Chapter 4

Physics - Nobel Prize


Technological artifacts such as

• bridges
• buildings
• vehicles, 
• cell phones
•  computers 

The process definition of the engineering design process.

Engineering design is the process of devising a system, component, or process to meet desired needs. It is a decision-making process (often iterative), in which the basic sciences, mathematics, and the engineering sciences are applied to convert resources optimally to meet these stated needs.

• What a design process is.
• How engineering design differs 
• Different steps in the engineering design process.
• Apply each step of the engineering design process to design a product 
• Implementation the design process affects the quality 

Plan or drawing that shows the look and function of an object
 before it is made.

Design of a building, specifying the building’s appearance and the layout of rooms, doors, and hallways


Design Process

• Involves creativity
• Making decisions
• Engineering design specialized knowledge of technology, math, and science 

Engineering Design

Projects involve modifying product or process;
incremental design. 
developed from scratch.  a new design. 

Iterative Design

Process that meets the needs of customers and stakeholders.

• Customer use the designed object;
• Stakeholder  has an interest in the product.

Design problems are open ended
No single correct solution.
Several solutions  satisfy the needs.
Number of possible solutions.
Design team make many decisions.
Defined process to meet the needs of  stakeholders;

Use a structured design process
 provide a framework team decision-making

Design process should not be applied blindly
Should be adapted to fit the circumstances  project.

 Continuous improvement process 

Not result in a viable design for several reasons:

• Incorrect or unrealistic assumptions
• A lack of understanding of the needs or problems 
• Errors in design specifications or representations (e.g. models and drawings).
• Inadequate testing of prototypes.
• Poor design choices.

The Design Process

Each step being completed before the next step

Sequential
Team may revisit a step create the final design. 

Define the problem.  needs of customers
 competitors are identified and market positions are characterized;

 constraints imposed  are identified;
 available personnel, time, and money
definition process understanding of the scope of the project
resources available

 a problem statement

Problem Statement

Criteria and constraints are used to evaluate the quality of a design.
Constraints  must be met
 Criteria are values t to compare and determine which is better.

generates ideas for designs.
include existing products

brainstorming
other creative activities, and market and technical research.

Criteria and constraints

Explore possibilities. designs are generated, their characteristics and likely advantages and disadvantages.

Select a design concept.
designs are evaluated relative to the constraints and criteria,
designed in detail and prototypes. 

Selected design is developed in more detail.
 design architecture by identifying physical and functional chunks.

Shapes and dimensions are determined, materials and fabrication processes are selected, and product components are identified.

Design is developed in detail that prototypes of the design can be made.

Create models and prototypes.
 Prototypes  physical models which dimensions, materials, and fabrication processes emulate important aspects of the design.

Prototype


Test and evaluate. tested to see design meets all constraints
 performs relative to the criteria.

Refine the design.  reveal weaknesses of the design or
the design may be improved. 

Implementation. Depending on the context, the design is produced or constructed.

Communicate process and results. The activities and results of the design process are documented. 

Case Study

Develop a product that solves some of the problems of commuting options.

the sustainable commuter vehicle, or SCV for short.

• Vehicles create % of greenhouse gas emissions in the United States and appear to be a significant contributor to future climate change. Carbon dioxide is one of the principle greenhouse gasses emitted by vehicles.
• A typical American household spends more money on driving costs than it spends on food.
• In most major metropolitan areas, “rush hour” now lasts six/seven hours a day.
• Traffic congestion costs $63.1 billion per year. Each year, commuters stuck in traffic jams waste 2.3 billion gallons of fuel, not to mention their time or frustration.

Define the Problem

Problem definition is one of the most critical steps in the design process.

actually the problem that is important to customers.
clearly defined and understood 

gathering information from customers and other stakeholders,
finding expert information 

• Doing a root cause analysis to identify what the real problem is.

Vehicular commuting and traffic congestion.
Commute to and from work in car
Officials departments of transportation,
and representatives of environmental groups.

Design problem to be
Design a commuter vehicle that

• is environmentally friendly, 
• acceptable to a typical commuter, 
•  compatible with existing transportation infrastructure.”

Identify Criteria and Constraints

A constraint is a limitation  that must be satisfied by a design

a standard or attribute of a design that can be measured.

The constraints and criteria are used in subsequent steps of the design process to determine which of many possible designs should be implemented.

• Does not require new transportation infrastructure.

They identified the following criteria:

• The amount of pollution  emitted per mile traveled by a commuter.
• The percent of the energy used from renewable sources.
• The convenience for the commuter.
• The comfort of the commuter.
• The cost to use the vehicle for five years 

Generate Concepts

With criteria and constraints identified, the design team begins to generate concepts for the design.

discipline to ensure that they explore enough potential solutions

use a structured process to generate concepts for a design.

• the steps of problem 
• decomposition,
• searching externally and internally for ideas, 
• systematically exploring possibilities.

Decompose the Problem into Sub problems

decompose the problem into sub problems.

smaller problems that must be solved in order to solve the overall problem.

problem into subproblems 

Each of the subproblems is simpler to approach than the whole problem. 

energy source is how the vehicle gets energy to move; 

vehicle configuration is the number of wheels on the vehicle 

drive mechanism transforms energy into the locomotion of the vehicle.

