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Questions and Answers
What is the primary effect of torsion on a material?
What is the primary effect of torsion on a material?
Which of the following materials is likely to have high electrical conductivity and be heavy?
Which of the following materials is likely to have high electrical conductivity and be heavy?
What is the primary function of a linking component in a technical object?
What is the primary function of a linking component in a technical object?
What is the term for the ability of a material to be drawn into a thin shape without breaking?
What is the term for the ability of a material to be drawn into a thin shape without breaking?
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What is the term for the process of wear and tear on a metal due to chemical reactions?
What is the term for the process of wear and tear on a metal due to chemical reactions?
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Which of the following mechanical functions is responsible for controlling the motion of one or more moving parts?
Which of the following mechanical functions is responsible for controlling the motion of one or more moving parts?
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What is the term for the ability of a material to return to its original shape after deformation?
What is the term for the ability of a material to return to its original shape after deformation?
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What is the term for a system in which the driven component can become the driver and vice versa?
What is the term for a system in which the driven component can become the driver and vice versa?
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What is the term for the mechanical function that connects two or more parts of a technical object using a flexible component?
What is the term for the mechanical function that connects two or more parts of a technical object using a flexible component?
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What is the term for the mechanical function that transforms rotational motion into translational motion?
What is the term for the mechanical function that transforms rotational motion into translational motion?
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Study Notes
Mechanical Constraints
- There are five principal mechanical constraints: flexion, tension, torsion, compression, and shearing
- Flexion: bending stress, where an object is deformed by a force that is applied perpendicularly to its surface
- Tension: stretching stress, where an object is deformed by a force that is applied along its length
- Torsion: twisting stress, where an object is deformed by a force that is applied to rotate it around its axis
- Compression: squeezing stress, where an object is deformed by a force that is applied to reduce its size
- Shearing: sliding stress, where an object is deformed by a force that is applied parallel to its surface
Effects of Mechanical Constraints on Materials
- Elastic deformation: temporary deformation that returns to original shape when force is removed
- Plastic deformation: permanent deformation that does not return to original shape when force is removed
- Fracture: breaking of material due to excessive stress
Mechanical Properties
- Hardness: resistance to scratching or abrasion
- Stiffness: resistance to bending or deformation
- Tensile strength/rigidity: maximum stress that a material can withstand without breaking
- Elasticity: ability of a material to return to its original shape after deformation
- Ductility: ability of a material to be stretched or drawn without breaking
- Malleability: ability of a material to be shaped or molded without breaking
Metals, Alloys, and Plastics
- Pure metal: an element that is not combined with other elements
- Alloy: a combination of two or more elements, at least one of which is a metal
- Corrosion: a chemical reaction that breaks down a material, often due to exposure to air or water
- Metals have high electrical and thermal conductivity
- Examples of alloys: steel, bronze, brass
- Ferrous alloys: contain iron, e.g., steel
- Non-ferrous alloys: do not contain iron, e.g., bronze, brass
- Plastics: materials made from synthetic or natural organic polymers
- Thermoset plastics: cannot be melted and reformed, e.g., bakelite
- Thermoplastics: can be melted and reformed, e.g., polyethylene
Basic Mechanical Functions
- Definition: the role played by a component or group of components inside a technical object
- Guiding: controls the motion of one or more moving parts
- Rotational: guides rotational motion, e.g., bearings
- Translational: guides linear motion, e.g., rail guides
- Helical: guides helical motion, e.g., screw threads
- Linking: connects two or more parts of a technical object
- Direct: connects parts directly, e.g., welding
- Indirect: connects parts through an intermediate component, e.g., bolts
- Removable: can be disconnected, e.g., snap fits
- Non-removable: cannot be disconnected, e.g., rivets
- Rigid: does not deform, e.g., rigid frames
- Elastic: deforms and returns to original shape, e.g., springs
- Complete: connects all parts of a technical object, e.g., a complete linkage
- Partial: connects only some parts of a technical object, e.g., a partial linkage
Complex Mechanical Functions
- Comprises multiple components that work together
- Driver: the component that provides the power or motion
- Driven component: the component that receives the power or motion
- Intermediate: the component that transmits the power or motion from the driver to the driven component
- Motion transmission: systems that transmit motion from one component to another
- Friction gear system: uses friction to transmit motion
- Belt and pulley system: uses a belt and pulleys to transmit motion
- Gear trains: uses gears to transmit motion
- Chain and sprocket: uses a chain and sprockets to transmit motion
- Worm and worm gears: uses a worm gear to transmit motion
- Motion transformation: systems that change the type of motion
- Slider-crank: converts rotary motion to linear motion, e.g., pistons
- Cam and follower: converts rotary motion to linear motion, e.g., camshafts
- Rack and pinion: converts rotary motion to linear motion, e.g., steering systems
- Screw gear: converts rotary motion to linear motion, e.g., screw jacks
- System reversibility: when the driven component can become the driver and vice versa
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Description
Test your knowledge of the five principal mechanical constraints, their effects on materials, and the mechanical properties of metals, alloys, and plastics. Learn about elastic deformation, plastic deformation, fracture, and more.
