Publications

Results 1–25 of 52

Search results

Jump to search filters

Sandia Mechanics Challenge 2023 Information Packet: Structure with a Threaded Fastener Joint

Kramer, Sharlotte L.; Ivanoff, Thomas I.; Corona, Edmundo C.

This SAND report is an information packet for the Sandia Mechanics Challenge 2023, a benchmarking exercise for an international community of volunteer researchers to predict the behavior of an unfamiliar geometry and test scenario. The SAND report represents the experimental data described in the report. Once deemed UUR, this report and the associated data will be uploaded to the Materials Data Facility website and receive a DOI.

More Details
TYPE SAND Report YEAR 2023
DOIOSTI

Automated high-throughput tensile testing reveals stochastic process parameter sensitivity

Materials Science and Engineering: A

Heckman, Nathan H.; Ivanoff, Thomas I.; Roach, Ashley M.; Jared, Bradley H.; Tung, Daniel J.; Huber, Todd H.; Saiz, David J.; Koepke, Joshua R.; Rodelas, Jeffrey R.; Madison, Jonathan D.; Salzbrenner, Bradley S.; Swiler, Laura P.; Jones, Reese E.; Boyce, Brad B.

The mechanical properties of additively manufactured metals tend to show high variability, due largely to the stochastic nature of defect formation during the printing process. This study seeks to understand how automated high throughput testing can be utilized to understand the variable nature of additively manufactured metals at different print conditions, and to allow for statistically meaningful analysis. This is demonstrated by analyzing how different processing parameters, including laser power, scan velocity, and scan pattern, influence the tensile behavior of additively manufactured stainless steel 316L utilizing a newly developed automated test methodology. Microstructural characterization through computed tomography and electron backscatter diffraction is used to understand some of the observed trends in mechanical behavior. Specifically, grain size and morphology are shown to depend on processing parameters and influence the observed mechanical behavior. In the current study, laser-powder bed fusion, also known as selective laser melting or direct metal laser sintering, is shown to produce 316L over a wide processing range without substantial detrimental effect on the tensile properties. Ultimate tensile strengths above 600 MPa, which are greater than that for typical wrought annealed 316L with similar grain sizes, and elongations to failure greater than 40% were observed. It is demonstrated that this process has little sensitivity to minor intentional or unintentional variations in laser velocity and power.

More Details
TYPE Journal Article YEAR 2020
DOIOSTIScopus

Linking pyrometry to porosity in additively manufactured metals

Additive Manufacturing

Mitchell, John A.; Ivanoff, Thomas I.; Dagel, Daryl; Madison, Jonathan D.; Jared, Bradley H.

Porosity in additively manufactured metals can reduce material strength and is generally undesirable. Although studies have shown relationships between process parameters and porosity, monitoring strategies for defect detection and pore formation are still needed. In this paper, instantaneous anomalous conditions are detected in-situ via pyrometry during laser powder bed fusion additive manufacturing and correlated with voids observed using post-build micro-computed tomography. Large two-color pyrometry data sets were used to estimate instantaneous temperatures, melt pool orientations and aspect ratios. Machine learning algorithms were then applied to processed pyrometry data to detect outlier images and conditions. It is shown that melt pool outliers are good predictors of voids observed post-build. With this approach, real time process monitoring can be incorporated into systems to detect defect and void formation. Alternatively, using the methodology presented here, pyrometry data can be post processed for porosity assessment.

More Details
TYPE Journal Article YEAR 2020
DOIOSTIScopus
Results 1–25 of 52
Results 1–25 of 52