Question

(a) Describe, with the aid of a Strain versus Time diagram, how a creep test is carried out to determine the strain rate of the material under test. (8)

(b) Explain EACH of the stages sketched in the diagram in part (a). (8)

Answer 1

Part (a)

Creep testing is conducted using a tensile specimen to which a constant stress is applied at a constant temperature, often by the simple method of suspending weights from it. The test is recorded on a graph of strain versus time.

Part (b)

Creep occurs over three main stages: primary, secondary and tertiary. The primary stage occurs at the beginning of the testing period with transient deformation at a varying rate. The secondary stage is the point where deformation becomes more continuous and steady state. The tertiary stage is the point where deformation accelerates and the specimen fractures, ultimately ending the test.

✓ Verified Model Answer (Text Solution)

Creep testing is conducted using a tensile specimen to which a constant stress is applied at a constant temperature, often by the simple method of suspending weights from it. The test is recorded on a graph of strain versus time.