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End Fixture Design to Enhance Column Buckling Lesson

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2016 ASEE Annual Conference & Exposition


New Orleans, Louisiana

Publication Date

June 26, 2016

Start Date

June 26, 2016

End Date

August 28, 2016





Conference Session

Active Learning & Laboratories in Statics, Dynamics, and Mechanics

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Randy Dean Kelley P.E. University of Pittsburgh, Johnstown

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Dr. Kelley is an assistant professor at the University of Pittsburgh at Johnstown. He recieved his doctorate in Nuclear and Mechanical Engineering from Texas A&M University in 2010. Dr. Kelley's expertise and research interests are in the broad subject area of thermal sciences with a particular interest in Energy.

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Brian E Moyer University of Pittsburgh, Johnstown

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Brian E. Moyer is an Assistant Professor of Mechanical Engineering at the University of Pittsburgh at Johnstown, an adjunct professor for Bioengineering at the University of Pittsburgh, and an automation consultant for Crossroads Consulting, LLC. Brian's consulting, teaching and research focus areas include hardware and GUI software integration primarily using LabVIEW by National Instruments and kinematic and kinetic data collection and analysis methods for human body movement characterization especially as related to normal and perturbed (slipping) gait. Dr. Moyer earned a BS in mechanical engineering from Carnegie Mellon in 1993, a MS in mechanical engineering from the University of Pittsburgh in 1996, and a PhD in Bioengineering from the University of Pittsburgh in 2006. Brian teaches courses in computer programming for engineers, design, measurements, and dynamics.

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Roelof Harm deVries P.E.

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Prof. deVries has been the Assistant Professor of Mechanical Engineering Technology at the University of Pittsburgh at Johnstown since 2008, with 25 years of experience in design and engineering management.

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Column Buckling Lesson


Column buckling is an important topic in teaching strength of materials. This topic is emphasized with a compression / buckling experiment using a Satec uni-axial testing machine. Polyvinyl Chloride (PVC) pipe (1/2 inch diameter) was used as the columns. Ambiguity of end fixity led to difficulty in correlating the resulting load – defection curves to theory. Several lengths of pipe had been use to give the students a good representation of the transition between straight compression to column buckling. In the past, the PVC pipes had been placed against the table and the cross piece of the Satec machine to approximate end fixity condition similar to that of a fixed end. Often, buckling would occur due to an induced moment cause by the load not being applied at the centroid of the pipe and transitions of end fixity from something close to cantilevered to something more closely related to pinned, albeit eccentrically pinned, made interpretation of the results difficult. This become more pronounced as the PVC pipe length grew longer. To alleviate this problem and to provide a better learning experience, two sets of “cups” were designed to hold the ends of the PVC pipe. One set (top and bottom) were rotationally fixed and provided support for the pipe ends to simulate a cantilevered end fixity condition. The second set, were design to hold the pipe end but allowed rotation about one axis, a “pinned” joint. Both sets of “cups” worked very well in practice. The K constant was calculated by the students in the experiment write up and was very comparable to published values. Load – deflection plots of the pipe buckling showed results more consistent with theoretical plots. Rather than limiting students to more idealized experimental conditions, the next portion of the experiment asked the students to extend their understanding of the underlying theory. By revisiting the original procedure, one with a non-ideal end fixity, the students were expected to compare the two types of end conditions and draw conclusions regarding how the non-ideal case might analyzed.

Kelley, R. D., & Moyer, B. E., & deVries, R. H. (2016, June), End Fixture Design to Enhance Column Buckling Lesson Paper presented at 2016 ASEE Annual Conference & Exposition, New Orleans, Louisiana. 10.18260/p.26958

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