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Equibiaxial Ring on Ring Ceramic composite flexural strength per ASTM ISO

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Equibiaxial Ring on Ring Ceramic composite flexural strength per ASTM ISO

The ring on ring test was developed because traditional 4 point bend tests of ceramics suffer from the maximum biaxial stress occurring at the center of the sample on the lower side. Since the lower side of the sample is loaded or rests on the test fixture anvils, surface finish became critical. Poor surface finishes produce low test results. ASTM C1499 Ring on Ring is a general test method with variable sample sizes that target ceramic composites including monolithic, whisker-reinforced or particle-reinforced, and discontinuous fiber reinforced types. ASTM C1499 defines the relationship of material thickness to specimen and test fixture dimensions, so the fixture dimensions vary. Test fixtures are made with different contact radii and different ring on ring diameters. Its important that the sample be manufactured flat for ASTM C1499 to be successful. Note that the loading ring can optionally be articulated and swivel on a spherical seat. Another approach is to place a thick rubber sheet between the two rings. ISO 13356 is the original ring on ring ceramic flexural strength test method. ISO 13356 requires a specific sample geometry with specimen diameter of 36 mm (1.4 in), thickness of 2 mm (0.08 in), support ring diameter of 30 mm (1.18 in), loading ring diameter of 12 mm (0.47 in) and ring cross-sectional radii of 2 mm (0.08 in). It is more limited in terms of applications.