Mechanical Engineering And Sum Other Shit Flashcards
Name the 5 constraints.
- torsion
- compression
- tension
- deflection
- sheering
What is torsion?
The act of something being twisted
What is compression?
A forced being pushed from both sides of the object “Crushing” it ——>
What is tension?
Being stretched
What is deflection force?
To resist an impact being forced upon it
What is sheering?
The forcing of something tearing
Properties
What is ductility?
Ability to be drawn into a wire
Properties
What is malleability?
Ability to be shaped or flattened into a sheet
Properties
What is resilience?
Ability to resist impact
Properties
What’s is rigidity/stiffness?
Inability to be bent or forced out of shape
Properties
What is flexibility?
Will not keep its shape when subjected to a force
Properties
What is thermal conductivity?
Ability to allow heat to go through
Properties
What is electrical conductivity?
Ability to allow an electrical current to flow through
Properties
What is resistance to corrosion?
The ability to resist rusting
Ceramics
Name common properties of ceramics
Low electrical conductivity: used as insulators in electronics
Hardness: used in building materials(bricks) and for certain cutting tools
Heat resistance
Low thermal conductivity: used in ducts for fumes and water
Resistance to corrosion: used in engines
Ceramics
What causes ceramics to degrade?
Acids ( like sulphur) and bases ( like calcium hydroxide)
And variation in temperature degrade the properties of the material
Ceramics
What is used as a protection to protect ceramic from degradation?
There is no protection since practice are so durable
Plastics
What is a thermoplastic?
Plastics that can be heated and reshaped many times without losing its properties.
Plastics
What is thermosetting plastic?
Type of plastic that can only be heated and shaped once… otherwise if heated more than once it will lose its properties
Plastics
Which type of plastic is recyclable?
Thermoplastic(because they need to be heated and reshaped to be reused)
Plastics
Name 3 causes of degradation of plastics
- penetration by liquid
- Oxidation
- Ultraviolet rays
These causes makes the plastic crack and change its colour
Plastics
How can you protect plastics from degradation?
- Protection with a waterproof coating
- Adding antioxidants (fights against oxidation
- adding pigments that absorb UV rays
Links
What’s the difference between direct and indirect link?
Direct: two parts held together without a linking component
Indirect: two parts that need a linking component to hold them together
Links
What’s the difference between rigid and flexible?
Rigid: unable to bend or be forced out of shape
Flexible: linking component can be deformed(rubber,spring)
Links
What’s the difference between complete and partial?
Complete: the link prevents parts from moving independently from one another
Partial: link allows one part to move independently from the other.
Links
What’s the difference between removable and non removable?
Removable: parts can be separated without damaging them ( pen and cap)
Non removable: removing the link component will damage its parts
Guiding controls
Name three guiding controls
Translation
Rotational
Helical
Friction
What is adhesion?
Two surfaces remain in contact with each other without slipping
Friction
When friction is increased do you slip less or more?
Less
Friction
Name 5 ways to reduce friction
Lubrication Low temperature Smooth surface Lower the weight=less friction Sanding
Friction
Name 5 ways to increase friction
No lubrication
High temperature
Rougher surface=more friction
Higher the weight=more friction
Gears
What does it mean when a motion transmission or transformation system is réversible?
The driven can be the driver and it still functions
Gears
Any gear with teeth needs what to lower friction?
Lubrication
Gears
- The more teeth a gear has the_________ it will rotate
- The less teeth a gear has the_________it will rotate
- Slower
2. Faster
Motion transmission system
Name the 5 types of motion transmission systems.
- Gear trains
- Chain and sprocket
- worm and worm gear
- Friction gears
- Belt and pulley system
Motion transmission system
Which motion transmission system is irreversible?
Worm and worm gear system
Motion transmission system
What are some elements you need to consider when building a gear train?(4)
Gear teeth must be identical
Must have same shape
Be equally spaced
Contains at least 2 gears that mesh together
Ex eggbeater,watch
Motion transmission system
What is a chain a sprocket system?
