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

Mallikarjuna B. currently serves as Assistant Professor at the Department of Mechanical Engineering, School of Engineering, Amrita Vishwa Vidyapeetham, Coimbatore Campus.

Education

  • July 2014 - Till Date: Ph. D. in Mechanical Engineering (Pursuing)
    NITK Surathkal, Mangaluru, D. K., India
  • September 2013: M. Tech. in Computer Integrated Manufacturing
    M. S. Ramaiah Institute of Technology, Bengaluru, India

Experience

Research Experience

  • Research Scholar (Ph. D.), National Institute of Technology Karnataka, Surathkal, Mangaluru, India, July 2014 – August 2019.

Industrial Experience

  • Application Engineer at Cycloid System Pvt Limited, Bengaluru, 2013 –2014

Membership of Professional Societies

  • Associate Member in Indian Engineers Institute (IEI)-AM147064-5

Publications

Publication Type: Journal Article

Year of Publication Title

2019

Mallikarjuna B., Bontha, S., Krishna, P., and Balla, V. Krishna, “Laser surface melting of y-TiAl alloy: An experimental and numerical modeling study”, Materials Research Express, vol. 6, no. 4, 2019.[Abstract]


The objective of present work is to study the evolution of thermal stresses during laser surface melting (LSM) of γ-TiAl alloy using experimental and numerical modeling approaches. LSM of γ-TiAl alloy samples were carried out at different processing conditions in a controlled atmosphere. Material characterization of the melted region was investigated using scanning electron microscope. It was found that fully lamellar microstructure was transformed into predominantly γ-TiAl with little amount of α 2-Ti3Al. A maximum improvement in hardness of over 72% was noticed in the melted region compared to that of the substrate. Three-dimensional thermomechanical finite element analysis of LSM of γ-TiAl alloy was carried out. Melt pool dimensions, temperature history, and residual stresses were predicted from the finite element models. Measured and predicted values of melt pool depth were in good agreement with a maximum error of 13.6% at P = 400 W and V = 10 mm s−1. Predicted residual stress in the melted region exceeded the yield strength of γ-TiAl alloy and resulted in cracking of the melted region at all process conditions.

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2019

Mallikarjuna B., Bontha, S., Krishna, P., and Balla, V. K., “Prediction and validation of residual stresses generated during laser metal deposition of γ titanium aluminide thin wall structures”, Materials Research Express, vol. 6, no. 10, 2019.[Abstract]


The focus of the current work is to predict and validate residual stresses developed during Laser Metal Deposition (LMD) of Gamma Titanium Aluminide (γ-TiAl) alloy by using a combination of numerical modeling and experimental methods. Laser Engineered Net Shaping (LENS), which is one of the commercially available LMD techniques, was used to fabricate γ-TiAl alloy thin wall structures at various processing conditions. These deposits are expected to develop residual stresses due to the rapid heating and cooling cycles involved in the LMD process. 3D transient thermomechanical finite element analysis was used to simulate the LMD process. Thermal gradients and residual stresses were predicted from the thermomechanical models. It was found that the magnitude of thermal gradients increases with the addition of each deposited layer. Tensile residual stresses were observed at the edges of the thin-wall, while compressive residual stresses were observed at the center of the wall as well as in regions away from the edges. Residual stresses in the deposited samples were also measured using the x-ray diffraction technique. Reasonable agreement was observed between the predicted and measured values of residual stresses. © 2019 IOP Publishing Ltd.

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2013

Mallikarjuna B. and chandrashekar, U., “Innovative Modeling and Rapid Prototyping of Turbocharger Impeller”, International Journal of Engineering Research & Technology (IJERT), vol. 2, no. 9, pp. 1426-1432, 2013.[Abstract]


