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 present work, parametric instability of asymmetric shaft mounted on bearings is studied. Towards this end, four different models of increasing complexity are studied. The equations corresponding to these models are formulated in the inertial reference frame. These equations involve a periodically varying coefficient. This is similar to classical Mathieu equation but in a multi-degree of freedom context. As such, under suitable parameter combination these systems result in growing oscillation amplitudes or instability. For wider generalization, the equations and results are presented in a non-dimensional form. The unstable parameter regimes are found using the Floquet theory and perturbation methods. These results are also corroborated with existing results in the literature. The nature of the stability boundary and its dependence on various system parameters is discussed in elaborate detail. The stability boundary can be used to determine unstable operating speed ranges for different asymmetric shaft cross-sections. Further, material, geometry and bearing selection guidelines for ensuring stable operations can be inferred from these results. © 2015 Elsevier Ltd. All rights reserved.

World University root node

Journal of Sound and Vibration

Instability of asymmetric shaft system

6 th International and 43 rd National Conference on Fluid Mechanics and {\ldots}

Impinging Flame Jets of Perforated Plate Burner: Heat Transfer Aspects

Oblique flame jet impingement finds a wide range of domestic and industrial applications. An experimental investigation is carried out to study the effect of oblique flame jet impingement on the heat transfer characteristics. An asymmetric boundary layer is formed on the impingement surface due to oblique impingement. Steady state technique using one dimensional energy balance across the target plate is employed to determine the local heat transfer coefficient and the reference temperature of the impinging flame jet. The effect of the mixture Reynolds number (400-1200), mixture equivalence ratio (0.8-1.5), burner or plate inclination (0-45°) and burner to plate distance (2-6 times the burner diameter) on the heat transfer characteristics are investigated. It is found that stoichiometric mixture provides optimum Nusselt number distribution and lower burner to plate spacing provides maximum effectiveness for impinging premixed cone flames. Normal impingement resulted smooth heat flux distribution and better thermal performance. Correlations are developed for stagnation point Nusselt number and effectiveness. © 2016 Elsevier Ltd. All rights reserved.

International Journal of Heat and Mass Transfer

Heat transfer characteristics of premixed methane-air flame jet impinging obliquely onto a flat surface

In this paper, a robust nonlinear proportional–integral–derivative (PID)-like fuzzy control scheme is presented and applied to complex trajectory tracking control of a 2PRP-PPR (P-prismatic, R-revolute) planar parallel manipulator (motion platform) with three degrees-of-freedom (DOF) in the presence of parameter uncertainties and external disturbances. The proposed control law consists of mainly two parts: first part uses a feed forward term to enhance the control activity and estimated perturbed term to compensate for the unknown effects namely external disturbances and unmodeled dynamics, and the second part uses a PID-like fuzzy logic control as a feedback portion to enhance the overall closed-loop stability of the system. Experimental results are presented to show the effectiveness of the proposed control scheme. © 2016 ISA

ISA Transactions

Robust nonlinear PID-like fuzzy logic control of a planar parallel (2PRP-PPR) manipulator

Fibrous materials are widely utilized as tissue engineering scaffolds for tissue regeneration and other bioengineering applications. The structural as well as mechanical characteristics of the fibrous matrices under static and dynamic mechanical loading conditions influence the response of the cells. In this paper, we study the mechanical response of the non-woven fibrous matrices under oscillatory loading conditions and its dependence on the structural properties of fibrous matrix. We demonstrate that under oscillatory shear and elongation, the fibrous matrices demonstrate nonlinear viscoelasticity at all strain amplitudes. This is contrary to the behavior of other soft polymeric materials for which nonlinearity in the viscoelastic response vanishes for small strains. These observations suggest that despite their prevalence, the measures of linear viscoelasticity (e.g., storage and loss moduli) are inadequate for the general description of the viscoelastic nature of the fibrous materials. It was, however, found that linear viscoelastic nature of fibrous matrices for small amplitudes is restored when a pre-stretch is applied to the fibrous matrix along with oscillatory strains. Further, we also explored the influence of the structural properties of the fibrous matrices (fiber orientation, alignment and curvature) on their viscoelastic nature. © 2016, Springer-Verlag Berlin Heidelberg.

