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

Micropipette aspiration technique can be very useful for describing the shape transitions of lipid bilayer vesicles with fluid phase coexistence modulated by the line tension and the bending rigidity. For example, composition dependence of the line tension at the liquid-ordered and liquid-disordered phase interface has been investigated using this technique. Recently, using a very simple mechanical model, the instabilities that occur during suction and release experiments of aspirated vesicles have been discussed. Due to its simplicity the model could not predict the influence of the bending rigidity. In this work, we incorporate the contributions from Helfrich bending energy and the line energy in the vesicle free energy and investigate the shape transitions in micropipette aspirated vesicles. We discuss how the critical aspiration pressure depends on the bending moduli of the phases, the line tension at the interface, and the reduced volume of the vesicle. The ratio of the bending moduli that we predict using the critical aspiration pressure data from recent experiments agrees with the literature. © 2010 The American Physical Society.

Physical Review E - Statistical, Nonlinear, and Soft Matter Physics

Influence of the bending rigidity and the line tension on the mechanical stability of micropipette aspirated vesicles

The objective of this study is to analyze the dynamic behavior of composite shafts with particular interest on estimation of damping. The composite shafts have been chosen as potential candidates for the replacement of conventional metallic shafts in many applications. This study analyzed the dynamic behavior of different materials such as glass/epoxy, carbon/epoxy, and boron/epoxy at different speeds. Detailed dynamic studies on the effect of different materials, stacking sequences on the unbalance responses, and eigenfrequencies are required, particularly with respect to the damping present in the composite material. Different methodologies such as logarithmic decay curve, half-power method, and hysteresis loop method using force sensors have been used for determining the damping of the composite shafts. Composite tube-shafts and solid shafts have been modeled and analyzed using ANSYS. A parametric study has been carried out to analyze the effect of stacking sequence on eigenfrequencies of composite tube-shafts. This study aims to have a comprehensive view of numerical and experimental analyses of composite shafts for eigenvalues, damping estimation, and unbalance response. Eigenfrequencies of composite tube-shafts and solid shafts were estimated through modal testing and are compared with analytical and FEM results. In this study, torsional vibration analysis for composite solid shafts has also been carried out using the rotational laser vibrometer. © The Author(s) 2010.

World University root node

Journal of Reinforced Plastics and Composites

Dynamic analysis of shafts of composite materials

In this work, we study the adhesion of multicomponent vesicle membrane to both flat and curved substrates, based on the conventional Helfrich bending energy for multicomponent vesicles and adhesion potentials of different forms. A phase field formulation is used to describe the different components of the vesicle. For the axisymmetric case, a number of representative equilibrium vesicle shapes are computed and a few energy diagrams are presented which reveal the dependence of the calculated shapes and solution branches on various parameters including both bending moduli and spontaneous curvatures as well as the adhesion potential constants. Our computation also confirms a recent experimental observation that the adhesion may promote phase separation in two-component vesicle membranes. © 2010 The American Physical Society.

Fulltext

Adhesion of multicomponent vesicle membranes

In aircrafts and missiles, actuators are commonly utilized for driving various subsystems including flight control surfaces. Brushless DC motor (BLDC) based electromechanical actuation systems are getting increasingly popular due numerous advantages. Electromechanical Linear actuators (EMLA) are common due to their high torque amplification. The failure modes for these systems transcend electrical, mechanical, and electronic systems are masked by external forces and the dynamic properties of control systems making it difficult to use model based condition monitoring techniques. Generally these systems are stored for longer times before operation, so a comprehensive health monitoring strategy is required for their fault free operation as and when required. The aim of this paper is to identify gear faults signatures in motor current of closed loop electromechanical linear actuators by experimental approach. It also considers the effect of load on the Motor Current Signature Analysis (MCSA) signatures and their comparison with vibration signatures. An amplified error spectrum method devised for such feedback systems was also compared for its fault signature detection capability with vibration and MCSA signatures.

16th International Congress on Sound and Vibration 2009, ICSV 2009

Condition monitoring of BLDC motor based electromechanical linear actuators

Application of robust design techniques in the design of controllers for Autonomous Underwater Vehicles (AUVs) is discussed in this paper. Proper tuning of controllers is essential in achieving the desired positional and tracking accuracy of AUVs in underwater missions. A new scheme of gain tuning using Taguchi method is introduced here for the proportional-integral-derivative (PID) control of an under-actuated AUV with less controllable degrees of freedom than the total number of degrees of freedom. With four controllable states, this vehicle has twelve controller gains to be tuned. Through the help of design of experiments (DOE) and robust design techniques, as applied in the Taguchi optimization method, an optimal and robust set of PID controller gains have been obtained. A simulation study of the pitch control of an AUV using the above method is presented in the paper. The simulation results are compared with the other tuning methods like Ziegler - Nichols, Auto tune, Tyreus - Luyben and Cohen-Coon method. The results show that the index of aggregate absolute error has reduced to 78.73% and 24.34% from the Ziegler - Nichols method 1 and Tyreus-Luyben method respectively. Copyright © 2009 by The International Society of Offshore and Polar Engineers (ISOPE).

Proceedings of the ISOPE Ocean Mining Symposium

Application of robust design techniques for underwater vehicle control

After unbalance, coupling misalignment is the most common fault present in rotating machines. However, limited research has been carried out on coupling misalignment and its effects. The present study aims to explore the research on coupling misalignment by briefly summarizing the research work done so far on different modelling techniques, effects on the system behaviour, fault identification and condition monitoring techniques.

Noise and Vibration Worldwide

Coupling misalignment in rotating machines: Modelling, effects and monitoring

IIT Kharagpur

Surface modification of Aluminium by electrical discharge coating in EDM

Hydrodynamic parameters play a major role in the dynamics and control of Autonomous Underwater Vehicles (AUVs). The performance of an AUV is dependent on the parameter variations and a proper understanding of these parametric influences is essential for the design, modeling, and control of high-performance AUVs. In this paper, the sensitivity of hydrodynamic parameters on the control of a flatfish type AUV is analyzed using robust design techniques such as Taguchi's design method and statistical analysis tools such as Pareto-ANOVA. Since the pitch angle of an AUV is one of the crucial variables in the control applications, the sensitivity analysis of pitch angle variation is studied here. Eight prominent hydrodynamic coefficients are considered in the analysis. The results show that there are two critical hydrodynamic parameters, that is, hydrodynamic force and hydrodynamic pitching moment in the heave direction that influence the performance of a flatfish type AUV. A near-optimal combination of the parameters was identified and the simulation results have shown the effectiveness of the method in reducing the pitch error. These findings are significant for the design modifications as well as controller design of AUVs. Copyright © 2009 M. Santhakumar et al.

International Journal of Quality, Statistics, and Reliability

Analysis of parameter sensitivity using robust design techniques for a flatfish type autonomous underwater vehicle

The composite material shafts have been sought as new potential candidates for replacement of the conventional metallic shafts in many applications. These shafts are proved to have not only lighter in weight but also have greater strength. However, detailed dynamic studies on the effects of different materials, speeds and unbalance response are required, particularly with respect to the damping present due to the composite material. The main aim of the paper is to estimate the damping in rotor system consists of a composite solid shaft. The study is carried out to analyze the dynamic behaviour at different speeds and for different materials such as glass/epoxy, carbon/epoxy. Three different methodologies have been carried out for determining the damping of the composite shaft- rotor. The first one is to measure the signal at any speed, with impact hammer and get the logarithmic decay curve at that speed. From this the damping was estimated. The second method is to use half-power method to estimate the damping from the response of the rotor. In third methodology force sensors are used to get the unbalance force of the system and consequently hysteresis loops are obtained between the force and displacement for different speeds to get the equivalent damping. Simultaneously the Finite Element Analysis of the same rotor system using ANSYS software is carried out for eigenfrequencies. These results for different materials are compared with those of experiments.

Damping estimation and dynamic analysis of a composite shaft - Rotor system

Hydrodynamic parameters play a major role in the dynamics and control of Autonomous Underwater Vehicles (AUV). The performance of an AUV is dependent on the parameter variations and a proper understanding of these parametric influences is essential for the design, modelling and control of high performance AUVs. In this paper, a six sigma framework for the sensitivity analysis of a flatfish type AUV is presented. Robust design techniques such as Taguchi's design method and statistical analysis tools such as Pareto-ANOVA, and ANOVA are used to identify the hydrodynamic parameters influencing the dynamic performance of an AUV. In the initial study, it is found that when the vehicle commanded in forward direction, it is in bow down configuration which is unacceptable for AUV motion. This is because of the vehicle buoyancy and shape of the vehicle. So the sensitivity analysis of pitch angle variation is studied by using robust design techniques. Six prominent hydrodynamic coefficients are considered for the analysis. The results show that there are three critical hydrodynamic parameters such as buoyancy, added mass, and hydrodynamic moment in heave motion that influence the performance of a flat fish type AUV. These findings are significant in the design modifications as well as controller design of AUV. Copyright © 2009 SAE International.