Stress (MPa) 1000 Problem 3 (5 points). A piece of cylindrical steel rod has a diameter of 20 mm and a length of 400 mm. It has the stress-strain behavior shown in the diagram below. (a) If the rod is pulled in tension, how much loading force (in N) is required to produce an elongation of 1 mm? (2 point) (b) If an INTERNAL crack exists in the alloy with a length of 160 μm and a radius of curvature of 5 um at the tip, what will be the magnitude of the maximum stress at the tip of the internal crack under the same loading force? Will the specimen withstand such a load, and why? (3 points) 2000 Stress 300 103 psi 300 MPa 2000 200 200 1000 100 0 0.000 0.005 0.010 0.015 Strain ° 0.000 0.020 0.040 0.060 0.080 Strain 100 Stress (10 psi)