Chapter-1
Stress and Strain Fst
From equation (1)
FA1
60 u 103 3.001
S K Mondal’s
19.99 kN or 20 kN
20 kN
FA1 Fst
20 kN ½ ¾ Answer. 20 kN ¿
Conventional Question GATE The diameters of the brass and steel segments of the axially loaded bar shown in figure are 30 mm and 12 mm respectively. The diameter of the hollow section of the brass segment is 20 mm. Determine: (i) The maximum normal stress in the steel and brass (ii) The displacement of the free end ; Take Es = 210 GN/m2 and Eb = 105 GN/m2 Question:
Answer:
As
S 4
A b BC Ab CD
u 12
S 4
S 4
2
u 30
36S mm2 2
36S u 10 6 m2
225S mm2
u 302 202
225S u 10 6 m2
125S mm2
125S u 10 6 m2
(i) The maximum normal stress in steel and brass:
10 u 103 u 10 6 MN / m2 88.42MN / m2 6 36S u 10 5 u 103 V b BC u 10 6 MN / m2 7.07MN / m2 225S u 10 6 5 u 103 V b CD u 10 6 MN / m2 12.73MN / m2 125S u 10 6
Vs
(ii) The displacement of the free end:
Gl
G ls AB G lb BC G lb CD 88.42 u 0.15 7.07 u 0.2 12.73 u 0.125 9 9 6 6 210 u 10 u 10 105 u 10 u 10 105 u 109 u 10 6 9.178 u 10 5 m
§ ¨ G l ©
Vl · E ¸¹
0.09178 mm
Conventional Question IES-1999 Question: Answer:
Distinguish between fatigue strength and fatigue limit. Fatigue strength as the value of cyclic stress at which failure occurs after N cycles. And fatigue limit as the limiting value of stress at which failure occurs as N becomes very large (sometimes called infinite cycle)
Conventional Question IES-1999
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