Thermal stress in an unconstrained bar: heating a free steel bar from 15°C to 40°C A steel bar is heated from 15°C to 40°C and is perfectly free to expand (no constraint). State the stress induced in the bar as a result of heating. Choose the correct option.
Mechanical Engineering
Strength of Materials
Difficulty: Easy
Choose an option
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ANo stress induced
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BShear stress induced
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CTensile stress induced
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DCompressive stress induced
Answer
Correct Answer: No stress induced
Explanation
Concept/ApproachThermal strain = α ΔT. If the bar is completely unrestrained, it undergoes free expansion, so no internal force develops.
ResultThermal stress arises only when expansion/contraction is restrained. With no restraint: σ = 0.
Final AnswerNo stress induced.