Tribology Concepts Quiz
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Questions and Answers

What effect does an increase in viscosity have on the coefficient of friction?

  • It decreases the likelihood of solid surface contact.
  • It increases the coefficient of friction at higher speeds. (correct)
  • It has no effect on the coefficient of friction.
  • It decreases the coefficient of friction at all speeds.

In which lubrication regime does direct contact between solid surfaces occur?

  • Hydrodynamic lubrication
  • Boundary lubrication (correct)
  • Mixed lubrication
  • Full lubrication

What type of friction occurs when one object rolls on another?

  • Dynamic friction
  • Kinetic friction
  • Sliding friction
  • Rolling friction (correct)

What happens to the Stribeck curve when the load is increased?

<p>It increases and shifts up and to the right. (D)</p> Signup and view all the answers

Which application of nanotribology focuses on increasing machine efficiency and lifetime?

<p>Tribotronics (C)</p> Signup and view all the answers

Which field involves the modeling of tribological systems by integrating multiple disciplines?

<p>Computational Tribology (B)</p> Signup and view all the answers

Which lubrication regime is characterized by a wedge of lubricant film forming between sliding surfaces?

<p>Hydrodynamic lubrication (D)</p> Signup and view all the answers

What is the primary support for load in mixed lubrication?

<p>Both asperities and liquid lubricant. (C)</p> Signup and view all the answers

What kind of wear is characterized by a hard surface sliding over a softer surface?

<p>Abrasive wear (D)</p> Signup and view all the answers

Which phenomenon does space tribology specifically examine?

<p>Tribological systems in harsh environments (B)</p> Signup and view all the answers

What method is used to study the deformation of solids that touch each other at one or more points?

<p>Contact mechanics (C)</p> Signup and view all the answers

Which of the following describes kinetic friction?

<p>Friction between two objects sliding against each other (C)</p> Signup and view all the answers

What is the primary tool that has advanced nanotribology research?

<p>Atomic Force Microscopy (A)</p> Signup and view all the answers

What did Leonardo da Vinci contribute to the understanding of tribology?

<p>Observed how to reduce friction using lubricant (C)</p> Signup and view all the answers

Which of the following is a law formulated by Guillaume Amontons?

<p>The relationship between frictional force and applied load (B)</p> Signup and view all the answers

What was one of the technological advancements introduced in 1794 that impacted tribology?

<p>The invention of the ball bearing (D)</p> Signup and view all the answers

Who coined the term 'tribology' and when?

<p>Peter Jost in 1966 (C)</p> Signup and view all the answers

What does the Stribeck curve illustrate?

<p>The lubrication regimes and lubricant properties (C)</p> Signup and view all the answers

Which of the following is NOT an application of tribology?

<p>Psychological behavior in consumers (C)</p> Signup and view all the answers

Which field within tribology deals specifically with traditional friction concepts?

<p>Classical tribology (D)</p> Signup and view all the answers

What aspect of tribology can be vital for the design and manufacturing processes?

<p>Material compatibility and surface roughness (C)</p> Signup and view all the answers

What property of lubricating oil is evaluated by the flash point?

<p>Its fire resistance (D)</p> Signup and view all the answers

What is the significance of a high fire point in lubricating oil?

<p>It prevents the lubricant from igniting easily (A)</p> Signup and view all the answers

Which of the following is NOT a factor affecting the viscosity of lubricating oil?

<p>Color of the oil (C)</p> Signup and view all the answers

Which organization is responsible for the viscosity classification of lubricating oils?

<p>Society of Automotive Engineers (SAE) (B)</p> Signup and view all the answers

What can higher impurities in lubricating oil lead to?

<p>Formation of sludge and varnish (D)</p> Signup and view all the answers

How does temperature affect the viscosity of lubricating oil?

<p>Higher temperatures typically reduce viscosity (D)</p> Signup and view all the answers

What does sludge formation in lubricating oil indicate?

<p>Presence of aromatics (C)</p> Signup and view all the answers

Which of the following statements about the fire point is correct?

<p>It is the temperature at which oil burns continuously (C)</p> Signup and view all the answers

What does Classical Tribology primarily focus on?

<p>Friction and wear in machine elements (A)</p> Signup and view all the answers

Which classification system was established by the International Organization for Standardization in 1921?

<p>ISO viscosity classification system (C)</p> Signup and view all the answers

What is a primary characteristic of Biotribology?

<p>Focus on lubrication in biological systems (C)</p> Signup and view all the answers

What does Open System Tribology examine?

<p>Systems affected by the natural environment (D)</p> Signup and view all the answers

Which of the following best describes Green Tribology?

<p>It emphasizes reducing environmental impact of tribological losses (B)</p> Signup and view all the answers

What is Geotribology primarily concerned with?

<p>Friction and wear in geological systems (A)</p> Signup and view all the answers

What is the definition of static friction?

<p>Friction acting when two objects are not moving relative to each other (D)</p> Signup and view all the answers

What material is often used in total hip replacements within Biotribology?

<p>Stainless steel or cobalt-chromium alloy (B)</p> Signup and view all the answers

What is the term for the lowest temperature at which a lubricant will flow as a liquid?

<p>Pour Point (C)</p> Signup and view all the answers

Which property of a lubricant indicates its ability to resist decomposition due to temperature changes?

<p>Thermal Stability (A)</p> Signup and view all the answers

What property of a lubricant is essential for its performance in wet environments such as marine applications?

<p>Demulsibility (B)</p> Signup and view all the answers

When does friction increase between two surfaces in contact?

<p>When the surfaces are rough (D)</p> Signup and view all the answers

What happens to a lubricating oil when mixed with water?

<p>Loses lubricating properties (C)</p> Signup and view all the answers

What is the primary cause of corrosion that lubricants are designed to prevent?

<p>Moisture exposure (D)</p> Signup and view all the answers

Which point is higher, the fire point or the flash point of a lubricant?

<p>Fire point is higher (B)</p> Signup and view all the answers

What describes the condition when oil starts to solidify and appears cloudy?

<p>Cloud Point (A)</p> Signup and view all the answers

Flashcards

Tribology

The science that studies friction, wear, and lubrication in interacting surfaces.

Amontons' Laws of Friction

Empirical laws that relate friction force to contact pressure and the area of contact.

Stribeck Curve

A graphical representation showing the relationship between friction, lubrication regime, and lubricant properties.

Lubricant Layer

A lubricant layer between moving surfaces, reducing friction.

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Boundary Lubrication

A lubrication regime where the surfaces are mostly in direct contact, with little or no lubricant film.

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Mixed Lubrication

A lubrication regime where a combination of fluid film lubrication and boundary lubrication occurs.

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Hydrodynamic Lubrication

A lubrication regime where a thick film of lubricant separates the surfaces, minimizing direct contact.

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Wear

The process of removing material from a surface through contact with another surface.

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Abrasive Wear

Occurs when a hard surface scrapes against a softer surface, removing material.

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Nanotribology

The study of friction, wear, and lubrication between surfaces in contact, especially at the nanoscale.

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Tribotronics

A field combining mechanical elements and electronic components to create active tribological systems.

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Computational Tribology

Deals with simulating the behavior of tribological systems using computer models.

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Space Tribology

The ability of a system to operate under harsh space environments.

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Rolling Friction

Occurs when two objects move relative to each other and one rolls on the other, like a car wheel on the ground.

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Sliding Friction

Occurs when two objects move relative to each other and rub against each other, like a book sliding on a table.

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Kinetic Friction

Occurs when two objects rub against each other, like a person sliding down a slide.

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Biotribology

A discipline that studies friction, wear, and lubrication in biological systems, such as human joints.

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Friction

A force that opposes motion when two surfaces come into contact.

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Static Friction

A type of friction that acts on stationary objects, preventing them from moving.

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Green Tribology

A sub-discipline of tribology that aims to minimize the environmental impact of tribological systems.

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Geotribology

A sub-discipline of tribology that investigates friction, wear, and lubrication in geological systems, such as faults and glaciers.

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Open System Tribology

A sub-discipline of tribology that studies tribological systems that interact with the natural environment.

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Classical Tribology

The study of friction, wear, and lubrication in machine elements such as bearings, gears, and brakes.

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Surface Roughness Effect on Stribeck Curve

The increase in surface roughness pushes the Stribeck curve up and to the right, requiring higher speeds to achieve hydrodynamic lubrication.

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Load Effect on Stribeck Curve

Increased load pushes the Stribeck curve up and to the right, increasing friction. This means more force is needed to overcome friction.

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Pour Point

The lowest temperature at which a lubricant will flow as a liquid. This property is important for determining if a lubricant is suitable for cold climates.

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Flash Point

The temperature at which a liquid gives off enough vapors to ignite in the presence of a flame.

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Thermal Stability

The ability of a lubricant to resist decomposition when exposed to temperature changes. This property helps predict how a lubricant will change physically and chemically in varying temperatures.

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Demulsibility

The ability of a lubricant to separate water from the liquid. This property is important in applications where the hydraulic system is exposed to water, such as marine environments or construction sites.

