A novel test method to measure the fracture toughness of ceramic balls used in bearings

作者：Piotrowski A E; O'Brien M J^*

来源：Fatigue and Fracture of Engineering Materials and Structures, 2006, 29(7): 558-572.

DOI：10.1111/j.1460-2695.2006.01027.x

• fracture toughness
• hybrid bearings
• silicon-nitride balls

A novel mechanical test has been developed to measure the fracture toughness of the silicon-nitride (Si3N4) balls used in modern hybrid bearings. The ball is compressed diametrally between two hemispherical conforming dies, which causes the ball's equator to bulge, generating a tensile hoop stress. Under applied load, a precrack placed at the equator grows. To calculate the ball's fracture toughness at crack instability, finite-element calculations of the applied stress field and an analytical solution for the stress intensity factor are used in the 'two point plus semiellipse' method. Tests of 16 Si3N4 balls and three soda-lime glass balls gave fracture toughness measurements in good agreement with accepted published values. The new technique appears to be more accurate than the indentation technique used to measure the toughness of ceramics. As future work, the test can be extended to measure fatigue and stress corrosion properties for Si3N4 balls.

• 出版日期2006-7