Tribological Behaviors Of The Ridge Shape Bionic Structure Surface Under Free Abrasive Wear

The free style grinding abrasion is one kind of attrition forms which occurs on many equipments and the mechanical spare part. Especially the farm machinery working part, having the contact with agricultural material including the soil in the work process, would wear-out to failure, which leads to the huge economic loss. The efficiency and the energy consumption of the farm machinery are decided by the operating type of farm machinery working part and the material. The friction attrition of the farm machinery working part agricultural material is one of the important factors affecting its efficiency and the energy consumption, and the working part's friction caused by the soil has the typical nature. At present, the research for the free style grinding abrasion focus in the characteristic aspect of material, in other words, it aims to develop different anti-friction materials in connection with the different grinding compound and the service condition of mechanical part. The free abrasive wear occurs on the working surface, and it not only due to material`s own properties but also closely related to the geometrical structure on the working surface that much large than roughness scale.The different geometrical structures can change the interface structure and dynamic characteristics that the two interact each other. Some biological organs showed excellent wear-resistance property in the high wear condition, which not only related to its genetic, but also directly due to the habit and living environment. The character is developed through hundreds of millions of years in order to adapt to the living environment. Therefore, the research on the free abrasive wear became a new content in the wear research field based on the biological surface wear-resistant geometrical structure. This research namely take this as a starting point, the biomimetic research was carried out based on the wear-resistant geometrical structure of pangolin scale and Chlamys farreri shell surface with ridges and the wear mechanism were systemic analyzed.The geometrical structure information of the two biological surfaces were collected Then point cloud data of the geometrical structure of the two biological surfaces were obtained using LSV50 3D laser scanning system and reverse engineering technology for the pangolin scale and Chlamys farreri shell. The point cloud was introduced into CATIA and then the data treatment was carried out, finally the coordinate data of the biological surfaces geometrical structure was got. After the two biological surfaces geometrical structure data points were fitted with the least square method, the result showed that the two curves have very similar mathematical feature, the two surfaces structure showed sine curve shape. So, the sine curve was used to fit the pangolin scale and Chlamys farreri shell surfaces geometrical structure 3D scanning data points finally the fitting curves and mathematical models were obtained.The biometrical geometrical structure sample and the mould were designed by Pro/E 3D modeling software. Three biometrical geometrical structure surface samples of different distribution distance with ridges and the 3D solid modeling mould were designed based on f ( x)= 3sin(0.4x). The mould 3D solid data was introduced into Mastercam and the executable processing program was compiled finally the bottom mould was manufactured.Three distribution distance (15.71mm,12.56mm,9.42mm)geometrical structure surface sample with ridges were prepared using JFY50 type special hot-pressing machine with hot pressing molding process, respectively taking phenolic resin, light calcium carbonate and zinc stearate as the substrate, filler and release agent. The free abrasive wear experiment was carried out using JMM type rotating-disk test machine. The result showed that the samples wear loss showes decreasing trend gradually from forward to backward. According to the wear condition of three ridges geometrical structure on the samples surface, the wear loss of the first ridge is serious, the second one is less, while the third one wear loss is least Orthogonal test method (L9(34) orthogonal table ) was used to process and analysis wear data.The influence factors including the distribution of geometrical structure, wear speed and particle size were studied by the variance analysis method. The result showed that the wear loss of geometrical structure samples surface with ridges increases with the wear speed and the particle size, but it decreases with the ridges distribution distance increases. The particle size effect is significant, the wear speed effect is less and the distribution distance is least in three effect factors. The significant level is successively B (particle size), C (wear speed) and A (distribution distance). Three significant levels of effect factor are all 0.01, and finally, the optimal experiment factors combination (B1C1A1) are gained.The wear loss of common flat samples and ridge geometrical structure samples are compared under the same experiment condition. The result showed that the wear loss of all ridge geometrical structure samples is lower than that of the common flat samples. Therefore, the ridge geometrical structure has excellent protective effect to the friction surface.The wear mechanism of ridge geometrical structure surface sample is scientific analyzed. The samples showed above result because of ridge geometrical structure which changed the kinematics characteristic and dynamic characteristics of particles on the sample surface. The rebound particles of the first contact sample surface and coming flow particles both offset after the two impacting each other, which leads to the particles quantity and probability of falling onto surface again decreasing, and the impulsive force and the kinetic energy are both weakened in different degree after contacting with surface. Finally, the wear loss is decreased. In addition, the vortex is produced at the ridges backward because of the periodical distribution of ridges on the sample surface, when the particle-fluid two-phase flow on the sample surface (solid wall turbulent shear flow) , the"air cushion mat effect"caused by the vortex and the particles of near the solid wall are comprehensive effected by viscous resistance, Saffman force and Magnus force strongly because of the effect, the speed and the impulsive force both decreasing, which leads to the reducing of wear loss.The simulation research of wear experiment process is performed. The result showed that the stress field and the speed field are both larger than that of others near the sample surface front-end, and the result show that the large impact speed lead to the large stress Finally, the"plough wear"to the sample surface is increased when the particles contact the front-end of sample surface Therefore, the wear loss of front-end is larger than that of the back-end, and the results are very similar to the conclusions of data analysis and mechanism analysis before. Those conclusions showed that the ridge geometrical structure obviously possess excellent wear-resistant property.