lost steel reinforcing bars manufactured in the U.S. exhibit a sharp yield plateau. Two xceptions, however, are bars that are quenched and tempered and bars that are coiled nmediately after they are hot rolled. The coiled bars are later straightened by a fabricator. Both ) quenched-and-tempered bars and (2) straightened bars have stress-strain curves that are itially linear, but yielding is gradual, producing what is described as a "round-house" curve. The reason for the round-house behavior is the same for both types of steel.

The data in Table 1.5.3 were obtained from a tensile test of a metal specimen with a rectangular cross section of 0.2011in.2 in area and a gage length (the length over which the elongation is measured) of 2.000 inches. The specimen was not loaded to failure. a. Generate a table of stress and strain values. b. Plot these values and draw a best-fit line to obtain a stress-strain curve. c. Determine the modulus of elasticity from the slope of the linear portion of the curve. d. Estimate the value of the proportional limit. e. Use the 0.2 offset method to determine the yield stress.

The frame of a space shuttle type vehicle must have a high yield strength and high stillness, and the most important design factor is weight. Of all the materials presented in this chapter, what material might be the most suitable for the frame of a space shuttle? Assume that there will be both tensile and compressive stresses. For a space shuttle, cost is not a limiting factor. (a) You can eliminate entire classes of materials from consideration with a brief statement about their unsuitability. (b) What material has the highest specific yield strength? Give the yield strength, specific gravity, specific yield strength, elastic modulus, and specific elastic modulus for this material. (c) What material has the highest specific elastic modulus? Give the yield strength, specific gravity, specific yield strength, elastic modulus, and specific elastic modulus for this material. (d) Compare the materials with the highest specific yield strength and highest specific elastic modulus for suitability in the space shuttle frame. (C) Discuss the suitability of the top-rated material for this design from the viewpoint of the ability to produce a frame.

A tensile test was performed on a metal specimen having a circular cross section with a diameter of 1 2 inch. The gage length (the length over which the elongation is measured) is 2 inches. For a load 13.5 kips, the elongation was 4.6610 3 inches. If the load is assumed to be within the linear elastic rang: of the material, determine the modulus of elasticity.