Lubrication by tiny oil drops shows its advantages over traditional ways in the aspects of energy conservation and environmental-friendliness. However, fundamentals of this kind of lubrication have to be fully understood if more progress will be made in this lubrication technique. Thus this project is proposed and devoted to the study of micro-liquid drop spreading and its lubrication behavior between the confined gaps in a tribo-pair:

1. To build an optical system for visualizing lubrication film building by micro-liquid drops;

2. to observe the adhesion and spreading of micro-liquid drops under confined gaps and shear;

3. to study the non-steady/non-continuous lubricating film building by micro-liquid drops;

4. to numerically simulate the lubrication behaviors by micro-liquid drops.

This project will present a model describing micro-liquid drop lubrication considering thin film flow, interface effect and hydrodynamic effect, which will definitely provide new data for its further application in MEMs, high-precision bearing and other conponents.

With the rapid progress of interface science, the liquid film lubrication are being re-examined in the tribological design of micro-devices with sliding contacts. For the control of this kind of lubrication, the applicant and several other researchers have proposed a new device which makes use of interface slippage to generate hydrodynamic effect. Through the surface tension/energy modification of the stationary inlet surface, its heterogeneous affinity to the lubricant is achieved and its resistance to liquid flow is reduced at the inlet. Therefore without the classical geometrical wedge, hydrodynamic action can be generated by this heterogeneous slip, and this is termed as slip-step effect. Due to limited experimental techniques, this postulation has never been validated. Thus this project is proposed for studying this slip step effect under conditions of conformal lubrication at micro/sub-micro film thickness, including:     1) Development of a measuring system for lubricating films in a slider-on-disc conformal contact.                                         2) Preparation of low-affinity surfaces and slip-step surfaces;                                           3) Experimental validation of slip-step effect and its parameter study.                                 

4) A novel approach to evaluate the film interface slippage by a step bearing and building of a new slip model.                        5) Numerical simulation of the slip-step effect in lubricant film lubrication in conformal contacts with the proposed lubricant film slip model. This project will be among the first to validate the slip-step effect, and the proposed theory will provide new approaches to the lubrication design of MEMs and biomedical engineering.

People more and more pay attention to improve the national vehicle’s high speed performance in China. This project will avoid the problem of driver model parameter uncertainty, transform the problem of vehicle minimum time handling into the optimal control, establish the inverse dynamics model of vehicle minimum time handling, and get the handling input model of driver's steering wheel using the direct parallel - Sequential Quadratic Programming mixing. Considering the factors of safety, time, driver, this project will build the simulational objective evaluation index model of minimum time handling performance using mathematical modeling methods, based on real vehicle testing estimate the subjective evaluation model of vehicle minimum time handling performance by multi-level fuzzy comprehensive methods, and verify the rationality of objective and subjective evaluation model adopting regression method to replace the subjective evaluation by objective evaluation, and optimize the structural parameters reflecting the vehicle minimum time handling performance using genetic algorithm. Research results can provide new ideas and methods for vehicle handling dynamics, and provide theoretical basis for improving national vehicle high speed and safety, thus have important scientific significance. Moreover, the results can provide theoretical guidance for the training of race car drivers, and apply to performance design of high-speed vehicles, thus have a good prospect.

Active screen plasma nitriding (ASPN)is a new surface modification technology developing on the basis of traditional direct current plasma nitriding(DCPN).It can overcome many process problems existing in the DCPN.There are two sets of direct powers in the ASPN,which are the main power and the bias power.The main power was connected with active screen and the bias power was connected with the samples.A special pattern of double glow discharge was formed in ASPN,which is different from other tradition double glow diacharge technologies.It was showed that the pattern is the key to overcome the all kinds of process problems in DCPN.There are few reserches and porters related to this special double glow discharge.Many experiments and theory analysis was to be carried out in our project in order to make clear the regularity of bias power under the different condition of the mian glow discharge.In our project the influence between the glow discharge by main bias and by the bias was compared.And the characteristics of the plasma sheath formed by the bias were explored in order to establish the model and theory about this plasma sheath.It is very important for ASPN technology that all kinds of particles collide with each other and transport in the bias plasma sheath.The influence of this special discharge pattern and the plasma sheath on ASPN technology was analysed.By our project,it can make further efforts to study the mechanism of the ASPN technology.It can be helpful to make optimal process parameters.And It also can be used to provide reference to all kinds of technologies based on low temperature plasma.

   With exploration for the proposed strategy of liquid film lubrication in miniature devices and measures of less lubricant usage in precision mechanical units, lubrication with limited lubricant supply (LLS) has attracted more and more attention. Enhancing lubricant replenishment on the lubricated surfaces is a key in the LLS lubrication, however there is knowledge vacuum in this area. Therefore this project is proposed for an idea of functional surfaces with enhanced lubricant replenishment by patterned wettability to achieve desired lubricant migration and distributions with different surface-to-volume ratios for efficient lubrication under flat-on-flat contact. The main work will include: 1) To develop a fluorescence-based measuring system for lubricant distribution on the lubrication track. 2) To investigate the influence of surface wettability on oil film thickness and friction of flat-on-flat contact with limited lubricant supply. 3) To study design principles of the functional surfaces with enhanced lubricant replenishment for lubricant distributions of stripes, meshes and droplets. 4) To experimentally study the lubrication behaviors with limited lubricant supply under functional surfaces with enhanced lubricant replenishment. 5) To build a mathematical model for theoretical analyses of thin hydrodynamic lubrication with limited lubricant supply, and thereafter to study the mechanism of the functional surfaces with enhanced lubricant replenishment. In this project the effect on oil lubrication of the functional surfaces with enhanced lubricant replenishment will be first-ever demonstrated. And in the meaning time the relationship between the lubricant quantity and the parameters of the functional surface under efficient lubrication will also be presented. The theory and the data obtained will be beneficial to the tribological design of liquid lubrication, and of course contribute to the energy saving and environmental protection.

