scholarly journals Effect of Surface Topography Parameters on Friction and Wear of Random Rough Surface

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2762 ◽  
Author(s):  
Ruimin Shi ◽  
Bukang Wang ◽  
Zhiwei Yan ◽  
Zongyan Wang ◽  
Lei Dong
Keyword(s):  
Surface Topography ◽  
Fluid Dynamic ◽  
Dynamic Pressure ◽  
Functional Characterization ◽  
Three Dimensional ◽  
Measuring System ◽  
Height Distribution ◽  
Worn Surface ◽  
The Relationship

In order to explore the relationship between the surface topography parameters and friction properties of a rough contact interface under fluid dynamic pressure lubrication conditions, friction experiments were carried out. The three-dimensional surface topography of specimens was measured and characterized with a profile microscopy measuring system and scanning electron microscope. The friction coefficient showed a trend of decreasing first and then increasing with the increase in some surface topography parameters at lower pressure, such as the surface height arithmetic mean Sa, surface height distribution kurtosis Sku, surface volume average volume Vvv, and surface center area average void volume Vvc, which are the ISO 25178 international standard parameters. The effects of surface topographic parameters on friction were analyzed and the wear mechanism of the worn surface was presented. The wear characteristics of the samples were mainly characterized as strain fatigue, grinding, and scraping. The results provide a theoretical basis for the functional characterization of surface topography.

Dynamic Stability Analysis of a Flexible Rotor Filled With Liquid Based on Three-Dimensional Flow

2018 ◽  
Vol 141 (5) ◽  
Author(s):  
Guangding Wang ◽  
Huiqun Yuan
Keyword(s):  
Dynamic Stability ◽  
Numerical Technique ◽  
Fluid Dynamic ◽  
Dynamic Pressure ◽  
Three Dimensional ◽  
Frequency Equation ◽  
Fourier Series Expansion ◽  
Flexible Rotor ◽  
Three Dimensional Flow ◽  
Dimensional Flow

This paper deals with the dynamic stability of a flexible liquid-filled rotor. On the basis of three-dimensional flow, the fluid perturbation motion is analyzed and the fluid–structure interaction equation is established, combining with continuity equation, the expression of fluid force exerted on rotor is derived in terms of Fourier series expansion. Considering the complex nonlinear relationship between fluid dynamic pressure and the rotor deformation function, they are expanded in terms of the eigenfunction of a dry rotor. The whirling frequency equation of a flexible rotor partially filled with liquid is obtained based on the rotor static equilibrium equation. Finally, the numerical technique is used to analyze the dynamic stability of the rotor system, and the influences of system parameters on unstable region are discussed.

Fabrication and Characterization of Photonic Crystals by Two-Photon Polymerization Using a Femtosecond Laser

2013 ◽  
Author(s):  
Yinan Tian ◽  
Yung C. Shin ◽  
Galen B. King
Keyword(s):  
Sol Gel ◽  
Three Dimensional ◽  
Quantitative Relationship ◽  
Scanning Speed ◽  
Sem Images ◽  
Two Photon ◽  
High Uniformity ◽  
The Relationship ◽  
Two Photon Polymerization

Two-photon polymerization is a powerful technique in fabricating three dimensional sub-diffraction-limited structures. Recently, new sol-gel material, SZ2080, was introduced into two-photon polymerization and was proved to be better than the conventional materials for its negligible shrinkage. In this paper, two-photon polymerization was applied to generate woodpile structures, one kind of photonic crystal, using SZ2080. First, the relationship between scanning speed, laser power and resolution was determined through fabricating free-hanging lines. Based on this relationship, woodpile structures with different period distances were fabricated with high uniformity as shown by SEM images. Then optical properties of woodpile structures were investigated using Fourier Transform Infrared Spectroscopy (FTIR) and a quantitative relationship between band gap and period distance was established.

scholarly journals Multifeature Extraction of Three-Dimensional Topography of Carbon Steel Specimen during Fatigue Process

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Tao Liu ◽  
Jingxiong Wu ◽  
Jingfa Lei ◽  
Xue Wang ◽  
Bingqi Zhang ◽  
...  
Keyword(s):  
Surface Topography ◽  
Metal Surface ◽  
Fatigue Damage ◽  
Feature Fusion ◽  
Early Stage ◽  
Three Dimensional ◽  
Mean Deviation ◽  
Height Distribution ◽  
Fusion Method ◽  
Fatigue Process

In order to investigate the variation of three-dimensional metal surface topography during fatigue process, a three-dimensional (3D) topography acquisition platform was built with an in situ tensile tester and a three-dimensional profilometer. Q235 steel specimens were chosen as research objects, and the three-dimensional surface topography information at various stages of fatigue damage was obtained. Through the characterization of three-dimensional roughness, combined with surface height distribution and multifractal analysis, the variations of metal surface topography in the fatigue process were described. Results show that the arithmetic mean deviation of the surface (Sa), the width of the multifractal spectrum (Δα), and the mean value of surface height distribution (μ) and its standard deviation (δ) increase nonlinearly with the increase of fatigue cycles. The rate of fatigue damage is slow in the early stage and high in the middle and late stages. The surface height distribution amplitude (A) decreases with the increase of fatigue cycles, which indicates that the height data concentration decreases, and the metal surface becomes uneven. The Bayesian data fusion method was applied to establish a nonlinear mapping between the topography features and the damage, with the above five characteristic parameters (Sa, Δα, A, μ, and δ) as the data layer. Finally, a surface topography feature fusion method is proposed, and a case study is conducted to verify its applicability. The research results can provide reference for fatigue damage assessment.

