Enhancement Of An Introductory Course In Dynamics And Machine Elements

This paper discusses improvements which were made to an introductory dynamics and machine elements course at Penn State Altoona, in Altoona, Pennsylvania, in the Fall of 1998. The improvements included implementing two team design projects, one on kinematics and the other incorporating kinetics and machine elements as well; inclusion of peer assessment of the design projects; balanced incorporation of graphical, analytical and design software-based analysis and synthesis throughout the course; involvement by an engineering technology student intern to foster team collaboration; implementation of an industrial topic thread through the course; and a pre-team-formation assessment of background and skills of students, followed by team selection based on the assessment. The outcome of the course improvements included improved student morale and interest level, and higher student evaluations. Course Overview Mechanical Engineering Technology 206, Dynamics and Machine Elements, is a sophomorelevel course in kinematics and kinetics as applied to mechanism and machine design. It is delivered each Fall semester to Mechanical Engineering Technology (Associate Degree) P ge 575.1 students at Penn State Altoona. The course develops an understanding of the application of mathematics to the design of mechanisms and machines to perform certain tasks (synthesis, or creation of new mechanisms, and analysis, of existing mechanisms), and provides an introduction to complex machine elements such as gears and cams. The course has traditionally been taught with side-by-side use of analytical techniques and graphical techniques, with the students also building physical models of mechanisms. Mechanical drawing was complementary to the analytical techniques, and the models gave a connection to physical reality. The course text [Norton] included simulation software (Windows-based), but the software was used only sparingly, and only in parts of the course. The course as traditionally delivered was judged by the instructor to be inadequate in some ways, including the fact that the broad scope was difficult to cover adequately, the students had some difficulty visualizing the connection between the mathematics and the functions of mechanisms with which they had limited exposure, and had a limited ability to quickly visualize and physically model the mechanisms. Project Description In Fall Semester 1998, a grant was awarded by the Penn State University Schreyer Institute for Innovation in Learning to help reduce these limitations of the course as it is traditionally taught. Two areas were focused on: • Developing a tight interlacing, throughout the course, of 1. analytical software, which provides for visualization as well as analysis and synthesis; 2. mathematical (analytical) techniques; 3. hands-on experimentation; 4. model-building; and 5. graphical (mechanical drawing) techniques; and P ge 575.2 • Establishment of project-based team collaborations for peer support throughout the course. Improvements in the first area were directed at providing for a much more extensive use of the simulation software provided with the text. The software allows students to design simple mechanisms and machines and immediately visualize the impact of design changes. An example of a software screen, for link length and position input, is shown in Figure 1. The program is relatively easy to learn and use, and relates clearly to analytical concepts described in the text, so it avoids the so-called "black-box syndrome," where "students will not understand or perhaps even care what it [the software] is doing." [Wankat, p.156] Figure 1: Simulation Software P ge 575.3 In addition to the increased emphasis on the software, a sequence of classes in a modular arrangement was developed which would address a concept in a lecture format (50 minutes, two days a week), followed with a laboratory (2 hours per week) in which analytical software and/or graphical techniques are used to develop and visualize the problem solution. For instance, a lecture might cover graphical synthesis for two positions. The laboratory, early the next week, has the students perform graphical analysis in a drafting room. In the next lecture, the laboratory experience is reinforced and a new topic introduced (three-position graphical synthesis, for instance), to be covered more fully in the following lecture, and so on. Homework (assigned weekly) is given in analytical, graphical and software solutions to problems, pointing out the relationship between and limitations of all three. The second area, establishment of project-based team collaborations, was targeted to help alleviate both the prior broad scope and real-world experience limitations of the course, with two projects assigned in which teams would address mechanism and machine design problems. The first project is limited to kinematics, where the masses of the parts of a mechanism are not considered, and hence forces are not involved. Kinematics involves a geometric solution to a motion problem, and is followed in design by kinetics, which introduces real parts with mass, and real forces and torques. The second project involves adding masses and designing for forces and torques, as well as including complicated machine elements such as gears. The former course outline was modified to include better integrated laboratory experiences and two class projects, using the same text which was used in earlier deliveries, which included simulation software. The general outline for the course includes the topics, in sequence: