DM308: Week 1 Hard

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Questions and Answers

What are the three main principles central to the discipline of materials science and engineering?

The three main principles are: How structure of materials controls their properties, how processing determines the material structure, and how properties determine performance in a given application.

What is the purpose of a Wheatstone bridge in measuring strain?

The Wheatstone bridge offers a possible solution for measuring strain electrically.

What is the modulus that is always positive, and what is the stress at which a material fractures known as?

The modulus E is always positive, and the stress at which the material fractures is known as the tensile, compressive, or shear strength depending on the deformation mode.

What method is used for measuring local strain in complex parts without physical contact with the material surface?

Digital image correlation (DIC) is used for measuring local strain without physical contact with the material surface. Signup and view all the answers

What are the two types of composites discussed in the text, and how are they typically reinforced?

The two types of composites are metal matrix composites (MMCs) and polymer matrix composites (PMCs). They are typically reinforced with ceramics. Signup and view all the answers

What is the purpose of stress-strain testing, and what does it help determine about a material?

Stress-strain testing helps determine the relationship between stress and strain in a material, and it helps determine material properties such as stiffness, strength, and ductility. Signup and view all the answers

What are the key structural properties of materials, and how do they influence material behavior?

The key structural properties are stiffness, strength, hardness, ductility, fracture toughness, wear resistance, and environmental resistance. These properties influence how materials respond to different external forces and environments. Signup and view all the answers

What are the main principles of materials science and engineering, and why are they important?

The main principles are understanding the structure of materials, how processing affects material structure, and how properties determine performance. They are important for developing new materials and ensuring their optimal performance in applications. Signup and view all the answers

What are the main material properties that engineers have less control over, and why is it important to understand them?

Engineers have less control over density, cost, scarcity, and toxicity of materials. It is important to understand them as they impact material selection, manufacturing, and sustainability. Signup and view all the answers

Why is the measurement of local strain important in materials engineering, and what method is used for this purpose?

The measurement of local strain is important for understanding how strain is distributed in complex parts. Digital image correlation (DIC) is used for this purpose, providing a contactless method for strain measurement. Signup and view all the answers

What are the main material families discussed in materials engineering, and how do they differ in terms of behavior and bonding?

The main material families are metals and alloys, ceramics, glasses, polymers, composite materials, and natural composites. They differ in behaviour and bonding. Signup and view all the answers

What is the Paris’ law model used to predict?

Sub-critical crack growth rate Signup and view all the answers

What are the two constants in Paris’ law model dependent on?

Properties of the material, environment, and stress ratio Signup and view all the answers

What is the incubation period in the stages of creep characterized by?

No measurable deformation Signup and view all the answers

What is the primary creep stage characterized by?

An initially high rate of deformation Signup and view all the answers

What happens in the secondary creep stage?

A steady deformation rate is observed Signup and view all the answers

When does the tertiary creep stage occur?

When the material reaches a certain level of plastic deformation Signup and view all the answers

What is the final stage of creep characterized by?

Failure Signup and view all the answers

What does the extent of plasticity in a material depend on?

Strain rate Signup and view all the answers

What is an important aspect of materials design and selection?

Operating environment consideration Signup and view all the answers

What are the three factors to consider regarding the operating environment when selecting materials?

Chemical reactivity, temperature effects, sudden changes Signup and view all the answers

What are the categories of material properties mentioned in the text?

Structural or Functional Signup and view all the answers

What do fatigue properties become important for?

Cyclic loading Signup and view all the answers

What is the transition stress between elastic and plastic behavior known as?

Yield strength Signup and view all the answers

What is the maximum stress sustained by the material known as?

Ultimate Tensile Strength Signup and view all the answers

What is the relationship between elastic modulus and the strength of the bonds between atoms in a material?

Elastic modulus is related to the strength of the bonds between atoms/ions in a material. Signup and view all the answers

What does the Vickers Hardness Test measure?

The Vickers Hardness Test measures the ability of a material to resist scratching or indentation. Signup and view all the answers

What is the ability of a material to absorb energy during deformation known as?

Toughness Signup and view all the answers

What is the abbreviation for the temperature at which some materials undergo a ductile-to-brittle transition?

DBTT (Ductile-to-Brittle Transition Temperature) Signup and view all the answers

What caused the catastrophic hull tear during the iceberg collision of the Titanic?

