Design Projects

Assistive Technology

Technology to assist people with disabilities.

Design Challenge – Prosthetic Hand

Scenario • You are working with a team of engineers from a biomedical engineering

company that specializes in the design and manufacturing of prosthetic devices. Your team’s challenge is to design a prosthetic hand that can perform ONE function to help improve the quality of life of the amputee who uses the prosthesis.

• Example functions to design for: • holding a pen or pencil • brushing teeth • clasping • picking up an object • using sign language • holding a utensil • throwing • eating something

• Design Constraints • Time: 1 week!

– Therefore, it is important to agree on a design that is functional, yet not overly complex.

• Materials: The materials available to you are listed below: – foam core, balsa wood, Plexiglas – wooden dowels, metal rods – springs, rubber bands, adhesives, such as epoxy, super

glue, hot glue – sander, saw, drill fasteners, such as eye hooks – wire, string, laser cutter

• Project Deliverables:

– Background research

– Preliminary sketches and materials list

– Progress report

– Design portfolio

– Final prototype

– Class/expo presentations

Background research

Research the Problem Activity — Patent Search Worksheet

• Patent Search Worksheet

• Names________________________________

• Date _________________________________

• Work with your partner to conduct research to answer the following questions. What is the design challenge that you are working on?

• What are some possible products that relate to the design challenge?

• Give at least three examples of existing patents that relate to your design challenge.

• Suggested websites to use: US patent and Trademark Office: http://www.uspto.gov

• Google patent search: http://www.google.com/patents

• Patent name:

• Website:

• Brief description:

• How this relates to your design challenge:

Research the Problem Activity — Reverse Engineering Worksheet

• Names_______________________________________ • Date ________________________________________ • Work with your partner to reverse engineer an existing

product. Describe the product that you will reverse engineer. Where is it typically used? Who might use it?

• What is the function of this product? • What are the major components of this product? • List the detailed procedures you used to reverse engineer

this product. • What are the results and recommendations you have after

reverse engineering this product?

Research the Problem Activity — Standards and Codes Search Worksheet

• Names________________________________ • Date _________________________________ • Standards and Codes Search Worksheet • Work with your partner to conduct research to answer the following

questions. What is the design challenge that you are working on? • Suggested websites to use: • Standards.gov: http://standards.gov/standards_gov/standards.cfm • US government regulations: http://www.regulations.gov/ • List three possible standards that relate to the design challenge.

(Example: size of fasteners, footprint, etc.) • List three possible safety issues that relate to the design challenge. What

existing codes relate to those issues? • List three possible environmental issues that relate to the design

challenge. What existing codes relate to those issues?

Research the Problem Activity — User Interview Worksheet

Question Customer Statement Interpretation

Rank Customer Need

1

Work with your partner to conduct user interviews. This information helps you determine if your design will meet customer needs and also may help you find hidden customer needs. •Gather raw data from your user using video, audio or notes. Here are some possible questions: When do you use this product? Why do you use this product? What do you like about existing products? What do you dislike about existing products? What improvements would you make to the product? •Fill in the following chart to document user feedback.

•Look at the chart above and look for any repeating comments. Group these comments together by using a descriptive word (Such as “casing” or “function”). These are indications of your customer needs. •Rank the needs in the chart below in order of importance for the user.

Prosthetic Arm Challenge Introduction

• A classmate has recently lost part of her arm below the elbow. She now needs a prosthesis that is low-cost and easily maintained that will allow her to complete daily tasks in school and at play.

What is a Prosthesis?

• A prosthesis is an artificial limb (an artificial substitute) that replaces a missing leg or arm due to disease, accidents, or congenital defects.

• Main types of artificial limbs: – Transtibial prosthesis

– Transfemoral prosthesis

– Transradial prosthesis (MESA Prosthetic Arm Challenge)

– Transhumeral prosthesis

A U.S. soldier demonstrates table football with two transradial prosthetic limbs

i-limb ultra, by Touch Bionics, has five individually powered digits and went on sale in 2007 for $17,454

The Jaipur foot, a transtibial prosthesis, is readily available to impoverished nations and costs $35. In contrast, prosthetics in the U.S. cost from $5,000 to over $100,000.

