Homework Assignment No. 2
1. The stress-strain diagram of a structural material is given below. Find the following: (A)
Elastic modulus. (B) Johnson’s Apparent Elastic Limit. (C) Yield Strength at 0.2% offset. (D)
Modulus of Resilience. (E) Modulus of Toughness. (4 pts.)
0 2 4 6 8 10 12 14 16 18 20
STRAIN (10-3)
50
40
30
20
10
0
STRESS
(KSI)
2. The S-N diagram of a structural material is shown below. (A) A structural member made of
this material is to be subjected to 100,000 cycles of cyclic stress of 140 MPa during its design
life. What is the maximum magnitude of an additional steady stress that can be put on top of the
cyclic load without fracture during its design life? Use (a) Soderberg's theory, and (b)
Goodman’s theory for this problem. (2 pts.) (B) A structural member made of this material is to
be subjected to 50 cycles at 260 MPa, 100 cycles at 240 MPa and 300 cycles at 220 MPa per day.
Determine the number of days of service before it will fracture according to Minor’s Rule. (2
pts.)
10 102 103 104 105 106 107
300
260
220
180
140
CYCLIC
STRESS
(MPa)
NUMBER OF CYCLES
yield = 320 MPa
ultimate = 360 MPa
σyield =320 MPa
σultimate =360 MPa
Docsity.com
