The Experts below are selected from a list of 205530 Experts worldwide ranked by ideXlab platform
Tarasankar Debroy - One of the best experts on this subject based on the ideXlab platform.
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guaranteed fillet weld geometry from heat transfer model and multivariable optimization
International Journal of Heat and Mass Transfer, 2004Co-Authors: A. Kumar, Tarasankar DebroyAbstract:Abstract Numerical heat transfer models of gas metal arc (GMA) fillet welding do not always predict correct temperature fields and fusion zone geometry. The inaccuracy results, to a large extent, due to the difficulty in correctly specifying several input parameters such as arc efficiency from scientific principles. In order to address this problem, a heat transfer model is combined with an optimization algorithm to determine several uncertain welding parameters from a limited volume of experimental data. The resulting smart model guarantees optimized prediction of weld pool penetration, throat and leg-length within the framework of phenomenological laws. A boundary fitted coordinate system was used to account for the complex fusion zone shape. The weld pool Surface Profile was calculated by minimizing the total Surface energy. Apart from the direct transport of heat from the welding arc, heat transfer from the metal droplets was modeled considering a volumetric heat source. The Levenberg–Marquardt and two versions of conjugate gradient method were used to calculate the optimized values of unknown parameters. An appropriate objective function that represented the difference between the calculated and experimental values of the penetration, throat and leg-length was minimized. The calculated shape and size of the fusion zone, finger penetration characteristic of the GMA welds and the solidified free Surface Profile were in fair agreement with the experimental results for various welding conditions.
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modeling of temperature field and solidified Surface Profile during gas metal arc fillet welding
Journal of Applied Physics, 2003Co-Authors: Cheolhee Kim, Wei Zhang, Tarasankar DebroyAbstract:The temperature Profiles, weld pool shape and size, and the nature of the solidified weld pool reinforcement Surface during gas–metal arc (GMA) welding of fillet joints were studied using a three-dimensional numerical heat transfer model. The model solves the energy conservation equation using a boundary fitted coordinate system. The weld pool Surface Profile was calculated by minimizing the total Surface energy. Apart from the direct transport of heat from the welding arc, additional heat from the metal droplets was modeled considering a volumetric heat source. The calculated shape and size of the fusion zone, finger penetration characteristic of the GMA welds, and the solidified free Surface Profile were in fair agreement with the experimental results for various welding conditions. In particular, the computed values of important geometric parameters of fillet welds, i.e., the leg length, the penetration depth, and the actual throat, agreed well with those measured experimentally for various heat inputs...
Chen Lu - One of the best experts on this subject based on the ideXlab platform.
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study on prediction of Surface quality in machining process
Journal of Materials Processing Technology, 2008Co-Authors: Chen LuAbstract:Abstract The Surface Profile and roughness of a machined workpiece are two of the most important product quality characteristics and in most cases a technical requirement for mechanical products. Achieving the desired Surface quality is of great importance for the functional behavior of a part. The process-dependent nature of the Surface quality mechanism along with the numerous uncontrollable factors that influence pertinent phenomena, make it important to find a straightforward solution and an absolutely accurate prediction model. Firstly, this paper reviews the methodologies and practice that are being employed for the prediction of Surface Profile and roughness, each approach with its advantages and disadvantages is summarized. Finally, the author's present work—prediction of Surface Profile using RBF neural network and future trend are also introduced.
Sajeev Joh - One of the best experts on this subject based on the ideXlab platform.
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achieving an accurate Surface Profile of a photonic crystal for near unity solar absorption in a super thin film architecture
ACS Nano, 2016Co-Authors: Ping Kuang, Meili Hsieh, Sergey Eyderma, Anthony Pos, Sajeev JohAbstract:In this work, a teepee-like photonic crystal (PC) structure on crystalline silicon (c-Si) is experimentally demonstrated, which fulfills two critical criteria in solar energy harvesting by (i) its Gaussian-type gradient-index Profile for excellent antireflection and (ii) near-orthogonal energy flow and vortex-like field concentration via the parallel-to-interface refraction effect inside the structure for enhanced light trapping. For the PC structure on 500-μm-thick c-Si, the average reflection is only ∼0.7% for λ = 400–1000 nm. For the same structure on a much thinner c-Si ( t = 10 μm), the absorption is near unity (A ∼ 99%) for visible wavelengths, while the absorption in the weakly absorbing range (λ ∼ 1000 nm) is significantly increased to 79%, comparing to only 6% absorption for a 10-μm-thick planar c-Si. In addition, the average absorption (∼94.7%) of the PC structure on 10 μm c-Si for λ = 400–1000 nm is only ∼3.8% less than the average absorption (∼98.5%) of the PC structure on 500 μm c-Si, while t...
Anand Asundi - One of the best experts on this subject based on the ideXlab platform.
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fast full field out of plane deformation measurement using fringe reflectometry
Optics and Lasers in Engineering, 2012Co-Authors: Lei Huang, Chi Seng Ng, Anand AsundiAbstract:Full-field out-of-plane deformation measurement of specular Surfaces can be implemented quickly and conveniently using fringe reflectometry. The system configuration is simple and processing is fast. With the assistance of an advanced fringe pattern processing technique, the windowed Fourier ridges method, only a single two-directional fringe pattern is necessary for determination of the deformed Surface Profile. Thus, the whole measurement only requires a single image with the potential for high speed or even real time measurement.
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dynamic three dimensional sensing for specular Surface with monoscopic fringe reflectometry
Optics Express, 2011Co-Authors: Lei Huang, Chi Seng Ng, Anand AsundiAbstract:Dynamic full-field three-dimensional sensing of specular reflective Surfaces can be conveniently implemented with fringe reflection technique. A monoscopic fringe reflectometric system can be adopted as a simple measuring setup. With the assistance of the windowed Fourier ridges method as an advanced fringe demodulation technique, only one cross grating is needed to reconstruct the three-dimensional Surface shape changes. A suitable calibration enables determination of the actual three-dimensional Surface Profile. Experimental results of water wave variations are shown to demonstrate the feasibility of the proposed approach.
Lalit M. Kukreja - One of the best experts on this subject based on the ideXlab platform.
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study on weld bead Surface Profile and angular distortion in 6 mm thick butt weld joints of ss304 using fiber laser
Optics and Lasers in Engineering, 2014Co-Authors: Parag Bhargava, C H Premsingh, Sanskruti Mishra, D Nagpure, Atul Kumar, C P Paul, G. Mundra, Lalit M. KukrejaAbstract:Abstract We deployed a 2 kW continuous wave fiber laser integrated with the 5-axis workstation to understand the effect of various processing parameters (laser power, welding speed, beam spot size and chamfer at welded edges) on depth of penetration, angular distortion and welded bead Surface Profile during autogenous laser welding of 6 mm thick austenitic stainless steel type 304 plates. Full penetration with reduced weld bead Surface undulation ( 0.1 and 235±10 HV 0.1 respectively. The tensile testing of laser welded samples indicated the ultimate strength >605 MPa and these samples could be bent for an angle >170° without noticeable crack during bend test. The study opened the avenues for the deployment of fiber laser welding technology for applications demanding critical values of Surface weld bead Profile and distortion.
