During a tensile test on a 1 cm cross-section specimen, the peak load was 8 tonnes and the neck cross-sectional area was 0.5 cm2. What is the ultimate tensile strength___________________?
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Answer: B. 8 tonnes/cm2
Explanation
Ultimate tensile strength is calculated using the peak load divided by the original cross-sectional area, giving 8 tonnes/cm². Dividing the peak load of 8 tonnes by the initial cross-sectional area of 1 cm² yields the engineering tensile strength. Engineering stress calculations conventionally use original cross-sectional dimensions rather than necked areas. Tensile tests pull standard material specimens apart until fracture while recording applied loads and elongation. Ultimate tensile strength represents the maximum engineering stress a material can withstand before necking failure. Cross-sectional necking occurs locally during the final stages of a destructive tensile test.
Material testing laboratories determine ultimate tensile strength to certify metals for aerospace and construction use. Engineers use these certified strength values to calculate safe working loads for structural steel components. Quality control inspectors verify material batches against established metallurgical strength standards. Four tonnes/cm² underestimates the ultimate strength by using incorrect cross-sectional area ratios. Sixteen tonnes/cm² incorrectly divides load by the necked area instead of the original cross-section. Twenty-two tonnes/cm² exceeds the actual calculated stress value derived from the test data parameters.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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