With the development of surface science and technology, it is possible for wall slippage to be one important approach for active control of oil film ubrication. However, due to the lack of an efficient method, the wall slippage of lubricating films cannot be observed directly in laboratories. At present,film squeeze forces are employed to predict the wall slippage under some conditions which cannot be applied to engineering practices. This proposed project aims to present a novel method for wall slippage measurement. Visulization of the wall slippage is achieved through the fringe movement of an entrapped impact oil film by interferometry. Direct measurement of wall slippage of lubricating film under high pressures can be attained.The project includes: 

1. to study the measurement principle, to understand the kinematic relationship between the oil core and the solid surfaces, to determine the characteristic parameters for wall slippage;    

2. to develop the measuring system;               3. to investigate the effect of pressure, shear rate and surface properties on the oil film wall slippage, and to validate previuos postulations of wall slippage employed as mechanisms for friction modifiers and related abnormal lubricating films;             4.to propose a model of oil film wall slippage, and to reveal the flow of lunbricating oils within the contact region. Success of the proposed research will provide a new means for studying wall slippage of lubricants in highly pressurized contacts, allow more fundamental understanding of the wall-slippage and present basic data to facilitate control strategies for lubrication and traction in high-precision microdevices.

The proposed project is aimed at the slippage viscosity wedge in thin film lubrication. The slippage viscosity wedge is here referred to as the drastic drop of effective viscosity of a thin lubricant layer immediately adjacent to the bounding surface. The project includes: a. to develop a measuring system based on multi-interference intensity and phase change for accurately evaluating micro\nano oil film thickness and any tiny film thickness variation; b. to experimentally study the effect of slippage viscosity wedge, which may be changed by ZEV pre-running or surface modification, on thin film lubrication under line and point contact; c. to investigate the effect of ZEV prerunning on the slippage viscosity wedge and to carry out SPM analysis for the purpose of characterizing the boundary film in the view of micro-tribolgy; d. to propose a physical model of limited boundary slippage and perform related lubrication numerical analyses. As the possible output, new approaches for the lubrication control of micro- and ultraprecision machines will be explored by the slippage viscosity wedge. In the meaning time, experimental validation of an abnormal theoretical EHL film shape will be given for refreshing the existing EHL theory. The project will be a contribute to the fundamental understanding and practical engineering in tribology.

The boundary slippage condition is crucial in the analysis of liquid flow on the micro-nano scale. The related research is considered to be one of the promising direction of the mechanical development in the near future. However, it is still unknown whether the slippage occurs at the solid-liquid interface or the fluid inside under high pressure conditions.The uplifting news is that an anomalous Elastohydrodynamic Lubrication Film(EHL) shape characteried by an inlet dimple is experimentally obtained by our team group and find that friction coefficient curve deviates from the classical Stribeck curve when taking the inlet dimple into consideration. We conjecture that some observed abnomal EHL films and friction behavious under large slidings could be tentatively related to boundary slippage. Unfortunately these proposed boundary slippage could not be confirmed because of the lack of theoretical analysis.So this project aims to study the mechanism based on the slippage phenomena of highly pressurized EHL.Equivalent ultra-low viscosity pseudo boundary slippage model instead of limit shear stress rheological model and continuous conditions is set with the aid of viscosity-temperature relationship interface.Contact beam interferometry technology with impact oil technology, a new method is expected to design in order to measure the occurrence of boundary slippage,so that the influences of the influences of pressure, surface energy, entrainment velocity will be explored.The influence of boundary slippage will be refered to design the friction measurement system and solve the effect of bearing revolute pair on the friction measurement results. A new model is built by the experiment observed the abnormal friction change.So it can reveal the abnormal friction mechanism and correct the classical Stribeck curve and provide some references on lubrication problems in engineering.

The technique with fixed oil amount feeding has primarily used in high speed bearings lubrication. However, at high speeds, the lubricant will discretely distribute on bearing surfaces due to splash and poor adhesion. This distribution pattern is negative for lubricant replenishment, resulting in low performance of bearings and mechanical parts. Therefore, considering the distributions of droplet-shape lubricant, it is attempted to build a wettability gradient surface to induce the lubricant motion and replenishment. The purposes of this proposal are to enhance the utilization of lubricant and to regulate the lubrication of rolling bearings.

   Water-lubricated bearings have proven to be simple in structure, and environmentally friendly, but the bearings are prone to wear and noise due to poor lubrication by the extremely low viscosity of water. This project thus proposes a concept of enhancing water lubrication with micro oil droplets as the second lubricant agent. When the water lubrication in the bearings is poor, it is anticipated that the second lubricant agent can correspondingly improve the bearing lubrication, and reduce wear and eliminate noise. The project will study the supply of micro oil droplets into the water medium, and carry out theoretical and experimental researches on the water lubrication with micro oil droplets as the second lubricant agent. Upon on the success of the project, a new water-lubricated bearing prototype, with completely independent intellectual property rights, will be obtained, which can contributes to the marine equipment and ship safety.