Engineering is the branch of science and technology concerned with the design, building, and use of engines, machines, and structures.
Unit 1
Simple machines is the mechanisms that manipulate magnitude of force and distance. The 6 basic simple machines are levers, pulleys, wheel and axles, inclined planes, wedges, and screws.
When mechanical advantage is less than 1, less effort force is needed to overcome resistance force. When mechanical advantage is greater than 1, more effort force is needed to overcome resistance force.
IMA- Ideal Mechanical Advantage
The IMA is a ratio of distance traveled by effort and resistance force
AMA- Actual Mechanical Advantage
The AMA is a ratio of magnitudes
The effort force is where the IMA=AMA.
Efficiency is [(AMA/IMA)x100]
1st Class Lever System
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Pulleys:
-Fixed Pulley
-Fixed Pulley
- IMA of 1
- changes direction of force
- IMA of 2
- force direction stays constant
- combination of movable and fixed pulley
- IMA= number of strands opposing the force of the load and movable pulleys
There are different types of gears. The gear ratio is basically the ratio of teeth on the gear. Simple Gear Trains and Compound Gear Trains. Compound Gear Trains is more complicating, but simple and easy to use.Gears, Pulley, Drives, and Sprockets
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Bread-boarding (also called a proto boarding) is a reusable platform for temporarily built electronic circuits.
- printed circuit boards are used for the final product/project
Parallel Circuits-
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Series Circuits-
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Combination Ciruits
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Electricity - movement of electrons
Elements- simplest form of matter
Atoms- smallest piece
Valence electrons- outermost ring of electrons (negative charge)
Black- negative
Red- positive
Electrical circuits- system of conductors and components forming a complete path for current to travel
Work(joules)= Force(newtons) x Distance(meters)
Energy
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Energy Transformations
chemical --> kinetic radiant--> chemical electrical --> thermal |
Power(watt)= Work(joules)/Time(seconds)
- Electrical power
- Mechanical power
- Fluid power
Introduction to Thermodynamics
- the effects of work, heat flow, and energy on a system
- an increase in temperature, an increase in motion
- a decrease in temperature, a decrease in motion
- thermal energy is in joules
- temperature is in degree
- absolute zero means the there is no kinetic energy
- different units of temperature: Celsius, Fahrenheit, kelvin
- thermal equilibrium is when two objects reaches the same temperature
- 1st law of thermodynamics- energy can be converted but can not be created or destroyed(conservation law)
- 2nd law- energy flows from hot to cold
Unit 2
Moment of Inertia (I)- mathematical property of a cross section that gives important information about how that cross-sectional area is distributed about a centroidal axis.
Modulus of Elasticity (E)- ratio of the increment of some specified form of stress to the increment of some specified form of strain. Also known as coefficient of elasticity, elasticity modulus, elastic modulus. This defines the stiffness of an object related to material chemical properties.
Modulus of Elasticity (E)- ratio of the increment of some specified form of stress to the increment of some specified form of strain. Also known as coefficient of elasticity, elasticity modulus, elastic modulus. This defines the stiffness of an object related to material chemical properties.
Statistics- study of forces and their effects on a system in a state of rest or uniform motion
Newton's 1st Law
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Static Equilibrium:
a condition where there is not a net external force acting upon a particle or rigid body and the body remains at rest or continues at a constant velocity Translational Equilibrium: the state in which there are no unbalanced forces acting on a body Rotational Equilibrium: the state in which the sum of all the clockwise moments equal the sum of all the counter-clockwise moments |
Moment
- a measure of the tendency of the force to rotate the body upon which it acts
- the distance is perpendicular to the force.
