Improving the reliability of a ceramic plain bearing

In this study, we search for a design solution to ensure a reliable and long-term operation of a friction unit with a ceramic plain bearing. To that end, the stress-strain state of the ceramic insert is optimized with respect to actual loading conditions. The bearing unit is designed accounting for the properties of ceramic materials, which show low strength reliability under the action of tensile stresses. To improve the solution accuracy, we determine the actual contact area, taking into account the load unevenness in the bearing. In addition, since the insert surface is assumed to be complexly stressed, the calculation is based on equivalent stresses. The criterion is to minimize equivalent stresses, which corresponds to the optimal tension justifying the bearing application. The analysis involves the discrete-continuous option of the finite element method with the variational principle according to the Lagrange method. The calculation software provides for the values of equivalent stresses depending on tension and selects its optimal value. As a result of the performed analysis, the geometric shape of the ceramic insert is optimized. In the proposed design, the brittleness inherent in ceramic materials can almost be compensated by minimizing tensile stresses. Thus, the reliability and durability of the plain bearing increase. An original design of a plain bearing with a ceramic insert is proposed. This design allows advanced ceramic structural materials to be used in plain bearings, which extends the operational range of friction units. In order to overcome the fragility of ceramic materials, special design techniques should be developed to withstand tensile stresses through optimally selected tensions creating compressive stresses in the insert. Optimal tension parameters can be selected using numerical methods of stress-strain state analysis, in particular, the finite element method.