Two specimens of the same cross-section are tested in tension
PHYSICS · Subjective · Fermi University Physics · Fluids & Continuum Physics · Solid continuum mechanics and complex fluids · Solid continuum mechanics and complex fluids
Fluids and Continuum Physics, Ch Mechanical properties of materials: the Young modulus, plasticity and fracture
Problem
Two specimens of the same cross-section are tested in tension. The nylon monofilament has an initial slope of 3.0 GPa, begins to flow near 50 MPa, draws out steadily, and breaks at 80 MPa at a strain of 0.30. The grey cast iron bar has a slope of 100 GPa, its curve is a straight line to fracture at 250 MPa at a strain of 0.0025, and the fracture face is flat with no necking. Which one of the following statements is correct? (a) The cast iron is brittle and the nylon ductile; the cast iron is both the stiffer and the stronger of the two. (b) The nylon is brittle, because it is the weaker of the two. (c) The cast iron is ductile, because it is the stiffer of the two. (d) Both are brittle, because both curves contain a straight portion. (e) The cast iron is brittle, so it must be the weaker of the two.