Date of Award

11-2009

Degree Name

MS in Mechanical Engineering

Department

Mechanical Engineering

Advisor

Brian Self

Abstract

Model eliciting activities are assignments which require students to develop models to describe realistic situations. Every MEA follows six principles: model-construction, reality, self-assessment, model documentation, generalizability, and effective prototype. The six principles provide a solid guideline in which instructors can develop more MEAs, which can then be shared and used among several participating universities. Under NSF CCLI Grant #0717595, Cal Poly is currently developing Model Eliciting Activities for the subject of Mechanical Engineering.

This report documents the undertakings to implement and enhance two Model Eliciting Activities (MEAs) into the Cal Poly curriculum. Specifically, the development of the Vehicle Accident Reconstruction (VAR) MEA and the Catapult MEA will be covered in detail.

The VAR MEA was a project assigned in ME212 “Engineering Dynamics,” which required students to apply momentum principles to a two-vehicle collision. Because of the heavy development time experienced by the MEA research team, a MatLab program which accepted user inputs via a graphical user interface (GUI) was developed. This GUI solved for initial velocities during two-vehicle collisions by applying appropriate momentum and work-energy principles. With this program, instructors can more easily develop crash scenarios, as well as check student work.

The Catapult MEA was also a project assigned to ME212 students. It required them to analyze the launch trajectory of an actual scaled catapult using angular motion and work-energy principles. This scaled-catapult was instrumented with one ADXL278 dual-axis accelerometer and four CEA-06-240UZ-120 strain gages. This instrumentation allowed for the experimental data acquisition of the catapult angular velocity, acceleration, and strains. By postprocessing this experimental data using a MatLab program, the experimental results can then be compared to theoretical results.

The overall goal for the VAR MEA GUI programming was to reduce instructor workload in order to promote usage the MEA through a broader range of universities. The goal of the Catapult instrumentation was to provide students with actual experimental data, which could then be used to confirm their theoretical model. The system was set up so that they could easily record their own experimental data for each catapult launch.

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