Papers by Keyword: Contact Pressure

Abstract: Knowing the stresses and pressures in the contact between two deformable solids is fundamental in order to optimize the strength and the lifetime of mechanical components such as bearings or gears. These constraints can be determined by the calculation (finite element method or Hertz theory) or by experimental methods such as photoelasticity. The objective of this study is to model and compute the stress field and contact pressure using 3D finite element software. The validation of obtained results is done by comparison with the classical results of the non linear Hertz theory between two deformable cylinders. An application to spur gears with a circle involute profile is done and also validate with the same Hertz theory.

Abstract: A hexagonal joint is mechanically analysed. A cross section of the receding contact between the male and female components is modelled as a plane strain problem. Particular attention is paid to the effect of the presence of fillets in the hexagonal male. Finite Element (FE) results show that, for each side of the hexagonal contact, the contact zone constitutes a small portion of the length of the hexagonal side, and separation occurs elsewhere. The normalized peak contact pressure and the contact length along the male sides are numerically evaluated.

Abstract: The novel geometry of a gasket’s cross-section to optimize the sealing performance was proposed in spite of corrosion of its counterparts or tilted assembly. EPDM was applied for the rubber material and the sealing performance including stress, strain and contact pressure was estimated by finite element analysis (FEA) in both cased of normal and tilted assemblies. If the gaskets were to be normally assembled in the grooves, both gaskets (single-point contact and double-point contact) could be utilized for sealing systems. Even at the tilted assembly, the double-point contact gasket showed two discrete contact pressure areas; thus it could maintain its sealing performance over time at various operating conditions, compared to the single-point gasket.

Abstract: The contract model of the freight ropeways bearing cable and the saddle is established by FEM software, and the simulation calculation is carried out. The calculating formula for total contact pressure is fitted from the analysis result. According to setting requirement of the freight ropeway, simulation calculations of the different bearing cables are carried out under different operation conditions, and the relationships are obtained between contact pressure and influent factors, such as curvature radius of the saddle, the envelope angle and the drawing force. The results shows that contact pressure is in inverse proportion to the curvature radius of the saddle, in direct proportion to envelope angles and drawing force of the cable. Friction force between the bearing cable and the saddle made of nylon, bronze and steel three different materials are summarized through field test, and the friction coefficients applicable to the saddle of different material are obtained in combination with simulation results of the touch models.

Abstract: Accurate prediction of the material removal rate (MRR) distribution is very important for the control of the polishing process. However, the widely used prediction method of MRR based on the Preston equation is still incapable of predicting the roll-off phenomenon in polishing process. One of the reasons is that many of the researchers’ neglected the effect of the surface profile of the workpiece on the MRR. In this paper, the evolutionary process of MRR distribution with the change of surface profile using two different polishing pad is studied, it is found that MRR varies gradually with the change of surface profile and tends to be uniform finally. Based on the analysis of contact pressure considering the actual surface profile of workpiece and modified Preston equation, the distribution of MRR is analyzed. It is found that the Preston coefficient distribution on workpiece surface is stable when the surface profile variation is small and shows obvious differences from the center to the edge of the workpiece. Through the comparison it is found that correlation between the regularities of Preston coefficient distribution and the type of polishing pad is significant. The research results in this paper will play an important guiding role in the quantitative prediction method research of polishing process.

Abstract: This article describes a complex and generally applicable computational model for solving the frictional losses of directionally oriented and non-oriented sliding surfaces working under mixed lubrication regime. In the primary phase of this paper are described ways to get characteristics data describing rough surfaces together with the formula for determination of surface pattern directional dependence. Furthermore, formulae describing used contact model are listed and also the structure of the whole powertrain dynamics solution is briefly explained. In the closing section of this paper are shown and discussed results of several types of slide bearing analysis.

Abstract: Development of internal combustion engine’s components is based on the use of advanced computational models in order to compare and verify the individual design proposals. Connecting rod, which performs a general planar motion, is exposed to the gas pressure forces, inertia, contacts, and hydrodynamic pressure during the engine operation cycle. To incorporate all these aspects, Finite Element Method (FEM) is extended by Finite Difference Method (FDM) simulating a slide bearing of connecting rod’s end. It includes different properties of lubricating oil (pressure and temperature dependent viscosity and density) and elastic deformations, so the pressure distribution in an oil film can be evaluated. The computational process concludes with an estimation of the endurance safety factor of the connecting rod. The four-cylinder inverted aircraft engine is used as an example.

Abstract: Gold-based alloys are widely used in electrical contact environment which requires small contact resistance, and friction pair components consisting of electrical contact has a direct impact on the properties of electrical contact. In this thesis, an experiment of AuNI9 brushes/AuCuAgZn gold sheets in a organization is designed to show the elastic properties of the brush, friction pair wear properties and environmental adaptability of the contact resistance, whose result indicates that the elastic properties of the brushes are stable, alloy sheets mainly produce wear when the brushes and gold sheets are used in matched pair and environmental assessment tests do not significantly increase the degree of wear of the friction pair components in low load condition.

Abstract: The mathematical description of the wear processes of brushes of brush-type motors is described. The actions directed on increase of the lifetime of brushes are offered. The proposed mathematical model of the wear processes of brushes considers the highest number of parameters of a sliding contact, including sparking energy of windings switching and the mechanical condition of a commutator and bearings. The approach for evaluating the optimum pressure on the brush in order to increase its resource is offered. The real and the virtual lifetime tests of the universal motor considering changing of the mechanical state of the commutator and bearings during lifetime were carried-out. The constant force value acting on the brush which provides its lifetime increase by 11% is proposed.

Abstract: To get the low temperature transformation product of austenite, study of cooling behavior of coil is essential. Temperature distribution profile of the hot strip coil has been determined by using finite volume method (FVM) vis-à-vis finite difference method (FDM). It has been demonstrated that FVM offer greater computational reliability in estimation of contact pressure distribution and hence the temperature distribution for curved and irregular profiles, owing to the flexibility in selection of grid geometry and discrete point position, Moreover, use of finite volume concept allows enforcing the conservation of mass, momentum and energy, leading to enhanced accuracy of prediction.