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Students’ Struggles to Explain the Atomic Behavior of Metals in a Tensile Test Lab Supported by a Molecular Dynamics Simulation

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Conference

2015 ASEE Annual Conference & Exposition

Location

Seattle, Washington

Publication Date

June 14, 2015

Start Date

June 14, 2015

End Date

June 17, 2015

ISBN

978-0-692-50180-1

ISSN

2153-5965

Conference Session

Materials Division Technical Session 1

Tagged Division

Materials

Page Count

17

Page Numbers

26.1437.1 - 26.1437.17

DOI

10.18260/p.24774

Permanent URL

https://peer.asee.org/24774

Download Count

35

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Paper Authors

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Heidi A. Diefes-Dux Purdue University, West Lafayette Orcid 16x16 orcid.org/0000-0003-3635-1825

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Heidi A. Diefes-Dux is a Professor in the School of Engineering Education at Purdue University. She received her B.S. and M.S. in Food Science from Cornell University and her Ph.D. in Food Process Engineering from the Department of Agricultural and Biological Engineering at Purdue University. She is a member of Purdue’s Teaching Academy. Since 1999, she has been a faculty member within the First-Year Engineering Program, teaching and guiding the design of one of the required first-year engineering courses that engages students in open-ended problem solving and design. Her research focuses on the development, implementation, and assessment of modeling and design activities with authentic engineering contexts. She is currently a member of the educational team for the Network for Computational Nanotechnology (NCN).

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Aisling Coughlan Purdue University, West Lafayette

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David R. Johnson

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Kerrie A Douglas Purdue University, West Lafayette

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Dr. Douglas is a Visiting Assistant Professor in the Purdue School of Engineering Education. Her research is focused on methods of assessment and evaluation unique to engineering learning contexts.

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Tanya Faltens Purdue University, West Lafayette Orcid 16x16 orcid.org/0000-0003-4035-1908

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Tanya Faltens is the Educational Content Creation Manager for the Network for Computational Nanotechnology (NCN) which created the open access nanoHUB.org cyber-platform. Her technical background is in Materials Science and Engineering (Ph.D. UCLA 2002), and she has several years’ experience in hands-on informal science education, including working at the Lawrence Hall of Science at UC Berkeley. While at Cal Poly Pomona, she taught the first year engineering course, mentored student capstone research projects, and introduced nanoHUB simulation tools into the undergraduate curriculum in materials science and engineering and electrical engineering courses. Much of her work has focused on introducing STEM concepts to broad audiences and encouraging students, including women and others in traditionally under-represented groups, to consider graduate school. Four of her former research students are currently in Ph.D. programs and a few more are in the pipeline.

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Abstract

Students’ Struggles to Explain Atomic Behavior of Metals in a Tensile Test LabIn traditional mechanical tensile test labs, engineering students interact with macroscale samples,and while they learn about dislocation motion and slip from their readings or from lectures, theyhave no opportunity to directly explore the atomic-level behavior of metals. The representationsthey are exposed to are often static figures, or at best a simplified animation depicting dislocationmovement. This low level of interaction with the concepts results in students having difficultyexplaining the atomic-level processes that lead to plastic deformation, or why slip planes are atan angle from the tensile axis. While a nanoscale tensile test simulation has been used in arequired sophomore level materials laboratory course for a number of semesters, the integrationwith the traditional tensile test lab has not realized an optimal impact on students’ learning. Toimprove the integration of the traditional tensile and nanoscale simulation components of thetensile test lab, a better understanding of the concepts that students struggle with as a result of theexisting integration must be investigated.Sophomore materials engineering students performed, analyzed, and compared results from botha traditional tensile test of metals and a molecular dynamics simulation tensile test of a nanowire.The latter was performed using the Nano-Materials Simulation Toolkit on nanoHUB.org.Students’ lab reports and responses to a related exam question were qualitatively analyzed.When students compared the macro- and nanoscale test results, they did not tend to makereference to the characteristic features of stress-strain curves. That is, many did not explicitlycall out differences or similarities in the values of the Young’s modulus, the yield strength, theultimate tensile strength, or the segments of the stress-strain curve indicating the elastic andplastic regions. Students were distracted by thermal noise in the nanoscale stress-strain curvesthat was absent from the macroscale tests.From the exam question analysis, it was evident that students did not have enough practicecomputing the characteristic features of stress-strain curves. For instance, they confused Young’smodulus with yield strength.In both the lab report and the exam question, many students could repeat phrases they had reador heard concerning dislocation motion and slip, but they struggled to associate those phraseswith concepts or with the characteristic features of either the macroscopic or nanoscale stress-strain curves or the atomic images generated by the simulation.Based on the results of this study, a number of revisions were recommended to better capitalizeon the simulation component of the lab. First, greater explanation of the input parameters andthe outputs of the simulation are needed so that the simulation is treated less like a black box.Second, directions need to be incorporated into the analysis of the results to ease comparison ofthe mechanical and simulation tests, both standardizing the presentation of the resulting stress-strain curves and pointing students to look at the characteristic features. Third, students need tobe directed to conduct some analysis of the atomic motion that is visible in the simulationimages.

Diefes-Dux, H. A., & Coughlan, A., & Johnson, D. R., & Douglas, K. A., & Faltens, T. (2015, June), Students’ Struggles to Explain the Atomic Behavior of Metals in a Tensile Test Lab Supported by a Molecular Dynamics Simulation Paper presented at 2015 ASEE Annual Conference & Exposition, Seattle, Washington. 10.18260/p.24774

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