Mechanical Properties of Metals - Chapter 8

Question 1

Engineering stress

Answer 1

= F/Ao

Question 2

Engineering Strain

Answer 2

= Delta[L]/Lo

Question 3

Shear stress

Answer 3

= F/Ao

Question 4

E-modulus

Answer 4

stress/strain

Question 5

Anelasticity

Answer 5

Time-dependent elastic strain component -> elastic deformation will continue after the stress application, and upon load release, some finite time is required for complete recovery.

Question 6

Poisson’s ratio

Answer 6

v= Lateral strain/axial strain

Question 7

Relation between shear and elastic moduli?

Answer 7

E = 2G (1 + v)

Question 8

Yielding

Answer 8

The point of yielding may be determined as the initial departure form linearity of the stress-strain curve; this is sometimes called the proportional limit. The strain offset is usually 0.002

Question 9

Ductility

Answer 9

It is a measure of the degree of plastic deformation that has been sustained at fracture.

Question 10

Percentage elongation (%EL)

Answer 10

%EL = [(Lf-Lo)/Lo] x 100

Question 11

Percent reduction in area (%RA)

Answer 11

%RA = [(Ao-Af)/Ao] x 100

Question 12

Resilience

Answer 12

Resilience is the capacity of a material to absorb energy when it is deformed elastically and upon unloading, to have this energy recovered.

Question 13

Modulus of Resilience (Ur)

Answer 13

Ur = Integration[stress d(strain)]

Assuming a linear elastic region:

Ur = 1/2 (stress)(strain)

Also,

Ur = Stress^2/2E

Question 14

Toughness

Answer 14

indicates a material’s resistance to fracture when a crack is present.

Also indicates the ability of a material to absorb energy and plastically deform before fracturing.

Question 15

Hardness

Answer 15

Hardness is a measure of a material’s resistance to localized plastic deformation.