CharacterizATION of Surface Defects in Additively Manufactured Components via Scalable Optical Imaging (2017-2018)

Defects are inevitable in Additively Manufactured components due to the nature of the process. In this project, the goal was to develop a novel method of characterizing horizontal and vertical notch defects observed in a cylindrical Fused Deposition Modeling (FDM). The method developed was scalable i.e. was implementable by smart phone imaging and also high speed/resolution camera. Using Digital Image Correlation (DIC), the surface speed of the part was characterized during rigid body rotation, followed by normalization with respect to rotational speed. Accuracy of the method was validated by laser scanning method.

Methods: Digital Image Correlation, Laser Scanning

Tools: Fused Deposition Modeling, Matlab, PCO.edge High-Speed camera, Keyence Laser Scanner

Publications: NAMRC 2018, MS&T 2018

Microstructure Evolution during indentation of Direct Metal Laser Sintered Inconel 718 (2018-2020)

Shot peening is a post processing step performed in additively manufactured parts to provide them with better fatigue strength and create noncrystalline grains. In this project, indentation has been used to study the microstructure evolution which can be compared to a unit impact of shot peening process. Understanding the grains response and the residual stress build up after indentation was one of the prime goals of this project. Exploring the effect of surface texture, porosity defect and gradient structure on indentation was also an objective of this study.

Methods: Direct Metal Laser Sintering, Digital Image Correlation, Finite Element Analysis, Optical Imaging Microscopy, Quantitative analysis of microstructure properties

Tools: Mtex 5.1.1, PCO.edge High-Speed camera, Scanning Electron Microscope, Aztec by Oxford Instruments, Matlab, Abaqus, Python

Publications: NAMRC 2020 , MSEC 2020, Materials Science and Engineering: A

Effect of initial surface orientation and texture on the residual stress and surface roughness after Bead blasting Electron Beam Melted Ti-6Al-4V (2019-Present)

[works related to this project was a finalist in Millennium Cafe Pitch Competition, 2021 (organized by Materials Research Institute, Penn State) won 3rd Prize in Graduate Exhibition 2021, Penn State]

Depending on the surface orientation with respect to build direction, various surfaces in Electron Beam Melted (EBM) parts are produced with different surface roughness. Exploring the effect of surface orientation and texture on the bead blasting of EBM Ti-6Al-4V was the goal of this study. To be more specific, how different surface roughness/texture of the parts can effect the mechanics of residual stress was explored in this project.

Methods: Residual stress measurement, Surface roughness measurement, Finite Element Analysis

Tools: Electron Beam Melting (EBM), Abaqus, X-ray diffraction, White light profilometry, Electric Discharge Machining (EDM)

Publications: MDPI Crystal Journal's special Issue Defects in Crystals

Deformation behavior of direct metal laser sintered inconel 718 during nanoscratch (2020-Present)

[Works related to this project won Society of Tribologists and Lubrication Engineers Scolarship,2021 and 3rd Prize in College of Engineering Research Symposium (CERS), 2022 organized by College of Engineering, Penn State]

Abrasive surface finishing processes like centrifugal disc finishing is implemented in aerospace industry to finish rough AM surfaces. The relative motion between the AM surface and abrasive particles can be thought of a combination of numerous nanoscratches. In this study, we investigate the pile-up behavior of the nanoscratches made during the scratch in the material surface.

Methods: Microstructural characterization, Surface characterization, Microhardness test, Heat treatment, Finite Element Modeling

Tools: Direct Metal Laser Sintering (DMLS) , Abaqus, X-ray diffraction, Electric Discharge Machining (EDM), Electron Backscattered Diffraction (EBSD), Atomic Force Microscopy (AFM)

Publications: Work in process...

Deformation behavior of direct metal laser sintered and wrought inconel 718 during centrifugal disc finishing (2021-Present)

The roughness evolution of DMLS and wrought Inconel 718 during centrifugal disc finishing is investigated in this study. Analytical model relating the effect of media roughness evolution to the final surface roughness and starting surface roughness with the final surface roughness are proposed. Mechanism of surface finishing in case of DMLS and wrought samples are delineated. Lastly, effect of using unimodal and bimodal media is investigated.

Methods: Microstructural characterization, Surface characterization, Analytical Modeling, Image Analysis

Tools: Direct Metal Laser Sintering (DMLS) , X-ray diffraction, Electric Discharge Machining (EDM), Centrifugal Disc Finishing

Publications: Work in process...