Capstone Mechanical Engineering Laboratory Uses Racecar

A capstone mechanical engineering laboratory course is being implemented at the University of South Carolina that develops the student's abilities to analyze complex mechanical and thermal systems, to design experiments, and to develop their professional skills. The course is based upon an integrated sequence of laboratory experiments on a Legends-class racecar. This vehicle is chosen as the system of study because it provides opportunities for the students to apply the spectrum of their mechanical engineering knowledge. It's also exciting to the students. As the students progress through the series of experiments, they are increasingly involved in experimental design (selecting sensors, sensor locations and experimental operating conditions). The course culminates in a truly open-ended design of an experiment of their choosing. This course development project is supported by the National Science Foundation’s Instrumentation and Laboratory Improvement Program, the NSF’s Course, Curriculum and Laboratory Improvement Program, and the University of South Carolina. This paper describes the work in progress. I. Motivation and Context for this Project An integral part of the undergraduate mechanical engineering curricula at the University of South Carolina is sequence of four mechanical engineering laboratory courses. The capstone senior laboratory course, Mechanical Systems Laboratory is a two-credit hour course that includes one hour of lecture and three hours of lab each week. Laboratories are offered to sections of about eight students. A major function of this course is to illustrate upper-level mechanical engineering topics. Historically, the experiments were selected primarily to do this and, as a result, they were not directly related to one another. As a result, there were a large number of relatively expensive laboratory equipment items to be maintained, which occupied laboratory space, yet were used only once a semester. Because the students went from one unrelated experiment to another throughout the semester, they did not have the opportunity to develop the “system level” perspective necessary to analyze and understand complex thermal and mechanical systems. Further, because the students were required to run a different experiment each week, many of the laboratories were “canned” in that they did not require any design of the experiment. In 1997 the department began implementing an outcomes-based assessment process in preparation for ABET accreditation under Engineering Criteria 2000. As part of that processes, it was determined that the capstone Mechanical Systems Laboratory should support several of the program’s outcomes, including: • The graduates shall have the ability to analyze, design and realize mechanical and thermal systems. Page 537.1 • The graduates shall have the ability to use contemporary computation techniques and tools. • The graduate shall have competence in design of experiments, experimental practices and data interpretation. • The graduates shall have the ability to apply statistical methods to analyze and interpret data. • The graduates shall have the ability to plan, schedule and execute engineering projects. • The graduates shall have effective oral and written communication skills. • The graduates shall have an understanding of and the ability to engage in life-long learning. It was clear that a new approach for the course was required to accomplish the goal of supporting these student outcomes. The approach taken was to select once complex thermal-mechanical system of study. The students then perform an integrated sequence of laboratory experiments with this system. As the students progress through the series of experiments, they are increasingly involved in experimental design (selecting sensors, sensor locations and experimental operating conditions). In this way, the students develop a systems approach to engineering problems, the ability to design and conduct experiments, and further develop their professional skills. II. Systems Approach to Engineering Problems Constructivist learning theory asserts that knowledge is not simply transmitted from teacher to student, but is actively constructed by the mind of the learner through experiences (Piaget, 1973; Vygotsky, 1978). Founded in developmental psychology, constructivism suggests: (a) the learner should be an active organism within the environment, not just responding to stimuli, but engaging and seeking to make sense of things; (b) knowledge is best generated internally, not absorbed from an external source; and (c) the motivation for learning should be intrinsic. To facilitate such learning by discovery, the teacher and instructional environment must allow repeated, prolonged experiences with the materials and events associated with the topic to be learned. Therefore, students in the Mechanical Systems Laboratory course perform a sequence of experiments on one complex system, investigating it in detail. The selected system must provide opportunities for the students to apply the spectrum of their mechanical engineering knowledge, including the principles of mechanics, dynamics, thermodynamics, and heat transfer. An automobile is the ideal system for this laboratory for several reasons: • It is compact, yet it incorporates such a variety of subsystems that it involves almost all of the fundamental principles of mechanical engineering; • For all its complexity, it is a relatively inexpensive system for study; and • It is in the realm of experience of all students, so they can easily relate to system performance criteria such as efficiency, handling and other factors affecting vehicle operation. These features make the automobile a powerful learning vehicle. The automobile selected for study in this laboratory course is the Legends car shown in Figure 1. The Inter-Collegiate Association for Racing (ICAR), an academic motor sport involving P ge 537.2 engineering colleges throughout the country, currently races these 5/8-scale replica vehicles. There are primarily two reasons to use the Legends car: • There is tremendous enthusiasm among our students for the ICAR sport. The students get excited about applying their engineering knowledge and experimenting it. Such enthusiasm can be a tremendous asset to any required course, particularly a laboratory course; and • The relationship between the Mechanical Systems Laboratory course and the ICAR racing team is synergistic. Corporate sponsorship of the ICAR team provides funds that supplement the College's resources for updating the lab equipment, and the course provides an opportunity for all mechanical engineering students to benefit educationally from the ICAR program. Figure 1. A Legends racecar is used in the Mechanical Systems Laboratory. Left: USC’s ICAR team formerly raced the lab car. Right: The car is accessorized for the instructional laboratory. An important and relatively unique aspect of the laboratory design is the use of remote wireless telemetry equipment, which allows the entire lab section to control and monitor the experiments while the car is driven. Other equipment procured through the ILI grant has been previously described (Lyons 1999). It should be noted that the instrumentation is of general purpose so the experiments can be modified from semester-to-semester to keep them from getting "stale." III. Design of Experiments The engineering education literature describes several methods for students to learn statistical design of experiments (Burke 1993, Ludlow 1995, Abu-Khalaf 1998). Such literature deals with the determination of the smallest number of tests that give the needed answer, factorial design of experiments to determine main effects and interactions, and parametric studies to determine the constitutive behavior of a component or system. The abilities to apply statistics to experimental design and data interpretation are a valuable skill for an engineering graduate. At USC, the mechanical engineering students develop these abilities in their sophomore and junior laboratory courses and apply them in the capstone laboratory course. Therefore, it was determined that the important skills to develop in the students in the capstone Mechanical Systems Laboratory course should be related to the physical design of experiments. In the context used here, physical design of experiments deals with identifying a problem and solving P ge 537.3 it. It includes the determination test variables and data requirements, the selection of sensors and the design of the instrumentation system. Physical design of experiments has received very little attention in the engineering literature. Arce (1997) described what was termed a student-designed experiment in an introductory chemistry laboratory. In that experiment, the students were given the necessary equipment and supplies to find out how much heat is needed to melt ice, but were not given a written procedure to follow. Middelberg (1995) discussed a conceptual open-ended experimental design experience performed at the conclusion of a traditional chemical engineering laboratory course. Those students selected a topic from their coursework and then designed an experiment to investigate it. Their design report included background theory, experimental procedures, a budget, a plan for implementation and an examination of safety implications. Middleberg noted the many positive benefits of this experience. However, it was also stated that the students needed more time for consultation with the instructors than was planned, and that they relied too much on the technical staff to select equipment and components. The approach taken in the Mechanical Systems Laboratory course is very similar to that proposed by Middleberg. However, the laboratory experiments and lecture material presented throughout the semester are designed specifically to develop in the students the ability to design experiments. This includes a formalization of t