Prostheses in the United States are made from materials such as plastic, metal (aluminum, steel, titanium), silicon, latex, and carbon fiber. These devices can also have robotics components.

Man builds himself bionic hands

• Sun Jifa lost both his hands when a homemade blast fishing bomb exploded prematurely. Unable to afford the prosthetic limbs offered by a hospital, he created his own. – Source: http://news.yahoo.com/photos/man-builds-

himself-bionic-hands-slideshow/#crsl=%252Fphotos%252Fman-builds-himself-bionic-hands-slideshow%252Fbionic-hands-photo-1345045308.html

“I survived, but I had no hands,” he explained.

After the accident, Sun Jifa, 51, of Guanmashan, Jilin province in northern China desperately needed to work on his family farm, according to the Daily Mail.

Jifa spent eight years handcrafting prototypes before finally creating metal hands that could grip and hold.

“I couldn’t afford to buy the false hand the hospital wanted me to have, so I decided to make my own,” Jifa says.

The devices depend on a series of wires and pulleys inside, and are controlled by movements in his elbows.

“I made this from scrap metal for virtually nothing,” Jifa says.

Jifa says he will further develop the design for other disable people.

“There is no need to pay hospitals a fortune,” Jifa says.

Prosthetic Arm Challenge Overview

The MESA USA Prosthetic Arm Challenge involves the development of a low-cost prosthetic device to complete pre-defined tasks. The challenge has four components: Performance, Technical Paper, Academic Display and Oral Presentation. Objective:

Teams will build a low-cost prosthetic arm for use by a classmate who recently lost part of her arm below the elbow. The device should be designed to be low-cost and easily maintained and allow her to complete daily tasks in school and at play. The device must meet the criteria outlined in the rules and be designed to perform the pre-defined tasks.

• Device Performance – 150 points

– Distance Accuracy Relay

– Object Relocation

– Dexterity (high school only)

• Device Efficiency – 50 points

• Technical Paper – 100 points

• Academic Display – 100 points

• Oral Presentation – 100 points

Challenge Performance Tasks

1. Distance Accuracy Relay: greatest distance and accuracy achieved by tossing balls of different sizes into target containers at different distances

2. Object Relocation Task: greatest mass-to-time ratio achieved by placing objects of varying weights into a container

3. Dexterity Task: greatest number of bolts and nuts correctly placed and secured onto testing device

General Rules

• Device must attach halfway between elbow and wrist, and extend beyond real hand.

• Device must include hand mechanism (at least 2 fingers) and must open and close w/o assistance from opposite elbow, forearm or hand. – Hand mechanism must open at least 10 cm.

– Objects in each task MUST be grasped, taken hold of, or grabbed on part of device that extends beyond hand (i.e. the “fingers” of device). Can NOT use any other part of device or parts of own hand, wrist, or arm to grasp, take hold of, or grab objects.

• Device, including all parts of all configurations, cannot weigh more than 3 kg.

• All parts and materials of the device cannot exceed $40 pre-tax price limit

• Must complete and submit provided itemized budget sheet and attach receipts and/or online retail price print-outs to support prices listed.

• Device cannot utilize team member’s wrist, hand, or fingers in any way.

• Team will determine their method of immobilization and must demonstrate this for judges.

• In addition, a latex glove will be placed over member’s CLOSED FIST before attaching device.

• Parts may NOT be added, removed, replaced, or readjusted during trial; between trials is allowed.

Distance Accuracy Relay Highlights

• Target containers at three different distances – Containers are Home Depot’s “Homer’s All-Purpose Buckets

• 2 meters from launch line

• 3.5 meters from launch line

• 5 meters from launch line

• Relay objects are three different size balls • 5 standard size tennis balls (≈ 2.5 inches)

• 5 vinyl kick balls (2 inches)

• 5 standard size ping pong balls (≈ 1.5 inches)

Diagram 2

Relay objects randomly placed in cardboard box

Top lid of an Office Depot Copy Paper 10 reams box

• 1 minute to prepare and demonstrate device, and to place device and box with Relay Objects anywhere on table.

• When given start order, first designated team member enters Working Area, attaches device, and tosses as many of the SAME TYPE of balls.

