Consider the following statements regarding two dimensional stress formulations : 1. In a plane stresses are identical for any given geometry, loading. 2. The in-plane stresses are different for plane strain or plane stress. 3. Linear viscoelastic stress fields are different for constant load and change with time. Which of the above statements is/are correct ?
- A1 only
- B1 and 2
- C3 only
- D2 and 3Correct
Solution
Concept
Plane stress, plane strain and viscoelasticity
Step-by-step solution
1. Statement 1 claims stresses are identical for any geometry and loading, which cannot be generally true. 2. In-plane stresses differ between plane stress and plane strain formulations (true). 3. In linear viscoelasticity the stresses change with time even at constant load (true).
Explanation
Plane strain and plane stress give different in-plane stresses because of the different out-of-plane constraint. A viscoelastic material relaxes or creeps, so the stress field changes with time.
Why the other options are wrong
Statement 1 is too general and statements 1 and 2 contradict one another.
Shortcut
Plane stress ≠ plane strain; viscoelastic = time dependent.
Correct answer: D) 2 and 3