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Summer Research Fellowship Programme of India's Science Academies

Geometric Modelling and Experiments with Moving Laser Melt Pool

CHIRAG ANILKUMAR

Government Engineering College, Thrissur, Kerala 680009

DR. PRANAB SAMANTA

Central Mechanical Engineering Research Institute, Durgapur, West Bengal 713209

Abstract

Laser DMD is an additive manufacturing technique in which multiple layers of material are used to build complex parts. The study involves a mathematical modelling of melt pool geometry and its relationship with parameters such as laser power, powder mass flux, traverse speed etc. Determination of the melt pool geometry is carried out by the application of energy and mass balances based on one-dimensional heat flow into the substrate. The modelling is done by assuming a single layer cladding, with the build material assumed to be 316L SS and the laser source is taken to be HPDL. The mathematical model involves a series of coupled non-linear equations which are solved using MATLAB. The results predicted by the model are validated based on experimental observations. Linear regression analysis is carried out to determine the relation between the geometrical parameters of the laser formed melt pool such as height and width, with respect to the process parameters. Various regressive models are analysed and the optimal one is chosen based on the value of the coefficient of determination. Transient coupled thermal and structural analysis is carried out using ANSYS, to determine the maximum temperature attained during the process and also to determine the residual stress and deformation of the substrate after the process.

Keywords: rapid prototyping, cladding, analytical model, laser, energy balance, mass balance, regression, transient thermal, transient structural

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