Development of a Portable Experimental Platform to Demonstrate the Role of Material and Cross-section in Beam Bending

Aldo A. Ferri; James I. Craig; Bonnie H. Ferri; Meltem Alemdar

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Conference: 2019 ASEE Annual Conference & Exposition
Location: Tampa, Florida
Publication Date: June 15, 2019
Start Date: June 15, 2019
End Date: June 19, 2019
Conference Session: Experimentation and Laboratory-Oriented Studies Division Technical Session 4
Tagged Division: Experimentation and Laboratory-Oriented Studies
Page Count: 20
DOI: 10.18260/1-2--32649
Permanent URL: https://strategy.asee.org/32649
Download Count: 495

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Paper Authors

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Aldo A. Ferri Georgia Institute of Technology

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Al Ferri received his BS degree in Mechanical Engineering from Lehigh University in 1981 and his PhD degree in Mechanical and Aerospace Engineering from Princeton University in 1985. Since 1985, he has been a faculty member in the School of Mechanical Engineering at Georgia Tech, where he now serves as Professor and Associate Chair for Undergraduate Studies. His research areas are in the fields of dynamics, controls, vibrations, and acoustics. He is also active in course and curriculum development. He is a Fellow of the ASME.

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James I. Craig Georgia Institute of Technology

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Prof. Craig has been on the faculty at Georgia Tech for more than fifty years and continues to teach as an emeritus professor and to develop classroom engagement methods and tools. His past research is in the general area of experimental structural mechanics, dynamics and structural control with applications to aerospace and earthquake engineering. He is coauthor of a textbook on structural analysis with application to aerospace structures.

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Bonnie H. Ferri Georgia Institute of Technology

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Dr. Bonnie Ferri is a Professor in the School of Electrical and Computer Engineering as well as a Vice Provost at Georgia Tech. She performs research in the areas of active learning, embedded controls and computing, and hands-on education. She received the IEEE Undergraduate Education Award and the Regents Award for the Scholarship of Teaching and Learning. She received her BS in EE from Notre Dame, her MS in ME/AE from Princeton, and her PhD in EE from Georgia Tech.

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Meltem Alemdar Georgia Institute of Technology

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Dr. Meltem Alemdar is Assistant Director and Research Scientist II at Georgia Tech's Center for Education Integrating Science, Mathematics, and Computing (CEISMC). Dr. Alemdar has experience evaluating programs that fall under the umbrella of educational evaluation, including K-12 educational curricula, K-12 STEM programs after-school programs, and comprehensive school reform initiatives. Across these evaluations, she has used a variety of evaluation methods, ranging from a multi-level evaluation plan designed to assess program impact to methods such as program monitoring designed to facilitate program improvement. She received her Ph.D. in Research, Measurement and Statistics from the Department of Education Policy at Georgia State University (GSU).

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Abstract

Beam bending is one of the foundational concepts that is critical in several fields including mechanical engineering, aerospace engineering, and civil engineering. At the authors’ institution, the topic is treated thoroughly in a lecture-based, sophomore-to-junior level class in strength of materials (mechanics of materials.) Still, many students come to the topic of mechanics of materials courses with significant pre-conceptions and misunderstandings that make it difficult to overcome through lecture material alone (Brown, et al, JEE, 2018). Indeed, when students are shown that their preconceptions are faulty, it enhances their retention of the correct material and has the ancillary benefit of developing their critical thinking skills in other engineering topics.

There are many laboratory experiments that focus on beam bending but they fall into two main categories. Experiments that take place in dedicated instructional labs and which make use of sensors to obtain detailed, quantitative data on beam bending. Such labs can study beams in different types of loading, and are helpful in allowing students to compare measurements to theoretical predictions. Another category of experiments uses hand-held demos to show qualitative behavior. The main advantage of these types of teaching aids is that they are inexpensive, portable, and can be used within classroom lectures as a means of just-in-time reinforcement of concepts. The goal of this research project is to create an experimental platform that is a compromise between the two extremes. A student team was charged with designing and building a prototype, which is being used presently in the mechanics of materials course at the authors’ institution. The platform is portable, but is also instrumented with strain gauges, displacement actuators (turn screws), and rotational sensors. Data acquisition is accomplished using a National Instruments myDAQ and a laptop computer running Matlab. The device is designed to accept beams of different materials and cross-sections, and can apply loading in different ways.

