A finer modeling approach for numerically predicting single track geometry in two dimensions during Laser Rapid Manufacturing Atul Kumar n , C.P. Paul, A.K. Pathak, P. Bhargava, L.M. Kukreja Laser Materials Processing Division, Raja Ramanna Centre for Advanced Technology, Indore 452013, India article info Article history: Received 11 May 2011 Received in revised form 29 August 2011 Accepted 29 August 2011 Available online 16 September 2011 Keywords: Numerical modeling Single track geometry Laser Rapid Manufacturing abstract We simulated the temperature distribution and single track geometry in Laser Rapid Manufacturing (LRM) of metal structures using two dimensional FEM with a finer modeling approach. This approach involved the calculation of excessive enthalpies above melting point for all nodal points in the process domain and using those for the computation of local track height at every node along the track width on the substrate. Laser power, laser beam size with its spatial profile, scan speed, powder feed rate and powder stream diameter with its flow distribution were taken as user-defined input parameters to simulate the single track geometry during LRM. The simulated results were experimentally verified. The percentage errors in simulated and corresponding experimental track heights along the normalized track width were calculated and compared with those of other existing models. With our modeling approach, the localized errors in predicting track geometries were found to be the least. This model is capable of dynamically predicting the temperatures and track geometry at various user-defined input parameters. & 2011 Elsevier Ltd. All rights reserved. 1. Introduction Laser Rapid Manufacturing (LRM) is one of the fastest emerging additive fabrication techniques with next generation ‘‘feature based design and manufacturing’’ approach that finds a wide range of applications, specifically because of its capability to facilitate multi- materials and multi-functional fabrication of engineering and pros- thetic components in niche utilitarian areas [1]. Traditionally, it is employed for component repairing and reconditioning [2] and rapid prototyping. Recently, the application is extended to the production of functionally graded materials [3, 4] and porous materials [5]. The experimentalists at various national laboratories and renowned universities [6–9] are currently exploiting the commercial viability of the developed process, while others are augmenting the technology with the process modeling using analytical and numerical tools. These modeling approaches with newer or alternative strategies are being investigated for better process insight and superior under- standing of LRM process. Jendrzejewski et al. investigated the time- dependent temperature and stress fields developed during laser cladding in order to understand the cause of micro-cracking in the laser deposited metallic coatings [10]. Wang et al. developed a two- dimensional thermal model to predict the temperature distribution in the deposited metal for SS316 during the LENS process as a function of time and process parameters [11]. Vasinonta et al. presented process maps to identify a manufacturing strategy for obtaining a consistent melt pool size while limiting residual stress in thin-walled parts [12]. Peyre et al. used a three-step analytical and numerical approach with a finite element calculation to predict the shapes of manufactured structures and thermal loadings [13]. The effects of heat conduction, Marangoni flow and thermal buoyancy on melting process and the shape of molten pool were numerically analyzed by Yang et al. [14]. Recently, Ahmed et al. used analytical model to predict the effect of beam shape on melt pool shape and optimized the overlap required for laser surface processing applications [15]. Toyserkani et al. studied in their numerical model for pulsed laser cladding and established the correlation between the track geometry and laser pulse shaping parameters (laser pulse frequency and energy) when the other process parameters were constant [16]. A theoretical model supported by experiment is investigated by Liu et al. of the optimization of process parameters for the fabrication of less than 1 mm thin wall [17]. A self-consistent three-dimensional model was developed by Qi et al. for a coaxial laser powder cladding process, which simulates heat transfer, phase changes, and fluid flow in the molten pool [18]. A mathematical 3-D model was developed by He et al. to simulate the temperature and composition distribution during the laser cladding process of H13 tool steel for laser beam of TEM 00 [8]. The model assumed that the temperature independent thermo-physical properties and absorption coefficient of laser and they were considered the same for substrate and powder. Alimardani et al. developed a comprehensive model to evaluate the track geometry during LRM [19]. This model is based on conservation of mass within the process domain for material addition. It predicts local track height by incorporating catchment efficiency into powder feed on the molten substrate surface for each time interval. Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/optlastec Optics & Laser Technology 0030-3992/$ - see front matter & 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.optlastec.2011.08.026 n Corresponding author. E-mail address: atulk@rrcat.gov.in (A. Kumar). Optics & Laser Technology 44 (2012) 555–565