Search Externally for Ideas

search for ideas to solve each sub problem.

look at existing products to see whether there are already solutions

external information

• interviews with experts in the areas
• patent and other technical databases
• existing products

find potential energy sources for their commuter vehicle

• Solar energy  using photovoltaic solar cells
• Nuclear energy
• Wind Energy converted into electricity using a turbine and generator
• Human power
• Gasoline, a nonrenewable fossil fuel
• A fuel cell that converts hydrogen and oxygen into electricity
• Ethanol made from corn or other plants
team discarded nuclear energy and a fuel cell as being unfeasible given the current state of technology.

searched for possible drive mechanisms. 

• A clutch, gearbox, and drive shaft similar to the drive train
• Electric motors located in the hubs of wheel and drive each wheel directly. 
• A chain drive similar to that used in motorcycles and bicycles. 

Search Internally for Ideas

internally for ideas is often called brainstorming

develop as many ideas as possible without worrying whether they are feasible. 

configuration is an arrangement of wheels around the passenger compartment.

each have between one and four wheels.

two-wheel configurations would require some method of balancing, 

Explore Systematically

generate many possible solutions for each of the sub problems.

structured process to examine possible combinations of sub problem solutions.

solution for each sub-problem is combined
sketch of the resulting concept is created.

standard bicycle with an added solar cell
pedals of the bicycle would be replaced by an electric motor

Concept 1: The design in Figure 17.

Concept 2:
energy source is solar cells and wind energy;
the solar cells and wind turbines are installed at charging stations
three-wheeled car with an enclosed passenger cabin that seats two
drive mechanism is wheel hub motors in each wheel
these motors use regenerative braking to recover energy 

Concept 3:
 combines a gas engine with a four-wheeled configuration
clutch, gearbox and drive shaft to form a traditional automobile.
 design would be a two-seater subcompact.

Concept 4:
same as Concept 3, engine is run on ethanol. 

Concept 5:
combination of solar cells and human power
three wheels, and the drive mechanism is a chain drive with gears. 

Concept 6:
solar cells mounted on the vehicle plus a battery;
charged at the user’s home plugged into  home electricity system.
the solar cells extend the life of the battery on sunny days.
two wheels side by side with room for a single passenger.

Explore Possibilities and Select a Design

The design concepts are explored to understand their characteristics. For example, exploring Concept 1, the solar-powered bicycle in Figure 17, leads to the following conclusions:

• The design  only renewable energy.
• The design  inexpensive to manufacture and low cost to operate.
• The design may not the commuter, since the motor run when sunlight falls impossible to commute at night 
• The design not  comfortable for the commuter,  hot, cold, and rainy weather,

• design can be improved. 
•  Concept 1 comfortable seat and  adding a battery that can store energy 

design team must choose one concept that will be used to create the design for the product.

structured decision process, each of the concepts is evaluated to see whether it meets the constraints and is compared with the other concepts using the criteria; the best concept according to the criteria that meets the constraints is typically selected to implement the product.

 Concept 2 did not meet the constraint because it would require cities to build charging stations,

 Concept 1 and Concept 5. They ranked high because of low pollution, using only renewable energy, and being low cost compared with other options.

 one of these designs and go forward in the design process;

 did not accurately capture their customers’ desires. In this case, they may go back and improve their criteria, then repeat the decision process.

 Or, they may determine that better concepts may have been developed with different combinations of sub-problem solutions or through different assumptions

Sometimes, a design does not satisfy the constraints but could be easily modified to satisfy the constraints. 

Develop a Detailed Design

 how each sub-problem will be addressed
overall understanding of the design.
 team needs to develop the details of the design.
 A detailed design includes

• The shapes and dimension of all physical components.
•  understanding of components from external vendors  
• fabricated within the company
• the materials and fabrication processes 
• detailed schematic diagram of any electrical subsystems
• computer code for any embedded processors.
• Assembly processes.

design concept  majority of time allocated to a new product design project.
impact on the success of the project;
poor detailed design can ruin a good design concept.

subsequent design steps of prototyping, testing, and refinement.

may require many iterations as the testing reveals previously unknown characteristics of the design.

going from a design concept to a detailed design is the development of the design architecture.

assignment of the functional elements of the product to the physical building blocks of the product

Prototype, Test, and Refine

prototype or model is a representation of some aspect of the design.
provide additional understanding of the design
may implement only a small portion of design
may be comprehensive and implement the whole design.

A physical prototype may be implemented out of materials
similar to those that will be used to manufacture the final design.

virtual prototype may be created using a
computer-aided design and drafting (CADD) program. 

prototype is to test whether the design will work as expected.

Testing procedures should be planned to ensure questions about the design are answered without requiring too much time 

Testing may reveal weaknesses in the design
the design will often be refined
if it does poorly with respect to some of the criteria or constraints.

Communication and Implementation

information is used to create user and maintenance manuals for the product.
 members who will be required to update or modify the design in the future.

 the effort to implement the design increases.
a product that is manufactured, a manufacturing system must be developed.