GATE 2019: Machine Design Quiz 1- Dynamics load Design

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Question 1

For a brittle material, subjected to fluctuating loading has stress concentration factor of 1.8 and stress of 200 MPa. Find the fatigue stress concentration factor (take notch sensitivity = 1)?

• A1.8
• B2.0
• C1.11
• D9.0

Question 2

A cylindrical shaft is subjected to alternate stress of 100 MPa. Fatigue strength to sustain 1000 cycles is 490 MPa. If endurance limit is 70 MPa. Find shaft life.

• A2.81 x 10⁵ cycles
• B3.16 x 10⁵ cycles
• C1.14 x 10⁵ cycles
• Dnone of these

Question 3

A machine element has an ultimate strength , and endurance limit of . The fatigue curve for the element on log-log plot is shown below. If the element is to be designed for a finite of 10000 cycles, the maximum amplitude of a completely reversed operating stress is _________ .

• A350
• B365.23
• C386.19
• D395

Question 4

A bar is subjected to fluctuating tensile load from 20 kN to 100 kN. The material has yield strength of 240 MPa and endurance limit in reversed bending is 160 MPa. According to the Soderberg principle, the area of cross-section (in mm²)of the bar for a factor of safety of 2 is

• A400
• B600
• C750
• D1000

Question 5

Fatigue failure is caused due to effect of:

• AStress
• BStrain
• CStress and strain
• DNone of these

Question 6

A spherical vessel of a1000 mm inner diameter is subjected to an internal pressure which varies from 5 MPa to 10 MPa. The material of the vessel is cold drawn steel having ultimate strength 450 MPa and yield strength 240 MPa. If the reliability of the vessel is 90% and required factor of safety is 2, the thickness of pressure vessel for an infinite life period is _____ mm.

• A2.18
• B21.8
• C218
• D25.6

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