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A thermal-mechanical finite element workflow for directed energy deposition additive manufacturing process modeling

Additive Manufacturing

Stender, Michael S.; Beghini, Lauren L.; Sugar, Joshua D.; Dagel, Daryl D.; Subia, Samuel R.; Veilleux, Michael V.; San Marchi, Christopher W.; Brown, Arthur B.

This work proposes a finite element (FE) analysis workflow to simulate directed energy deposition (DED) additive manufacturing at a macroscopic length scale (i.e. part length scale) and to predict thermal conditions during manufacturing, as well as distortions, strength and residual stresses at the completion of manufacturing. The proposed analysis method incorporates a multi-step FE workflow to elucidate the thermal and mechanical responses in laser engineered net shaping (LENS) manufacturing. For each time step, a thermal element activation scheme captures the material deposition process. Then, activated elements and their associated geometry are analyzed first thermally for heat flow due to radiation, convection, and conduction, and then mechanically for the resulting stresses, displacements, and material property evolution. Simulations agree with experimentally measured in situ thermal measurements for simple cylindrical build geometries, as well as general trends of local hardness distribution and plastic strain accumulation (represented by relative distribution of geometrically necessary dislocations).

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TYPE Journal Article YEAR 2018
DOIOSTIScopus

Changing the Engineering Design & Qualification Paradigm in Component Design & Manufacturing (Born Qualified)

Roach, R.A.; Bishop, Joseph E.; Jared, Bradley H.; Keicher, David M.; Cook, Adam W.; Whetten, Shaun R.; Forrest, Eric C.; Stanford, Joshua S.; Boyce, Brad B.; Johnson, Kyle J.; Rodgers, Theron R.; Ford, Kurtis R.; Martinez, Mario J.; Moser, Daniel M.; van Bloemen Waanders, Bart G.; Chandross, M.; Abdeljawad, Fadi F.; Allen, Kyle M.; Stender, Michael S.; Beghini, Lauren L.; Swiler, Laura P.; Lester, Brian T.; Argibay, Nicolas A.; Brown-Shaklee, Harlan J.; Kustas, Andrew K.; Sugar, Joshua D.; Kammler, Daniel K.; Wilson, Mark A.

Abstract not provided.

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TYPE Presentation YEAR 2018
OSTIOSTI

Anomalous Annealing Response of Directed Energy Deposited Type 304L Austenitic Stainless Steel

JOM

Smith, Thale R.; Sugar, Joshua D.; Schoenung, Julie M.; San Marchi, Christopher W.

Directed energy deposited (DED) and forged austenitic stainless steels possess dissimilar microstructures but can exhibit similar mechanical properties. In this study, annealing was used to evolve the microstructure of both conventional wrought and DED type 304L austenitic stainless steels, and significant differences were observed. In particular, the density of geometrically necessary dislocations and hardness were used to probe the evolution of the microstructure and properties. Forged type 304L exhibited the expected decrease in measured dislocation density and hardness as a function of annealing temperature. The more complex microstructure–property relationship observed in the DED type 304L material is attributed to compositional heterogeneities in the solidification microstructure.

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TYPE Journal Article YEAR 2018
DOIOSTIScopus

Strong Photothermoelectric Response and Contact Reactivity of the Dirac Semimetal ZrTe5

ACS Applied Materials and Interfaces

Leonard, Francois L.; Yu, Wenlong; Celio, Kimberlee C.; Medlin, Douglas L.; Sugar, Joshua D.; Talin, A.A.; Pan, Wei P.

The family of three-dimensional topological insulators opens new avenues to discover novel photophysics and to develop novel types of photodetectors. ZrTe5 has been shown to be a Dirac semimetal possessing unique topological, electronic, and optical properties. Here, we present spatially resolved photocurrent measurements on devices made of nanoplatelets of ZrTe5, demonstrating the photothermoelectric origin of the photoresponse. Because of the high electrical conductivity and good Seebeck coefficient, we obtain noise-equivalent powers as low as 42 pW/Hz1/2, at room temperature for visible light illumination, at zero bias. We also show that these devices suffer from significant ambient reactivity, such as the formation of a Te-rich surface region driven by Zr oxidation as well as severe reactions with the metal contacts. This reactivity results in significant stresses in the devices, leading to unusual geometries that are useful for gaining insight into the photocurrent mechanisms. Our results indicate that both the large photothermoelectric response and reactivity must be considered when designing or interpreting photocurrent measurements in these systems.

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TYPE Journal Article YEAR 2017
DOIOSTIScopusDOIOSTIScopus

Recrystallization Behavior of a Laser Additive Manufactured Austenitic Stainless Steel

JOM. Journal of the Minerals, Metals & Materials Society

Smith, Thale R.; Sugar, Joshua D.; Schoenung, Julie M.; San Marchi, Christopher W.

Directed energy deposition (DED) and forged austenitic stainless steels possess distinct microstructures, but may exhibit similar mechanical properties. In this study, annealing is used to evolve the microstructures of these materials, and scanning electron microscopy techniques are used to probe the similarities and differences of the microstructure-property relationships. A strong correlation between geometrically necessary dislocation (GND) density and hardness is observed for the forged material. Finally, a more complex relationship is observed in the DED material and is attributed to the thermally driven dissolution of the solidification microstructure.

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TYPE Journal Article YEAR 2017
DOIDOIOSTIOSTI

Enhanced Kinetics of Electrochemical Hydrogen Uptake and Release by Palladium Powders Modified by Electrochemical Atomic Layer Deposition

ACS Applied Materials and Interfaces

Benson, David M.; Tsang, Chu F.; Sugar, Joshua D.; Jagannathan, Kaushik; Robinson, David R.; El Gabaly Marquez, Farid E.; Cappillino, Patrick J.; Stickney, John L.

Electrochemical atomic layer deposition (E-ALD) is a method for the formation of nanofilms of materials, one atomic layer at a time. It uses the galvanic exchange of a less noble metal, deposited using underpotential deposition (UPD), to produce an atomic layer of a more noble element by reduction of its ions. This process is referred to as surface limited redox replacement and can be repeated in a cycle to grow thicker deposits. It was previously performed on nanoparticles and planar substrates. In the present report, E-ALD is applied for coating a submicron-sized powder substrate, making use of a new flow cell design. E-ALD is used to coat a Pd powder substrate with different thicknesses of Rh by exchanging it for Cu UPD. Cyclic voltammetry and X-ray photoelectron spectroscopy indicate an increasing Rh coverage with increasing numbers of deposition cycles performed, in a manner consistent with the atomic layer deposition (ALD) mechanism. Cyclic voltammetry also indicated increased kinetics of H sorption and desorption in and out of the Pd powder with Rh present, relative to unmodified Pd.

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TYPE Journal Article YEAR 2017
DOIOSTIScopus
Results 101–150 of 195
Results 101–150 of 195