• Teams MUST toss all types of same balls before tossing subsequent types of same balls.

• At least two team members MUST participate in the relay. One member must not toss more than two types of balls.

• Only ONE of the balls may be grabbed at a time.

• Only balls inside designated box may be used for tossing.

• Trial will conclude: – At end of 90 seconds

– When a member grabs more than one ball

– When a member tosses wrong type of ball

– When any part of member’s body including arm and device crosses launch line when tossing ball

– When target container is knocked over

Score Matrix 2m Target

3.5m Target

5m Target

Tennis Ball 10 15 25

Kick Ball 15 20 30

Ping Pong Ball 25 30 40

Object Relocation Task Highlights

• Objects 1. Two – 20 ounce Dasani bottles of water

2. Two – 1 liter Dasani bottles of water

3. Two – 1 lb boxes of Crayola Modeling Clay

4. Two – Master Lock 1500D 1 ⅞” Combination Locks

5. Two – Quart size Ziploc bags with 200 Pennies

6. Two – Spindle of 30 CD’s

7. Two – 2 inch by 20 yard Rolls of Duct Tape

8. Two – 4 oz. bottles of Elmer’s Glue All (white school glue)

9. Two – Packages of 12 AA Energizer Batteries

10. Two – Composition Notebooks, 100 pages, page size 7.5” L x 9.5” W

11. Two – 1 lb Box of Grip-Rite Nails any size, box dimensions approximately 2” H x 4.75” W x 3.5” L

12. Two – Packs of 100 3” x 5” Index Cards

13. Two – Spiral Bound 3 Subject Notebooks, 120 pages, size 10.5” L x 8” W

14. Two – Rolls of 1” x 60 yards masking tape

15. Two – 1 pound bags of pony beads (approximately 2000 beads)

• 10 of the 15 item groups will be selected on day of competition

1 minute to prepare, attach, and demonstrate device, and to place container in one “Container Area”.

76 cm

50 cm 50 cm

Diagram 3

83 cm

At end of 1 minute or when device is prepared, attached and ready, designated team member will stand outside of Working Area.

1 ½ minutes (90 seconds) to complete task.

At least 5 different item types MUST be place in container or trial will be declared a mistrial.

Team may call end of trial before 1 ½ minutes have passed by calling out “done”.

Any item held by device when time is called will not be counted towards total mass of container.

Dexterity Task Highlights

• For high school teams ONLY

• Testing device made from two 1 foot x 6 inch x 1 inch boards attached perpendicular to each other.

1’ Length

6” Height A B C

3”

FRONT VIEW

Diagram 6

Vertical board with three pre-drilled holes

3 inches from edge and 3 inches from top

Hole “A” = 6.9mm Metric Drill (US-17/64)

Hole “B” = 10.0mm Metric Drill (US-27/64)

Hole “C” = 14.2mm Metric Drill (US-35/64)

Dexterity Materials include: Hole “A” = 8mm x 1.25mm hex bolt and nut, and 13 mm wrench

Hole “B” = 12mm x 1.5mm hex bolt and nut, and 19mm wrench

Hole “C” = 16mm x 2.0mm hex bolt and nut, and 24mm wrench

• 1 minute to prepare, attach, and demonstrate device, and to prepare “Testing Area” and dexterity materials. – Testing Device can be placed in either Testing Area (50 cm square).

– Dexterity materials placed outside of Testing Area.

• At end of 1 minute or when device is prepared, attached and ready, designated team member will stand outside of Working Area.

• 2 minutes to complete task.

• Member may sit or stand and may move chair and/or stand anywhere in Working Area.

• Task is as follows: – Grab and place hex bolt into corresponding pre-drilled holes.

• May hold head of hex bolt with non-prosthetic hand ONLY. May NOT twist or screw in any way or trial will stop and be declared a mistrial.

– Grab corresponding hex nut and place onto bolt.

– Grab corresponding wrench and screw hex nut onto bolt.

– Repeat for all three hex bolt and nut sets.

• May choose in what order each bolt/nut set is secured but must place a nut on a bolt before attempting another. Once all three nuts have been placed on bolts, may re-visit any bolt/nut set to score more points.

