# Probabilistic Sensitivity Analysis of Wear Property for MEMS Gas Bearing
## 4 Conclusions  
In this investigation, the sensitivity of MEMS gas bearing performance to axial and circumferential wear was investigated in detail considering the rarefaction effect. In the actual operation of MEMS gas bearing, specifically, the following conclusions can be drawn from the analysis of this paper:  
Figure 19: Standard deviation of the eight dynamic coefficients.  
Figure 18: Damping coefficients distribution with wear in circumferential regions. (**a**) circumferential region 3. (**b**) circumferential region 4. (**c**) circumferential region 5. (**d**) circumferential region 6.  
1. An approximate mathematical model and calculation method for characterizing the wear of MEMS gas bearing' inner wall is proposed, and the statistical method is put forward to describe the static and dynamic characteristics of the MEMS gas bearing, then the sensitivity of bearing' performances to circumferential and axial wear is obtained.
2. When there is an axial wear, as the wear position moves from the bearing ends toward the center, the distribution points of static performance and the dynamic characteristic coefficients tends to be dense, indicating that the operating stability of the bearing is relatively stronger when there is wear near the axial center. The standard deviations of the eight dynamic coefficients tend to decrease as the wear position moves toward the center.
3. When there is a circumferential wear, the wear near the minimum film thickness area has a greater influence on the static and dynamic properties of the MEMS gas bearing. The standard deviations of the eight dynamic coefficients reach a maximum with the wear region near the minimum film thickness area.
4. For both the circumferential and axial wear states, in general, the correlation coefficients of the dynamic coefficients for each group are high, which means that the wear can be equivalent to a small perturbation.
5. According to the analysis results, in order to obtain better stability and dynamic performances of gas bearing, in the actual manufacturing process of gas bearing, a higher standard of smoothness and wear resistance should be imposed in the main loading region and the area near both ends.  
Some practical approaches can be adopted to resist wear. Firstly, in the actual operation process, periodic replacement of the bearing loading region can be applied to reduce the wear of gas bearing and make the wear of the whole bearing more uniform, which should achieve the purpose of improving the service life of gas bearing. Secondly, increasing the purity of the lubricant and preventing fine particles from entering the gas. Because the rotating speed of gas bearing is very high, these kinds of fine particles will impact the inner surface of the bearing at a very high speed, which will lead to wear and tear.  
Conceptualizeation, L.L., D.Z. and Y.X.; investigation, L.L.; methodology, L.L. and D.Z.; resources, D.Z. and Y.X.; software, L.L. and Y.X.; supervision, D.Z. and Y.X.; validation, D.Z.; writing-original draft preparation, L.L.; review and editing, L.L., D.Z. and Y.X.  
This research received no external funding.  
The authors declare no conflict of interest.