ENCE 2311 STRENGTH OF MATERIAIS LAB FINAL SPRING 2018 SHORT ANSWER QUESTIONS: (P
ID: 2087150 • Letter: E
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ENCE 2311 STRENGTH OF MATERIAIS LAB FINAL SPRING 2018 SHORT ANSWER QUESTIONS: (Points are shown separately) 1. Explain the difference between the Ultimate Tensile strength and the Fracture Tensile Strength of a steel specimen. (10 points) 2. Why did we test our concrete cylinders seven days after pouring them and then again, 28 days after the pour? what compressive strength is usually used for design purposes? 15 points) 3. Describe the concrete specimen, its ingredients and its preparation prior to any actual compression tests (5 points) 4. When points). The produced stress is.a measure of a shaft's ability to resist torsion? 10 points a shaft is subjected to Torque or Twisting. stress is produced in the shaft? (10 at the outside surface (outer fiber) of the shaf.. Is theExplanation / Answer
1. Ultimate tensile strength of steel refers to the maximum strength of the steel in stress strain curve , it can be said that the maximum stress at the necking condition when a STATAIC load is applied is called ultimate tensile strength.
Whereas fracture strength is the strength of the steel when subjected to fluctuating loading condition. It is generally less than ultimate strength in static loading condition.
2. A 7 day test may help to detect the potential problem with the concrete quality or testing procedure but is not the basis of rejection , with a requirement of 28 day test as furthur procedure. Moreover, concrete gains its 100% strength over a period of time , hence 28 days is taken as the standard time.
3. Concrete consists of sand , cement and coarse aggregate as its ingredients, it is advised to thoroughly mix the constituents for better strength. Water is also mixed in specified proportion.
4. When a shaft is subjected to torque, shear stress is produced in the member. It is maximum at the outer fibre as shear stress is directly proportional to the radius. Torsional rigidity(G*J) is the measure of shaft ability to resist torsion.
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