Papers by Keyword: 3D Surface

Abstract: A number of different mechanisms and devices in mechatronic systems may involve sliding-friction surfaces. The issues of service life and its prediction for the details of such surfaces have always been of particular importance. Having studied the wear process prediction theories that have been developed in the course of time, which can be classified by dividing them in definite groups based on similar theoretical approach one can state that each of them has different shortcomings, which might affect the result precision, when essential basic parameters have been disregarded, as well as create a need for useless additional practical experiments, as a result of which theoretical calculation becomes unnecessary. [4] The article determines the most suitable wear calculation model that allows considering the set of parameters necessary for calculating slide-friction pair. Wearing usually proceeds in three stages: the running-in stage, the normal wear stage, and the intensive wear stage. The proposed model is provided for normal wear stage calculations. The proposed model for wear calculation is based on the application of theories from several branches of science to the description of 3D surface micro-topography in accordance with random field theory, assessing the material’s physical and mechanical characteristic quantities, substantiating the regularities in creation of material particles separated during the wear process and taking into consideration definite service conditions of fittings. Since the wear process is variable and many-sided, it is influenced by numerous different parameters, for example, surface geometry (roughness, waviness, form deviation, etc.), physical and mechanical conditions of the upper layer, material components, wear regime, wear temperature, etc. Based on the regularities stated in the article one can propose the following wear calculation sequence [4]:1) Initial data should be stated which will be further necessary in calculations: constructive-kinematic characteristic quantities (rated area A_a of wearing component, load P, gliding movement speed v, movement time t), fatigue characteristic of friction component material (friction coefficient f (f≤0,1) and material fatigue destruction parameters (m, σ_-1, N₀), mechanical characteristic quantities of material (E, μ);2) Parameters should be stated after attachment: surface roughness parameters (S_a, S_m1, S_m2, S_m2^a), initial wear U_p and corresponding time T_p, tolerated wear U_max.

Abstract: This paper proposes an easy approach to obtaining 3D surface models in parametric CAD software products from random sets of points, based on the analogy of level curves from geodesic disciplines. The points could be obtained from measurements on existing mechanical parts, as a stage in reverse engineering processes, or can be defined arbitrary in space, as part of the design process. The present research shows that good approximations of the true surface can be obtained by measuring a relative small group of carefully selected points and constructing level curves, following the same procedure as in the case of topography. The instrument to build level curves is an original application developed for AutoCAD using VB.NET which allows the user to construct the level curves parallel to the xy plane for any number of points in space. We tested the application on more set of points sampling the same surface, obtaining the level curves in AutoCAD and using these to build the final 3D model. The surfaces obtained this way were then compared to draw some conclusions regarding the influence of the number of sampled points on the precision of the model.

Abstract: The surface micro-topography characteristics of micro-WEDM, which can have a directly significant impact on the parts usability properties, have been attached more and more importance by people. In this study, the method of statistical analysis is applied to work out the two-dimensional autocorrelation function figure and the power spectrum density function figure of the surface micro-topography of micro-WEDM. It can be seen that there are more sharp and narrow peaks and high frequency components, meanwhile, there are some low frequency wave components on the surface. A conclusion is arrived at that the three-dimensional (3D) surface micro-topography of micro-WEDM shows isotropy through analyzing its texture characteristics. The results can provide the theoretical basis for further establishing the appropriate evaluation parameters for the surface roughness of micro-WEDM.