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62 Cards in this Set
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Systems Engineering Process |
DGEPTE 1. Define The Problem 2. Generate Possible Solutions 3. Evaluate Possible Solutions 4. Plan and Make Model 5. Test, Modify and Improve Design 6. Evaluate Final Design/Product |
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Define The Problem (Systems Engineering Process) |
Identify and document problem/need/opportunity/situation. -Ideas -Design Brief |
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Generate Possible Solutions (Systems Engineering Process) |
Research feasibility and alternatives. -Processes -Components -Sub-Systems -Costs |
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Evaluate Possible Solutions (Systems Engineering Process) |
Design and Model the system. -Drawings -Flow Diagrams -Trial and Testing (using actual parts) -Computer simulation/modelling -Calculations |
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Plan and Make Model (Systems Engineering Process) |
Plan, build, fabricate and/or integrate sub-systems. -Timeline/Sequence -Components/Material List -Production Work |
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Test, Modify and Improve Design (Systems Engineering Process) |
Test and diagnose/analyse performance -Make adjustments/repairs -Modification -Fix Problems -Improve Design -Do More Testing |
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Evaluate Final Design/Product (Systems Engineering Process) |
Evaluate and report on system produced and processes used. -Draw Conclusion -Make Recommendations For Improvement |
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What is Energy |
The capacity to perform work |
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Measurement of Energy |
Joules |
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Law of Conservation of Energy |
Energy cannot be created nor destroyed, but it can be changes from one form to another and heat will be given off. |
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Examples of Levers |
Hand Brake, Scissors, Wheel Burrow, Nut Cracker |
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List Six Simple Machines |
1. The Lever 2. Wheel and Axle 3. Pulley 4. Inclined Plane 5. Screw 6. Wedge |
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Wheel and Axle and Lever Combination Makes? |
The Wheelbarrow |
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Single Pulley System |
Used to change the direction of forces. In a single pulley system, to move the load up one metre, you have to pull the rope down one metre.
If the load is 10 newtons you will have to use a force of 10 newtons to lift it. |
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Two Pulley System |
In this, you sacrifice distance in favour of force. To move the weight up one metre you have to pull the end of the rope down two metres. But if the load is 10 newtons, you will only have to use a force of 5 newtons to lift it.
The effort is half the load, but the effort must travel twice the distance. |
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Winding Drum |
Converts the rotary motion of the crank to linear motion of the bucket
The longer the crank, the less 'effort' needed to lift the load |
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Mechanical Advantage |
Load ÷ Effort |
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Velocity Ratio |
Distance Moved by Effort ÷ Distance Moved by Load |
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Efficiency |
Mechanical Advantage ÷ Velocity Ratio |
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Applications for a Pulley System |
Winding Drum, Well, Elevator |
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Belt Drive |
Simple and Efficient way to transfer Drive. Disadvantage is slipping if too loose, or causing premature bearing wear if too tight.
If you do not want slippage, a chain is an excellent way of transmitting rotational motion. |
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Velocity Ratio of Pulleys |
Number of input revolutions (input motion) ÷ Number of output revolutions (output motion) |
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What are Spur Gears? |
Have straight teeth cut parallel with the axis of rotation of the gear body. Used to connect shafts whose axis are parallel. |
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What are Bevel Gears? |
Used to transmit motion between shafts whose centre lines intersect. Used to transmit motion through an angle, usually 90 degrees |
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What is a Worm and Wheel Gear? |
The wheel gear is driven by a worm which resembles a large screw. Quiet operation and have a long life (used extensively as speed reducers) |
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What are Helical Gears? |
Helical Gears have teeth cut on a cylinder and at an angle with the axis of rotation of the gear body. Used where shafts do not intersect and quiet smooth operation is required.
Should be run in an oil bath due to contact action is sliding rather than rolling |
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What are Herringbone Gears? |
Herringbone Gears have helical teeth which diverge from the centre of the face toward the sides of the gear body.
