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Using a Pair of iPods to Measure Angle of Twist in a Torsion Experiment

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2012 ASEE Annual Conference & Exposition


San Antonio, Texas

Publication Date

June 10, 2012

Start Date

June 10, 2012

End Date

June 13, 2012



Conference Session

Innovations in Materials Education

Tagged Division


Page Count


Page Numbers

25.1416.1 - 25.1416.8



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Paper Authors


Surendra K. Gupta Rochester Institute of Technology

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"Vinnie" Gupta is a professor of mechanical engineering, and a member of the graduate faculty of materials science and engineering at the Rochester Institute of Technology (Rochester, N.Y.). He is a recipient of the 2000 Eisenhart Award for Excellence in Teaching. At RIT, he teaches undergraduate and graduate courses in applied mechanics, computational techniques, and materials science.

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Steven John Kosciol Rochester Institute of Technology

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Steven John Kosciol is Lab Manager of the Mechanical Engineering Machine Shop. He teaches the lab section of the course "Manufacturing Process." This introduces the students to the machine shop environment and hands-on engineering.

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Using a pair of iPods to Measure Angle of Twist in a Torsion Experiment AbstractAt our university, every mechanical engineering student must take a sophomore level one-credithour course titled “Mechanics of Materials Lab”. One of the five experiments in the coursefocuses on the study of elastic and plastic deformation behavior of a circular cross-sectionmetallic rod in torsion. The shear strain on the surface of the rod is determined by measuring theangle of twist over a gage length. Until recently, the angle of twist was measured using atroptometer that was designed and fabricated in-house more than thirty years ago. There havebeen several difficulties in using this troptometer: (i) mounting it on the specimen; (ii) easilyreading the angle of twist; and (iii) taking it off after the plastic deformation begins.Last year, we designed and fabricated several sets of specimen clamps to which we can attach apair of commercially available digital inclinometers. This new way of measuring the angle oftwist eliminated all the three difficulties mentioned above. However, the data from inclinometersshowed more scatter than that from a troptometer. We found the inclinometer’s electronicequilibration and response to be sluggish.This year, we replaced each inclinometer with an iPod Touch loaded with an “app” to measurethe relative angular orientation.This paper will describe the selection of materials and design of specimen clamps for mountingthe iPods, present typical experimental results, and summarize the benefits of replacing theinclinometers by iPods. We believe that this paper will of significant interest to all instructorswho teach a lab course in mechanical properties of materials.

Gupta, S. K., & Kosciol, S. J. (2012, June), Using a Pair of iPods to Measure Angle of Twist in a Torsion Experiment Paper presented at 2012 ASEE Annual Conference & Exposition, San Antonio, Texas. 10.18260/1-2--22173

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