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 this paper an experimental investigation was carried out to optimize the performance characteristics (surface roughness and Metal removal rate) simultaneously in hot machining process. The experiments were conducted on 15-5PH stainless steel using K313 carbide tool based on Taguchi L27 orthogonal array design. The work-piece material was heated using oxy-acetylene gas flame which is the cost effective method compare to other heating technique used in hot machining process. Analysis of variance is performed to get the contribution of each parameter on the performance characteristics and it was observed that cutting speed is most significantly affect the performance characteristics compare to feed, depth of cut and temperature. The optimal set of process parameters were found to be cutting speed at 31 m/min, feed rate at 0.4mm/rev, depth of cut at 0.4mm and workpiece temperature at 400°C to maximize material removal rate and minimize surface roughness.

World University root node

Procedia Materials Science

Multi Objective Optimization of Hot Machining of 15-5PH Stainless Steel Using Grey Relation Analysis

Proceedings of the International Conference on Computer Aided Engineering {\ldots}

Estimation of stand-off distance of a pipe for increased entrainment from a turbulent air jet

A new nonlinear disturbance observer-based tracking control scheme for an underwater manipulator is presented in this paper. This observer overcomes the disadvantages of existing disturbance observers, which are designed or analyzed by the linear system techniques. It can be applied in underwater manipulator systems for various purposes such as payload compensation, interaction effects compensation, underwater current or external disturbance compensation, and independent system control. The performance of the proposed tracking control scheme is demonstrated numerically by the payload compensation and interaction effects compensation for a two degrees of freedom vertical underwater manipulator. © 2013 Taylor & Francis and The Robotics Society of Japan.

Advanced Robotics

A nonregressor nonlinear disturbance observer-based adaptive control scheme for an underwater manipulator

This paper presents a new tracking control scheme for an underwater vehicle-manipulator system (UVMS). The proposed task space passivity based controller is not only used to track the given desired path but also allows the use of the self-motion of the vehicle to perform power efficient trajectory because of its kinematically redundant nature. In the proposed scheme, the primary task is to track the given end-effector task space trajectory despite of the system associated with external disturbances, system uncertainties and internal noises. The secondary task as the energy savings requirement, the vehicle motion is controlled and to be aligned with the estimated underwater current orientation. The performance and effectiveness of the proposed coordinated control motion of the UVMS is demonstrated numerically and confirmed with the specified UVMS tasks. Simulation results show that the required control inputs for the given tracking task are reduced, and the UVMS can successfully track the given desired spatial trajectory.

Indian Journal of Marine Sciences

Task space trajectory tracking control of an underwater vehicle-manipulator system under ocean currents

Micro electric discharge milling (μ-ED milling) is an effective and economic process for the fabrication of micro channels. In the present work, the bulk approach of μ-ED milling is being attempted to make complex shaped micro channels. For a straight channel the bulk approach of μ-ED milling was found to be a successful approach. A tungsten tool of diameter 500 μm was used to fabricate semi-circular micro channels on EN-24 steel. Important machining parameters had earlier been optimized to make straight channels on EN-24 steel by the same method. The effect of geometrical parameters such as radius of curved channel and aspect ratio on MRR and TWR were studied by full factorial experimental design for single pass at optimized machining parameters. Finally complex shapes like T-type and serpentine channels were made by using optimized conditions of straight and curved channels by bulk approach with multiple passes of μ-ED milling. Copyright © 2013 by ASME.

ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE)

Fabrication of complex micro channels by micro electric discharge milling (μ-ED milling)

In the present study the detection of the crack in rotor system has been carried out using the statistical features such as kurtosis, skewness and crest factor of vibration response. Such features, mainly kurtosis have been used in literature for identifying bearing and gearbox defects. The simulation results of crack detection have been compared with those of experiments carried out using laser vibrometer. Single and two cracks have been identified. It has been noted that the kurtosis and skewness changes are significant when the crack is closer to the bearing locations. The skewness is mostly negative but as the crack depth increases the positive values of skewness increase beyond the middle part of the shaft. The crest factor deviation curve is developed, which could successfully identify even cracks of small depths. © KRISHTEL eMAGING SOLUTIONS PRIVATE LIMITED.

Advances in Vibration Engineering

Vibration based statistical features for shaft crack detection in a rotor

High speed rotating machinery operating with higher load capacity in extreme working conditions can induce fatigue crack into the systems. To avoid failure of the system, it has to be monitored continuously for cracks before it becomes critical. There is a need for the newer techniques that can detect even small cracks. The aim of the present work is to identify the crack in a rotor-bearing system using the concept of operational deflection shape and using kurtosis of vibration response. In the literature kurtosis is used for identifying bearing and gearbox defects. Higher kurtosis means more of the variance is due to infrequent extreme deviations, as opposed to frequent modestly sized deviations. In this study kurtosis deviation curve and amplitude deviation curves are also used for shaft crack detection. It has been noted that the kurtosis changes are significant when the crack is closer to the bearing locations. Single cracks and two cracks have been identified. The rotational laser vibrometer has been used to measure the response from the rotating system. The simulation results of crack detection compare well with experimental results. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

JVC/Journal of Vibration and Control

Crack detection in a rotor by operational deflection shape and kurtosis using laser vibrometer measurements

Unbalance and bow are found to be one of the most common causes of synchronous machinery vibrations in rotating systems. Concentrated lumped mass models are adopted in most of the finite element approach for modeling unbalances and subsequent balancing in rotating systems. But this assumption may not be appropriate for long slender rotors with unbalances distributed along the length of the rotor. A polynomial curve for eccentricity distribution with finite element modeling is used to identify the distributed unbalance. The unbalance eccentricity distributions are estimated using the measured vibration responses at a speed below the balancing speed. Modal correction mass required to balance a rotor at its first bending critical speed, having both distributed unbalance and bow is computed knowing the amplification factor at critical speed. The rotor is balanced at its first bending critical speed using modal balancing method in a single trial run and using a single balancing plane. The method thus avoids multiple trial runs required for modal balancing of flexible rotors. This method is verified on an experimental rotor having both bow and unbalance. The concept of quantifying the distributed unbalance using 'Norm' of eccentricity polynomial function is also introduced for the first time. © 2013 Published by Elsevier Ltd.

Journal of Sound and Vibration

Modal balancing of flexible rotors with bow and distributed unbalance

10th International Conference on Multi-Material Micro Manufacturing (4M)

Enhanced surface integrity and dimensional accuracy in micro-EDM drilling using D-shaped electrodes

We study inextensional vibrations of zig-zag single-walled carbon nanotubes using nonlocal elasticity theories and molecular mechanics simulations employing MM3 potential. We find that the frequency expressions for the Rayleigh and Love modes of inextensional vibrations, predicted by the stress and strain gradient theories, differ from the classical continuum theory expressions by a multiplicative factor only. The factor is different for stress and strain gradient theories. We also observe that the strain gradient theory with positive sign exhibits a saturation-like behavior of the inextensional mode frequency with the circumferential wave number. Using this fact and molecular mechanics simulation data we derive an expression for the nonlocal parameter. © 2013 Elsevier Ltd. All rights reserved.