ME/MECA 238A 1

ME/MECA 238A - Mechanical/Mechatronic

Design Project I

Course notes prepared by G.A. Kallio, based on The Mechanical Design Process, by D.G. Ullman

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I. Introduction to the Engineering Design Process

Reading: Ullman, Ch. 1-4

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What is Engineering Design?

• Solving a problem that – is not fully-defined in terms of its requirements – has a multitude of satisfactory solutions– requires creativity and engineering knowledge

in generating and evaluating solutions (iterative process)

– usually results in a piece of working hardware

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Textbook Design vs. Real Design

• Textbook design: “What size SAE grade 5 bolt is required to fasten two pieces of 1045 sheet steel, each 4 mm thick and 6 cm wide, which are lapped and loaded with 100 N?”

• Real design: “ Design a joint to fasten two pieces of 1045 sheet steel, each 4 mm thick and 6 cm wide, which are lapped and loaded with 100 N.”

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Measuring Effective Design

• Cost - Quality - Time (cheaper) (better) (faster)

• The cost of designing is small but design has a large effect on manufacturing cost, overall product quality and time-to-market (Figures 1.2, 1.3)

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Measuring Effective Design, cont.

• Product cost is committed early in the design process and spent late in the process (Figure 1.4)

• Changes made early in design process are more cost-effective than those made later (Figure 1.6)

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This Course …

• Focuses on product design, where – the product solves a problem, or fulfills a

genuine need– there is an identifiable customer– there are specific customer requirements– the product requires engineering design– the product will be manufactured and tested as

a prototype

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Life of a Product

• Product development

• Production and delivery

• Use

• End of life

(Figure 1.8)

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Concurrent Design

• Concurrent, or simultaneous, design has replaced the outdated “over-the-wall” design method (Figure 1.7)

• Most important feature: simultaneous development of the product design and manufacturing process

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Concurrent Design, cont.

• Design for “X” (DFX)X = M (Manufacturability)

X = Q (Quality)

X = A (Assembly)

X = E (Environment)

X = R (Reliability)

X = S (Safety and Serviceability)

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The Design Paradox

• As the design process progresses, you gain knowledge but you lose freedom to use what you know (Figure 1.11)

• Time and cost normally drive the design project, so there is rarely an opportunity to start over or to redo a design

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Types of Design

• Conceptual design

• Selection design

• Configuration design (packaging)

• Parametric design

• Original design

• Redesign

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Design Teams & Personalities

• Extrovert vs. Introvert

• Fact- vs. possibility-oriented

• Objective vs. subjective

• Decisive vs. flexible

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Design Team Goal

• Solving a problem through:

– Collaboration

– Compromise

– Consensus

– Communication

– Committment

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Documentation

• Each team member must maintain a notebook (logbook) to document entire project development

• Bring notebook to all team and advisory meetings

• Notebook must be bound – no looseleaf pages; each completed page dated with your initials

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Overview of the Design Process

• Establish a need

• Develop project plan

• Determine engineering specifications

• Develop concepts

• Develop product

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Develop Project Plan (Ch. 5)

• Form design teams

• Identify tasks & objectives

• Estimate personnel, time, and other resources needed for each task

• Develop a task sequence

• Estimate costs

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Determine Engineering Specifications (Ch. 6)• Identify the customers

• Determine customer needs (marketing)

• Determine relative importance of needs

• Evaluate competition & current customer satisfaction

• Convert customer requirements to engineering specifications

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Develop Concepts (Ch. 7-8)

• Functional decomposition

• Generate concepts for each function

• Evaluate concepts

• Product safety & liability

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Develop Product (Ch. 9-12)

• Generate components– Based upon spatial, strength, power, thermal,

temporal, acoustic, etc. constraints

• DFX

• Materials & fabrication selection

• Modeling & simulation

• Prepare drawings