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

Modifying the surface topography by fabricating the microfeatures on-top of interacting surfaces has the potential to enhance the tribological behavior of mechanical components having sliding motion. In the additive manufacturing process, Laser powder bed fusion process (LPBF) is chosen to fabricate microfeatures for metals. In LPBF, microfeature characteristics are based on the energy supplied and strategies used for fabrication. In this work, a single layer single track (SLST) experiment is carried out for a different combination of the laser power and scanning speed for fabricating continuous and uniform track width with good shape controllability. Further, the interaction between the lateral and vertical deposition to a single track is also analyzed by using single layer double track (SLDT) and double layer single track (DLST) strategies. It has been found that the LPBF process parameters have a significant influence on the track's morphology and its geometry irrespective of the build strategies. The continuous and uniform tracks are formed when the LED is greater than 0.3 J/mm for investigated build strategies. The microfeatures of width 150 μm to 300 μm and height 40 μm is recommended to fabricate by SLST strategy whereas for 60 μm height of microfeature DLST strategy is recommended. If the microfeatures width is greater than 300 μm then SLDT strategy is recommended. SLST and DLST show good control on the microfeatures characteristics as compared to SLDT strategy. © 2022 The Society of Manufacturing Engineers

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Journal of Manufacturing Processes

Investigation of build strategies for microfeatures fabrication using laser powder bed fusion

The article proposes a lower limb rehabilitation system based on a passive orthosis and an active parallel robot 3-PRRR. Numerical algorithms have been developed to determine the workspace of the parallel mechanism, taking into account the interference of the links. The optimization of the geometrical parameters of the mechanism has been carried out, and the configuration of the robot has been selected based on the criterion of maximizing the workspace. The analysis of the workspace and the influence of various geometric parameters on it is carried out. The simulation results of the workspaces, as well as the positions of the robot at which interference occur, are rendered using the transformation of a set of 3D boxes to an STL file. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.

Mechanisms and Machine Science

Determination of the Workspace of the System Based on the 3-PRRR Mechanism for the Lower Limb Rehabilitation

The study aims to develop a neural network classification model to predict machining failures during wire electric discharge machining. Also, a process control algorithm retunes the process parameters based on the remaining useful time before failure. In the proposed methodology, an artificial neural network (ANN) classifier receives four in-process discharge characteristics as input. These extracted features are discharge energy, spark frequency, open spark ratio, and short circuit ratio. Output classes are labeled normal machining, wire breakage, and spark absence. One hundred eight experiments were conducted according to a full factorial design to train the classifier model, with 90% classification accuracy.Parallelly, another trained ANN model predicts the remaining useful time before failure, based on which process parameters are retuned to restore the machining stability. The algorithm was successful in ensuring continuous failure-free machining. © 2021, The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.

International Journal of Advanced Manufacturing Technology

Wire EDM failure prediction and process control based on sensor fusion and pulse train analysis

Journal of Energy Resources Technology

Theoretical analysis of Rankine cycle operating with zeotropic mixtures of carbon dioxide and hydrocarbons

We consider steady, fully-developed flows of deformable, inelastic grains driven by gravity between identical bumpy walls. Using constitutive relations from extended kinetic theory (EKT) for the erodible bed near the centreline and the collisional flow between the surfaces of the bed and the walls, we calculate the fields of mean velocity, fluctuation velocity and solid volume fraction across the chute. We consider both situations in which the solid volume fraction at and near the centreline is high enough to form a bed and when it is not. We compare results predicted by EKT with recent discrete element simulations results, and obtain very good agreement.

Journal of Fluid Mechanics

Extended kinetic theory for granular flow in a vertical chute

Curvature induced sorting of lipid membrane bound proteins has been widely studied through experiments that induce curvature variation in a giant unilamellar lipid-bilayer vesicle with adsorbed proteins by pulling thin cylindrical tethers. In the theoretical space, this has been supplemented with models that capture curvature dependent interaction between membrane and idealized protein particles, through free energy contributions. Many membrane proteins such as the BAR domain proteins are known to have extremely anisotropic shapes and soft interacting potentials, whereas the idealizations of protein particles explored in models have only assumed them as hard disk-like particles with curvature anisotropy. Here, we present a model of sorting of the proteins while including the effects of softness in their interaction potentials, shape anisotropy in the protein structure and curvature anisotropy in the interactions with the membrane. This is based on a clean separation of free energy contributions from non-ideal fluid behavior of soft anisotropic particles and curvature interactions between proteins and membranes. We probe the behavior of the sorting function under limiting conditions and show that it converges to the previously derived models. In addition to this, we present a comparison of the variation in sorting ratio due to the observed variation in the shape parameter values in known membrane proteins. Finally, using published experimental data for membrane proteins, we perform fitting and derive model parameters. We observe that shape anisotropy adversely affects the sorting of proteins to a high curvature region, whereas curvature anisotropy and softer interaction between proteins favor sorting. This journal is © The Royal Society of Chemistry.