• Each hex bolt will have a marking every 0.5 cm from base of bolt head.

Reminders

• Safety first: Since transradial prosthesis will be attached to student’s arm, please keep safety in mind at all times.

• Stay within all the parameters of the project.

• Research, brainstorm, build, test, record, revise, build, test, record, revise, build, test,…

– Use the Engineering Design Process

• READ ALL THE RULES!!!

Activity 1 – Relocating Objects

• Objective – Design, build and operate a transradial prosthesis from given

supplies to grab various size objects one a time and release them into a container

• Supplies per group – 2 sheets of card stock paper

– 5 feet of string

– 9 straws

– 14 craft sticks

– 3 beads

– Activity Sheet

Activity 1 Instructions

• Using the given supplies, design and build a transradial prosthesis. The prosthetic arm should be attached half way between the elbow and wrist and should extend beyond the real hand.

– Device MUST have hand mechanism and MUST open and close.

– Can NOT use opposite elbow, forearm or hand OR real hand to operate or control the prosthetic arm.

Creating One Finger with Two Joints

• Cut one craft stick into three equal pieces.

• Cut two pieces of straw slightly shorter than the pieces of sticks.

• Glue one piece of straw to one piece of stick. Put the glue on the stick and not the straw or the straw may melt. Do this for a total of TWO straw/stick segments.

• Glue the two stick segments onto a full straw. The sticks should be sandwiched between the straws now. Leave a small space in between each segment, so that bending is possible at the joint.

• Glue full straw’s excess onto a full length craft stick. Leave a small space between the full length craft stick and the first segment, so that bending is possible at the joint.

Activity 1 Instructions continued

• Glue one more straw segment onto the top of the full length craft stick in line with the other two segments.

• Tie a bead onto the end of piece of string. Use the bamboo skewer to thread the other end of the string through the first short straw segment and through the two other short straw segments.

• Wrap each segment with tape to reinforce the glue. Pre-bend the finger at each joint.

Creating Arm and Operation

• Using the remaining supplies, create two more fingers, the arm and the operation of the fingers.

Testing

• Attach the transradial prosthesis and pick up the different objects from a table one at a time and release them into the container/box.

Activity 2 – Tossing Balls into Targets

• Objective – Design, build and operate a transradial prosthesis from any of

given supplies to toss various balls one a time into cups at different distances.

• Supplies per group o 5 – sheets of 9” x 12”

construction paper o 3 feet of masking tape o 5 index cards o 1 pair of scissors o 2 plastic spoons o 3 feet of string o 5 straws

o 10 craft sticks o 5 – 3 ½” rubber bands o 10 small paper clips o 10 large paper clips o 10 fasteners o Activity Sheet

Activity 2 Instructions

1. Using any of the given supplies, design and build a transradial prosthesis. The prosthetic arm should be attached half way between the elbow and wrist and should extend beyond the real hand. Device MUST have hand mechanism and MUST open and close.

Can NOT use opposite elbow, forearm or hand OR real hand to operate or control prosthetic arm.

2. Place cups 1 foot, 2 feet, and 3 feet from launch line. No part of team member or device may cross launch line.

3. Arrange different balls from smallest to largest.

4. Attach transradial prosthesis and grab and toss one ball at a time; toss same type of ball before tossing subsequent type of same ball.

Designs and constructs a simple, autonomous robot

• Motors

• Sensors

• Computer controller

Mobile Robots Why do robots need to move?

What defines a robot?

• Sense – a robot has to take in information about its environment

• Plan – a robot has to use that information to make a decision

• Act – a robot needs moving parts to carry out commands

What ways do robots move?

• Rotate

• Convey

• Walk

• Swim

• Fly

• Reach

• Bend

• Poke

• Roll

Snake Robot

Manipulative Movement

• Robots that use an arm, belt or other means to grab and maneuver objects

Mobile Movement

• Robots that can move from place to place

Why go from place to place?

• Transport goods and materials

• Carry messages

• Get there faster

• Do a task while you’re getting there or when you get there

• Collect information about what’s there

• Get away from something

• See if you can!

