Qualification: 
Ph.D
r_ajith@cb.amrita.edu

Dr. Ajith Ramesh currently serves as Associate Professor at Department of Mechanical Engineering, School of Engineering, Coimbatore Campus. His areas of research include FEM, Creep and Faliure Analysis, Contact Mechanics and Composite Structures.

Publications

Publication Type: Journal Article

Year of Conference Publication Type Title

2016

Journal Article

Ma Haridas, Gopal, Gb, Dr. Ajith Ramesh, and Katta, R. Kb, “Modelling and simulation of single and multi-pass flow forming to investigate the influence of process parameters on part accuracy”, International Journal of Manufacturing Research, vol. 11, pp. 274-289, 2016.[Abstract]


Flow forming is an incremental forming process used for making long, thin-walled seamless tubes with high strength and dimensional accuracy. This is carried out by compressing the pre-formed tube using one or more rollers, leading to the plastic flow of material in the radial, axial, and tangential directions. This ultimately results in reduction in thickness and elongation of the tube. In order to achieve the required accuracy and to reduce the shop floor costs, a better understanding of the influence of process parameters on part geometry, deformation mechanism, and stress-strain patterns will be required. This paper describes the development of a detailed finite element model, using Abaqus/Explicit, to accurately simulate the flow forming process for AISI-1045 MC-Steel, and attempts to predict the influence of process parameters like axial stagger, feed ratio, and percentage reduction, on output parameters like ovality, diametral growth, and spring back. The effect of multi-pass on surface finish is also investigated.

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2015

Journal Article

Dr. Ajith Ramesh, Sumesh, C. S., Abhilash, P. M., and Rakesh, S., “Finite Element Modelling of Orthogonal Machining of Hard to Machine Materials”, International Journal of Machining and Machinability of Materials, vol. 17, pp. 543-568, 2015.[Abstract]


This paper presents a detailed finite element model to predict deformation and other machining characteristics involved in high-speed orthogonal machining (cutting speed > 54 m/min) of hard-to-deform materials like Ti6Al4V. The influence of various cutting parameters like feed rate, spindle speed, and rake angle, on the output parameters like cutting force and surface finish, was analysed. The paper tries to relate the degree of surface finish with the variance of the effective plastic strain. The Johnson-Cook material model is used to describe the material constitutive behaviour, and the Johnson-Cook damage model is used to establish the damage criteria. Due to the high machining costs associated with the titanium alloy, the model is first validated using aluminium alloy (Al2024-T351), and the same model is then extended to predict the results for titanium alloy. The matrix for the design of experiments (DOE) considers a full factorial approach, with about 48 simulations, for a proper understanding on the influence of the major machining parameters. A dynamic, explicit integration scheme is used along with the arbitrary Lagrangian-Eulerian (ALE) technique to accurately predict material flow. This paper also presents a unique method to tackle the commonly encountered numerical issues involved in modelling self-contact. More »»

2012

Journal Article

K. Devarajan, Dr. Ajith Ramesh, and K Marimuthu, P., “FEM Analysis of Effect of Rolling Parameters on Cold Rolling Process”, Bonfring International Journal of Industrial Engineering and Management Science, vol. 2, no. 1, 2012.

2011

Journal Article

R. V. Prakash, Arunkumar, S., and Dr. Ajith Ramesh, “Spherical indentation of nickel thin film on steel - 4340 substrate”, ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011, vol. 3, pp. 745-750, 2011.[Abstract]


In this paper, finite element simulations of spherical indentation of Nickel thin film on Steel-4340 are studied for single and multiple cycle of indentation as well. The objective was to understand the mechanics of coated systems, from load-displacement (P-h) curves, stress distribution in the film and the effect of substrate yield strength on the indentation response. The loading portion of P-h curve showed displacement bursts and the reason for this is investigated. A transition in the deformation behavior of the film from Hertz-type to flexure was observed for a normalized indentation depth of h/tf≈0.2. The influence of coating-substrate properties on P-h curve is also investigated for different h/tf ratios and yield strains. Attempts are also made to explore the possibility of understanding the creep-fatigue behavior of coated specimen subjected to cyclic indentation at room temperature from Indentation depth v/s time, Indentation depth v/s number of cycles and Plastic dissipation energy v/s number of cycles curve.

