Engineering Design - Engineering Design and Analysis - Lecture Slides, Slides of Engineering Drawing and Graphics

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Engineering 11

Engineering

Design

OutLine  Engineering Design

• What is engineering design, really?
• Function to form
• Design process
• Phases of design
• Product Realization/Development Process
• Concurrent engineering
• Teamwork
• Summary

Well-Defined vs. Open-Ended

• Design Problems Have NO “Correct” Solution;
  • Have only: Successful and UNsucessful Solutions
  • Compare to Skills-Development (practice) problems

 Skills Development (Textbook Type)

• Well-defined,
• Complete (correctly stated, unique)
• Correct answer exists
• Money not involved
• You know When You Arrive at the Answer
• Requires Application of Very Specific Knowledge

 Design Problems (Open Ended)

• Poorly-defined
• No Unique Solution; Depends on Approach
• Cost & Schedule are Critical Factors
• “Done Point” Very Hard to Identify
• Need MultiDisciplinary Knowledge

Analysis vs. Synthesis

• Analysis → Know What IS/OCCURS and Then Try

to EXPLAIN it

• A separating or breaking up of a whole into its parts, with an examination of these parts to reveal their nature, proportion, function, interrelationships, etc.
• Synthesis → Know What IS NEEDED and Then Try

to CREATE (Design) it

• The putting together of parts or elements so as to form a whole

Design vs. Analysis

• Which of the following is design and which

is analysis?

a) Given that the customer wishes to fasten together two steel plates, select appropriate sizes for the bolt, nut & washer b) Given the cross-section geometry of a new airplane wing we determine the lift it produces using Fluid Mechanics principles

 Form is the solution to a design problem

• In this Case the Bolt SIZE & Material

Form FOLLOWS Function

• Function “Directs” Form
• Form ≡ Shape, Size, Configuration, Weight,

Human InterFace Appearance, Materials of

Construction, etc.

• DESIGN connects Form (the OutPut) to the

desired Function (the InPut) Thru a DECISION-

MAKING PROCESS

Engr-Design as Decision-Making

• Design Definition  Short Version
  • Set of decision making processes and activities to determine the FORM of an object, given the customer’s desired FUNCTION
• Design Definition  Long Version
  • The process of devising a system, component, or process to meet desired needs. It is a decision- making process (often iterative), in which basic- science, mathematics and the engineering-sciences are applied to convert optimally resources to meet a stated objective

Decision-Making  Design Process

Formulating Problem

Generating Alternatives

Analyzing Alternatives

Evaluating Alternatives

ReDesign Iteration

 Establish Functional Requirements  Determine Constraints DESIGN Specs^ ^ Set Performance Goals  CREATE Alternative Forms (Shape, Configuration, Size, Materials, Power-Sources, etc.) ALL Alternatives

FEASIBLE Alternatives

BEST Alternative MANUFACTURING Specs

FORMULATION Phase - Brake

• Early in the design process, we decide upon

the nature of the Functional Requirements,

and Inputs for the Design

 Decide upon a satisfactory rate of deceleration

 Determine the length of the shaft

 Determine where it is supported

 Determine what actuating energy is available  Decide to Learn From existing similar products  Choose to research brakes in the library

CONCEPT Design Phase - Brake

• Decide PHYSICAL PRINCIPLES that will

perform the braking function

1. surface friction (e.g. drum brake, disk/caliper)
2. opposing magnetic fields (e.g., inverse motor)
3. air friction (e.g. fan blades)

• Assume we DECIDE on

surface friction

CONFIGURATION Dsgn Phase

• Decide upon PART features & how they are

arranged/configured

• Part configuration:
  • relative size of hub to disk
  • relative size of rotor thickness to diameter

PARAMETRIC Design Phase

• Decide upon SPECIFIC VALUES for design

variables/parameters

1. rotor diameter (outer)
2. rotor thickness
3. brake pad area
4. pad material
5. hydraulic pressure on piston

Final FORM is the Design Solution

• FUNCTION  stop a spinning shaft
• FORM 
  • rotor: 10 inch diameter, Cast Iron, 3/8-inch thick, cooling passages
  • Forged 4140 steel caliper/housing
  • brake pads, 2 opposing, 4 sq. in., metal particles in epoxy matrix
  • Stainless steel 304 piston,1.25-inch diameter, with elastomeric seals
  • 105 psi hydraulic piston pressure

Design

Phase

Summary

Configuration Design

Problem Formulation

Concept Design

ParaMetric Design

Detail Design

Preliminary Design Embodiment Design