Consists of at least 2 gears that do not mesh and are connected by a chain. This system is used to transmit motion between two or more distant parts
Motion transmission system
When building a chain and sprocket system what are some elements to consider when building the system?(4)
- teeth on sprocket must be identical
- the chain links must mesh with the sprocket teeth
- system requires frequent lubrication
- smaller the sprocket faster it turn
Motion transmission system
What is a belt and pulley system?
Similar to chain and sprocket system however the gears have NO teeth and are referred to as pulleys, they are connected by a belt.
Motion transmission system
What are elements needed to be considered when building a belt and pulley system?(3)
- pulleys must contain a groove where the belt can fit and the groove must be smooth
- the belt must adhere (stick) to the groove and not slip.
- the smaller the pulley the faster it turns
Motion transmission system
What’s a worm and worm gear system?
Consists of worm(screw) whose rotational motion is transmitted to one or more worm gears
Motion transmission system
What are some elements to consider when building a worm and worm gear system?(3)
- the groove of the worm must fit in the gear Teeth
- the driver must be the worm(screw)
- 1 rotation of the worm (screw)= gear moves 1 tooth a head
Motion transmission system
What is a friction gear system?
Similar to gear trains except that friction gears do not have teeth. Motion is transmitted by friction between the gears.
Motion transmission system
What are some elements to consider when building a friction gear system?(3)
- Type of rotational axes
- the larger the diameter=slower rotation
- made of material that will adhere( stick) to one another
Speed changes in a Motion transmission system
Explain the speed change in a worm and worm gear.
For each full turn of the worm(screw), the worm gear move a distance equal to the width of one tooth on the worm gear.
The greater the number of teeth on the worm gear=major decrease in speed
Speed change in motion transmission system
When the driver is bigger/has more teeth than the driven gear. What is the speed change?
Increase
Speed change in motion transmission system
When the driver gear is smaller/less teeth than the driven gear. What is the speed change?
Decrease
Speed change in motion transmission system
When the driver and driven have the same diameter/number of teeth. What is the speed change?
No change
What is the speed ratio?
Driver
——-
Driven
What is the difference between an mission transmission system and a motion transformation system?
Motion transmission: transfers same type of motion from one gear to another (rotational to rotational, translational to translational)
Motion transformation: When a motion from one gear is transformed into a different motion when in contact with another gear (translational to Rotational)
Motion transformation system
Name the 5 motion transformation systems.
- Rack an pinion
- Cam and follower
- Screw gear system 1
- Screw gear system 2
- Slider Crank
Motion transformation system
Which systems are irreversible?
- Screw gear system 1&2
- Cam and follower
Motion transformation system
What is a rack and pinion?
Contains at least one gear called a pinion and one straight bar called the rack
Motion transformation system
What are 3 elements to consider when building a rack and pinion system?
- teeth on rack and pinion must be identical
- system requires lubrication
- the greater the number of teeth on the pinion= slower its rotation
Motion transformation system
What’s the difference between screw gear system 1 & 2?
Both contain a screw and nut
Screw gear system 1:
- the screw is the driver
- it’s rotational motion is transformed into translational motion of the nut
Screw gear system 2:
- nut is driver
- it’s rotational motion is transformed into translational motion of the screw
Motion transformation system
What is the motion transformation of a Cam and follower?
The rotational motion of the Cam makes the follower have a translating motion
Motion transformation system
What are elements to be considered when building a Cam and follower system?(2)
- the follower must be guided in its translational motion
- a spring is needed to keep the follower in contact with the cam
Motion transformation system
What motion transformation does the slider crank endure?
The translational motion of the piston, makes the crank rotate causing the wheels to turn
Motion transformation system
What elements should be considered when building a slider crank mechanism?
- rod connects the piston to the crank
- the Cylinder must guide the slider
- need lubricantiom