Soft Matter

Sorting of proteins with shape and curvature anisotropy on a lipid bilayer tube

In a recent article, Pawar and Sharma (2017) presented a mathematically and numerically efficient methodology based on solution to the magnetic induction equation which was referred to as the A4 approach for simulation of nozzle arcs. Despite the issue of current singularity, they demonstrated that the A4 approach is a fast and accurate strategy for predicting arc characteristics by also comparing with a singularity-free hybrid model also proposed by them. Revisiting the A4 approach, we show that a simple coordinate transformation can mitigate the axial current singularity and also describe a new hybrid approach that offers a consistent, cost-effective, and accurate alternative for magnetohydrodynamic (MHD) simulations of nozzle arcs. © 1973-2012 IEEE.

IEEE Transactions on Plasma Science

Comments on 'Modeling of Magnetohydrodynamics in Nozzle Arc: A Mathematically and Numerically Efficient Approach'

The grain size of materials is significantly reduced by dynamic recrystallization (DRX), which improves the properties and performance of the materials, and it helps to extend the applications further. DRX behavior of the composite materials is greatly affected by the addition of reinforcement to the matrix due to the heterogeneous temperature of the composite. Therefore, the present investigation aims to study the DRX behavior of hot upset sintered Al-B4C composite with various percentages of B4C content (2, 4 and 6 wt.% of B4C) with 90% of initial relative density. Hot upset tests were performed for various temperatures (300-500 °C) and strain rates (0.1-0.3 s−1). The DRX grain size was significantly altered not only with deformation conditions but also with the addition of reinforcement in the matrix. The fracture surface of the sintered composite was analyzed for various compositions. Ductile fracture is observed in the 2 and 4 wt.%B4C content, and ductile and brittle fractures were observed in the 6 wt.%B4C composites. DRX models were established between grain size and deformation conditions for various compositions to predict the grain size, and the developed models were validated. The measured and calculated DRX grain size absolute error and mean absolute error were not exceeding 8.9 and 7.7%, respectively.

Journal of Materials Engineering and Performance

Influence of Reinforcement Particles on Dynamically Recrystallized Grain of Hot Upset Sintered Al-B4C Composites

Laser powder bed fusion(LPBF) is an emerging manufacturing process by which components ranging from bulk to micro size are fabricated by layer upon layer. Though the micro features are fabricated by LPBF, it is very difficult to super finish them by the secondary processes. There is a demand to fabricate a micro features with high surface finish and high dimensional accuracy. To meet such a demand the one of the options is the optimization of the process parameters for getting high surface finish. Hence, this study investigates the effect of the laser power and scanning speed on the surface integrity of the Ti6Al4V single tracks. The waviness, adhered powder particles, and track profile were analysed. The findings show the significance of the process parameters on the surface quality of a single track. © 2022 The Authors.

Procedia CIRP

Effect of Process Parameters on Surface Integrity of LPBF Ti6Al4V

We investigate arbitrarily large indentations of beams in two dimensions by a frictionless and rigid cylindrical punch whose axis is perpendicular to the plane of the beam. The beam is modeled as a geometrically exact beam that admits large displacements and rotations. Absence of both friction and inter-penetration between the contacting surfaces allows the normal contact pressure and the separation between the surfaces to be related by the Karush–Kuhn–Tucker (KKT) conditions. This is then implemented in a nonlinear finite element framework through both penalty and augmented lagrangian methods. We solve for the contact domain and the forces and moments acting within it, and relate them to the total applied force and the extent of indentation. We report results for several punch radii and beam thicknesses and consider both pinned and clamped beams. In this, we discuss the importance of nonlinear effects such as wrapping of the beam around the punch and the stiffening of the beam due to axial stretch. We demonstrate the importance of utilizing a nonlinear beam formulation by comparing our results with the predictions of theories predicated on small deformations. For example, while the latter claim loss of contact with the beam in the vicinity of the punch’s apex as the indentation proceeds, we find that the punch and the beam remain in contact. &nbsp;