# Study on Lubrication Performance of Journal Bearing with Multiple Texture Distributions
## 6 Conclusions  
The potential use of the spherical texture is studied in terms of the effects of texture type and parameters on the bearing lubrication performance. A theoretical model of a textured bearing is developed and validated. A novel convex-concave composite texture is proposed after discussing the effects of texture depth and area density on the load capacity and the friction coefficient of the bearing. The performance of the composite texture is then simulated and compared with the convex texture. The main conclusions can be drawn as follows:  
1. The load capacity of the concave spherical textured bearing is lower than that of the plain bearing, and the friction coefficient is hardly affected by the concave texture. The convex spherical texture can increase the bearing load capacity and friction coefficient at the same time, but the reduction in friction coefficient is fairly slight.
2. The concave-convex composite spherical texture can improve the load capacity and the friction coefficient of the bearing. In contrast to the convex texture, the beneficial effect introduced by the composite texture on the friction coefficient is as significant as that on load capacity.
3. In addition to the load capacity and the friction coefficient, the oil film region is expanded in the composite texture case, as well. That is to say, the proposed convex-concave composite texture has significant potential for lubrication improvement of the bearing.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Texture Types** & \(W\) **(KN)** & \(\Delta W\) **(\%)** & \(\mu\) & \(\Delta\mu\) **(\%)** \\ \hline Plain (baseline) & 1.09 & 0 & 0.073 & 0 \\ Convex & 1.22 & +11.93 & 0.072 & \(-\)1.4 \\ Concave-convex composite & 1.22 & +11.93 & 0.066 & \(-\)9.59 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Load capacity and friction coefficient of bearings with the optimal parameters.  
Figure 9: Circumferential oil film pressure distribution.  
**Acknowledgments:** The authors wish to acknowledge the financial support from the National Key R&D Program of China (2016 YTD0700701).  
**Author Contributions:** [PERSON] developed the bearing models with textures and conducted the analyses; [PERSON] contributed analysis tools; [PERSON] wrote and revised the paper; [PERSON] developed the baseline bearing model.  
**Conflicts of Interest:** The authors declare no conflict of interest.  
**Nomenclature**  
**Parameters and Variables**  
\(c\) & radial clearance  
\(e\) & eccentricity  
\(F\) & friction force  
\(h\) & film thickness  
\(h_{0}\) & film thickness of the untextured bearing  
\(h_{p}\) & texture depth  
\(L\) & width of the journal bearing  
\(m,n\) & number of grid points along \(X\) and \(Z\) directions  
\(M,N\) & number of meshes along \(X\) and \(Z\) directions  
\(O_{1},O_{2}\) & centers of the journal bearing and the shaft  
\(p\) & film pressure  
\(R,r\) & radii of the journal bearing and the shaft  
\(r_{b}\) & base radius of the spherical texture  
\(U\) & relative linear sliding velocity of the bearing and the shaft  
\(W\) & total load capacity  
\(W_{X},W_{Y}\) & load capacities along \(X\) and \(Y\) direction  
\(x,y,z\) & local coordinates of the mesh along \(X\), \(Y\) and \(Z\) directions  
\(X,Y,Z\) & coordinates of the bearing along circumferential, radial and axial directions  
\((x_{0},z_{0})\) & coordinates of the texture center  
\(\Delta W\) & ratio of the load capacity between the textured bearing and the smooth bearing  
\(\Delta\mu\) & ratio of the friction coefficient between the textured bearing and the smooth bearing  
\(\varepsilon\) & eccentric ratio  
\(\eta\) & dynamic viscosity of lubricant  
\(\mu\) & friction coefficient  
\(\tau\) & shear stress of the slip plane between the friction pairs  
\(\psi\) & angle between the load coordinate and the centerline \(O_{1}O_{2}\)  
\(\omega\) & angular velocity of the shaft