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BYOE: Strain Measurement in a Simply Supported Beam

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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

Division Experimentation & Lab-Oriented Studies: Bring-Your-Own-Experiments 2

Tagged Division

Division Experimentation & Lab-Oriented Studies

Page Count

8

Page Numbers

26.315.1 - 26.315.8

DOI

10.18260/p.23654

Permanent URL

https://peer.asee.org/23654

Download Count

97

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Paper Authors

biography

Bridget M. Smyser Northeastern University

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Dr. Smyser is an Assistant Academic Specialist and the Lab Director of the Mechanical and Industrial Engineering.

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Abstract

BYOE: Strain Measurement in a Simply Supported BeamThe overall goal of this experiment was to allow students to gain proficiency in using straingauges and working with Wheatstone bridge circuits for strain measurement. Measurements andAnalysis with Thermal Science Application is a junior level required course at __________University. Students are asked to investigate the effect of different numbers of strain gauges onthe output of a bridge circuit, and observe the relationship between physical location on theobject and location in the circuit. This experiment has the following specific goals:The primary goals of this experiment are: 1. To use strain gauges to measure strain in a simply supported beam with a load equally distributed across two points 2. To determine the effect of different Wheatstone bridge circuit arrangements on the measured strain 3. To use the strain data to develop a relationship between strain and weight, in order to use the aluminum beam as a homemade scale.The experiment was performed in groups of 3-4 students. The experimental setup consists of analuminum beam resting on two legs. The beam is instrumented with four strain gauges, two intension and two in compression, which rest between two supports. A board placed on top of thetwo supports is loaded with weights. Students use a VISHAY Precision Groups Model P3 StrainGauge Indicator box connected through spring loaded connectors permanently wired to the straingauges to measure the strain which results. Students then vary the number of active strain gaugesin the circuit to observe the strain which results from correctly and incorrectly wired circuits ofdifferent types. Measured values are compared to theoretical values calculated using beamtheory. After the students have gotten a feel for the different types of bridges they are asked todevelop a calibration curve to turn their aluminum beam into a scale. They then choose someobject – a backpack, a textbook, or even a classmate – and weigh the object on a standard scaleas well as their aluminum beam scale in order to determine the accuracy of their scale. Otherthan the strain gauge indicator boxes, the remainder of the equipment cost less than $300 persetup. The strain indicator boxes, which cost on the order of $5K, are often used by the studentsfor independent projects and capstone design projects beyond the Measurements and Analysisclass. This experiment teaches the fundamentals of strain measurement, requires students toconnect concepts learned in previous statics classes to the current problem, and also providesstudents with knowledge of a valuable tool for their future research. Wire connections Supports Strain gaugesFigure 1: Strain gauge set up, viewed from the top. A board will be placed across the two supports to put the weight on. There are two morestrain gauges at the same location on the underside of the board.Figure 2: Strain Gauge Indicator Box - Main Panel

Smyser, B. M. (2015, June), BYOE: Strain Measurement in a Simply Supported Beam Paper presented at 2015 ASEE Annual Conference & Exposition, Seattle, Washington. 10.18260/p.23654

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