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Session 2259

AN INSTRUMENTED EGG DROP EXPERIMENT IN SUPPORT OF COURSES IN MECHANICAL CONTROL AND EXPERIMENTAL ANALYSIS

David Walters, Vince Wilczynski, Kirk Hiles United States Coast Guard Academy New London, Connecticut

ABSTRACT

During the Fall Semester of 1996, digitized video and real time force data were used to determine the system characteristics necessary to model a bungee cord egg drop experiment as a damped second order system. This effort was unique, in that, video tape of student “drops” were digitized and analyzed to determine position, velocity, and acceleration, as a function of time, while simultaneous in- line force data was acquired. Both sets of were used to determine the system damping factor and damped natural period. These parameters were then used by the students to calculate the system response with excellent results.

An attempt was made to use the force data to infer acceleration, velocity, and final position during the first half cycle of motion. However, this effort was unsuccessful since the mass of the elastic cord was not negligible. The experience with the force data did highlight the subtleties associated with such an experiment, in terms of the overall goal of modeling the system as a damped second order system.

INTRODUCTION

One of the goals of the USCGA courses "Mechanical Control of Dynamic Systems" and "Experimental Methods in Thermal and Fluids Sciences" is to use design projects to demonstrate phenomena and solve problems. A unique project, involving having students design a bungee cord to minimize the distance from the ground that an attached egg reaches when released from a distance of 35 feet above the ground. In the mechanical controls class, the students design the bungee cord system and in the experimentation course, the bungee cord's characteristics are determined and the experiments is conducted. Since the project includes mathematical modeling, numerical methods solutions of differential equations, design, system response, and the collection and analysis of experimental data, the exercise is a capstone experience for the mechanical engineering and naval architecture/marine engineering students.

Through this project, the students are exposed the dependence of academic courses, for they see how material covered in one discipline is used in another discipline. The project is design driven, for the students have to design their own system, and experience the joys and/or frustrations of transferring a design done on paper into a working system. The necessity for and results of experimentation are highlighted in the project, for it is only through experimentation that the system's performance characteristics can be identified. Similarly, it is through experimentation that the designs are verified and compared to theory. The value of concomitant methods of data collection is demonstrated, as the

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Hiles, K. E., & Walters, D. L., & Wilczynski, V. (1997, June), An Instrumented Egg Drop Experiment In Support Of Courses In Mechanical Control And Experimental Analysis Paper presented at 1997 Annual Conference, Milwaukee, Wisconsin. 10.18260/1-2--6625