A Turbocharger is a forced induction device that is used to allow more power to be produced for an engine of a given size driven by the engine’s exhaust gases is used in petrol, diesel powered cars, trucks, marine applications, aircraft etc.In exhaust gas turbo charging, part of exhaust gas energy, which would normally be wasted is used to drive a turbine. The turbine shaft is connected to a compressor, which draws in combustion air, compresses it, and then supplies it to the engine. The increased air supply enables more fuel to be burnt, thus leading to lower fuel consumption and less emission; hence the engine develops higher power. Development of impeller for turbochargers through conventional manufacturing has got many challenges due to the blade geometry complexity and high competition in industries due to cost management. The normal manufacturing route involves casting and machining this would lead the cost. Time consumption and not efficient for small manufactures. The aim of the project is to make impeller for turbochargers with great design flexibility, less time consumption by integrating the reverse engineering (RE) and rapid prototyping (RP) techniques called Stereolithography apparatus (SLA). SLA technique would give the design flexibility with reduced cost and it can be used for visualization, mechanical testing etc.

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Publication Type: Conference Paper

Year of Publication Title

2016

B. Hazarika, Mallikarjuna B., Krishna, P., Balla, V. Krishna, and Bontha, S., “Numerical Modelling of Laser Additive Manufacturing Processes”, in NAFEMS India Regional Conference , Bengaluru, 2016.[Abstract]


Since its development in the 1980's, additive manufacturing has progressed from manufacturing polymer prototypes to actual industrial products made from metals, polymers, composites, etc. The focus of the present work is to understand the thermal behavior during Laser Additive Manufacturing (LAM) of Titanium alloy Ti-6Al-4V using thermal finite element models. Transient thermal finite element analysis is carried out to study the effect of distribution of laser power on melt pool and microstructure in laser-deposited Ti-6Al-4V. Three different types of laser power distributions are considered: Moving point heat source, Heat source with uniform distribution of power and Heat source with Gaussian distribution of power. Results indicate significant variation of melt pool depth for different power distributions. Further, cooling rates and thermal gradients extracted from numerical models are interpreted in the context of a solidification map for Ti-6Al-4V material system to understand the effect of power distribution on grain morphology. Solidification map results indicate that the distribution of laser power does not have a significant effect on grain morphology. Next, numerical models using the element birth and death technique are used to simulate the multi-layer deposition of thin-wall geometries in Laser Additive Manufacturing Processes. In the multi-layer model, deposition of 15 layers was simulated. The temperature distribution in each layer is studied to understand the thermal cycling that each layer is subjected to in LAM processes. The temperature history of the multi-layer model showed that for the first few layers the temperatures of successive layers was much higher than the previous layers, indicating the effect of the substrate to act as a heat sink and conduct the heat away in the lower layers. This also results in the increase of melt pool dimensions with the increase in layer number for the first few layers. The melt pool dimensions stabilize as the number of layers increase indicating the diminishing effect of the substrate.

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2016

Mallikarjuna B., Krishna, P., Balla, V. Krishna, Das, M., and Bontha, S., “Understanding Thermal Behavior in Laser Processing of Titanium Aluminide Alloys”, in 6th International & 27th All India Manufacturing Technology, Design and Research Conference (AIMTDR-2016), Pune, India, 2016.[Abstract]


Titanium Aluminide (TiAl) alloys are promising materials for applications in aerospace, automotive and power plant sectors because of their low density and high oxidation resistance. Conventionally these alloys are processed using Casting and Powder Metallurgy techniques. However, processing of these alloys is a major challenge due to their low ductility and fracture toughness. Therefore, research is ongoing to find new processing methods for TiAl alloys. Additive Manufacturing is one of the processing techniques that is currently being explored to fabricate these alloys. In this work, Laser Engineered Net Shaping (LENSTM) technique is used to remelt a TiAl alloy sample fabricated using Electron Beam Melting (EBM) under different processing conditions. The focus of this work is to understand the thermal behavior during laser processing of TiAl alloys using a combination of computational and experimental approaches. Transient thermal finite element analysis is carried to simulate the laser remelting process. The dimensions of the melt pool, and the maximum temperature within the melt pool are extracted from the FEM models. Next, melt pool depths of the remelted samples have been measured using Scanning Electron Microscopy. The value of the laser absorption coefficient of TiAl alloy is then determined by comparing the measured and FEM predicted melt pool depths.

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