Most robots get around by rolling

• Walking is hard – it requires balancing

• Swimming only works in water

• Flying requires a lot of speed and energy

• Wheels and treads make moving over ground easier

• They provide stability with multiple points that touch the ground

How do rolling robots work?

• Sensors

• Motors

• Wheels

• Programming!

Main Components of Robotics

• Build – Mechanics, Mathematics, Physics

• Program – Building behaviors

• Test – Multiple trials

• Communicate – What did you work on or accomplish? What conclusions did you come to?

Run your program. What happens? Did your robot perform as you expect? If not, adjust your robot or your program and try again!

Program your robot using the LEGO MINDSTORMS Education NXT Software. Download your program to the NXT brick with the wireless Bluetooth connection or the USB cable.

Build your robot.

Overview NXT Brick An intelligent, computer-controlled LEGO® brick, the NXT is the brain of the LEGO MINDSTORMS® Education robot.

Touch Sensors Enable the robot to respond to obstacles in the environment.

Sound Sensor Enables the robot to respond to sound levels.

Light Sensor Enables the robot to respond to variations in light level and color.

Ultrasonic Sensor Enables the robot to measure distance to an object and to respond to movement.

Lamps & Converter Cables Add lamps and then program flashing lights, or use them to activate the Light Sensor,. Three Lamps and three Converter cables are included in the Base Set.

Interactive Servo Motors Ensure that robots move smoothly and precisely

Rechargeable battery Provides power to the NXT so the robot can move and respond.

Building

• Gears and axles

• Beams and connectors

• Motors and wheels

• Sensors and wires

• NXT programmable brick

We will be using LEGO® pieces

to build our robots

Building LEGO® Pieces

Building LEGO® Motors and Sensors

Motors

Sound

Sensor

Touch

Sensor

Light

Sensor

Ultrasonic

Sensor

Building LEGO® NXT

Sensor

Input

Ports

Motor

Output

Ports

Navigation

Buttons

LCD

Display

Screen

USB connection socket

Connections

Connecting Motors To connect a Motor to the NXT, plug one end of a black wire to the Motor. Plug the other end into one of the output ports (A, B, C).

Connecting sensors To connect a Sensor to the NXT, plug one end of a black wire into the Sensor. Plug the other end into one of the input ports (1, 2, 3, 4).

Downloading and uploading The USB port and wireless Bluetooth connection are used for downloading and uploading data between your computer and the NXT. If your computer has Bluetooth, you can download programs to the NXT without using the USB cable. If your computer does not have Bluetooth, you must use the USB cable

Programming Behaviors

• Giving the robot behaviors

• Complex behaviors are built from simple ones

The basic behavior… is used in the simple behavior:

Programming …which is used in the complex behavior:

Programming Screen Interface

Programming Area

Properties Area

Blocks

Programming Blocks and Functions

Program by dragging blocks

from the menu

on the left

Place them on the grid,

and wire them together

Can create your own

blocks called My Blocks

Touch Sensor

• The Touch Sensor is a switch: it can be pressed or released.

• You can add the Touch Sensor to an NXT model and then program the model behavior to change when the Touch Sensor is pressed or released.

Sound Sensor

• The Sound Sensor detects the decibel level: the softness or loudness of a sound. The Sound Sensor detects both dB and dBA.

• dBA: the sounds human ears are able to hear.

• dB: all actual sound, including sounds too high or low for the human ear to hear.

• The Sound Sensor can measure sound pressure levels up to 90 dB – about the level of a lawnmower.

• Sound sensor readings on the LEGO® MINDSTORMS® NXT are displayed in the percentage [%] of sound the sensor is capable of reading.

• For comparison, 4-5% is like a silent living room and 5-10% is about the level of someone talking some distance away.

• From 10-30% is normal conversation close to the sensor or music played at a normal level and 30-100% represents a range from people shouting to music playing at high volumes.

• These ranges are assuming a distance of about 1 meter between the sound source and the Sound Sensor.

Light Sensor

• The Light Sensor enables the robot to distinguish between light and darkness, to read the light intensity in a room, and to measure the light intensity on colored surfaces.

Ultrasonic Sensor

• The Ultrasonic Sensor enables the robot to see and recognize objects, avoid obstacles, measure distances, and detect movement.

