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Who Needs the Method of Sections and the Method of Joints? Just Pick a Strategy and Define Your System!

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2020 ASEE Virtual Annual Conference Content Access


Virtual On line

Publication Date

June 22, 2020

Start Date

June 22, 2020

End Date

June 26, 2021

Conference Session

Teaching Statics: What and How?

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Phillip Cornwell Rose-Hulman Institute of Technology

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Phillip Cornwell currently teaches at the United States Air Force Academy and is an Emeritus Professor of Mechanical Engineering at Rose-Hulman Institute of Technology. He received his Ph.D. from Princeton University in 1989 and his present interests include structural dynamics, structural health monitoring, and undergraduate engineering education. Dr. Cornwell has received an SAE Ralph R. Teetor Educational Award in 1992, and the Dean’s Outstanding Teacher award at Rose-Hulman in 2000 and the Rose-Hulman Board of Trustee’s Outstanding Scholar Award in 2001. He was one of the developers of the Rose-Hulman Sophomore Engineering Curriculum, the Dynamics Concept Inventory, and he is a co-author of Vector Mechanics for Engineers: Dynamics, by Beer, Johnston, Cornwell, and Self. In 2019 Dr. Cornwell received the Archie Higdon Distinguished Educator Award from the Mechanics Division of ASEE.

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Amir Hossein Danesh Yazdi Rose-Hulman Institute of Technology

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Dr. Danesh-Yazdi is Assistant Professor of Mechanical Engineering at Rose-Hulman Institute of Technology.

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Aimee Monique Cloutier Rose-Hulman Institute of Technology

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Statics courses can sometimes give students the misconception that there are many different approaches to solving statics problems, such as the “method of sections” or the “method of joints.” Students may also believe that trusses, frames, and machines are all fundamentally different and that they therefore require different approaches. As a result, many students believe that there is a “right” approach to use in solving a particular problem and that they need to remember it and use it. In this paper, we present a simple, unified problem-solving approach for solving all statics problems, including particle problems and rigid body problems; the calculation of internal forces or external forces; and problems involving a frame, a machine, or a truss. This approach is also applicable to solving problems in other courses such as Strength of Materials and Dynamics. In this approach, the first step in solving any problem is to articulate a “Strategy.” This simple step requires the students to take a few moments to reflect on the problem and write down a strategy rather than trying to pattern match or “find the right equation.” If the strategy is Newton’s 2nd law, which it often is in Statics, then the next step is for students to “Choose a System.” Students are required to define the system by drawing a dotted line around it or by stating the system in words. Once a system is chosen, and only after it is chosen, then students draw a free-body diagram (FBD) for the system. The mnemonic BREAD (B-Body, R-Reaction forces, E-External forces, A-Axis, D-Dimensions) has been found to be very helpful in teaching students how to draw complete and accurate FBDs. In this paper, we will present this problem-solving approach with a specific focus on defining the system and drawing a complete FBD.

Cornwell, P., & Yazdi, A. H. D., & Cloutier, A. M. (2020, June), Who Needs the Method of Sections and the Method of Joints? Just Pick a Strategy and Define Your System! Paper presented at 2020 ASEE Virtual Annual Conference Content Access, Virtual On line . 10.18260/1-2--35510

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