Plastic properties and Tensile testing II Flashcards
Provide 3 examples of elastic properties
- Young’s modulus
- Modulus of resilience
- Poisson’s ratio
Provide 4 examples of plastic properties
- Yield strength
- Ultimate tensile strength
- Ductility
- Toughness
Define true stress
Load divided by the instantaneous cross-sectional area
True strain
Natural logarithm of ratio of instantaneous gauge length
to original gauge length
What type of process is plastic deformation?
Plastic deformation is a constant volume process
What type of values are hardness values?
Relative values
What is hardness?
A material’s resistance to localized
plastic deformation
Which test can you NOT use to determine hardness?
A tensile test
What can hardness be used to estimate?
Yield stress and ultimate tensile stress
What is the difference between engineering stress and true stress in terms of magnitude?
Engineering stress is less than true stress, which makes them conservative.
What is the difference between engineering strain and true strain?
Engineering strain is greater than true strain.
What does the corrected true stress-strain curve take into account?
Adjustments made upon necking.
Are “corrected” stresses lower or higher than true stresses? Why or why not?
“Corrected” stresses are lower than that of the
“true” curve due to the
complex stress state in the
neck.
What is a factor of safety?
A non-zero positive number that is used to calculate a working stress, based on a yield stress
What is a factor of safety used for and not used for?
This is used for non-critical applications, and not for critical applications such as aircraft and bridge components
