Xie Youbai

Advances in research on a multi-channel on-line ferrograph

This paper introduces the basic principle, functions and test results of a multi-channel on-line ferrograph. The instrument catches wear debris with an electromagnet, detects wear debris with a photoelectric sensor, and controls sampling and data processing with an 8098 single-chip microprocessor which can communicate with a master computer. The instrument has four sampling channels, which can monitor not only one machine but also four machines one by one. The software of the instrument includes five modules which are a main program, a keyboard control program, a floating point operation program, a serial communication program and a self-checking program. The results of experiments on a gear box show that increasing average values detected by the instrument correspond to increasing load, so the instrument can meet the need for on-line monitoring of the wear condition of machines.

Revision to the concept of equilibrium concentration of particles in lubrication system of machines

Abstract This paper analyzed the numerical characteristics of distribution function of particles concentration in oil cycle system of machines by solving the stochastic differential equation, then revised the concept of equilibrium concentration of particles and put forward a new concept-stationary concentration. It is proven that the particle concentration in a machine tends towards a wide-stationary process from a non-stationary process in the condition that the running parameters are constant and the white noise is introduced as a random component. The statistics histogram of data distribution obtained by on-line ferrograph showed different distributions depending on whether running parameters are varied or constant, and it confirms the theoretical analysis. Eventually, a new oil sampling concept is advanced for oil condition monitoring and ferrography. That is oil sampling should be on-line sampling or of larger volume (> 100 ml) for off-line sampling in order to get the time mean and space mean.

Two-body microcutting wear model part IV: theoretical analysis of friction

Abstract The theoretical analysis of friction between surfaces considering both ploughing and adhesive effects is presented. It is shown that, when considering both ploughing and adhesive effects, the friction coefficient is generally dependent on the load and the topographies of two surfaces in contact. However, if the differential of the profiles of hard surfaces is independent of the profiles itself, the coefficient of friction will be independent of the load. When the mean tangent of the surfaces is less than, for example, 0.04, the ploughing effect may be neglected.

Two-body microcutting wear model part III: Stable profile height distribution of a worn surface

Abstract It is known that the profile height distribution for worn surfaces eventually reaches a stable state. We call the stable state the stable profile height distribution (SPHD). The expressions for the SPHD are given for two conditions: 1. o 2. (1) there is no relative normal motion between the two sliding surfaces; 3. (2) the load is constant throughout the wear process. Results for numerical examples of the expressions were compared with those obtained by the recursive method. Both results agree well with each other, from which it can be concluded that both methods are correct.

Effects of phosphorus-free antioxidants on oxidation stability and high-temperature tribological properties of lubricants

Oxidation stability plays an important role on the engine oil service performance. In this paper, the phosphorus-free antioxidants of diphenylamine, hindered phenol and dibutyldithiocarbamate, combined with zinc dialkyldithiophosphate were added as antioxidants in the base oil and the fully formulated 5W-30 oil, and the oxidation stabilities were evaluated by pressurized differential scanning calorimetry and Romaszewski oil bench oxidation standard tests. Meanwhile, the tribological properties of the fresh and aged oils were evaluated by a SRV tribo-meter. The results indicated that (i) an optimal ternary complex antioxidant of dibutyldithiocarbamate: diphenylamine: hindered phenol (ratio of 2:1:2) displayed good antioxidation property, and (ii) the fully formulated 5W-30 oil containing optimized ratio phosphorus-free antioxidants had better tribological properties than the commercial SN 5W-30 oil.

