Department of Mechanical Engineering
Indian Institute of Technology Madras
Materials and Design (ME2200)
Date: 21-March-2022
Assignment - 6
Maximum Marks: 15
1. Make suitable assumptions where necessary.
2. Refer to text books or material data handbooks for properties that are not given.
1. Shown in Figure 1, shaft A, is made of AISI 1010 hot-rolled steel is welded to a fixed
support and is subjected to a loading by equal and opposite forces F via shaft B. A
theoretical stress concentration Kts of 1.6 is induced by the 3mm fillet. The length of
the shaft A from the fixed support to the connection at shaft B is 1 m. The load F
cycles from 0.5 to 2 kN.
a) For shaft A, find the factor of safety for infinite life using the modified Goodman
fatigue faire criterion.
b) Repeat the above using Gerber fatigue failure criterion.
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Figure 1: Figure corresponding to Question 1
2. A rotating-beam specimen with an endurance limit of 350 MPa and an ultimate strength
of 700 MPa is cycled 20 percent of the time at 490 MPa, 50 percent of the time at 385
MPa and 30 percent at 280 MPa. Estimated strength at 103 cycles = 0.9 Sut . Estimate
the number of cycles to failure.
Assignment - 6
Submission Due: 21-March-2022
ME2200
5
3. A bar of steel has the following properties Se = 276 MPa, Sy = 413 MPa and Sut = 551
MPa. The bar is subjected to a steady torsional stress of 103 MPa and an alternating
bending stress of 172 MPa. Find the factor of safety or the expected life of the part
using:
a) Modified Goodman criterion.
b) Gerber criterion.
Assignment - 6
Submission Due: 21-March-2022
ME2200
5