1. A brass rod 2m long is fixed at both its ends. If the thermal stress is not to exceed 76.5 MPa, calculate the temperature through which the rod should be heated . Take the vale of alpha as 17x10-6 /K and E=90 GPa.
(Ans:t=50 K)
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2. A steel bar, fixed at its both ends, is heated through 15 K. Calculate the stress developed in the bar, if modulus of elasticity and coefficient of linear expansion for the bar material is 200 GPa and 12x10-6 /K respectively.
(Ans:stress 36 Mpa,)
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3. An alloy bar 2m long is held between two supports. FInd the stress developed in the bar, when it is heated through 30 K if both the ends (i) do not yield (ii) yield by 1 mm. Take the value of e and alpha for the alloy as 120 GPa and 24x10-6 /K .
(Stress= 86.4 MPa, 26.4 Mpa)
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4. An alloy bar 6m long is held between two supports by a steel rod 25 mm diameter passing through metal plates and nuts at each end.. The rod is held at temp. of 100 0 C.Determine the stress in the rod, when the temperature falls down to 60 0 C, if
(i) do not yield
(ii) yield by 1 mm. Take the value of e and alpha for the alloy as 200 GPa and alpha = 12x10-6 /K .
(Stress= 96 MPa, 62.6MPa)
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5. Two parallel walls 6m apart are stayed together by a steel rod 2.5 cm diameter at a temperature of 80 0 c passing through washers and nuts at each end. Calculate the pull exerted by the rod when it has cooled to 220 C if,
(i) do not yield (ii) yield by 1.5 mm. Take the value of E & alpha for the alloy as 200 GPa and 11x10-6 /K .
(Stress= 127.6 kN, 77.6m/mm2)
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6. A steel bar of 30 mm diameter is heated to 800 C and then clamped at the ends. It is then allowed to cool down to 300 c. During cooling, only 1 mm contraction was allowed. Calculate the temperature stress developed and reaction at the clamps.Take the value of e and alpha for the alloy as 200 GPa and 12x10-6 /K .Take length of bar 10 meters.
(F=70.68 KN)