The macroscopic deformation of plates are found by solving the three dimensional state of stress using finite element analysis. The slope parameter connecting TCC and contact pressure is estimated for each torque, for a specified heat flux and sink temperature, via an inverse technique by minimizing the difference between the simulated temperature obtained by the assumed value of slope parameter and the one obtained from the experiments in a least square sense. Subsequently, the estimated values of the TCC are validated by comparing the simulated temperatures with the measured ones obtained from the experiments performed at different conditions (heat fluxes and sink temperatures) for each bolt torque. As the bolt torque increases, due to the deformation of the asperities, the actual contact area increases and approaches the macroscopic contact area. Consequently, the TCC increases and tends to reach a saturation value. This is also manifested by the estimated slope parameter approaching a constant value asymptotically as the bolt torques are increased. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2023.

Heat and Mass Transfer/Waerme- und Stoffuebertragung

Estimation of spatially varying thermal contact conductance of non-conformal bolted joint

This paper proposes a new two-degrees-of-freedom (dof) cable-actuated mechanism which can be utilized for lightweight variable-stiffness manipulators. Using numerical methods, a kinematic model for the proposed mechanism is derived for determining the mechanism’s configurations and cable lengths for a pair of independent task-space variables. The numerical algorithm used for estimating the workspace is cross-validated with a virtual prototype of the mechanism using ONSHAPE®. The work presented in the paper concludes with the static modelling of the mechanism, which yielded insights regarding the magnitude of the actuation forces, depending on the desired wrench-feasible workspace of the mechanism. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

Mechanisms and Machine Science

Kinematic and Static Modelling of a New Two-Degree-of-Freedom Cable Operated Joint

Approximate multidimensional Riemann solvers are essential building blocks in designing globally constraint-preserving finite volume time domain and discontinuous Galerkin time domain schemes for computational electrodynamics (CED). In those schemes, we can achieve high-order temporal accuracy with the help of Runge&ndash;Kutta or ADER time-stepping. This paper presents the design of a multidimensional approximate generalized Riemann problem (GRP) solver for the first time. The multidimensional Riemann solver accepts as its inputs the four states surrounding an edge on a structured mesh, and its output consists of a resolved state and its associated fluxes. In contrast, the multidimensional GRP solver accepts as its inputs the four states and their gradients in all directions; its output consists of the resolved state and its corresponding fluxes and the gradients of the resolved state. The gradients can then be used to extend the solution in time. As a result, we achieve second-order temporal accuracy in a single step. In this work, the formulation is optimized for linear hyperbolic systems with stiff, linear source terms because such a formulation will find maximal use in CED. Our formulation produces an overall constraint-preserving time-stepping strategy based on the GRP that is provably L-stable in the presence of stiff source terms. We present several stringent test problems, showing that the multidimensional GRP solver for CED meets its design accuracy and performs stably with optimal time steps. The test problems include cases with high conductivity, showing that the beneficial L-stability is indeed realized in practical applications. &copy; 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.

Fulltext

Journal of Scientific Computing

Multidimensional Generalized Riemann Problem Solver for Maxwell’s Equations

We investigate the indentation of thin adhesive beams by a rigid frictionless circular punch in two-dimensions through computations and experiments. A non-linear geometrically exact (GE) beam formulation that allows for arbitrarily large displacements and rotations is employed for the thin beam. The Karush–Kuhn–Tucker condition for unilateral contact is adapted to model adhesive interaction in a nonlinear finite element (FE) framework. In this, contact is enforced through a penalty method and adhesion is incorporated through two different cohesive zone models (CZMs), viz. exponential and bilinear. The indentation of the adhesive GE beam is then studied in terms of the variations of the applied force, the pressure distribution, the cross-sectional rotation and the sizes of the contact area and the adhesive zone for different indentation extents, adhesive strengths, punch radii, beam thicknesses and end supports. We find that the system is largely agnostic to the CZM utilized, as well as the type of end supports unless the contact area spans the beam. At the same time, thinner beams tend to initiate contact with a punch more easily and are harder to detach. We then demonstrate that thin beams may undergo large rotations even if the indentation is small, which necessitates a nonlinear beam theory. Under such conditions approximating a circular punch by a parabolic one used typically when indentations are small introduces errors. Finally, we conduct experiments on clamped adhesive beams made of two different types of PDMS (polydimethylsiloxane) and various thicknesses and find a good match with our computations. © 2023 Elsevier Ltd

International Journal of Solids and Structures

Indentation of geometrically exact adhesive beams

In the originally published PDF version of the article, the list of author affiliations was incomplete. The complete list of affiliations is shown as follows: Geethapriyan Thangamani, Mechatronics and Instrumentation Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Indore, Indore, Madhya Pradesh, India; and Department of Applied Science and Technology (DISAT), Politecnico Di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy; I.A. Palani, Mechatronics and Instrumentation Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Indore, Indore, Madhya Pradesh, India; Mayank K. Singh and Dhirendra K. Rai, Sustainable Energy and Environmental Materials (SEEM) Lab, Department of Metallurgy Engineering and Materials Science (MEMS), Indian Institute of Technology Indore, Khandwa Road, Indore 453552, India; V.G. Shanmuga Priyan and S. Kanmani Subbu, Department of Mechanical Engineering, Indian Institute of Technology Palakkad, Palakkad, 678623, Kerala, India. The original article has been corrected. © 2023, ASM International.

Journal of Materials Engineering and Performance

Correction to: Post-processing of Wire Arc Additive Manufactured Stainless Steel 308L to Enhance Compression and Corrosion Behavior using Laser Shock Peening Process (Journal of Materials Engineering and Performance, (2023), 10.1007/s11665-023-08592-z)