Structural Properties Flashcards
Name the 4 Material Families
Metals & Alloys, Ceramics, Polymers and Glasses
Name the Properties of the Metal and Alloys Family
Metallic Bonding, Crystalline, Conducting, Ductile
Name the Properties of the Ceramic Family
Ionic or Strong Covalent Bonding, Crystalline, Insulating or Semi-Conducters
Name the Properties of the Polymer Family
Covalent Bonding, Non or Semi-crystalline, Mostly Insulating, Brittle or Plastic
Name the Properties of the Glass Family
Covalent Bonding, Non-Crystalline, Insulating, Brittle
Name the 9 Structural Properties found in materials
Stiffness, Strength, Hardness, Ductility, Fracture Toughness, Wear Resistance, Environmental Resistance, Thermal Expansion and Thermal Shock Resistance
What behavior do brittle materials exhibit before fracture
Purely Elastic
What is meant by Elastic Behaviour
When all Strain is recovered when the stress on the material is unloaded
The Elastic Gradient is also known as?
Youngs Modulus
What behavior is exhibited on Ductile Materials under tension?
Up to the elastic Limit = Deformation is reversible & Linear
After Elastic Limit = Deformationn id permanent and non-Linear
What is the transition point between elastic and plastic deformation known as?
The Yield Strength
What is the Ultimate Tensile Strength (UTS)?
The measure of maximum stress a material can take before its deformation/fracture point
How is Ductility Measured?
Ductility = Yield Strain - Strain Fracture
What is Ductility
How much a material can withstand plastic deformation under tensile stress before failure
How is the Young’s Modulus Determined
Taking a gradient of a Stress/Strain curve up to certain stress to determine E
What is the Elastic Modulus
Strength of bonds between atoms and ions
What is repulsion
When Atoms are compressed together
What is Attraction
When Atoms are Pulled from each other
What is Hardness
The ability of a material being able to resist scratching or Indentation
In Ductile Materials what does the Hardness Correlate to?
Tensile Strength
What is the Vickers Hardness Number Equation?
0.1891 F/D^2 (N/mm^2)
How is the Vickers Hardness Number Test carried out?
Using a Diamond Indenter with an Apex angle of 136 degrees, force is applied onto a specimen and the specimen is measure and put into the equation.
What is Toughness
Ability to absorb energy during deformation
On the Stress-Strain graph, where is the energy per unit volume stored?
Under the Elastic Deformation Area
On the Stress-Strain graph, where is the energy per unit volume dissipated?
Under the Plastic Deformation Area
What is the Stored Elastic Equation?
Uelastic = 1/2 x Stress x Strain
Or
Uelastic=1/2 x Youngs Modulus x Strain^2
What is The Toughness Equation?
Integral of the Stress with the fracture strain as the max and 0 as the min
What test is done to compare toughness and how?
Charpy Impact Test, Materials with a machined notch, that is broken by the swing of a pendulum hammer.
What is the fracture transition called when temperatures change that apply to only some materials
Ductile to Brittle Transition
What is the Stress Intensity Factor?
Stress intensity factors K tell us how much the effective stress is increased at the tip of a crack or initiation site.
What are the 3 criteria needed to measure a Stress Intensity Factor?
1) Crack Opening Mode (Opening, In-plane Shear or Outplane Shear)
2) Crack Geometry
3) Material/Specimen Geometry
What is Critical Stress Intensity Factor
The value at which the specimen is fully fractured due to the propagation of the crack.
What is Fatigue
Damage was done to material by cyclic loading
what does a material with High Cycle Fatigue mean?
A High Frequency
Low-Stress Amplitude
Elastic Deformation
Large No Cycles before failure
what does a material with Low Cycle Fatigue mean?
A Low Frequency
High-Stress Amplitude
Some Plasticity
Low No Cycles before failure
What is a crack that does not lead to fracture called
Sub-Critical
What is Creep?
Material loaded with elastic limits exhibits plastic deformation over a long period of time.
When does Creep become problematic?
At Higher Tempartures
What are the 5 Stages of Creep?
Incubation Period Primary Creep Secondary Creep Tertiary Creep Failure
During the Incubation stage of creep, what happens?
No Measurable Deformation Happens, Not all materials have an incubation period
During the Primary stage of creep, what happens?
Defect Density Increases at a high rate, rate decreases when dislocation entangles
During the Secondary stage of creep, what happens?
Entanglement is equal to the generation and increases at a steady rate over a long period
During the Tertiary stage of creep, what happens?
Voids begin to form and the growth rate increases proportionally
During the Failure stage of creep, what happens?
Unable to Deform any further and the Material Breaks
