1. Pass in your Technical Drawing Lab and your final Paper Mousetrap (someone else’s that you constructed).

2. If you are missing either assignment (or both), pass in a piece of paper with your name and missing assignment title on it.

“Give me a lever long enough and I shall move the world.” Archimedes

Unit 3: Engineering Design

http://www.math.rochester.edu/u/faculty/doug/UGpages/archimedes_lever.gif

Isometric Section Standard View Development Perspective Oblique

Cut-away Pictorial

Com

mun

icati

on T

echn

olog

y A B C

D E F

G

E

B

C

F

G

D

A

[REVIEW]

Which of the following images are parallel projections?

TECHNICAL GRAPHICSTe

chni

cal G

raph

ic C

omm

unic

ation

[REVIEW]

– Print Graphic Communication Visual, lingual messages that include printed media

– Photographic Communication Using photographs, slides, or motion pictures to

communicate a message– Telecommunications

Communicating over a distance– Technical Graphic Communication

Specific information about a product or its parts

Classes of Communication Technology

[REVIEW]

– Major Processes:• Relief

– A modeled work that is raised (or lowered) from a flat background.

– Cuneiform by the Sumerians ~6000 years ago. – Wood block printing ~200 C.E.– Movable type printing ~1040 C.E. (Gutenberg ~1450)– Intaglio (in-tal-yo) ~1430– Rotary printing press ~1843

• Lithography (offset printing) ~1796– The source and destination are not on raised surfaces– Grease and water do not readily mix– A chemical process– Most modern books and newspapersPr

int G

raph

ic C

omm

unic

ation Intaglio

(in-tal-yo)

1. Depressions cut into printing plate

2. The plate is covered in ink

3. Excess ink is removed from surface

4. Paper placed on plate and compressed

5. Paper is removed and ink has been transferredLow ReliefHigh Relief

Communication Technology

Cuneiform

[REVIEW]

• Telecommunication– Communicating over a distance

Tele – Greek, “far off” Communicare – Latin, “to share”– Rely on the principles of electricity and magnetism – 2 types:

• Hardwired systems (telephone, cable, fiber-optic)• Broadcast systems (radio and t.v., mobile phones)

– Point-to-point: • One transmitter and one receiver

– Broadcast:• One powerful transmitter to numerous receiversTe

leco

mm

unic

ation

sCommunication Technology

[REVIEW]

– Smoke signals and drums– Chains of beacons (Middle Ages)

• Navigation signals• Enemy troops approaching

– Homing pigeons • Carrier pigeons used as early as 1150 in Baghdad• Olympic victors, Greece; Stock options, Europe

– Optical telegraph (semaphore, 1792, France)• Towers with pivoting shutters• Information encoded by the position of the mechanical

elements

Tele

com

mun

icati

ons

Communication Technology

[REVIEW]

No drawing tools

SKETCHESTe

chni

cal G

raph

ic C

omm

unic

ation

[REVIEW]

Standard Views

Sectional Views

Auxiliary Views

Developments

Working Drawings

MULTI-VIEW DRAWINGSTe

chni

cal G

raph

ic C

omm

unic

ation

[REVIEW]

Show a likeness of an object as viewed by the eyeIsometric

Perspective

Oblique

Exploded Assembly

Cutaway Pictorial

Tech

nica

l Gra

phic

Com

mun

icati

onPICTORIAL DRAWINGS

[REVIEW]

Essential Elements of Engineering

1. Thorough understanding of scientific principles• Mechanics, Electricity and Magnetism, Thermodynamics, etc.

2. Practical and useful designs• Based on design requirements• KISS – Keep It Short and Simple

3. Good communication skills• Great design is worthless if not effectively communicated

ORAL WRITTEN DRAWINGS [REVIEW]

Engineering Communication

[REVIEW]

[REVIEW]

TEST FRIDAYTEST FRIDAYIncluding multiple choice, isometric and orthographic Including multiple choice, isometric and orthographic

drawing, and 2 algebra problemsdrawing, and 2 algebra problems

UNIT 2: Engineering CommunicationUNIT 2: Engineering Communication

Topics Covered

1. Force, Energy, Work, Power, and Efficiency2. Topics in Mechanical Engineering3. Topics in Electrical Engineering4. Engineering Design Process5. Teams and Projects6. PROJECT: Mechanically Controlled Electromagnetic Crane

Unit 3: Engineering Design

1. A push, pull, twist (or bend)2. A vector quantity

1. Magnitude2. Direction

3. Thrust – increases velocity4. Drag – decreases velocity5. Torque – changes rotational speed

Units: Newton (N), Pound-force (lbf)

FORCE

1. Inertia“Objects continue to move in a state of constant velocity unless

acted upon by an external net force.”

2. Fnet = ma“An unbalanced force acting on an object will result in the

object’s momentum changing over time.”

3. Reciprocal Actions“Forces always occur in action/reaction pairs.”

Newton’s Laws of Motion

1. Energy1. A scalar quantity2. The amount of work that is (or can be) performed by a

force

2. Potential Energy1. Energy stored within a physical system with the potential

to be converted into other forms of energy (e.g., kinetic, thermal, sound, light)

2. Types:Gravitational, Elastic, Chemical, Electrical, Nuclear

3. Kinetic EnergyThe energy an object possesses due to its motion

“Energy can be transformed, but cannot be created or destroyed.”

ENERGY

1. Work1. “The amount of energy transferred to a system by a force

acting through a distance.”2. The change in kinetic energy of a system

2. W = F x d1. The work done on an object is the product of the

component of the force in the direction of the displacement and the magnitude of the displacement.

2. A force does no work if the object doesn’t move

Units: Joule (J), Newton-meter (Nm), Foot-pound (ft-lb)

WORK

1. Power1. “The rate at which work is performed or energy is

converted.”2. The rate of change of work or energy.

2. P = W / t

Units: Watt (W), Foot-pound per second (ft-lb/s), Horse power (hp)

POWER(Mechanical)

1. Efficiency1. The ratio of the energy delivered by a system to the energy

supplied to it.2. The ratio between the output of a system and the input

2.

3. When is efficiency 100%?2. Never – 2nd Law of Thermodynamics3. Some of the input energy is converted to heat, sound,

light, etc.

Units: Dimensionless or %, Situational

EFFICIENCY

EFFICIENCY = x 100%OUTPUT INPUT

1. Equations1. W = F x d2. P = W / t3. F = m x a4. Eff = (output / input) x 100%

2. Problem Solving Process1. Write Given, Assign Variables, Sketch and Label Diagram2. Write Formulas / Equations3. Substitute and Solve4. Check Answer, THEN Box Answer

Engineering Problems

1. Use dimensional reasoning (and the power-law expression) to determine expressions for the terms on the left side of the equations:

1. W = f(F, d)2. P = f(F, d, t)3. F = f(m, a)4. Eff = f(output, input)

2. Complete front side of worksheet by Wednesday’s class

Homework