A three-point bending test is performed on a spinel (MgAl2O4) specimen having a rectangular cross section of height d = 3.8 mm (0.15 in.) and width b = 9 mm (0.35 in.); the distance between support points is 25 mm (1.0 in.).

(a) Compute the flexural strength if the load at fracture is 350 N (80 lbf).

(b) The point of maximum deflection Δy occurs at the center of the specimen and is described by

Where E is the modulus of elasticity and I is the cross-sectional moment of inertia. Compute Δy at a load of 310 N (70 lbf)?

N,(m-3) 5.7 x 109 T (C) P (g/cm) 750 3.50 3.45 1000 3.40 5.8 x 1017 1500