Metals and Alloys Flashcards
What must be considered when selecting materials for design?
-Mechanical properties
-Raw material cost
-Transportation costs
-Maintenance costs
Aesthetic factors
What mechanical properties must be considered when selecting materials for design?
-Material stiffness (Young’s modulus)
-Resistance to plastic deformation (yield strength)
-Ductility
Name some physical properties of materials.
-Density
-Mass
-Melting and boiling points
-Electrical and thermal conductivity
Name two examples of mechanical property.
Elastic response (stiffness) and plastic flow (yield stress)
What determines the ability for a material to resist deformation?
Internal structure
For metals and alloys, describe the constitutive relation.
Stress will be a function of strain and material microstructure
What experimental methods can be used to determine microstructure characterisation?
-Optical microscopy
-Scanning electron microscopy
-Transmission electron microscopy
What experimental methods can be used to determine mechanical characterisation?
-Tensile/compressive test (Uniaxial loading)
-Fatigue test (Cyclic loading)
Creep test (time dependent behaviour)
What computational material modelling methods can be used to derive structure-property relations?
-Physics-bases, phenomenological or empirical methods
-Simulate process induced microstructures
-Simulate mechanical properties
What does a tensile test provide?
An experiment approach to studying basic material behaviour
What assumptions are made during a tensile test?
Loading is pure axial and the deformation takes place uniformly, both along the length and cross section of the specimen
How is a tensile test carried out?
By moving one end of the specimen at constant speed, while holding the other end fixed
What are the primary variables recorded during a tensile test?
Load (F) and extension (L)
What is required to determine true stress?
Knowledge of the instantaneous area at all times during deformation
What determines plastic deformation?
When stresses exceed the yield stress
What determines elastic behaviour?
Total strain is entirely recoverable - total strain is equal to the elastic strain
What is plastic strain?
A function of the stress on unloading
In the stress tensor matrix, which components are considered to represent normal stress?
Sigma_11, Sigma_22, Sigma_33
What components are present in the hydrostatic stress tensor?
Pure tensile or compressive stress
What components are present in the deviatoric stress tensor?
Shear stresses of the total stress state
What physical change is caused by hydrostatic strain?
Volume change
What physical change is caused by deviatoric strain?
Change in shape
What are the principle stresses?
Where the stress tensor has zero shear components and non-zero normal stresses
How do you define the stress state?
By using all components of the stress tensor