Design of Machine Elements Objective Type Questions and Answers

21 In design process, which step is followed after defining the problem?

A Analysis

B Synthesis

C Optimization

D Evaluation

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Answer: Synthesis

22 For brittle materials having static load, factor of safety is given as the ratio of ______

A endurance strength and design stress

B design stress and allowable stress

C working stress and allowable stress

D ultimate strength and design stress

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Answer: ultimate strength and design stress

23 The ratio of endurance strength and allowable stress is used to determine FOS for _____

A fatigue loading

B static loading of brittle materials

C static loading of ductile materials

D all of the above

View Answer

Answer: fatigue loading

24 Which of the following factors are not considered while selecting values for factor of safety?

A Cost

B Failure consequences

C Degree of uncertainty about loading and material

D None of the above

View Answer

Answer: None of the above

25 What is the step ratio for R40 series?

A 1.44

B 1.05

C 4.0

D 0.4

View Answer

Answer: 1.05

26 Punching operation is an example of

A Static load

B Impact load

C Fluctuating load

D None of the above

View Answer

Answer: Impact load

27 Torsional Shear Stress is the stress induced when a component is subjected to equal and opposite _______.

A forces acting in perpendicular direction

B couples acting in perpendicular direction

C couples acting in parallel planes

D forces acting in parallel direction

View Answer

Answer: couples acting in parallel planes

28 What is bearing pressure?

A Compressive force acting on the contact area between two components having relative motion between them

B Tensile stress acting on the contact area between two components having relative motion between them

C Compressive force acting on the contact area between two components having no relative motion between them

D Compressive stress acting on the contact area between two components having relative motion between them

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Answer: Compressive stress acting on the contact area between two components having relative motion between them

29 Stress induced on contact area between cotter and socket collar is ______

A Tensile stress

B Direct shear stress

C Crushing stress

D None of the above

View Answer

Answer: Crushing stress

30 Which among the following is a type of transmission shaft?

A Spindle shaft

B Crankshaft

C Counter shaft

D All of the above

View Answer

Answer: Counter shaft

31 Which of the following statements is/are false for an axle?

A It is used to support rotating machine elements

B It can transmit torque

C It is subjected to axial force

D All of the above

View Answer

Answer: It can transmit torque

32 Which material cannot be used to manufacture shafts?

A Plain carbon steels

B Cast iron

C Both a. and b.

D None of the above

View Answer

Answer: Cast iron

33 Which type of key consists of two square tapered keys placed 90o apart?

A Tangent key

B Kennedy key

C Saddle key

D Woodruff key

View Answer

Answer: Kennedy key

34 Calculate diameter of shaft using maximum shear stress theory,when equivalent torque of 1000 x 103 N-mm acts on the shaft. 50 Mpa is the allowable shear stress for the shaft

A 100.9 mm

B 319.15 mm

C 46.70 mm

D Insufficient data

View Answer

Answer: 46.70 mm

35 Notch sensitivity (q) is given by the equation _______ where Kf = fatigue stress concentration factor and Kt = theoretical stress concentration factor

A ( Kf + 1 ) / ( Kt – 1 )

B ( Kf – 1 ) / ( Kt – 1 )

C ( Kf + 1 ) / ( Kt + 1 )

D ( Kf - 1 ) / ( Kt + 1 )

View Answer

Answer: ( Kf – 1 ) / ( Kt – 1 )

36 In S-N diagram, the graph plotted between fatigue strength and number of stress cycles becomes horizontal for which type of materials?

A Ferrous materials

B Non-ferrous materials

C Both a. and b.

D None of the above

View Answer

Answer: Ferrous materials

37 Which of the following equations is correct for Soderberg Criteria?

A (σm / Sut) + (σa / Se) = (1 / Nf)

B (σm / Sut) - (σa / Se) = (1 / Nf)

C (σm / Syt) + (σa / Se) = (1 / Nf)

D (σm / Sut) - (σa / Se) = (1 / Nf)

View Answer

Answer: (σm / Syt) + (σa / Se) = (1 / Nf)

38 Calculate overall efficiency of power screw, if the torque applied by the operator is 150 x 103 to move a load of 30 kN through a distance of 10 mm

A 22.36 %

B 37.69 %

C 31.83 %

D 30.23 %

View Answer

Answer: 31.83 %

39 Determine torque required to overcome collar friction in square threaded screw, if coefficient of friction is 0.12 and axial force of 20 kN is exerted by the screw. Mean radius of friction collar is 20 mm

A 48000 N-mm

B 120 N-mm

C 4800 N-mm

D 12000 N-mm

View Answer