Part 6: Mechanical Properties

Question 1

What is stiffness?

Answer 1

Resistance to elastic deformation

Question 2

How can young’s modulus be determined given a stress strain curve?

Answer 2

Young’s modulus is the slope of the elastic (linear) region

Question 3

What is the proportional limit?

Answer 3

The end of the elastic (linear) region and start of plastic deformation

Question 4

How do we measure yield strength?

Answer 4

Draw a parallel line starting from strain = 0.002. Yield strength is at the intersection

Question 5

What is tensile strength?

Answer 5

The maximum engineering stress in a material

Question 6

At what %EL is a material considered ductile

Answer 6

> 5%

Question 7

How do temperature increases impact ductility?

Answer 7

Increased ductility

Question 8

What is resilience and how is it measured?

Answer 8

Ability to absorb energy during elastic deformation.
Measured as the area under elastic region (up to yield strength)

Question 9

What is toughness and how is it measured?

Answer 9

Ability to absorb energy until fracture.
Measured as the area under the entire stress-strain curve

Question 10

What is hardness?

Answer 10

Material’s resistance to localized plastic deformation (e.g. a scratch)