The low-grade iron rivets in the bow of the ship became brittle in the icy waters of the Atlantic. Signup and view all the answers

What caused the mid-ocean breaking apart of the Liberty ships during WW2?

The welded hulls underwent a ductile-brittle transition at low temperatures. Signup and view all the answers

What is fatigue in materials caused by?

Fatigue is the damage done to a material by a cyclic load. Signup and view all the answers

What does the S-N curve show?

The S-N curve shows how the number of cycles to failure changes with the stress amplitude. Signup and view all the answers

What is High Cycle Fatigue (HCF) characterized by?

HCF is characterized by high frequency, low stress amplitude, elastic deformation, and large number of cycles to failure. Signup and view all the answers

What is Low Cycle Fatigue (LCF) characterized by?

LCF is characterized by low frequency, high stress amplitude, some plasticity, and a low number of cycles to failure. Signup and view all the answers

List the characteristics of Metals and Alloys

metallic bonding • crystalline • conducting • mostly break in a ductile manner Signup and view all the answers

List the characteristics of Ceramics

ionic or strong covalent bonding • crystalline • insulating or semi-conducting • break in a brittle manner Signup and view all the answers

List the characteristics of Polymers

covalent bonding • non or partly-crystalline • mostly insulating • can be brittle or plastic Signup and view all the answers

List the characteristics of Glasses

covalent bonding • non-crystalline • insulating • break in a brittle manner Signup and view all the answers

List the characteristics of Metal matrix composites

Matrix is ductile • Matrix is strong in tension • Typically reinforced with ceramics • Electrically conducting Signup and view all the answers

List the characteristics of Ceramic matrix composites

Matrix is hard and wear resistant • Matrix has thermal resistance • Reinforced with ceramics/metals Signup and view all the answers

List the characteristics of Polymer matrix composites

Matrix is very tough • Matrix can have low density • Typically reinforced with ceramics Signup and view all the answers

List the characteristics of Natural composites

Derived from evolution • Typically PMCs • Parts of plants and animals • The original engineering materials Signup and view all the answers

Study Notes

Dr. Vassili Vorontsov is lecturing in DM308 Production Techniques 2 at the University of Strathclyde in the Department of Design, Manufacture and Engineering management.
The lecture series covers topics such as: structural properties of materials, crystals, defects and interfaces, phases and microstructures, properties and processing of ceramics, glasses, light alloys, high-temperature alloys, and composites.
The course includes texts and books as resources: "Materials science and engineering" by Callister, "Engineering materials" by Ashby and Jones, "Materials: Engineering, Science, Processing and Design" by Ashby and Shercliff, "Introduction to dislocations" by Hull and Bacon, "Phase transformations in metals and alloys" by Porter and Easterling, "Light alloys" by Polmear, "Superalloys" by Reed, and "Introduction to composite materials" by Clyne and Hull.
Course assessment includes a written exam, two pieces of coursework, and the opportunity for online, open-book exams during the social distancing period.
The coursework will take the form of either essays or group presentations, with a topic different from the exam.
The lecture covers the basics of materials engineering, including the importance of understanding the relationship between a material's structure, processing, and performance.
Material engineering is concerned with the development of new materials through a holistic understanding of their behavior.
Materials are categorized based on their bonding, structure, and behavior, including metals and alloys, ceramics, glasses, polymers, and composite materials.
Engineers have less control over certain material properties like density, cost, scarcity, and toxicity, but they can control structural properties for specific applications.
Relevant material properties include stiffness, strength, hardness, ductility, fracture toughness, wear resistance, environmental resistance, and thermal expansion.
Hooke's law is a fundamental concept in materials engineering, describing the relationship between stress and strain.
Stress is the force per unit area applied to a material, while strain is the material's extension or deformation.
Stress and strain can be measured using methods like the Wheatstone bridge circuit or digital image correlation (DIC).
There are three main types of stress: tension, compression, and shear. The stress-strain behavior differs for brittle and ductile materials.
The Young's modulus is the measure of a material's elasticity and is related to the strength of the bonds between the atoms in a material.
Hardness is a measure of a material's resistance to scratching or indentation, and it correlates with the tensile yield strength.
The Charpy impact test is a method for determining the fracture toughness of materials.
Finite element analysis (FEA) is used to investigate stresses within complex components and assemblies using the 3D description of Hooke's law.

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Description

Test your knowledge of mechanical properties of materials with this quiz. Explore concepts such as yield strength, ultimate tensile strength, and stress vs. strain curves.