- clockwise (-)
- counterclockwise (+)
-direction- angle between a reference axis and the arrow’s line of action -magnitude- length of a line segment -sense- the direction shown by an arrow |
Force= pushing or pulling interaction of objects
British- lbF (pounds/force) International- N (Newtons) |
Simpler supported object- 1 pin and 1 roller
Contact- replace with a normal force Cable/Rope/Chain- replace with tension force Pin- replace with 2 reaction forces Roller- replace with a reaction force (perpendicular to the surface) |
Trusses
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Materials- Substances out of which all things are made
Physical Properties – Boiling point, melting point, density, color, hardness, and texture Chemical Properties – Reactivity to acid, oxygen, and flammability Metals are good conductors of heat and electricity
Nonmetal are :
Metalloids- Possess both metallic and nonmetallic properties |
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Different Materials:
Metallic Materials- Mechanical properties include strength and plasticity, Thermal and electrical conductors, Ceramic Materials- Compounds consisting of metal and nonmetal elements, Thermal and electrical insulators, Mechanical properties include high strength at high temperatures and brittleness, brick, tile, sewer pipe, chimney flue, china, porcelain, etc. Organic Materials-Are or were once living organisms, renewable, susatinable Polymeric Materials- Compounds consist of mostly organic elements, Low density, Mechanical properties include flexibility and elasticity Composite Materials- Composed of more than one material, Designed to obtain desirable properties from each individual material |
Recycling Materials:
Different Engineers:
Manufacturing Engineer- Select and coordinate specific processes and equipment Industrial Engineer- Responsible for the manufacturing system design Materials Engineer- Develop and select materials based on desired material properties and manufacturing processes |
Manufacturing Process- the process of turning materials into a product
Product Creation Cycle
Design → Material Selection → Process Selection → Manufacture → Inspection →Feedback
Product Creation Cycle
Design → Material Selection → Process Selection → Manufacture → Inspection →Feedback
Material Testing- reproducible evaluation of material properties
Evaluation of Material:
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Types of Testing:
Standardized Tests:
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Tensile Test:
- uniaxial
- destructive
- standard test sample: dog bone(ensures meaningful and reproducible results)
- tension force is applied to the dog bone til broken
- Thicker Diameter=Higher Resistance
- large samples indicate larger loads (elongation)
- stress=load/area
- Strain(E)- the amount of stretch per unit length strain= stretch(elongation)/original length
Stress and Strain Graphs
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Modulus of Elasticity(E)
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Elastic Limit- uppermost stress of elastic behavior
Resilience- the amount of energy per unit volume that a material can absorb while in the elastic range (area under the stress-strain curve)
Yield point- when the elastic limit is exceeded
Failure- if continued force is applied, necking will continue until fracture occurs
Ductility- amount of plasticity before fracture (the greater the ductility, the more deformation)
Brittleness- material failure with little or no ductility
Resilience- the amount of energy per unit volume that a material can absorb while in the elastic range (area under the stress-strain curve)
Yield point- when the elastic limit is exceeded
Failure- if continued force is applied, necking will continue until fracture occurs
Ductility- amount of plasticity before fracture (the greater the ductility, the more deformation)
Brittleness- material failure with little or no ductility
- lack of ductility, not lack of strength
Unit 3
Digital Sensors:
Bumper Switch/Limit Switch
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Analog Sensors:
Light Sensor
12 Digital Ports
8 Analog Ports Comments:
•// Single line comment – All material after “//” is ignored by the ROBOTC compiler •/* Multi-line comment*/ – All material between the “/*” and “*/” symbol is ignored by the ROBOTC compiler |
A flowchart is a schematic representation of an algorithm or a process.
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Three main types of behavior
–Complex behavior: Robot performs a complex task Example: automate fan control –Simple behavior: Robot performs a simple task Example: fan stops when sensor is activated –Basic behavior: Single command to a robot Example: start a motor |
Hydraulics:The use of a liquid flowing under pressure to transmit power from one location to another
Pneumatics: The use of a gas flowing under pressure to transmit power from one location to anothe Fluid Power:The use of a fluid to transmit power from one location to another |
Pneumatic Systems:
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Properties of Gases
- Pressure (P) - Volume (V)
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Absolute Pressure= Atmosphere pressure plus the gauge pressure
Gauge pressure- pressure on a gauge does not account for atmospheric pressure on all sides of the system Standard atmospheric pressure= 14.7 psi PSi- pounds per inches |
Absolute Zero= -460 degrees Fahrenheit
Absolute Temperature is measured in Rankine R= F + 460 degrees Perfect Gas Laws:
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Pascal's Law-
Pressure exerted by a confined fluid acts undiminished equally in all directions Pressure= the force per unit area exerted by a fluid against a surface P=F/A |
- Reservoir / Receiver
- Stores fluid
- Fluid Conductors
- Pipe, tube, or hose that allows for flow between components
- Pump / Compressor
- Converts mechanical power to fluid power
- Valve
- Controls direction and amount of flow
- Actuators
- Converts fluid power to mechanical power
Unit 4