MCQs on Stress Concentraion and its Factors

1 - Question

Stress concentration is defined as the localization of high stresses due to irregularities present in the component and no changes of the cross section.

a) True
b) False

View Answer

Answer: b
Explanation: The given statement is true apart from the fact that there is no change in the cross section.

2 - Question

Stress Concentration Factor is the ratio of nominal stress obtained by elementary equations for minimum cross-section and highest value of actual stress near discontinuity.

a) True
b) False

View Answer

Answer: b
Explanation: The stress concentration factor is just the reciprocal of that cited in the question.

3 - Question

If a flat plate with a circular hole is subjected to tensile force, then its theoretical stress concentration factor is?

a) 2
b) 3
c) 4
d) 1

View Answer

Answer: b
Explanation: For any ellipse, K=1+2 x (semi major axis/semi minor axis).

4 - Question

For an elliptical hole on a flat plate, if width of the hole in direction of the load decrease, Stress Concentration Factor will______

a) Increase
b) Decrease
c) Remains constant
d) Can’t be determined. Varies from material to material

View Answer

Answer: a
Explanation: K=1+2 x (semi major axis/semi minor axis. Hence K is inversely proportional to the semi minor axis.

5 - Question

In which of the following case stress concentration factor is ignored?

a) Ductile material under static load
b) Ductile material under fluctuating load
c) Brittle material under static load
d) Brittle material under fluctuating load

View Answer

Answer: a
Explanation: In ductile materials under static load, there is plastic deformation near yielding point and hence redistribution of stresses take place. The plastic deformation is restricted to a smaller area and hence no perceptible damage take place.

6 - Question

Is it logical to use fluid analogy to understand the phenomenon of stress concentration?

a) True
b) False

View Answer

Answer: a
Explanation: There is a similarity between velocity distribution in fluid flow in a channel and the stress distribution in an axially loaded plate. The equations for flow potential and in fluid mechanics and stress potential in solid mechanics are same.

7 - Question

Use of multiple notches in a V shaped flat plate will

a) Reduce the stress concentration
b) Increase the stress concentration
c) No effect
d) Cannot be determined

View Answer

Answer: a
Explanation: The sharp bending of a force flow line is reduced due to multiple notches.

8 - Question

Which of the following reduces the stress concentration?

a) Use of multiple notches
b) Drilling additional holes
c) Removal of undesired material
d) Each of the mentioned

View Answer

Answer: d
Explanation: All the mentioned options reduce the sharp bending of a force flow line.

9 - Question

A flat plate 30mm wide and “t”mm wide is subjected to a tensile force of 5kN. The plate has a circular hole of diameter 15mm with the centre coinciding with the diagonal intersection point of the rectangle. If stress concentration factor=2.16, find the thickness of the plate if maximum allowable tensile stress is 80N/mm².

a) 8mm
b) 9mm
c) 10mm
d) 12mm

View Answer

Answer: b
Explanation: σ=P/ (w-d) x t or σ=5000/(30-15)xt ; σ(max)=K x σ or σ(max)=2.16 x σ or σ(max)=720/t; Also σ(max)=80.

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