Focus-variation microscopy for measurement of surface roughness and autocorrelation length

2017 ◽  
Author(s):  
Erich Grossman
Keyword(s):  
Surface Roughness ◽  
Focus Variation ◽  
Autocorrelation Length

scholarly journals Resistance to fracture due to cyclic fatigue of stainless steel manual files and its association to surface roughness

2021 ◽  
Vol 34 (1) ◽  
pp. 18-26
Author(s):  
Javier Niño-Barrera ◽  
José Sánchez-Alemán ◽  
Luis Gamboa-Martinez ◽  
Carlos Cortes-Rodriguez
Keyword(s):  
Surface Roughness ◽  
Plastic Deformation ◽  
Stainless Steel ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Cyclic Fatigue ◽  
Focus Variation ◽  
Moderate Positive Correlation ◽  
Fractured Surface ◽  
Scanning Electron

The aim of this study was to evaluate the possible association between the roughness of 5 brands of stainless steel endodontic files and their resistance to fracture due to cyclic fatigue. The study included five different brands of stainless steel endodontic files: SybroEndo Triple-Flex Files (Kerr, Glendora, USA), Ready Steel K-Flexofile (Dentsply Sirona, Ballaigues, Switzerland), Mani Flexile Files (Mani, Tochigi- Ken, Japan), FKG K-Files (FKG, La Chaux-de-Fonds, Switzerland) and Zipperer Flexicut Files (VDW, Munich, Germany). Twelve files per brand (total 60 files) were evaluated. File surface roughness over an area (Sa) was quantified using a focus variation microscope. Then the files were subject to a cyclical fatigue test to determine the number cycles to fracture due to fatigue and length of fractured fragment. Finally, fractographic analysis was performed using a scanning electron microscope. The electropolished Ready Steel K-Flexofile® files had the highest roughness according to Sa parameters, though they also had the highest resistance to fracture due to cyclic fatigue and the longest fractured fragment. Moderate positive correlation was found between fractured fragment length and roughness. The fractured surface showed characteristics of ductile fracture with cracks and plastic deformation. The electropolished stainless steel Ready Steel K-Flexofile® files were the most resistant to fracture due to cyclic fatigue even though they had highest surface roughness.

The Many Faces of Turbine Surface Roughness

2001 ◽  
Author(s):  
Jeffrey P. Bons ◽  
Robert P. Taylor ◽  
Stephen T. McClain ◽  
Richard B. Rivir
Keyword(s):  
Surface Roughness ◽  
Film Cooling ◽  
Smooth Surface ◽  
Turbine Blades ◽  
Spatial Variations ◽  
Surface Degradation ◽  
Surface Conditions ◽  
The Many ◽  
Autocorrelation Length ◽  
Skewness And Kurtosis

Results are presented for contact stylus measurements of surface roughness on in-service turbine blades and vanes. Nearly 100 turbine components were assembled from four land-based turbine manufacturers. Both coated and uncoated, cooled and uncooled components were measured, with part sizes varying from 2 to 20cm. Spanwise and chordwise 2D roughness profiles were taken on both pressure and suction surfaces. Statistical computations were performed on each trace to determine centerline averaged roughness, rms roughness, and peak to valley height. In addition, skewness and kurtosis were calculated as well as the autocorrelation length and dominant harmonics in each trace. Extensive 3D surface maps made of deposits, pitting, erosion, and coating spallation expose unique features for each roughness type. Significant spatial variations are evidenced and transitions from rough to smooth surface conditions are shown to be remarkably abrupt in some cases. Film cooling sites are shown to be particularly prone to surface degradation.

Effect of surface roughness topography on percolation characteristic of contact interface

2020 ◽  
pp. 135065012097735
Author(s):  
Tong Zhang ◽  
Xiaojun Liu ◽  
Yan Zhang ◽  
Jiaxin Ye ◽  
Wei Wang ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Percolation Threshold ◽  
Critical Pressure ◽  
Rough Surfaces ◽  
Glass Plate ◽  
Peak Height ◽  
Elastic Contact ◽  
Contact Interface ◽  
Autocorrelation Length ◽  
Effect Of Surface

The contact geometry of rough surfaces markedly affects the functional properties such as sealing and lubrication. The effect of surface roughness on the percolation characteristic of elastic contact was studied. The elastic contact of randomly rough surfaces with a glass plate was performed using four different surface roughnesses of silicone rubber blocks as specimens. The results illustrate that the percolation threshold was significantly affected by the valley morphology of a surface. The increase in depth and void volume of valleys improved the connectivity between valleys, but impeded the coalescence of contact clusters, resulting in the extinction of the spanning void cluster allowing fluid flow when the relative contact area was large. Furthermore, the critical pressure and connectivity at the percolation threshold were related to the maximum peak height and autocorrelation length of a surface, respectively.

