problem 1: The three-point bending test was performed on an aluminum oxide specimen having a circular cross section of radius 3.5 mm; the specimen fractured at the load of 950 N when the distance between the support points was 50 mm. The other test is to be performed on a specimen of this same material, however one that has a square cross section of 12 mm length on each edge. At what load would you expect this specimen to fracture if the support point separation is 40 mm?
problem 2: The relatively large sheet of steel is to be exposed to cyclic tensile stresses of magnitudes 200 MPa and 50 MPa, respectively. Prior to testing, it has been determined that the length of the biggest surface crack is 2.5 mm. Estimate the fatigue life of this sheet if its plane strain fracture toughness is 30 MPa(m^{0.5}) and the values of m and A are 3.0 and 10^{-12}, respectively, for Δσin MPa and a in m. Suppose that the parameter Y is independent of the crack length and has a value of 1.0.