Chapter 2 - part 2 Flashcards
What is a composite material?
2 or more materials combined together to create a new material with improved functionality and properties ( enhanced material)
Glass reinforced plastic
GRP
Appearance- Covered with a smooth plastic resin, Easily coloured and moulded
Characteristics- Lightweight, good strength to weight ratio, heat+ chemical resistance
Uses- Helmets, Pipes, Liquid storage tanks
Carbon- fibre reinforced plastic
CRP
Appearance- a cloth woven from individual strands
Characteristics- very expensive, stiff rigid
Uses- Musical instruments, Sports equipment, Musical instruments
What is a technical textile?
Textile that has been developed with enhanced properties to withstand specific uses
Gore tex
- A waterproof and breathable material
- Material helps reduce build up of condensation inside jackets or boots
- It’s a very thin membrane sandwiched between a liner and outer material
Uses- Outdoor clothing
Kevlar
Poly-paraphenyoene terephthalamide
- Non flammable
- Extremely strong+tear resistance
Uses- bullet proof vests, personal armour
What are conductive fabrics?
- aka e-textiles
- allow an electrical impulse to pass through them
- A silvery fabric or thread, can be sewn
- Helps link electrical components together
Uses- Bluetooth connectivity, electronic sports equipment, anti-static clothing
Fire resistant fabric
- E.g Kevlar and Normex
- Made from armed fibres
- Can be dyed a range of colours
- Heat resistance + naked flame(protects wearer)
Uses- Aprons, Fire blankets
What are Microfibres?
They are group of synthetic fibres that are less than one dernier thick
What is Microencapsulation?
- Thin fibres that are used to hold chemicals in tiny capsules
- Break open releasing chemicals
Microfibres+ Microencapuslation
- Fine synthetic fibre woven into different products
- Can be absorbent but fast drying
Uses- Medical textiles, Clothing that is anti bacterial, towels
What does a system consist of?
Inputs, processes and outputs
What is a system diagram?
A diagram that breaks down the operation into 3 main components: Inputs, process and outputs
What is an open loop system?
- A system that has no feedback
- It’s unable to make a decision
- Input directly controls the output
What is a closed loop system?
It’s able to make decisions using feedback, usually from a sensor
Some electronic products have a polarity. What does that mean?
They have a positive and negative side to them, therefore it matters which way around they go in a circuit
Toggle switch
Input component
Uses- Lighting
Push to make switch (PTM)
Normally open
Input process
Uses-door bells, keyboard
Push to break switch
Normally closed
Input component
Uses- Alarm systems
Light dependant resistor
LDR
Input component
Uses- Street light
Thermistor
Input component
Uses- Thermostats
Pressure switch
Input component
Uses- Burglar alarms
Light emitting diode
LED
Output component
Uses- Torches, Tv screens
Lamp
Output component
Uses- Car headlamps, floodlights
Buzzer
Output component
Uses- Alarm system, electronic games
Speaker
Output component
Uses- Headphones, radios
What are integrated circuits?
They are used to form multiple tasks. Most common one is a microcontroller
What is an analogue signal?
It’s a continuous signal with an infinite range of values
What is a digital signal?
It’s either on or off
What is a monostable device?
- Aka a single shot timer
- it’s only stable in the off position
What is an astable device?
- Gives an oscillating output
What are counting devices?
They are used to keep a tally of how many times and event occurs
Linear movement
Movement in one direction along a straight line
Reciprocating motion
Repetitive up and down motion
Oscillating material
Similar to reciprocating but it’s in a curved motion
Rotary motion
A circular motion
What is a lever?
A simple way to gain mechanical advantage
What is equilibrium?
When the effort and load are equal
Class 1 lever
- Fulcrum in the middle
- Load and effort on the opposite ends
Class 2 lever
- Fulcrum on the side
- Load next to the fulcrum
- Effort next to the load
Class 3 lever
- Fulcrum is on the side
- Effort is near the fulcrum
- Load is next to the effort
Reverse motion linkage
Changes the direction of input so that the output is in the opposite direction
Parallel motion or push/pull linkage
Input and output travel in the same direction. Uses 3 linking bars
Bell crank linkage
Changes the direction of Input through a 90 angle
Crank and slider
Changes rotary motion into reciprocating motion and vice versa
Treadle linkage
Changes rotary motion into oscillating motion or vice versa
What is a cam used for?
To change rotary motion into reciprocating motion using a follower
Eccentric or circular cam
Steady rise and fall
Pear cam
Rapid rise and fall
Snail cam
Steady rise and sudden drop
Heart shaped cam
Slight rise and fall
Flat follower
Not very accurate, lots of friction, can cope well under load
Knife edged follower
Tracks movement of cam accurately, low friction
Roller follower
Some accuracy, Efficient under load
Block and tackle
2 or more pulleys used to reduce the effort required to lift or move a heavy load
