Papers by Keyword: Point Contact

Abstract: Internal lubrication condition affects dynamic characteristics of rolling ball bearing in operation.According to the calculating problem of the elastic fluid lubricant film stiffness in point contact zone, the oil-film stiffness calculation model was set up based on the elastohydrodynamic lubrication theory (EHL) ,which considers the oil-film distribution and the pressure characteristic of the whole contact region. The stiffness of the oil-film was obtained from this model and compared with the experiment. The results indicate that the data calculated by the model fit the experiment very well, improving the calculation accuracy of the oil-film stiffness.

Abstract: The interaction between vibration and friction exists widely in the mechanical system. In order to research the effect of the vibration amplitude on the contact point friction in the mechanical system, a new apparatus is developed independently to measure the point contact friction influenced by the changing amplitude. The data acquired through the apparatus show that the friction at the contact point decreases with increasing of the amplitude. In terms of theoretical analysis in this paper, the increasing of the amplitude actually reduces the contact area at the point. In addition, the friction at the contact point is proportional to the contact area. So, the friction decreases with the decreasing contact area caused by the increasing amplitude.

Abstract: A new kind of involute planetary gear drive with small teeth difference which meshes in point contact is put forward based on the kinematic method of gear geometry in this paper. The generation principle of tubular tooth surface is proposed according to a selected smooth curve attached to the planetary wheel tooth surface. The general equations of conjugate tooth surfaces are derived and its conjugated contact curve on the internal gear is also determined. Then the mathematical model is established. The parameter selection and meshing characteristics of point-contact involute planetary gear drive with small teeth difference are discussed respectively. The three dimensional model is finally established and its motion simulation is worked out. It lays the significant theoretical foundation and practical meaning for improving the gear transmission performance.

Abstract: In this article, a new type of visualizer for point contact flow field has been developed. The principle, constitution and application are introduced in details. The flow field of point contact area are captured and analyzed.

Abstract: Acoustic Emission (AE) signal has been used pervasively in the extraction of fault feature and the location of damage. The precision of the extraction and location is determined by the propagation characteristics of AE signal in different structures. In this paper, the propagation characteristics of AE wave in the point contact sphere under continuous and transient AE signal is analyzed; a series of experiments under different condition are conducted; based on wave propagation theory, a simulation model is built using the software of ANSYS LS-DYNA. The results of experiments and simulation models reveal that the propagation characteristics-attenuation, frequency features-of AE signal can be manifested clearly in the experiments and are simulated correctly by the simulation model.

Abstract: The elastic Euler buckling of an inextensible column is confined in a plane, and subject to fixed end displacement, in the presence of rigid, frictionless side-walls which constrain overall lateral displacements. The whole deflection is divided into some typical columns because of the symmetry. The governing equations of constrained buckling mode and deflection about axial load are deduced, based on linearized differential equation of beam. Point and line contact models are introduced to describe the behavior of the column in constrained buckling process, including load capacity, buckling wave and reaction force. The analysis on the deflection of column is helpful to the research about possible post-buckling paths.

Abstract: Thin film lubrication (TFL) and elasto-hydrodynamic lubrication (EHL) are different lubrication states, their lubrication mechanisms are different, but the transition from EHL to TFL is a continuous process at the aspect of film thickness change, it is important to establish a physical-numerical model that can be suited for both EHL and TFL. Based on rheological, the change of micro thickness is expressed by the change of viscosity, then the micro problem of TFL can be turn to macro problem. The adsorption layer is divided into two parts formatted by static contact and shear force in the calculation. In a given static adsorption film, other oil film parts will be comprehensive consideration, modified formula of the overall average equivalent viscosity is gained by the method of combining numerical calculation and experiment, then numerical model is established for both EHL and TFL. TFL and EHL typical characteristics and the effectiveness of the model can be obviously shown by the results.

Abstract: Two types of improved multi-grid composite wall called point contact multi-grid composite wall and light-steel skeleton multi-grid composite wall were proposed in this paper. In order to study the mechanical properties of improved multi-grid composite wall, the low-cycle reduplicative loading tests of 1/2 scale improved multi-grid composite wall were carried out. Through the analysis of testing phenomenon and final test results, the main failure patterns and failure processes of the walls were summarized, and the mechanical characteristics of improved multi-grid composite wall were discussed, then the seismic performance including bearing capacity, ductility, and hysteretic characteristics were researched. The experimental foundations were provided for the further theoretical research and application of improved multi-grid composite wall in practical application.