1. (SI Units) In a tensile test, the starting gage length = 100.0 mm and the cross-sectional area = 150 mm2.
During testing, the following force and gage length data are collected:
(1) 17,790 N at 100.2 mm,
(2) 23,040 N at 103.5 mm,
(3) 27,370 N at 110.5 mm,
(4) 28,910 N at 122.0 mm,
(5) 27,480 N at 130.0 mm, and
(6) 20,460 N at 135.1 mm.
The final data point (6) occurred immediately prior to failure. Yielding occurred at a load of 19,390 N (0.2% offset value), and the maximum load (4) was 28,960 N.
(a) Plot the engineering stress strain curve.
Determine
(b) yield strength,
(c) modulus of elasticity,
(d) tensile strength, and
(e) percent elongation.
2. USCS Units) During a tensile test, a metal has a true strain = 0.08 at a true stress = 37,000 lb/in2 . Later, at a true stress = 55,000 lb/in2 , true strain = 0.24. Determine the strength coefficient and strain-hardening exponent in the flow curve equation.
3. (S1 units) A bridge to be fabricated of steel girders is designed to be 500 m long and 12 m wide at ambient temperature (assumed 20 οC ). txpansion joints will be provided to compensate for the change in length in the girders as the temperature varies. Each expansion joint can compensate for a maximum of 20 mm of change in length. From historical records it is estimated that the minimum and maximum temperatures in the region will be - 35 οC and 40 οC , respectively. Determine
(a) the minimum number of expansion joints required and
(b) the length that each bridge section should be fabricated. Use Table 4.1 for reference.
4. (S1 units) Aluminum has a density of 2.70 g/cm3 at room temperature (20 οC). Determine its density at 650 οC , using data in Table 4.1 for reference.
TABLE • 4.1: Volumetric properties in U.S. customary units for selected engineering materials.
