## 5 Conclusions  
(1) To improve the friction performance of the piston, the diameter \((D)\) of the cylindrical pit should not be too large or too small. With the increase in \(D\), both \(F+\) and \(F-\) showed an initial upward trend followed by a decrease, reaching the minimum at \(D\) = 1.5 mm. The best friction performance of the piston was achieved with \(H\) = 0.5 mm. An excessively large cylindrical pit depth \((H)\) adversely affects the friction performance. When the number \((N)\) of cylindrical pits set to 36, the friction performance of the piston was better.  
(2) Under the conditions of a pressure of 0.5 MPa and 200 strokes per minute, the piston with cylindrical pit arrays can significantly reduce the wear rate \((w)\), increase the service life \((L)\) of the piston and also obviously reduce the temperature of the friction pair compared with the standard piston. The wear amount \(m\) of pistons 4, 13 and 22 was  
Figure 16: Contact pressure of standard and textured pistons.  
Figure 17: Piston and cylinder liner after test: (**a**) standard piston and (**b**) piston 4.  
reduced by over 50%, resulting in an improvement in their lifespan \(L\) of at least 30% or more. The temperature of the textured pistons was reduced by around 5-10 \({}^{\circ}\)C.  
(3) The maximum deformation \((x)\) of the piston with cylindrical pit arrays was small. Piston 4 showed the most significant decrease in its maximum deformation, with a reduction of 25.49%. And the maximum equivalent stress \((y)\) was distributed near the cylindrical pit, which could reduce the phenomenon of piston squeezing. The maximum equivalent stress of textured piston 4 decreased by 15.67%, while the \(y\) values of the other three textured pistons increased by no more than 10%. The maximum contact pressures of the textured pistons showed slight variations, with some increasing and others decreasing.  
(4) The cylindrical pit arrays can not only provide secondary lubrication but also capture part of the abrasive particles to reduce the three-body wear of the friction pair.  
Methodology, T.G.; Validation, T.G.; Resources, Y.W.; Data curation, H.C.; Writing--original draft, T.G.; Writing--review & editing, H.C. and D.T. All authors have read and agreed to the published version of the manuscript.  
This research was supported by the National Natural Science Foundation of China (Grant No. 52205309) and the Nanjing University of Science and Technology under Award No. AE89991/383.  
The data that support the findings of this study are available from the corresponding author upon reasonable request.  
[PERSON] would like to acknowledge the support from the Project of Philosophy and Social Science Research in Colleges and Universities in Jiangsu Province under Award No.2023 SJYBO015 and the 2022 High Level Innovation and Entrepreneurial Research Team Program in Jiangsu (JSSCBS20220262). [PERSON] would like to acknowledge the support from the Fundamental Research Funds for the Central Universities (No. 30922010719). We would like to thank [PERSON], [PERSON] and [PERSON] for their valuable contributions to this research.  
The authors declared no potential conflict of interest with respect to the research, authorship or publication of this article.