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MIME Thesis - Reza Javanbakht.pdf (3.94 MB)

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Melt pool size modeling and experimental validation for single laser track during LPBF process of NiTi alloy

Javanbakht, Reza
http://rave.ohiolink.edu/etdc/view?acc_num=toledo1620430474933088

Abstract Details

2021, Master of Science, University of Toledo, Mechanical Engineering.
NiTi Shape memory alloys (SMAs) have recently gained increased interest due to their unique features such as super elasticity and shape memory effect. There is an ongoing research effort on practical Additive Manufacturing (AM) processing to arrive at optimized AM process parameters to develop functional NiTi devices with minimal post-processing. Laser Powder Bed Fusion (LPBF) is a promising free-form AM method for fabricating this material. It is well established that LPBF AM can be used to tailor the properties of NiTi SMAs by adjusting various process parameters. Modeling approaches are cost and time-effective tools to expedite the study of process parameters optimization for AM fabricated parts. Since the LPBF process deals with ii thermal cycling over the material, thermal modeling of the LPBF process is an essential step of the process and material optimization. That is why it is essential to have a comprehensive thermal understanding of the phenomena using a thermal model to open the door for NiTi optimization. More specifically, melt pool geometry is an essential thermal parameter that affects the resulting material properties. In this thesis, a thermal model has been developed to predict the melt pool size during the LPBF of NiTi. Macroscale physics has been selected for the modeling framework utilizing COMSOL Multiphysics® to develop a thermal model for LPBF melt pool size of NiTi alloy. The Two main stages that are considered to model the melt pool are 1) thermal/melt pool modeling of single laser pass on a NiTi substrate and 2) thermal/melt pool modeling of single layer pass over a single layer of NiTi powder with a thickness of 30μm spread on a NiTi substrate. The model was calibrated in the first stage of modeling the thermal process over the substrate. Through matching the experimental and modeling results, the thermal properties were calculated. These properties were then used to calculate powder thermal properties in the second stage of simulation for laser melting of one layer of NiTi powder. Optical microscopy and in-situ thermal imaging have been used to compare the model by comparing the experimentally measured melt pool geometries and thermal profile width of the modeling results. The model shows good agreement experimental measurements in predicting the melt pool length and depth as well as the thermal profile.
Mohammad Elahinia, Dr. (Committee Chair)
Meysam Haghshenas, Dr. (Committee Member)
Ala Qattawi, Dr. (Committee Member)
108 p.
Mechanical Engineering
Physic-based modeling, Thermal modeling, NiTi alloy, Shape memory alloy, Additive manufacturing, Laser powder bed fusion, LPBF

Recommended Citations

Citations

  • Javanbakht, R. (2021). Melt pool size modeling and experimental validation for single laser track during LPBF process of NiTi alloy [Master's thesis, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1620430474933088

    APA Style (7th edition)

  • Javanbakht, Reza. Melt pool size modeling and experimental validation for single laser track during LPBF process of NiTi alloy. 2021. University of Toledo, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo1620430474933088.

    MLA Style (8th edition)

  • Javanbakht, Reza. "Melt pool size modeling and experimental validation for single laser track during LPBF process of NiTi alloy." Master's thesis, University of Toledo, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1620430474933088

    Chicago Manual of Style (17th edition)

toledo1620430474933088
1,047
© 2021, some rights reserved.Creative Commons License Melt pool size modeling and experimental validation for single laser track during LPBF process of NiTi alloy by Reza Javanbakht is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by University of Toledo and OhioLINK.