Liangcai Zeng

Series of disc-on-disc experiments are conducted to investigate the lubrication performance of fully/partially textured surface. All tests were conducted on a rotational rheometer under different conditions, which combined with different rotation speeds and different lubricants. Contact angle of three samples has been measured to research the relation between surface wettability and lubrication property.

In this study, static contact angle measurement experiments were conducted on smooth copper surface and microchannel structure surfaces under different droplet sizes. The results showed that shallow processing will more easily lead to the deformation of the processed interface. And the wettability of the microchannel surfaces with the same width and different depth were obviously different. Moreover, the contact angles on three microchannel surfaces were almost the same when the size of droplet was 12μl duo to action of gravity. The optimal droplet size is 9μl to measure contact angle in this study.

Reducing friction and wear in contact pairs is a formidable challenge in engineering applications. In this study, the influence of different particle distribution parameters on the flow field for elastohydrodynamic lubrication (EHL) friction pairs is analyzed using a multigrid method. In particular, the effects of the particle distribution density and location on the tribological properties are examined. A general Reynolds equation for an arbitrary non-Newtonian fluid is used to account for the non-Newtonian properties in the contact area. An inclusion-EHL model is established by coupling the flow field with the elastic field of heterogeneous particles below the contact surface, which are subject to eigenstrains. The results illustrate that the distribution density of the particles causes fluctuations in the film pressure and thickness and that the spacing ratio and position of the symmetry center have serious effects on the traction force. It is also found that the traction force can be effectively reduced by using a reasonable set of particle distribution parameters.

A numerical solution for line contact elastohydrodynamic lubrication (EHL) occurring on the rough surface of heterogeneous materials with a group of particles is presented in this study. The film thickness disturbance caused by particles and roughness is considered into the solution system, and the film pressure between the contact gap generated by the particles and the surface roughness is obtained through a unified Reynold equation system. The inclusions buried in the matrix are made equivalent to areas with the same material as that of the matrix through Eshelby’s equivalent inclusion method and the roughness is characterized by related functions. The results present the effects of different rough topographies combined with the related parameters of the particles on the EHL performance, and the minimum film thickness distribution under different loads, running speeds, and initial viscosities are also investigated. The results show that the roughness morphology and the particles can affect the behavior of the EHL, the traction force on a square rough surface is smaller, and the soft particles have more advantages for improving the EHL performance.

The impact of the size distribution of the reinforced particles on the mechanical properties of composite materials is studied, according to the corresponding parameters, the finite element model of the composites on the model of Al based SiC composites is established. With the method of finite element simulation, the surface displacement and stress distribution of particle reinforced composites whose surface is pressed by a line uniformly load is solved, the effects of reinforced particles buried depth, length to diameter ratio, the young’s modulus ratio of matrix and particles, and rotation angle on the mechanical properties of composites are also analyzed The article outlines concrete influences of the structure parameters and spatial distribution parameters of particles which distribute in the composites on the surface displacement and stress distribution of the composites.

Appreciable friction and serious wear are common challenges in the operation of advanced manufacturing equipment, and friction pairs may be susceptible to damage even with oil lubrication when point contact exists. In this study, a type of particle-reinforced composite material is introduced for one of the components of a heavy-load contact pair, and the performance improvement of elastohydrodynamic lubrication (EHL) is analyzed considering the rheological properties of non-Newtonian fluids. The Ree–Eyring EHL model is used considering the surface of the particle-reinforced composite, in which the film thickness includes the particle-induced elastic deformation. The problem of inclusions with different eigenstrains is solved by using Galerkin vectors. The influences of particle properties, size, burial depth, and interparticle distance on point-contact EHL are investigated. Furthermore, using several cases, the structural parameters of the particles in the composites are optimized, and an appropriate parameter range is obtained with the goal of reducing friction. Finally, the results for the EHL traction coefficient demonstrate that appropriate particle properties, size, burial depth, and interparticle distance can effectively reduce the traction coefficient in heavy-load contact.