Course Meeting Times
Lectures: 2 sessions / week, 1 hour / session
Recitations: 1 session / week, 1 hour / session
Labs: 1 session / week, 3 hours / session
Additional shop time may be scheduled by request.
This is an advanced course on modeling, design, integration and best practices for use of machine elements such as bearings, springs, gears, cams and mechanisms. Modeling and analysis of these elements is based upon extensive application of physics, mathematics and core mechanical engineering principles (solid mechanics, fluid mechanics, manufacturing, estimation, computer simulation, etc.). These principles are reinforced via (1) hands-on laboratory experiences wherein students conduct experiments and disassemble machines and (2) a substantial design project wherein students model, design, fabricate and characterize a mechanical system that is relevant to a real world application. Students master the materials via problems sets that are directly related to, and coordinated with, the deliverables of their project. Student assessment is based upon mastery of the course materials and the student’s ability to synthesize, model and fabricate a mechanical device subject to engineering constraints (e.g. cost and time/schedule).
“The man who sets out to carry a cat by its tail learns something that will always be useful and which never will grow dim or doubtful.” — Mark Twain
Many students misunderstand the purpose of the mathematics and engineering science/modeling content that they are exposed to early in their undergraduate programs. This leads to a misperception that models and associated equations embody all of the engineering ability that is required to employ the principles they are taught. In mechanical design, good models are critical, but they are not sufficient. If you are to use mechanical design principles in your engineering practice/research, your thoughts, decisions and actions must be based upon an understanding of the following:
- Engineering/science models and their associated equations are idealizations of mechanical systems. The only thing that “perfectly” models all characteristics of a mechanical system is a physical embodiment of that system. This is most evident in machines where high performance and/or high risk are involved. You need to understand the limits/power of modeling and simulation in the context of mechanical design. The process of “synthesizing-modeling-fabricating-testing” a prototype helps to provide this insight. This is important because the construction of sensitive/high-performance systems is cost and time intensive.
- Mastery of:
- Concepts, principles, design processes, and best practices is necessary, but not sufficient, to practice mechanical design;
- Mathematics, physics and engineering modeling is necessary, but not sufficient, to practice mechanical design;
- Practical skills and familiarity with best practices is necessary, but not sufficient, to practice mechanical design.
A judicious use of (a), (b), and (c) is necessary to understand and apply the principles of mechanical design. Toward this end, 2.72 will focus on:
(i) understanding the role of concepts, principles, design process, best practices, mathematics, physics, and engineering modeling within mechanical design;
(ii) rigorous application of concepts, principles, design process, best practices, mathematics, physics, and engineering modeling to realize a complex and high quality mechanical design.
You will learn “by doing” and learn by gaining insight/perspective via interaction with the staff. This year in 2.72, teams of about 5-6 students will model, design, build and characterize the performance of a desktop lathe. Each team will design a ‘group’ lathe and must build at least one lathe. Each student may elect to build their own lathe through the course of the term. The construction of a device that meets functional requirements is a critical element of receiving a good grade in 2.72.
Shigley, Joseph, Charles Mischke, and Richard Budynas. Mechanical Engineering Design. Boston, MA: McGraw-Hill, 2003. ISBN: 9780072921939.
Norton, Robert L. Design of Machinery: An Introduction to the Synthesis and Analysis of Mechanisms and Machines. Boston, MA: McGraw-Hill, 2007. ISBN: 9780073290980.
Oberg, Erik, Franklin D. Jones, Holbrook L. Horton, and Henry H. Ryffel. Machinery’s Handbook. 28th ed. New York, NY: Industrial Press, 2008. ISBN: 9780831128005.
|Project and lab||50%|
|In-class and take-home mini-quizzes||50%|
All materials are due by 5pm, via e-mail to the TA, unless otherwise stated. E-mail errors will not excuse late assignments.
You must understand what you are doing before you start to design/build/make parts, otherwise you are dangerous. Absolutely no student (or their group) will be given parts/resources to make a part unless they have passed the pertinent quizzes (grade > 80%) on the technical topics that are related to the part. For example, you must demonstrate that you understand shear and moment diagrams before you will be given the material to make your shaft. You must demonstrate you understand how to size/select bearings before your bearings are ordered. Make up quizzes may be given, but course schedules will not be changed. Some quizzes will be take-home quizzes, some will be in-class quizzes on assigned reading, and some will be focused upon in-class exercises.