Qualification: 
M.Tech
k_devarajan@cb.amrita.edu

Devarajan K. currently serves as Assistant Professor at the Department of Mechanical Engineering, School of Engineering, Coimbatore Campus. His areas of research include Nonlinear Dynamics, Non-Smooth Dynamical Systems, Energy harvesting from dynamical systems, Non-Linear Vibration Absorbers and Regenerative chatter control in machining.

EDUCATION

YEAR DEGREE/PROGRAM INSTITUTION
2012 M.Tech in Engineering Design Amrita School of Engineering, Coimbatore
2007 B. E. in Mechanical Engineering Kongu Engineering College, Erode

Teaching

  • Engineering Mechanics
  • Kinematics of Machines
  • Dynamics of Machines
  • Mechanical Vibrations
  • Instrumentation and Control Systems

Research Interests

  • Non-Linear Dynamics
  • Non-Smooth Dynamical Systems
  • Energy Harvesting from Dynamical Systems
  • Nonlinear Vibration Absorbers
  • Regenerative chatter control

Publications

Publication Type: Journal Article

Year of Publication Title

2019

D. L. Barathwaaj, Yegateela, S., Vardhan, V., Suresh, V., Kaliyannan, D., and Devarajan, K., “Effect of inerter in traditional and variant dynamic vibration absorbers for one degree-of-freedom systems subjected to base excitations”, Mechanics and Mechanical Engineering, vol. 23, pp. 9-16, 2019.[Abstract]


In this paper, closed-form optimal parameters of inerter-based variant dynamic vibration absorber (variant IDVA) coupled to a primary system subjected to base excitation are derived based on classical fixed-points theory. The proposed variant IDVA is obtained by adding an inerter alone parallel to the absorber damper in the variant dynamic vibration absorber (variant DVA). A new set of optimum frequency and damping ratio of the absorber is derived, thereby resulting in lower maximum amplitude magnification factor than the inerter-based traditional dynamic vibration absorber (traditional IDVA). Under the optimum tuning condition of the absorbers, it is proved both analytically and numerically that the proposed variant IDVA provides a larger suppression of resonant vibration amplitude of the primary system subjected to base excitation. It is demonstrated that adding an inerter alone to the variant DVA provides 19% improvement in vibration suppression than traditional IDVA when the mass ratio is less than 0.2 and the effective frequency bandwidth of the proposed IDVA is wider than the traditional IDVA. The effect of inertance and mass ratio on the amplitude magnification factor of traditional and variant IDVA is also studied. © 2019 Wydawnictwo Politechniki Lodzkiej. All rights reserved.

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2017

K. Devarajan and B. Balaram, “Analytical Approximations for Stick-Slip Amplitudes and Frequency of Duffing Oscillator”, Journal of Computational and Nonlinear Dynamics, vol. 12, no. 4, 2017.[Abstract]


Linear spring mass systems placed on a moving belt have been subjected to numerous investigations. Dynamical characteristics like amplitude and frequency of oscillations and bifurcations have been well studied along with different control mechanisms for this model. But the corresponding nonlinear system has not received comparable attention. This paper presents an analytical investigation of the behavior of a Duffing oscillator placed on a belt moving with constant velocity and excited by dry friction. A negative gradient friction model is considered to account for the initial decrease and the subsequent increase in the frictional forces with increasing relative velocity. Approximate analytical expressions are obtained for the amplitudes and base frequencies of friction-induced stick-slip and pure-slip phases of oscillations. For the pure-slip phase, an expression for the equilibrium point is obtained, and averaging procedure is used to arrive at approximate analytical expressions of the periodic amplitude of oscillations around this fixed-point. For stick-slip oscillations, analytical expressions for amplitude are arrived at by using perturbation analysis for the finite time interval of the stick phase, which is linked to the subsequent slip phase through conditions of continuity and periodicity. These analytical results are validated by numerical studies and are shown to be in good agreement with them. It is shown that the pure-slip oscillation phase and the critical velocity of the belt remain unaffected by the nonlinear term. It is also shown that the amplitude of the stick-slip phase varies inversely with nonlinearity. The effect of different system parameters on the vibration amplitude is also studied. Copyright © 2017 by ASME.

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2016

K. Devarajan, R, R., and K, B., “Free Vibration Behavior of Fiber Metal Laminates, Hybrid Composites, and Functionally Graded Beams using Finite Element Analysis”, International Journal of Acoustics and Vibration, vol. 21, no. 4, pp. 418-428, 2016.

2015

S. Saravanamurugan, Alwarsamy, T., and Devarajan, K., “Optimization of Damped Dynamic Vibration Absorber to Control Chatter in Metal Cutting Process”, Journal of Vibration and Control, vol. 21, no. 5, pp. 949-958, 2015.[Abstract]


This paper deals with finding the optimum parameters of a damped dynamic vibration absorber (DVA) to control chatter in metal cutting systems. The performance of conventional damped DVA is compared with the proposed skyhook damper in which the damper of the absorber system is connected between the absorber mass and an inertial reference in the sky, referred to as a skyhook damper. The damped DVA is optimized by reducing the magnitude in the positive side and increasing it in the negative side of the real part of the frequency response function of the main system. The optimum frequency ratio and the damping ratio of the damped DVA for the undamped and damped main system are obtained using analytical solutions and a numerical optimisation technique, viz genetic algorithm, respectively. The performance of the proposed skyhook damper is marginally better than the conventional type of damped DVA in controlling the vibration of the main system. This is verified by analyzing both the proposed and conventional models using finite element method-based commercial software ANSYS.

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2012

K. Devarajan, Dr. Ajith Ramesh, and K Prakash Marimuthu, “FEM Analysis of Effect of Rolling Parameters on Cold Rolling Process”, Bonfring International Journal of Industrial Engineering and Management Science, vol. 2, no. 1, pp. 35-40, 2012.[Abstract]


A FEM simulation study was carried out to investigate the influence of the rolling parameters on the rolling process. Using commercial FEM software, ABAQUS, a number of cases were studied. In this paper, a two-dimensional Elastic-plastic finite element model to simulate the cold rolling of thick strip with different roll angular velocity and roll diameter models is described. The angular velocity of the rigid rolls ranged from 30 to 480 revolutions per minute (r.p.m.) and the rigid roll diameter ranged from 100 to 300 mm. The initial feeding speed of the plate and friction was kept constant, thus causing a slip between the plate and the roll surfaces. The main interest of this study is to see whether the speed of the rolls and the diameter of the rolls have any influence on the contact pressure and the residual stress in cold rolling process. The roll speed is an easily controlled operational parameter which may be used to enhance the process and the quality of the final products by changing the roller diameter and see the effect of stress and contact pressure on the thick plates strip is new one.

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Publication Type: Conference Proceedings

Year of Publication Title

2014

M. Anand, Dr. Laxman Vaitla, Devarajan, K., Balaji, R., Shrivathsan, K. S., and Adithiyakkumaran, D. A., “Structural dynamic model for a horizontal axis wind turbine system”, International Conference on Theoretical, Applied, Computational and Experimental Mechanics. IIT Kharagpur, India, 2014.