Influences of hard particles lying in the lubrication region between piston ring face and cylinder wall, including the effects of a non-contact particle and contact particle, on tribological performances of the piston ring were numerically analysed. A modified Reynolds equation incorporating a non-contact particle effect was presented. The total friction force, deformation, and contact stress of the ring, with a non-contact particle and contact particle consideration, were solved separately by using finite-element program code of the authors and software ANSYS 5.7. The numerical results show that obvious changes in the total friction force and deformation of the ring can occur, if the diameter and height across the film thickness of a non-contact particle and axial velocity difference between the non-contact particle and ring are considered. The maximum contact stress of the ring is obviously affected by the contact particle's interfering time and velocity, and hardness value of the plastically deformed particle.

A dynamic modelling method for the piston-crankshaft system in an internal combustion engine, including two-dimensional oil-film forces of the piston pack, was proposed. In order to obtain the dynamic performance of this system, the dynamic equations for the components in the system were presented. Meanwhile, a radial base function neural network technology was employed to reconstruct the two-dimensional oil-film forces, which are then coupled to the presented dynamic equations for the components. The validity of the proposed modelling method for the piston-crankshaft system was demonstrated, and conclusions concerning the dynamic performance of the system were drawn. INTRODUCTIONlubrication performance of the piston pack provide more useful information for evaluating the dynamic properties of the piston-crankshaft system, and Investigations into the dynamic behaviour of the further for the safer and economical design of a new piston-crankshaft system in an internal combustion type of engine. However, even so, the theoretical engine, which consists of components such as the results usually show a large difference from the perpiston skirt, piston rings, connecting rod, crank and formance under the real operation condition of an main crankshaft, have been carried out for a long time engine. The major cause is that the one-dimensional for the purpose of reducing frictional power losses Reynolds lubrication equation cannot accurately by the piston pack and prolonging the lifetimes of characterize the lubrication behaviour of the piston these components. Much work has focused attention pack and further affects the accurate evaluation of on studies of the behaviours of the above-mentioned the dynamic performance of the piston-crankshaft individual components, e.g. by the analysis of their system. Although employing the two-or threedynamic or tribological performances. Examples dimensional Reynolds lubrication equation is a better involved can be found in the published literature. In way to investigate the lubrication behaviour of the more recent studies [1-3], a systematic approach, piston pack, doing this is difficult because simulconsidering appropriate sets of coupled dynamic taneously solving the dynamic equations for the above equations for these components and one-dimensional components and the two-or three-dimensional Reynolds lubrication equation for the piston pack Reynolds equation for the piston pack entails an (including the piston skirt and piston rings), was excessively time-consuming computation process. In applied to investigate the dynamic behaviours of order to overcome the difficulty in accurately and these components. These studies considering the quickly obtaining the oil-film forces for the piston of the piston-crankshaft system, a new modelling method of the piston-crankshaft system, considering 100084, People's Republic of China. email: fmmeng@xjtu.edu.cn JAUTO256