• The Ultrasonic Sensor uses the same scientific principle as bats: it measures distance by calculating the time it takes for a sound wave to hit an object and come back – just like an echo.

• The Ultrasonic Sensor measures distance in centimetres and inches. It is able to measure distances from 0 to 2.5 meters with a precision of +/-3 cm.

• Large-sized objects with hard surfaces provide the best readings. Objects made from soft fabrics, from curved objects (e.g. a ball), or from very thin and small objects can be difficult for the sensor to read.

• Two Ultrasonic Sensors in the same room may interfere with each other’s readings.

Testing Why do we test?

• Make sure it works!

• Understand what it can do

• Test everything multiple times to determine the repeatability

• Use the robot to test other phenomena

Testing

• When we test, we take data (numbers)

• We write our numbers down in organized charts

• We write down everything we can about the experiment

• Look at our data after we’re finished

Communicate Why is communicating your design so important?

• If no one knows what it is, how it works, or why it’s cool, why would they want to buy it?

• When it is well-documented, other people can build

on what you have started and create even cooler technologies!

Communicate

• Experiment worksheets and log books

• Presenting our work

• Sketching and describing ideas so teammates can understand too

Fork Lift

• This Forklift can drive around and steer on carpet or hard

floors, lift loads that are placed in the pallet bucket 7 inches

straight up, set them gently down on top of shelves or other

platforms, and take them back down.

• Color sensor is used as a "warning" light to signal different

operations.

• One can program the Forklift to do automatic tasks using the

rotations sensors in the motors and the Ultrasonic sensor on

top, or if you have a working Bluetooth connection between

computer and NXT, then you can drive it by wireless remote

control from your computer keyboard

• Or, if you have two NXTs, you can control it by Bluetooth

with the Dial Remote Control project.

Race Car

• This Race Car is designed to look and steer like a real car, with pivoting front wheel steering.

• It is also designed for speed, with gears to increase the speed of the rear drive wheels.

• The Color Sensor is positioned under the car so that the car do some basic autonomous operations by sensing the color of the surface.

• The sensor can distinguish six different colors, so you can make the car react to different colored tape lines, colored paper strips, etc.

• One can also operate the car by remote control with either a simple two button wired remote control (requires only one NXT kit), or by wireless Bluetooth remote control from another NXT such as the 5 Button Remote Control or the Steering Remote Control.

• Programs are provided for all three of these remote controls.

What is Engineering?

• Problem solving

• Teamwork

• Time management

• Testing

• Doing it over if it doesn’t work correctly the first time!

Engineering Process

Determine

the problem

What are you trying to

solve? Why do you

need it?

Research

Has anyone ever solved

this problem before?

How did they do it? Brainstorm

Come up with as many

solutions to the problem

as you can.

Pick the

best solution

Figure out the best

solution to solve the

problem and meet

budget and time

constraints.

Build

Physically constructing

something can be

difficult. Don’t get

discouraged!

Test

Does what you built solve the

original problem? Why or why

not? Redesign

How can you change it to

meet the problem

requirements?

How did you attack the

problem? What challenges

did you encounter? What was

your final solution? What

changes would you make?

Present

Personal Assistant Robot

Personal Assistant Robot

• We will be making a mobile robot to help out in the classroom

• We will run tests on the robot to determine its capabilities

• Before it can do complicated behaviors, we have to teach it simple ones

• But before we program anything, we need to build

Chapter V Shot Peening

History of Shot Peening

Discovered centuries ago by sword smith’s & black smith’s.

They found that peening the surface of sword or wagon spring greatly increases its resistance to breaking.

Round knob of the “ball peen” hammer was the smith’s tool for cold working/peening.

What is Shot Peening

Shot peening is a cold work process.

Used to finish machine components to improve fatigue and stress corrosion failures.

Small spherical shots bombards the surface.

Dimpling the surface and develops compressive stress.

Shot peening can be done without changing part design.

• Media used for the shot peening include: steel, ceramics and glass.

Shot Peening Mechanism

When a round part (steel ball ) strikes a part of surface at high velocity the contact area is a point.

