Evaluation of impact strength and reliability of ceramic bearing ball for next-generation airplanes

为了评价环件在冲击载荷作用下的断裂强度，研制了摆锤冲击试验装置和落锤冲击试验装置。在摆锤冲击试验中，由于球心的对准调整困难，造成了倾斜碰撞。虽然环形裂纹萌生的碰撞载荷在理论上是可以计算的，但测量是非常困难的。另一方面，在落锤试验中，使用测力传感器可以正确测量环形裂纹萌生的碰撞载荷。设备制造也相对容易。环裂纹是由于颗粒之间的玻璃相，杂质等粘合剂的破坏，它是可以从环裂纹强度调查微观断裂。在碰撞接触中，陶瓷球的强度上升，但它们之间的离散性变小，这是因为与静态接触相比，参与环形裂纹萌生的裂纹长度变小。

The equipments of pendulum impact test and weight-drop test were manufactured in order to evaluate the ring crack strength under impact load. In the pendulum impact test, a slanting collision is caused because alignment adjustment of balls center is difficult. The measurement is very difficult although collision load of ring crack initiation is theoretically computable. On the other hand, in weight-drop test, collision load of ring crack initiation is correctly measurable using a load cell. Equipment manufacture is also comparatively easy. The ring crack is attributed to binder destruction of the glassy phase between particles, impurities, etc. It is possible to investigate microscopic fracture from ring crack strength. In the collision contact, the strength of the ceramic ball rises and the scatter of them become small, because the crack length which participates in ring crack initiation is small compared with static contact.