Based on Hertz contact theory

the influence of rolling-ball diameter of ceramic bearing on bearing stiffness was analyzed.By these laws

it's possible to tune rotor critical speed in design of micro turbine jet engine and verify it experimentally.Two groups of hybrid ceramic bearings were taken as rotor supports to measure the critical speed.It is proved that we can change rotor critical speed effectively by this method.And it also provides experience for changing critical speed in micro turbine jet engine design.