Direct Strength Analysis of Semi-Submersible Platform Structures

2004 ◽  
Author(s):  
Haibin Zhang ◽  
Huilong Ren ◽  
Yangshan Dai
Keyword(s):  
Finite Element ◽  
Interpolation Method ◽  
Fluid Dynamic ◽  
Dynamic Pressure ◽  
Three Dimensional ◽  
Element Model ◽  
Strength Analysis ◽  
Wave Load ◽  
Element Analysis ◽  
Wet Surface

A kind of direct strength analysis method of semi-submersible platform structures is presented in this paper. With the differences in shape of pontoon, column and beam being considered, the method of accumulative chord length cubic parameter spline function combined with analytic expression is adopted to generate the mesh of platform wet surface. The hydrodynamic coefficients of the platform are calculated by the three-dimensional potential flow theory of the linear hydrodynamic problem for platforms with low forward speed. The equations of platform motions are established and solved in frequency domain, and the responses of wave-induced loads on the platforms are calculated. According to the mesh of hydrodynamic computation, the fluid dynamic pressure field of platform wet surface is built, and the pressure loads on shell elements in the finite element model of the structure are calculated by the interpolation method. The calculation conditions and loads in the finite element analysis (FEA) of the platform structures are determined according to the design wave analysis approach. A computer program based on this method has been developed, and a calculation example of semi-submersible platform is illustrated. Analysis results show that this method is a satisfying approach for wave load computation and direct strength analysis of the semi-submersible platforms.

Self-Contained Three-Dimensional Bioprinter for Applications in Cardiovascular Research

2019 ◽  
Vol 13 (3) ◽  
Author(s):  
Prabhuti Kharel ◽  
Likitha Somasekhar ◽  
Amy Vecheck ◽  
Kunal Mitra
Keyword(s):  
Functional Characterization ◽  
Three Dimensional ◽  
Environmental Parameters ◽  
3D Bioprinting ◽  
Cardiovascular Research ◽  
Form Complex ◽  
Tissue Constructs ◽  
Long Duration ◽  
Selection Of

Bioprinting is a technique of creating 3D cell-laden structures by accurately dispensing biomaterial to form complex synthetic tissue. The printed constructs aim to mimic the native tissue by preserving the cell functionality and viability within the printed structure. The 3D bioprinting system presented in this paper aims to facilitate the process of 3D bioprinting through its ability to control the environmental parameters within an enclosed printing chamber. This design of the bioprinter targets to eliminate the need for a laminar flow hood, by regulating the necessary environmental conditions important for cell survival, especially during long duration prints. A syringe-based extrusion (SBE) deposition method comprising multiple nozzles is integrated into the system. This allows for a wider selection of biomaterials that can be used for the formation of the extracellular matrix (ECM). Tissue constructs composed of alginate-gelatin hydrogels were mixed with fibrinogen and human endothelial cells which were then characterized and compared using two methodologies: casted and bioprinted. Furthermore, vasculature was incorporated in the bioprinted constructs using sacrificial printing. Structural and functional characterization of the constructs were performed by assessing rheological, mechanical properties, and analyzing live-dead assay measurements.

scholarly journals Functional Characterization of Three-Dimensional Cortical Cultures for In Vitro Modeling of Brain Networks

iScience ◽  
2020 ◽  
Vol 23 (8) ◽  
pp. 101434
Author(s):  
Yu-Ting L. Dingle ◽  
Volha Liaudanskaya ◽  
Liam T. Finnegan ◽  
Kyler C. Berlind ◽  
Craig Mizzoni ◽  
...  
Keyword(s):  
Functional Characterization ◽  
Brain Networks ◽  
Three Dimensional ◽  
In Vitro Modeling ◽  
Cortical Cultures

Experimental study on the characterization of worn surface topography with characteristic roughness parameter

Wear ◽  
2003 ◽  
Vol 255 (1-6) ◽  
pp. 309-314 ◽  
Author(s):  
Hua Zhu ◽  
Shirong Ge ◽  
Xiaolong Huang ◽  
Dekuen Zhang ◽  
Jinlong Liu
Keyword(s):  
Experimental Study ◽  
Surface Topography ◽  
Roughness Parameter ◽  
Worn Surface
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