2.72 Elements of Mechanical Design

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Syllabus (revision 5):
Synopsis:
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).
Lectures Reading (for next lecture) Laboratory Project
01.
Introduction		 3.1, 3.2, 3.4, 3.7, 3.8, 3.10 – 3.11
    
02.
2.00X		 Scan:

4.1–4.5, 5.1–5.5		 Read:

6.1–6.4, 6.7–6.12		    
03.
Deflection and Fatigue		 Read:

Dim. &  tol.		 Old V-M soln.

Are really correct?

For HTM M-lab:
2012-CAD_v1
Required
HTMs
 		 Required
Matrices 		Suggested:
pp 360-367
04.        
05.        
06.
Constraints		 Read:
11.1-11.6, 11.9		 Scan:
11.7-11.8, 11.10-11.12
HTM M-lab
Solution		  
07.
Sliding/rolling bearings		 No reading, but will be quiz on your spindle bearings at start of class
V-M quiz
Solution
Example Motor clamp
08.      
Hale
Read 2.5.1: Reversal Techniques (pages: 48-59)
09.      

Motor T-w

Bearings in the motor are labeled NSK 6080W
10.
Flexure bearings		 Read: 8.1,8.3-8.5, 8.7, 8.8

Skim: All other subsections 8.x

  
Battery safety sheet
11.      
Chuck CAD


Chuck print

 
12.
Bolted joints		 Read: 16.2, 16.5, 16.8, 16.9, 16.12, 17.1-17.4

Skim: 16.1, 16.4, 16.6, 16.10

  
 
13.        
14.        
15.        
16.        
17.        
18.      
 
19.        
20        
21.        
22.        
2.72 Mechanical Design Approach:
“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:

(1) 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 sensitive, 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.

(2) Mastery of:
 (a) Concepts, principles, design processes & best practices are necessary, but not sufficient, to practice mechanical design
 (b) Mathematics, physics and engineering modeling is necessary, but not sufficient, to practice mechanical design

A judicious use of (a) and (b) 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; and (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.
2.72 Mechanical Design Project Description:
“In theory there is no difference between theory and practice. In practice there is.” --Yogi Berra

The content of 2.72 has been scoped to include the majority of mechanical elements that are considered ubiquitous components of mechanical systems. All of these mechanical elements may be found in mechanical systems that could be the subject of a 2.72 design project. We have elected to use a desktop manual lathe as the 2.72 design project. This selection offers the unique opportunity to create a mechanical system that: (a) forms the basis of your assignments and laboratory activities (b) will be used to draw inter-related examples that demonstrate component/system design (c) you may keep as a “memento” of your mechanical design experience and accomplishment; and (d) you may use to create mechanical elements for future activities.

 

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