The following data were collected from a 20-mm-diameter test specimen of a ductile cast iron (l0= 40.00 mm):
Load (N)
?l (mm)
0
0.0000
25,000
0.0185
50,000
0.0370
75,000
0.0555
90,000
0.20
105,000
0.60
120,000
1.56
131,000
4.00 (maximum load)
125,000
7.52 (fracture)
After fracture, the total length was 47.42 mm and the diameter was 18.35 mm. Plot the engineering stress–strain curve and the true stress–strain curve. Since the instantaneous cross-sectional area of the specimen is unknown past the point of necking, truncate the true stress–true strain data at the point that corresponds to the ultimate tensile strength. Use of a software graphing package is recommended. Calculate
(a) the 0.2% offset yield strength;
(b) the tensile strength;
(c) the modulus of elasticity, using a linear fit to the appropriate data;
(d) the % elongation;
(e) the % reduction in area;
(f) the engineering stress at fracture; and
(g) the modulus of resilience.