Tribological Performances of Molded Micro-Cratered Surface of Superelasticity TiNi Alloy

Abstract The micro-crater texture of TiNi alloy was voluminously indented by a mold. Results show that the geometrical parameters of the texture will modify the tribological properties. With increasing of the circumferential pitch and the radial spacing of texture, the friction coefficient and wear rate of TiNi alloy present a decrease at the start, and then an increase after a minimum point. With gradual increasing of the ratio of depth to diameter, the friction coefficient and wear rate of TiNi alloy increase initially and then tend to decrease. When the sliding speed increases, the friction coefficient of TiNi alloy decreases firstly and then increases, following Stribeck curve. With the selected texture parameters such as micro-crater ratio of depth to diameter of 0.06, the radial distance of 1.5 mm, circumferential pitch of 15°, the surface show the best tribological properties of the friction coefficient of 0.098 and wear rate of 0.87× 10−5 mm3/N·m. It is concluded that the texture with appropriate parameters and shapes can reduce the friction coefficient and wear because of micro-hydrodynamic lubrication and the capture of wear debris from micro-crater texture.

Study on distributed knowledge information system for product design

To overcome the limitations of commercial CAD and handbook form of knowledge expression, the Distributed Knowledge Information System (DKIS) for product design is proposed. The structure of DKIS and the key issues in its implementation are introduced; the method of knowledge store and transfer of DKIS is discussed. The mechanism of knowledge representation, acquisition and utilization, based on Internet network, is achieved. Based on the concept of function driven, integrated Artificial Neural Networks and Active Server Pages techniques, transplanting the trained ANN into DKIS system, a new method for retrieving knowledge in DKIS over Internet is achieved. Finally, a prototype of DKIS is developed to demonstrate the feasibility of the structure and constructional method of DKIS. The work provides a scheme for speed knowledge acquisition and shortens the cycle of product development.To overcome the limitations of commercial CAD and handbook form of knowledge expression, the Distributed Knowledge Information System (DKIS) for product design is proposed. The structure of DKIS and the key issues in its implementation are introduced; the method of knowledge store and transfer of DKIS is discussed. The mechanism of knowledge representation, acquisition and utilization, based on Internet network, is achieved. Based on the concept of function driven, integrated Artificial Neural Networks and Active Server Pages techniques, transplanting the trained ANN into DKIS system, a new method for retrieving knowledge in DKIS over Internet is achieved. Finally, a prototype of DKIS is developed to demonstrate the feasibility of the structure and constructional method of DKIS. The work provides a scheme for speed knowledge acquisition and shortens the cycle of product development.

The deformation behavior of TiNi shape memory alloy under axial dynamic compression

The deformation behavior of Ti-50.9 at % Ni shape memory alloy under axial compression dynamic loads was investigated by an MTS 858 Mini Bionix test machine. The alloy were aged at 500°C for an hour before being machined into specimens. The compression experiments were conducted at 20°C and the variety of dynamic loads were controlled by the strain rate, which was 3 mm/min, 15 mm/min, 30mm/min and 50 mm/min, respectively. The experimental results indicate that in the case of 3 mm/min, stress-induced martensitic transformation occurs at about 350 MPa when loading and reverse transformation at about 200 MPa when unloading, during which the aged Ti-50.9 at % Ni alloy shows the recoverable nonlinear pseudoelastic strain of 4.3% with the residual strain of 1.2% reserved. With the strain rate increasing, the area encloses by loading-curve and unloading-curve, i.e stress (strain) hysteresis becomes smaller and smaller and the residual strain also decreases, while critical stress for inducing martensitic transformation rises. At a higher strain rate the alloy exhibits linear-like pseudoelasticity, which is up to 4.5%.

An on-line condition monitoring system linked by fibre-optic digital network

This paper introduces the basis structure and major function of an on-line condition monitoring system linked by a fibre-optic digital network. Fibre-optic digital networks have obvious advantages to larger enterprises with various locations for condition monitoring data transmission, which not only is an information highway between the main station (diagnosis enter) and substation (monitoring locations), but also combines the monitoring functions into one system. This is a two-level condition monitoring system. The first level monitoring is realized by a sub-station and the second level monitoring is realized by the main station. The system has strong hardware functions and software functions, which became a new model of real-time condition monitoring and was used in many oil refineries.