This concentrates the impact energy in a very small area.

causing a radial plastic flow at the impact point.

This plastic flow or movement of metal leaves compressive stresses in the part.

Complete coverage of the with overhauling ball impacts leaves a

thin permanent compressive stress layer in the part surface.

Why Residual Stress?

Metals fail under tension & not under compressive loads.

The failure crack usually initiate at the part surface where tension stresses are highest and a stress raiser exists.

when part is shot peened, the failure producing tensile stresses are thus reduced by the amount of compressive stresses (residual).

The lowering of the effective tensile strain will then allow the part to accept higher loading.

Typical Shot Peening Curves

www.wheelabratogroup.com

Shot Peening

(a) Mechanism for formation of residual compressive stresses in surface by cold plastic deformation (shot peening). (b) Hardness increased in surface due to shot peening.

Applications of Shot Peening

Gear Parts

Cams and Camshafts

Clutch Springs

Connecting Rods

Crankshafts

Gearwheels

Leaf and Suspension Springs

Rock Drills

Turbine Blades

Shot Peening vs Shot Blasting

Shot Peening (S.P.): Shot peening is a cold working process, which

uses the mass and velocity of a shot stream to produce residual

compressive stress at the surface of the part. precisely controlled

process relying on careful selection and control of media, intensity,

coverage and equipment.

Shot Blasting (S.B.): Shot blasting or blast cleaning is a process in

which an abrasive material is accelerated through a pressurized nozzle

or centrifugal wheel and directed at the surface of a part to clean or

otherwise prepare the part surface for further treatment.

Media Used in S.P. & S.B.

Shot Blasting: Blasting media includes sand; steel shot, cut wire shot, garnet, a sharp hard abrasive glass beads .

Shot Peening: Peening media must remain predominately round and uniform in diameter to avoid surface damage upon impact and to maintain a uniform compressive stress layer.

Applications S.P. & S.B.

Shot Blasting: Shot blasting can be used on castings, forgings, and stampings to produce a uniform surface texture and for descaling, deburring, and deflashing. Shot blasting is used in a wide variety of industries including automotive, marine, mining, and medical applications.

Shot Peening: connecting rods, crankshafts, compression springs, torsion and anti-sway bars and metal implants.

Aircraft As a Machine

Human Fascination with Flight

Passion to fly originated as early as prehistoric times.

The freedom to fly in any direction at certain determined height and speed is a capability that all of us view with envy.

Birds can fly by a variety of ways:

i. Gliding ii. Flapping Wings iii. Hovering

V-Formation Flight of Birds

Large birds are often observed flying in V format.

V-formation allows them to conserve energy.

reduces air resistance.

Better vision and communication in flight.

In aircraft, V-type formation helps in avoiding heavy wing tip vortices.

Main Aeronautical Clusters

Aerodynamics and airframe.

Propulsion and power plant.

Materials and structures.

Dynamics, stability and control.

Avionics, power and flight computers.

Maintenance, repair and overhaul.

Forces Acting on a Airplane

The four forces are Thrust, drag, lift, weight.

The four forces can be drawn oriented through the C.G.

weight = Lift & Thrust = Drag in a level flight

LIFT

THRUST

WEIGHT

DRAG

Forces on A/C During Climb/Descent

Forces remain same, lift, weight, thrust, drag.

In a climb, A/C is still flying in a straight line with constant

velocity.

LIFT ≠ WEIGHT & THRUST ≠ DRAG

THRUST > DRAG

Angle of climb is determined by excess of thrust over drag.

DRAG

WEIGHT

LIFT THRUST

Directional Control and Stability

Aircraft Stability

Positive stability : tends to return to original condition after a disturbance.

Negative stability : tends to increase the disturbance.

Neutral stability : remains at the new condition.

Static stability : refers to the aircraft's initial response to a disturbance.

Dynamic stability : refers to the aircraft response over time to a disturbance.

Roll Control: Aileron

Pitch Control : Elevators

Pitch stability, A/Care designed to be nose heavy.

C.G. is ahead of aerodynamics center.

This design feature is incorporated so that in the event of engine failure, A/C will assume a normal glide.

Yaw Control : Rudder

Roll, Pitch and Yaw Control