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Emulsification

Describes the tendency of a lubricating oil to form an emulsion (mixture) with water, which can compromise its lubrication properties.

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Corrosion Prevention

The ability of a lubricant to prevent corrosion, which can be a costly issue for companies.

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What causes friction?

The force that opposes motion when two surfaces come into contact.

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Friction - Molecular Adhesion

Molecular adhesion, or asperities (small bumps on surfaces) sticking together when surfaces touch. Electromagnetic forces between molecules and atoms on both surfaces cause them to attract each other.

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Fire Point

The lowest temperature at which a lubricant will sustain continuous burning after ignition. It signifies the oil's ability to resist burning in operation, ensuring safe use.

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Viscosity Classification

A classification system for lubricants based on their viscosity, which measures their resistance to flow. It ensures the right lubricant for specific operating conditions and machine requirements.

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API Base Oil Categories

The American Petroleum Institute (API) categorizes base oils based on their quality and characteristics. This classification helps select the right base oil for various lubrication applications.

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Viscosity Index

The ability of a lubricant to resist changes in viscosity over a range of temperatures. A high viscosity index indicates better performance at varying temperatures, ensuring proper lubrication across different conditions.

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Speed and Load Effects on Viscosity

The effect of speed and load on a lubricant's viscosity. Higher speeds and loads can increase viscosity, impacting lubrication performance.

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Lubricant Selection

The process of selecting the right lubricant for a specific application based on various factors like viscosity, temperature, and load. It ensures optimal lubrication performance and machine longevity.

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Study Notes

Lesson 1: Tribology

  • Tribology is the study of friction, lubrication, and wear.
  • The term "tribology" was coined in 1966.
  • Early civilizations understood and used tribology principles (e.g., lubrication, surface materials).
  • Leonardo da Vinci observed friction and lubrication.
  • Guillaume Amontons formulated laws of friction.
  • The invention of ball bearings revolutionized machinery.
  • The Stribeck curve represents the relationship between friction, lubrication, and lubricant properties.
  • ISO established a viscosity classification system for lubricants.
  • Elastohydrodynamic lubrication (EHL) describes lubrication in heavily loaded contacts.
  • Superlubricity was discovered, where friction is practically non-existent between smooth surfaces.
  • Advanced surface coatings (e.g., diamond-like carbon) and surface treatments significantly reduce friction and wear.
  • Computational tribology uses simulations to model tribological systems.
  • Tribological considerations are important in the design and use of components that come in contact.
  • Applications include individual components, assemblies, manufacturing, construction, and natural phenomena.
  • Classical Tribology focuses on friction and wear in machine elements, like bearings and gears, and manufacturing processes.

Lesson 2: Lubricants

  • Lubrication is a process to reduce wear by adding a substance (lubricant) between moving surfaces.
  • Lubricants can be liquid, solid, or gaseous.
  • Examples of lubricants include mineral oil, vegetable oil, animal oil, graphite, molybdenum disulfide, grease, air, and nitrogen.
  • Lubricants reduce wear and corrosion, control temperature, and provide a fluid seal.
  • Petroleum is a hydrocarbon chain, with differing boiling points based on chain length.
  • Petroleum and natural gas form from marine microorganisms.

Lesson 3: Properties of Lubricants

  • Viscosity measures a fluid's resistance to flow.
  • Viscosity decreases with temperature increase in liquids, and increases with temperature increase in gases.
  • Viscosity index is a parameter for lubricants that shows sensitivity to temperature fluctuations.
  • Flash point is the temperature at which a lubricant ignites.
  • Fire point is the temperature where a lubricant continuously burns.

Lesson 4: Friction in the Engine

  • Friction is the resistance to motion when surfaces contact.
  • Friction affected by surface smoothness and applied force.
  • Friction is often undesirable, causing energy loss and wear.
  • Molecular adhesion and surface roughness contribute to friction.
  • Ploughing occurs when a hard material moves across a soft one.
  • Lubrication reduces friction.

Advantages and Disadvantages of Friction:

  • Friction is considered undesirable due to energy loss, wear, and heat generation.
  • However, friction is also essential for functions like walking, gripping objects, and engine operation.
  • Reducing friction is a primary goal in many engineering applications.

Total Engine Friction:

  • Total engine friction is the difference between brake horsepower and indicated horsepower.

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Tribology: Friction, Lubrication, and Wear (PDF)

Description

Test your knowledge on the principles of tribology, including viscosity effects, types of friction, and lubrication regimes. This quiz covers key concepts such as the Stribeck curve and applications of nanotribology. Perfect for students and professionals alike looking to reinforce their understanding of tribological systems.

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