It is necessary to select a ceramic material to be stressed using a three-point loading sc...

It is necessary to select a ceramic material to be stressed using a three-point loading scheme (Figure 12.30). The specimen must have a circular cross section, a radius of 3.8 mm (0.15 in.) and must not experience fracture or a deflection of more than 0.021 mm (8.5 × 10–4 in.) at its center when a load of 445 N (100 lbf) is applied. If the distance between support points is 50.8 mm (2 in.), which of the materials in Table 12.5 are candidates? The magnitude of the centerpoint deflection may be computed using Equation 12.11.

Figure 12.30 A three-point loading scheme for measuring the stress–strain behavior and flexural strength of brittle ceramics, including expressions for computing stress for rectangular and circular cross sections.

Table 12.5 Tabulation of Flexural Strength (Modulus of Rupture) and Modulus of Elasticity for Ten Common Ceramic Materials

aPartially stabilized with 3 mol% Y2O3.

bSintered and containing approximately 5% porosity.

 (12.11)