Mechanical properties of mater Flashcards
What is the symbol for tensile stress?
sigma
What is the equation for tensile stress?
sigma = F/A
What does strain tell us?
How much something has changed by compared to it’s original length.
What is the symbol for strain?
Epsilon
What is the equation for strain?
Epsilon = x/L where x is the extension and L is the original length.
What are the units for stress?
Nm^-2
What are the units for strain?
Doesn’t have any units.
What is the symbol for Young’s modulus?
E
What is the equation to calculate Young’s modulus of a material?
E = stress/strain
What is the typical YM of steel?
210GPa
What is Young’s modulus a measure of?
The stiffness or a material.
What are the units for YM?
Pa or Nm^-2
Define Tensile stress.
The tension force per unit cross-sectional area of a material.
Define Tensile strain.
The extension per unit length of a material
Define Young’s modulus.
The tensile stress per unit tesnile strain.
Sketch a stress-strain graph labelling with the elastic limit, yield point, limit of proportionality and UTS.
Look at notes!
Define UTS.
Ultimate Tensile strength- the maximum stress a material can withstand before fracture.
Define Elastic limit.
The value if stress or force beyond which elasrtic deformation becomes plastic deformation; the material will not retun to its original shape and size when the stress or force is removed.
What can strain of 0.012 be written as?
1.2%
How would you describe copper?
Ductile
Define brittle.
A material that distorts very little even when subject to a large stress and does not exhibit much plastic deformation; for example, concrete or glass.
Define polymetric.
Materials that consist of long molecular chains; they experience a high strain beofre braking.
Define ductile.
Materials that have a large plastic region and therefore they can be drawn into a wire; for example copper.
Draw a hysterisis loop for: rubber, polyethene and a matal wire.
Look at notes!