Biomechanics and Modeling in Mechanobiology

Structure-induced nonlinear viscoelasticity of non-woven fibrous matrices

IC Engine valve components are generally made from Nickel based (Nimonic-80A) super alloys and these components are exposed to severe operating conditions while the engine is running. Interface fretting combined with impact wear causes major wear related failures to the valve and seat components. There is a need to predict wear of such interfaces so that their life and residual life (i.e. inspection) can be assessed. This paper focusses on a fretting wear of Nimonic-80A material line contact (cylinder-on-flat) at both room temperature and at high temperature conditions. The objective of this study is also to be able to understand the effect of interface fretting displacement, which is the key parameter that controls wear. Tests were performed at three different displacement amplitudes at room temperature (RT) and at high temperature (620°C) for 25,000 cycles. Experimental constants such as wear coefficient (k) and friction coefficient (µ) were derived from the test results. The wear and friction coefficients were then used in the wear-model to predict the wear depth. Further, this model was used to predict wear at 100,000 cycles. Predicted results are compared then with results from tests which have been run beyond 25,000 cycles (i.e. 100,000 cycles). © 2016 Elsevier Ltd

Tribology International

High temperature fretting wear prediction of exhaust valve material

This paper proposes two dynamic modelling approaches for a planar parallel manipulator with a 3-PPR configuration. The planar configuration has three legs each with a Prismatic-Prismatic-Revolute [PPR] configuration where the first joint is actuated. These three legs are joined by an end-effector which is in the form of an equilateral triangle. The dynamics of the manipulator was derived using an energy based Euler-Lagrangian approach and the DeNOC (Decoupled Natural Orthogonal Complement) matrices. Both the formulations are elucidated and the resulting formulation are compared under similar conditions to validate them. © Springer Nature Singapore Pte Ltd. 2016.

Communications in Computer and Information Science

Dynamic modelling approaches for a 3-PPR planar parallel manipulator

A finite flexible perforated panel set in a differently perforated rigid baffle is considered. The radiation efficiency from such a panel is derived using a 2-D wavenumber domain formulation. This generalization is later used to represent a more practical case of a perforated panel fixed in an unperforated baffle. The perforations are in the form of an array of uniformly distributed circular holes. A complex impedance model for the holes available in the literature is used. An averaged fluid particle velocity is derived using the continuity equation and the surface pressure is derived using an appropriate momentum equation. The discontinuity in the perforate impedance (due to different hole dimensions or perforation ratio) at the panel-baffle interface is carefully taken into account. It is found that there exists a 'coupling' of different wavenumbers of the spatially mean fluid particle velocity field. The change in the resonance frequencies and the modeshapes of the panel due to the perforations is taken into account using the Receptance method. Analytical expressions for the radiated power and radiation efficiency are derived in an integral form and numerical results are presented. Several comparisons are made to understand the radiation efficiency curves. Since both the resistive and reactive components of the hole impedance are taken into account, the model is directly applicable to micro-perforated panels also. © 2016 Elsevier Ltd. All rights reserved.

Sound radiation from a perforated panel set in a baffle with a different perforation ratio

The present work investigates the method of depositing a ceramic coating on the surface of aluminum by means of electrical discharge coating (EDC) in electrical discharge machining (EDM). The present study makes use of powder metallurgy (P/M) green compacts made of titanium, boron carbide, and aluminum (Ti + B4C + Al) powder as the EDM tool for surface modification of aluminum workpieces. EDM process was carried out with different tool parameters like composition of the electrode material, compaction pressure of the green compacts, and different settings of the process variables like peak current and pulse duration setting. Responses observed were material deposition rate (MDR), tool wear rate (TWR), and average layer thickness (LT). Experiments were designed and carried out using Taguchi L18 orthogonal array. The most influential parameter for responses MDR, TWR, and LT was found to be peak current (IP) with a percentage contribution of 60.72%, 59.52%, and 42.09%, respectively. In addition, various other characterization techniques such as optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectrum (EDX) analysis were performed in order to judge different attributes of the deposited coating. Copyright © Taylor & Francis Group, LLC.

Materials and Manufacturing Processes

Deposition and Analysis of Composite Coating on Aluminum Using Ti-B 4C Powder Metallurgy Tools in EDM

Present investigations are centered on passive control of shock wave boundary layer interaction (SWBLI) for double cone and double wedge configurations with leading edge bluntness. This study seeks the differences in the flow physics of SWBLI in case of two dimensional (2D) and axisymmetric flow fields. In-house developed second order accurate finite-volume 2D axisymmetric compressible flow solver is employed for these studies. It is observed that the idea of leading edge bluntness offers reduction in separation bubble for 2D flow fields, whereas it leads to enhanced separation zone in case of axisymmetric flow fields. Relevant flow physics is well explored herein using wall pressure profile and relative thicknesses of boundary layer and entropy layer. Thicker entropy layer and stronger favorable pressure gradient are found responsible for the possibility of separation control in case of 2D flow fields. Thin entropy layer due to three dimensional relieving effect and its swallowing by the boundary layer are attributed for higher separation bubble size in case of cone with range of radii under consideration. © 2016 Elsevier Inc.