Project ForgeStrength of Materials
Stress & Strain
GATE 2019
Medium
In a UTM experiment, a sample of length 100 mm was loaded in tension until failure. The failure load was 40 kN. The displacement, measured using the cross-head motion, at failure was 15 mm. The compliance of the UTM is constant and given by 5×10⁻⁸ m/N. The strain at failure in the sample is ___ %.
13 %(± 1 accepted)
Explanation
The cross-head displacement includes the UTM's own elastic deflection: δ_machine = compliance×load = 5×10⁻⁸×40,000 = 2×10⁻³ m = 2 mm. True sample elongation = 15−2 = 13 mm. Strain = 13/100 = 0.13 = 13%.
Source: GATE ME 2019 Session 1 (Set 1) (2019)
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