Process modeling for solidification microstructure and transient thermal stresses in laser aided DMD process
"Despite enormous progress in Laser Aided Direct Material Deposition (DMD) process adverse effects of process parameters on variety of properties and microstructure have been reported. De-bonding at substrate-deposition interface and cracking in deposited layers are a few that occur due to excessive stress build-up. Very high heating and cooling rates are inherent to this process. Consequently, the effects of solid state phase transformations cannot be neglected. A complete model that provides a quantitative relationship between process parameters, phase transformation kinetics, solidification parameters, thermal stresses and microstructure is highly desirable. This research deals with four key aspects of laser aided DMD. First, effect of solid state phase transformation on thermal stresses. Second, influence of high cooling rates on solidification microstructure at the scale of primary and secondary dendrite arm spacing. Third, effect of deposition patterns on both thermal stresses and solidification microstructure. And fourth, development of a fully coupled temperature-stress/strain field model"--Abstract, page iii.
Missouri University of Science and Technology
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