The experiment was intentionally designed to target students’ misconceptions about stress and strain. In particular, experimental exercises were developed to show how choice of materials can influence strain, but not stress under identical loading situations. Conversely, displacement loading of beams having different materials produces the same strain, but different stresses. Finally, the effect of the cross-sectional symmetry is investigated to yield quantitative and qualitative data about beam twist resulting from point loading. The platform plus all the instrumentation is purposely designed to be very portable, robust and simple to understand by students in ME, AE, and CE courses. Similar to (Pickel et al, ASEE, 2016), student engagement is reinforced through use of post-demo analysis of the quantitative data.

The paper will describe the experimental platform. It will also focus on the design of the learning exercises used in the classroom. Finally, preliminary results will be presented based on a concept inventory conducted pre-experiment and post-experiment.

Citation
Format

Ferri, A. A., & Craig, J. I., & Ferri, B. H., & Alemdar, M. (2019, June), Development of a Portable Experimental Platform to Demonstrate the Role of Material and Cross-section in Beam Bending Paper presented at 2019 ASEE Annual Conference & Exposition , Tampa, Florida. 10.18260/1-2--32649

TY - CPAPER
AB - Beam bending is one of the foundational concepts that is critical in several fields including mechanical engineering, aerospace engineering, and civil engineering. At the authors’ institution, the topic is treated thoroughly in a lecture-based, sophomore-to-junior level class in strength of materials (mechanics of materials.) Still, many students come to the topic of mechanics of materials courses with significant pre-conceptions and misunderstandings that make it difficult to overcome through lecture material alone (Brown, et al, JEE, 2018). Indeed, when students are shown that their preconceptions are faulty, it enhances their retention of the correct material and has the ancillary benefit of developing their critical thinking skills in other engineering topics.

There are many laboratory experiments that focus on beam bending but they fall into two main categories. Experiments that take place in dedicated instructional labs and which make use of sensors to obtain detailed, quantitative data on beam bending. Such labs can study beams in different types of loading, and are helpful in allowing students to compare measurements to theoretical predictions. Another category of experiments uses hand-held demos to show qualitative behavior. The main advantage of these types of teaching aids is that they are inexpensive, portable, and can be used within classroom lectures as a means of just-in-time reinforcement of concepts. The goal of this research project is to create an experimental platform that is a compromise between the two extremes. A student team was charged with designing and building a prototype, which is being used presently in the mechanics of materials course at the authors’ institution. The platform is portable, but is also instrumented with strain gauges, displacement actuators (turn screws), and rotational sensors. Data acquisition is accomplished using a National Instruments myDAQ and a laptop computer running Matlab. The device is designed to accept beams of different materials and cross-sections, and can apply loading in different ways.

The experiment was intentionally designed to target students’ misconceptions about stress and strain. In particular, experimental exercises were developed to show how choice of materials can influence strain, but not stress under identical loading situations. Conversely, displacement loading of beams having different materials produces the same strain, but different stresses. Finally, the effect of the cross-sectional symmetry is investigated to yield quantitative and qualitative data about beam twist resulting from point loading. The platform plus all the instrumentation is purposely designed to be very portable, robust and simple to understand by students in ME, AE, and CE courses. Similar to (Pickel et al, ASEE, 2016), student engagement is reinforced through use of post-demo analysis of the quantitative data.

The paper will describe the experimental platform. It will also focus on the design of the learning exercises used in the classroom. Finally, preliminary results will be presented based on a concept inventory conducted pre-experiment and post-experiment.

AU - Aldo A. Ferri
AU - James I. Craig
AU - Bonnie H. Ferri
AU - Meltem Alemdar
CY - Tampa, Florida
DA - 2019/06/15
PB - ASEE Conferences
TI - Development of a Portable Experimental Platform to Demonstrate the Role of Material and Cross-section in Beam Bending
UR - https://strategy.asee.org/32649
DO - 10.18260/1-2--32649
ER -