FOR FERROUS MATERIALS LIKE STEEL, S-N CURVE BECOMES ASYMPTOTIC AT 1...

2.

For ferrous materials like steel, S-N curve becomes asymptotic at 10

6

cycles.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

IES 3. Ans. (b) 1 is false: affected

Endurance Limit

IES 4. Match List I with List II and select the correct answer using the codes

given below the lists:

[IES-1993]

List I (Material properties)

List II(Tests to determine material properties)

A. Ductility

1. Impact test

B.

Toughness

2.

Fatigue

test

C. Endurance limit

3. Tension test

D. Resistance to penetration

4. Hardness test

Code: A B C D A B C D

(a)

3 2 1 4 (b)

4 2 1 3

(c) 3 1 2 4 (d)

4 1 2 3

IES 4. Ans. (c)

IES 5.

When

σ

and Young's Modulus of Elasticity E remain constant, the energy-

absorbing capacity of part subject to dynamic forces, is a function of its

[IES-1992]

(a) Length

(b) cross-section

(c) volume

(d) none of the above

IES 5. Ans. (c) Strain energy is given by,

σ

2

=

U A.L.

2E

Where

σ

and E remaining constant,

∴U is proportional to (A.L.) which is volume.

Also, since U is a function of

σ

2

, that portion of the part which is prone to high

localised will absorb a high amount of energy, making it vulnerable to failure. Such

a part, therefore, is designed to have such a contour that, when it is subjected to

time-varying or impact loads or others types of dynamic forces, the part absorbs or

less uniform stress distribution along the whole length of the part is ensured.

IES 6.

Fatigue strength of a rod subjected to cyclic axial force is less than that of

a rotating beam of the same dimensions subjected to steady lateral force.

What is the reason?

[IES-2009]

(a) Axial stiffness is less than bending stiffness

(b) Absence of centrifugal effects in the rod

(c) The number of discontinuities vulnerable to fatigue is more in the rod

(d) At a particular time, the rod has only one type of stress whereas the beam has

both tensile and compressive stresses

IES 6. Ans. (d)

Fluctuating Load Consideration for Design

S K Mondal’s

Chapter 5

Soderberg and Goodman Diagrams

IES 7.

Assertion (A): Soderberg relation is used for design against fatigue. [IES-1996]

Reason (R): Soderberg relation is based on yield strength of the material whereas

all other failure relations for dynamic loading are based on ultimate strength of the

material.

(a) Both A and R are individually true and R is the correct explanation of A

(b) Both A and R are individually true but R is not the correct explanation of A

(c) A is true but R is false

(d) A is false but R is true

IES 7. Ans. (a)

IES 8.

The design calculations for members subject to fluctuating loads with the

same factor of safety yield the most conservative estimates when using

(a) Gerber relation

(b) Soderberg relation [IES-1995]

(c) Goodman relation

(d) none of the above.

IES 8. Ans. (b)

IES 9. In the figure shown, it

the line AB represents

Goodman criterion of

failure, then soderberg

criterion could be

represented by line

(a) AD

(b) D

(c) DC

(d) AC

[IES-1992]

IES 9. Ans. (d)

Gyroscopic motion

IES 10. Consider the following statements:

[IES-2005]