Used where high speeds and high gear ratios are necessity. |
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What are Spiral Gears? (Spiral Bevel Gears) |
Spiral Gears have teeth cut on a conical surface so that they curve continuously toward or away from the apex of the cone upon which they are cut. |
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What are Hypoid Spiral Gears? |
The Hypoid Spiral Gear is the same as spiral gear but has the pinions offset from the crown wheel. This permits greater tooth contact. |
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Examples of Gears |
Car, Bike, Watch, Clock, Fan, Escalators, Shavers, Drills, etc. |
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What is an Idle Gear? |
An idle gear between the driver and the driven gear makes no difference to the gear ratio, but it changes the direction of rotation of the driven gear. |
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Velocity Ratio of Gears |
Revolutions of Driven Gear ÷ Revolutions of Driver Gear
or
Number of Teeth on Driven Gear ÷ Number of Teeth on Driver Gear |
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What is a Ratchet and Pawl? |
Useful if you want a shaft to turn only one way
The pawl allows the shaft to turn only one way |
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What is Linear Motion? |
Motion in a straight line |
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What is Reciprocating Motion? |
Linear motion going backwards and forwards |
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What is Rotary Motion? |
Motion that is circular |
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What is Oscillating Motion? |
Motion that is forward and backward in a circular arc |
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What is a 1st Class Lever? |
Has the fulcrum in the middle. (e.g. seesaw, scissors, wheel, single pulley system)
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What is a 2nd Class Lever? |
Has the load in the middle (e.g. wheelbarrow, nutcracker, wrench, door |
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What is a 3rd Class Lever? |
Has the effort in the middle (e.g. golf club, cricket bat, spoon, tweezers) |
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What is Torque? |
Torque is a rotational or twisting force that is influenced by the length of the arm that is being rotated, and the strength of the force acting on the arm |
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When Does Torque Increase? |
If you increase the length of the arm or the applied force , you increase the torque.
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Velocity Ratio for Wheel and Axle |
Radius of Wheel ÷ Radius of Axle
or
Diameter of Wheel ÷ Diameter of Axle |
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What is the Efficiency Formula? |
Output Energy ÷ x 100 Input Energy
or
Work done by Load ÷ x 100 Work done by Effort |
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Velocity Ratio of an Inclined Plane |
Length of Incline ÷ Height of Incline
or
d ÷ h |
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Velocity Ratio of a Scissor Jack |
Circumference of a circle made by effort ÷ Pitch of Screw |
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Velocity Ratio of a Compound Gear Train |
Product of no. of teeth of all driven wheels ÷ Product of no. of teeth of all driver wheels
(product = multiply ) |
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What is Inertia? |
The property of matter to resist a change in its state of rest or uniform motion. |
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What is Mass? |
A measure of the amount of matter in an object, depending upon; a) the type of atoms composing the substance, and b) the number of atoms |
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What is Force? |
A push or pull that tends to cause or prevent motion
Force = Mass x Acceleration (F=ma) |
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What is Weight? |
Measure of the gravitation force or pull acting on it
Weight = Mass x Acceleration due to gravity (W=mg) |
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What is Momentum? |
A vector quantity with the same direction as velocity (P=mv) |
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What is Static Friction? |
Frictional forces acting between surfaces at rest |
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What is Kinetic Friction? |
1. Sliding 2. Rolling 3. Fluid |
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Methods to Reduce Friction |
1. Using a smoother surface 2. Using lubrication 3. Substituting sliding friction for rolling friction 4. Using lighter materials |
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Power formula in a Hydraulic System |
Power = Work ÷ Time Taken |
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Pressure formula in a Hydraulic System |
Pressure = Force ÷ Area |
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What Types of Fluid Flow are there? |
1. Laminar 2. Turbulent |
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What is Laminar Fluid Flow? |
When a liquid is forced through a constant-diameter tube at low velocity the flow is smooth and even and the fluid's particles move in a parallel stream. The portion of liquid that touches the tube's walls is slowed because of friction.
This means the liquid near the centre moves at a higher velocity |
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What is Turbulent Fluid Flow? |
Resistance to a moving liquid is proportional to its velocity. When the velocity passes a critical point, the resistance increases until turbulent flow results
Derived from a sudden change in diameter of tube |
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When can Fluid Resistance Increase? |
1. Increase in the area of the tubes surface in contact with the liquid 2. An increase in the degree of roughness of the tube's interior surface 3. An increase in the viscosity of the liquid. |
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Difference between Pneumatics and Hydraulics |
In Pneumatics, the air does not circulate. While in Hydraulics, is moves the piston and then circulates back to the tank. |
