Question

Please label the following statements as either True (T) or False (F).

(a) The true stress is higher than the engineering stress for a sample under tension.
(b) Creep test is carried out with a dynamic stress under elevated temperature.

Answer 1

a. True

b. False

Step-by-step explanation:

a. Since true stress, σ' = σ(1 + ε) where σ = engineering stress and ε = engineering strain.

Also under tension ε > 0, so, (1 + ε) > 1

Since (1 + ε) = σ'/σ > 1, ⇒ σ' > σ

So, the true stress is greater than the engineering stress.

So, the statement is true

b. Creep is a time-dependent deformation under certain applied load.

Creep occurs at high temperatures under different types of stress.

But, Creep test is carried out at constant high temperature and constant stress.

This statement is false.