Strength

Question 1

True stress is given by
the incremental increase in length divided by the length at the start of the increment

the current applied force divided by the original cross sectional area

the total increase in length divided by the original length

the current applied force divided by the current cross sectional area

Answer 1

the current applied force divided by the current cross sectional area

Question 2

Answer 2

250

Question 3

The difference between true stress and engineering stress at the yield stress is large

Answer 3

FALSE

Question 4

The relationship between true strain and engineering strain is given by

Answer 4

Question 5

The ultimate tensile strength is given by

Answer 5

Question 6

For a metal that shows power law hardening with K = 1374 MPa and n = 0.20 calculate the engineering strain when the sample starts to neck. Give your answer to 2 decimal places.

Answer 6

0.22 +/- 2%

Question 7

Which of the following statements about UTS are true

The UTS is the value of true stress at which necking starts

The UTS is the value of engineering stress at which necking starts

UTS indicates the maximum tensile load (stress) that can applied to a sample with a given set of initial dimensions

UTS is the engineering strain at which necking starts

Answer 7

The UTS is the value of engineering stress at which necking starts

UTS indicates the maximum tensile load (stress) that can applied to a sample with a given set of initial dimensions

Question 8

For a metal that shows power law hardening with K = 1191 MPa and n = 0.39 calculate the UTS. Give your answer to the nearest 1 MPa.

Answer 8

559 +/1 (MPa)

Question 9

For a metal that shows power law hardening with K = 890 MPa and n = 0.42 calculate the true stress at the onset of necking. Give your answer to the nearest 1 MPa.

Answer 9

618 +/ 1 (MPa)