Study On Fractal Characterization, Reconstruction And Tribological Behavior Of Surface Wrinkle

In the field of tribology, surface texture is one of the effective ways to enhance theload capacity of surface and improve the tribological behavior by fabricatingmicrostructure on friction surface. As one kind of surface texture, surface wrinkle havegot much more attention in these years. In this paper, the fractal characterization,reconstruction and tribological behavior of surface wrinkle was studied.By replicating the wrinkle patterns on ginkgo leaf, the specimen with wrinklepatterns on PDMS was fabricated. The DLC/PDMS specimen was fabricated bydepositing thermal DLC film on PDMS. Then different kinds of wrinkle patterns onPDMS were obtained. By fractal image processing method of PIFS, different kinds ofwrinkle pattern surfaces were characterized. The results of characterization show thatthe frequency distribution of rotation coefficient represents the orientation of wrinklepatterns and scale coefficient&FD-PIFS represent the density of wrinkle patterns.Reconstruction of surface wrinkle image was realized by MATLAB language, andthe reconstruction image can be revised by changing the characterization coefficient. Inorder to operating different surface wrinkle patterns in parametric way, one software tocharacterize and reconstruct the surface wrinkle was designed. Coordinates of the pointcloud was obtained by the software, which was used to build3D digital model ofwrinkle patterns. The results show that the image obtained by PIFS completes thedetails of original image, and the3D model based on the PIFS image is closer to the realsurface wrinkle patterns.The contact status between PDMS and steel ball under different load, structuralparameters and etc. were obtained by Workbench. The analysis results show thatwrinkle patterns reduce the contact area between PDMS and steel ball. The frictionbehaviour between PDMS and steel ball under different load, velocity and etc. werestudied by using CETR UMT machine. The test results show that wrinkle patternsreduce the friction coefficient between PDMS and steel ball. And the comparisonbetween the results of experiment and simulation shows that the friction coefficientbetween PDMS and steel ball is proportional to their contact area when it is under lowvelocity. The effect of wrinkle patterns on surface wetting properties was studied byusing GonioStar-150machine and the test results show that wrinkle patterns of ginkgomakes the surface of PDMS more hydrophobic.