MSE 250 Final Review Questions With
Verified Answers
What types of materials are there? - Answers✔Metals
Ceramics
Polymers
Composites
Advanced Materials
Properties of Metals - Answers✔Metallic Bonding-composed of one or more metallic elements
Strong, stiff, ductile, resistant to fracture
High thermal and electrical conductivity
opaque, reflective
atoms arranged in orderly manner
Properties of Ceramics - Answers✔Ionic bonding-compounds of metallic and non-metallic
elements (oxides, carbides, nitrides, sulfides)
Stiff, strong, but brittle
Non-conducting (insulators)
Often chemically inert
Atoms arranged in orderly manner
Properties of Polymers - Answers✔Covalent bonding sharing of electrons composed of chain
molecules often with carbon backbone
Soft, ductile, low strength, low density
Thermal and electrical insulators
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optically translucent or transparent
long-chain molecules; only partially ordered
Properties of Composites - Answers✔Combination of two or more classes of materials
typically fused at microscopic scale
Combination of properties
-natural composites (wood and bone)
-Synthetic composites (human-made)
Advanced Materials - Answers✔material with enhanced properties
typically for high-tech applications
semiconductors
biomaterials
smart materials
nanomaterials
List the materials from highest to lowest densities - Answers✔Metals
Ceramics
Polymers
Composites
List the materials from highest to lowest resistance to fracture - Answers✔Metals
Composites
Ceramics
Polymers
List the design properties of materials - Answers✔Strength
Ductility
Stiffness
Toughness
Hardness
Hooke's Law
What is G? - Answers✔E=Young's modulus/modulus of elasticity, comes from the slope of the
graph
G=shear modulus
What are the 'characteristics' of Hooke's Law? - Answers✔Elastic
Reversible
Time independent
Notes of Poisson's Ratio - Answers✔Indicates a volume change during elastic deformation
Perfect, incompressible material, small elastic strains only (no volume change) v=.5
Most metals and alloys .25<v<.35
most metals and alloys 0.25<v<.35
v, E, G are called elastic constants
What is the equation that relates Elasticity, Shear and Poisson's ratio? - Answers✔E=2G(1+v)
Stress and Strain - Answers✔Geometry independent measures of load and displacement
Elastic Behavior - Answers✔Reversible displacement upon loading usually time-independent,
linear relationship between stress and strain. Described by Hooke's Law
Young's modulus - Answers✔Slope of the linear part of the stress-strain curve. Material's
Constant, measure of stiffness.
Poisson's ratio - Answers✔Relation between axial and lateral strain
Proportional Limit/ Elastic Limit - Answers✔Stress and strain values at the end of the linear-
elastic region
Point on stress strain curve where the slope of Young's modulus ends and the curve begins
Yield strength - Answers✔Stress at plastic strain offset of 0.002
The yield point is offset by .002 and is parallel to Young's modulus on the stress strain curve
Tensile Strength - Answers✔Maximum stress of the engineering stress-strain curve
The highest point on the stress and strain curve
Ductility on Stress Strain Graph - Answers✔Measure of degree of plastic deformation, that has
been sustained at fracture
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The last point on the graph, usually in a percentage
Ductility - Answers✔Plastic Strain at fracture
Additional data that can be gained from a stress-strain curve - Answers✔Amount of energy that
can be stored in a material
elastic: resilience
elastic and plastic: toughness
Modulus of Resilience Ur - Answers✔Energy absorbed per volume to yield point
Assumption: linear stress-strain-curve
Fracture Toughness - Answers✔ability of a material to resist fracture when a crack was present
Toughness - Answers✔Energy Stored in material per volume up to fracture
What is tougher a ductile material or a brittle one? - Answers✔Ductile because it does not break
as easily
Ductile materials have a smaller slope of modulus elasticity compared to brittle materials
Hardness - Answers✔Definition: resistance to localized plastic deformation, resistance to
denting, scratching, abrasion, cutting
Types of Hardness Measurement - Answers✔Rockwell (macroscopic)
Vickers (microscopic)
Rockwell Hardness Test - Answers✔A "macroscopic" and qualitative measure of the bulk
material
Inconsistent for materials that are multi-phase, non-homogenous or prone to cracking
Measurement scale depends on the applied load and indenter type
Vickers Hardness Micro-indentation Hardness Test - Answers✔A "microscopic" and quantitative
measure of a small area in the material
Small loads applied to a 10^-6 sized areas provide a measure of non-homogeneity
A well-polished surface is needed for accurate measure
one scale and indenter cover the entire measurement range
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