TEACHING ENGINEERING REASONING USING A BEAM DEFLECTION LAB

摘要

Well crafted laboratories reinforce theoretical concepts presented in class, but also sharpen students' technical reasoning skills and provide practice in technical communication. This paper presents an introductory mechanics laboratory on beam deflection, suitable for freshmen engineering courses or as an opening week experiment for Strengths of Materials. The lab consists of 4 distinct experiments, each requiring students to measure maximum deflection of a simply supported beam. In each experiment, a single variable is adjusted (first load, then span, then cross-sectional geometry, and finally material). Although the procedure is likely similar to laboratories typically conducted in Mechanics courses after simple beam theory has been presented, the author suggests alternative objectives and student requirements targeted toward a less experienced audience. The primary goal of the exercise is to model engineering reasoning and begin a discussion on what makes for sound analysis. In conjunction with this goal, a standard for technical reporting also begins to form. To fulfill a secondary purpose, a simple addendum to the experiment is useful to show students the differences between the questions addressed by Statics (i.e. forces on rigid bodies) and those they will face in Strengths of Materials. The final objective is to demonstrate how stiffness is affected by both geometry and material, highlighting implications for design. The lab has been conducted in various forms in both an introductory design course and as a first lab in Strengths of Materials.