Incorporating Experimental Design In A Mechanics Of Materials Course

A necessary part of any engineering design is the development of specifications that define its function. Once these specifications are developed, testing of that design to ensure it meets the design specifications is essential. At Grand Valley State University, we have incorporated design and build projects into most of our engineering courses, including the Mechanics of Material Course. In addition to design and build, in the Mechanics of Materials course, students are required to develop their own design specifications and design an experiment to test their apparatus. Students were presented with the challenge of creating a combined loading apparatus which models a real situation or to test a real product to determine the stresses incurred by that product in normal use. Strain rosettes were used to evaluate the stresses experimentally. Students determined the criterion by which the apparatus was tested and designed. They were then required to perform the testing. Prior to applying the strain gage and testing their apparatus, they also submitted a complete testing procedure and theoretical analysis for review. Next, a comparison of the test results to results obtained using analytical techniques and finite element analysis was made. In the process of completing this project, students learned many aspects of experimental design and stress analysis including developing testing criteria, implementation of strain gages for testing designs, correlation of theoretical and experimental results, and how to design an experiment and collect the experimental data so that it is most useful. Introduction The "Program Outcomes and Assessment" section of the ABET evaluation criteria for 20012002 strongly encourage both the teaching of design and design of experiments in the curriculum. This work addresses several of the ABET program objectives, specifically a, b, c, e and g. The objectives met include: (a) an ability to apply knowledge of mathematics, science, and engineering . . . (b) an ability to design and conduct experiments, as well as to analyze and interpret data . . . (c) an ability to design a system, component, or process to meet desired needs . . . Page 754.1 Proceedings of the 2002 American Society for Engineering Education Annual Conference and Exposition Copyright ” 2002, American Society for Engineering Education (e) an ability to identify, formulate, and solve engineering problems . . . (g) an ability to communicate effectively . . . In addition to design being emphasized in the ABET criteria, the Seymour and Esther Padnos School of Engineering at Grand Valley State University (PSE) emphasizes design project work and a practical approach to engineering while still upholding standards for the theoretical training of engineering graduates. Over eighty percent of engineering courses at PSE require design and build project work. In keeping with both ABET criteria and the overall philosophy of PSE; a design project was implemented in PSE’s junior level Machine Design I course. Although the title of this course is Machine Design I, only the final two and a half weeks are dedicated to studying fatigue and machine components. However, the remainder of the course is dedicated to Mechanics of Materials. In addition, the laboratory associated with the course is entirely Mechanics of Materials based. Syllabi for the Summer 2001 offering of both lecture and laboratory portions of the course are included in Appendix A and Appendix B. This project was first implemented three years ago (three offerings of the course) as a basic strain gage use experiment. Since, it has been expanded to include experimental design and correlation with both theoretical and FEA results. The project incorporated both a high degree of engineering analysis and experimental design and verification. The actual project assignment is presented in Appendix C. It is exceedingly important for students to understand the importance of planning when conducting experiments. To complete this project, students were required to either design a combined loading apparatus that models a real situation or to choose a real apparatus to study. They were then required to model the apparatus analytically and using finite element analysis (FEA). Finally, students designed and conducted an experiment to evaluate their analytical results. Through completing the project assigned in the Mechanics of Materials course, students learned the importance of designing experiments prior to conducting them, how to compare theoretical and experimental results and how to analyze a real apparatus. In addition, the use of strain gages and combined loading analysis were reinforced. Students also learned how to select FEA elements and model a real situation.