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Publication Type: Conference Proceedings

Year of Conference Publication Type Title

2013

Conference Proceedings

Dr. Ajith Ramesh, Prasad, M. P. Hari, and Renganathan, K., “Nonlinear Visco-Elastic Stress Analysis of a Circular Perforated Solid Propellant Grain”, International conference on Computer Aided Engineering (CAE). IIT-Madras, Chennai, 2013.

2013

Conference Proceedings

D. Karuppannan, Sivaraman, V., Gaddikeri, K. M., Sundaram, R., and Dr. Ajith Ramesh, “Effect of Tufting on Mechanical Properties of Laminated Composites”, ISAMPE National Conference on composite Materials. Amrita Vishwa Vidyapeetham, Coimbatore, 2013.

2011

Conference Proceedings

R. V. Prakash, Arunkumar, S., and Dr. Ajith Ramesh, “Spherical Indentation of Nickel Thin Flim on Steel-4340 Substrate”, International Conference on Advances in Materials and Techniques for Infrastructure Development (AMTID), vol. 17. NIT-Calicut, pp. 543-568, 2011.[Abstract]


In this paper, finite element simulations of spherical indentation of Nickel thin film on Steel-4340 are studied for single and multiple cycle of indentation as well. The objective was to understand the mechanics of coated systems, from load-displacement (P-h) curves, stress distribution in the film and the effect of substrate yield strength on the indentation response. The loading portion of P-h curve showed displacement bursts and the reason for this is investigated. A transition in the deformation behavior of the film from Hertz-type to flexure was observed for a normalized indentation depth of h/tf ≈0.2. The influence of coating–substrate properties on P-h curve is also investigated for different h/tf ratios and yield strains. Attempts are also made to explore the possibility of understanding the creep-fatigue behavior of coated specimen subjected to cyclic indentation at room temperature from Indentation depth v/s time, Indentation depth v/s number of cycles and Plastic dissipation energy v/s number of cycles curve.

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2011

Conference Proceedings

Dr. Ajith Ramesh, Prakash, R. V., S, A. Kumar, and N, D., “Contact Stress-Strain and Wear Analysis of some Thermo-Plastics on Zerodur Glass”, International Conference on Simulation, Modeling, and Analysis (COSMA). Amrita Vishwa Vidyapeetham, Coimbatore and NIT-Calicut., 2011.

2011

Conference Proceedings

Dr. Ajith Ramesh, K, D., and K, P. Marimuthu, “Finite Element Modeling of the Cold Rolling Process and Optimization using Genetic Algorithm”, International Conference on Simulation, Modeling, and Analysis (COSMA). Amrita Vishwa Vidyapeetham, Coimbatore and NIT-Calicut., 2011.

2010

Conference Proceedings

P. P. Sairam, R, S. M., Dr. Ajith Ramesh, and Dr. Meera Balachandran, “Mechanical And Visco-Elastic Properties Of Silicone Rubber – Nanoclay Composites And Its Application In Vibration Damper”, Proceedings of International Conference on Manufacturing Science and Technology (ICMST 2010). Indian Institute of Space Science and Technology and Materials Research Society of India, Thiruvananthapuram, 2010.

2009

Conference Proceedings

Dr. Ajith Ramesh, Bose, K., and Lawton, K. M., “Modeling the Creep Behavior of Torsional Springs”. The University of North Carolina at Charlotte, 2009.[Abstract]


This dissertation presents a detailed model of the ‘overall’ behavior of Torsional springs. Torsional springs (also called ‘Clock’ springs) are a kind of spiral springs which are supposed to provide a certain torque when wound-up to a certain rotation. However, it is observed that the moments that are developed relax when the springs are kept loaded over long periods of time. The research presented here is an attempt to investigate this behavior by identifying the role played by the various influencing parameters.

The dissertation focuses on the development of a detailed component-level finite element model to investigate the instantaneous moment-rotation response as well as the long-term (time-dependant) structural response of a torsional spring. Torsional springs belong to a class of planar spiral springs that are commonly made out of Elgiloy - an alloy of Cobalt, Chromium, Nickel, and Iron. Elgiloy has very high yield strength, and is commonly used as a spring material in analog clocks. In addition, the research also aims at developing a better understanding of the dependence of the response of the spring on the different design parameters that define its geometry and material properties. Frictional contact, large deformations, and nonlinear material behavior (plasticity and creep) are among the major challenges that need to be resolved in order to obtain a thorough understanding of the problem. The modeling effort also focuses on understanding the experimentally-observed hysteresis associated with a cyclic moment versus rotation response, as well as the development of simple analytical models which can approximately describe the structural response of a typical torsional spring.

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