Computational efficiency improvement of dimple textured hydrodynamic journal bearing using progressive mesh densification method

There is a considerable amount of study carried out on textured hydrodynamic bearings. The numerical solution of textured bearings is a matter of concern for the researchers. There are several methods used to estimate the performance parameters of textured bearings. However, Progressive Mesh Densification (PMD) method is not yet used for textured bearings while it has been used for mixed elastohydrodynamic lubrication (EHL) and thermo-elastohydrodynamic lubrication (EHL) problems. In the present analysis, the PMD method is implemented to estimate the performance parameters of the textured journal bearing. It is compared with the multigrid and the fixed mesh methods and found to be very effective in improving computational efficiency.

Three-dimensional garment pattern design using progressive mesh cutting algorithm

Purpose The purpose of this paper is to develop the core module of computer-aided three-dimensional garment pattern design system. Design/methodology/approach A progressive mesh cutting algorithm and mesh reshaping algorithm have been developed to cut a single mesh into multiple patches. A flat projection algorithm has been developed to project 3D patches into 2D patterns. Findings The software developed in this study is expected to enable its users to design complex garment patterns without the in-depth knowledge of pattern design process. Research limitations/implications The mesh model used in this study was a fixed model. It will be extended to a deformable garment model that can be resized according to the underlying body model Practical implications The software developed in this study is expected to reduce the time required for time-consuming and trial-and-error-based pattern design process. Social implications Fashion designers will be able to design complex patterns by themselves and the dependence upon expert patterners could be reduced Originality/value The progressive mesh cutting algorithm developed in this study can cut a mesh model using arbitrary lines. The mesh reshaping algorithm can improve the mesh quality of divided patches to increase the numerical stability during subsequent pattern flattening process. The flip removal algorithm can effectively remove the partially flipped mesh elements.

A Novel Adaptive Topology Optimization Method Considering Unnecessary Element Removal and Progressive Mesh Refinement

This paper proposes an adaptive topology optimization (TO) approach considering unnecessary element removal and progressive element refinement. A two-stage density filtering for element removal is developed to relax the design space for next iteration, and therefore make a trade-off between solution quality and optimization efficiency. An isolated element detection and deletion is also conducted between element removal and element refinement operation to guarantee the numerical stability. Two 2D numerical examples and one 3D design problems are investigated to demonstrate the effectiveness of the proposed method. Based on the numerical tests, the applicability range of the proposed method and recommended range of element density threshold are provided as well.

Thermo-elastohydrodynamic lubrication simulation of the Rayleigh step bearing using the progressive mesh densification method

The paper deals with the numerical simulation of thermo-elastohydrodynamic lubrication (Thermo-EHL) condition in the Rayleigh step bearing. Thermo-EHL involves rheology of the lubricant and deformation of the structure simultaneously under the influence of pressure and temperature, which makes this regime of lubrication more complicated. It is difficult to obtain a converged and accurate solution with ease under this condition. The effect of computational mesh density plays a significant role in obtaining a converged solution rapidly. In this paper, the progressive mesh densification (PMD) method has been applied to solve the Thermo-EHL condition numerically. To find out the best possible scheme of PMD for obtaining a converged solution quickly, the results of PMD and fixed mesh density (FMD) have been compared. Based on the comparison, it has been observed that Scheme 3 of PMD takes around 30% fewer iterations compared with FMD under both elastohydrodynamic lubrication (EHL) and Thermo-EHL conditions. Adopting Scheme 3 of PMD, the effect of temperature on the load capacity, coefficient of friction, no-pressure zone, and pressure distribution in the Rayleigh step bearing has been studied. Reductions in pressure, no-pressure zone, frictional coefficient, and load capacity are observed under the Thermo-EHL condition compared to the EHL condition.

Progressive Mesh Densification Method for Numerical Solution of Mixed Elastohydrodynamic Lubrication

Numerical solution of mixed elastohydrodynamic lubrication (EHL) is of great importance for the study of lubrication formation and breakdown, as well as surface failures of mechanical components. However, converged and accurate numerical solutions become more difficult, and solution process with a fixed single discretization mesh for the solution domain appears to be quite slow, especially when the lubricant films and surface contacts coexist with real-machined roughness involved. Also, the effect of computational mesh density is found to be more significant if the average film thickness is small. In the present study, a set of sample cases with and without machined surface roughness are analyzed through the progressive mesh densification (PMD) method, and the obtained results are compared with those from the direct iteration method with a single fixed mesh. Besides, more numerical analyses with and without surface roughness in a wide range of operating conditions are conducted to investigate the influence of different compound modes in order to optimize the PMD procedure. In addition, different initial conditions are used to study the effect of initial value on the behaviors of this transient solution. It is observed that, no matter with or without surface roughness considered, the PMD method is stable for transient mixed EHL problems and capable of significantly accelerating the EHL solution process while ensuring numerical accuracy.

Research on Optimization and Application of LOD Algorithm in Virtual Reality Visualization of Terrain

With the development of computer graphics, real-time rendering-based VF: technology has been applied in more and more fields. LOD is the key technology in large-scale terrain rendering. In this paper, the basic concept of LOD is introduced briefly and some algorithms of LOD in use are mentioned and analyzed; secondly as one of algorithms of LOD, View-Dependent Progressive Mesh algorithm is studied and improved, the result of implementing the large-scale terrain’s LOD by using VDPM is presented. There are key technologies in LOD Large-scale terrain real-time rendering are researched. Relative technologies are presented such as: LOD of the terrain, visibility culling, and cracks eliminate, view-dependent refine, LOD error, technologies of texture etc. Using LOD technology, VR system can greatly reduce the; number of polygons produced in real-time rendering procedure. Finally, we do experimental design work based on the methods and techniques presented by this paper.