Chapter 4, Problem 4.7QP

An aluminum alloy bar with a rectangular cross section that has a width of 12.5 mm, thickness of 6.25 mm, and a gauge length of 50 mm was tested in tension to fracture according to ASTM E-8 method. The load and deformation data were as shown in Table P4.7. Using a spreadsheet program, obtain the following:

a. A plot of the stress–strain relationship. Label the axes and show units.

b. A plot of the linear portion of the stress–strain relationship. Determine the modulus of elasticity using the best fit approach.

c. Proportional limit.

d. Yield stress at an offset strain of 0.002 m/m.

e. Tangent modulus at a stress of 450 MPa.

f. Secant modulus at a stress of 450 MPa.

TABLE P4.7

Load (kN)	∆L (mm)	Load (kN)	∆L (mm)
0	0	33.5	1.486
3.3	0.025	35.3	2.189
14.0	0.115	37.8	3.390
25.0	0.220	39.8	4.829
29.0	0.406	40.8	5.961
30.6	0.705	41.6	7.386
31.7	0.981	41.2	8.047
32.7	1.245