Surface Roughness Measurement of Additive Manufactured Parts Using Focus Variation Microscopy and Structured Light System

2019 ◽  
Author(s):  
Xiao Zhang ◽  
Vignesh Suresh ◽  
Yi Zheng ◽  
Shaodong Wang ◽  
Qing Li ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Data Fusion ◽  
Real Time ◽  
Point Cloud ◽  
Structured Light ◽  
Data Sets ◽  
Point Cloud Data ◽  
Cloud Data ◽  
Focus Variation ◽  
Structured Light System

Abstract Surface roughness is a significant parameter when evaluating the quality of products in the additive manufacturing (AM) industry. AM parts are fabricated layer by layer, which is quite different from traditional formative or subtractive methods. A uniform feature can be obtained along the direction of the AM printhead movement on the surface of manufactured components, and a large waviness value can be found in the direction perpendicular to printhead movement. This unique characteristic differentiates additive manufactured parts from casted or machined parts in the way of measuring and defining surface roughness. Therefore, it is necessary to set up new standards to measure surface roughness of AM parts and analyze the variation in the topographical profile. The most widely used instruments for measuring surface roughness are profilometer and laser scanner, but they cannot generate 3D topographical surfaces in real-time. In this work, two non-contact optical methods based on Focus Variation Microscopy (FVM) and Structured Light System (SLS) were adopted to measure the surface topography of the target components. The FVM captures images of objects at different focus levels. By translating the object’s position based on focus profile, a 3D image is obtained by data fusion. The lab-made microscopic SLS was used to perform simultaneous whole surface scanning with the potential to achieve real-time 3D surface reconstruction. The two optical metrology systems generated two totally different point cloud data sets. Limited research has been conducted to verify whether the point cloud data sets generated from different optical systems are following the same distribution. In this paper, a statistical method was applied to test the difference between two systems. By using data analytics approaches for comparison analysis, it was found that surface roughness based on the FVM and the SLS systems has no significant difference from a data fusion point of view, though point cloud data generated were completely different in values. In addition, this paper provided a standard measurement approach for a real-time, non-contact method to estimate the surface roughness of AM parts. The two metrology techniques can be applied for in-situ real-time surface analysis and process planning for AM.

The Many Faces of Turbine Surface Roughness

2001 ◽  
Vol 123 (4) ◽  
pp. 739-748 ◽  
Author(s):  
Jeffrey P. Bons ◽  
Robert P. Taylor ◽  
Stephen T. McClain ◽  
Richard B. Rivir
Keyword(s):  
Surface Roughness ◽  
Film Cooling ◽  
Smooth Surface ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Surface Conditions ◽  
The Many ◽  
Autocorrelation Length ◽  
Skewness And Kurtosis ◽  
Dimensional Surface

Results are presented for contact stylus measurements of surface roughness on in-service turbine blades and vanes. Nearly 100 turbine components were assembled from four land-based turbine manufacturers. Both coated and uncoated, cooled and uncooled components were measured, with part sizes varying from 2 to 20 cm. Spanwise and chordwise two-dimensional roughness profiles were taken on both pressure and suction surfaces. Statistical computations were performed on each trace to determine centerline averaged roughness, rms roughness, and peak to-valley height. In addition, skewness and kurtosis were calculated; as well as the autocorrelation length and dominant harmonics in each trace. Extensive three-dimensional surface maps made of deposits, pitting, erosion, and coating spallation expose unique features for each roughness type. Significant spatial variations are evidenced and transitions from rough to smooth surface conditions are shown to be remarkably abrupt in some cases. Film cooling sites are shown to be particularly prone to surface degradation.

The Effects of Surface Roughness and Topography on the Contact Behavior of Elastic Bodies

1994 ◽  
Vol 116 (4) ◽  
pp. 804-810 ◽  
Author(s):  
Ning Ren ◽  
Si C. Lee
Keyword(s):  
Surface Roughness ◽  
Root Mean Square Roughness ◽  
Asperity Contact ◽  
Performance Variables ◽  
Elastic Bodies ◽  
Real Area Of Contact ◽  
Wide Range ◽  
Autocorrelation Length ◽  
Mathematical Relationships ◽  
Effect Of Surface

The real area of contact, average gap, and mean asperity contact pressure are important variables for understanding friction, wear, and lubrication in contacting systems. They are known as “performance variables.” Contact simulations were conducted for a wide range of surface topographies and an extensive amount of information was generated. Using this information, the performance variables were curve fitted and convenient mathematical relationships were formulated. The surfaces used in the simulations were numerically generated and they varied widely in statistical roughness properties, ranging from isotropic to strongly anisotropic. The effect of surface roughness on the performance variables were studied using three parameters—composite Root Mean Square roughness (σ), autocorrelation length (λx*), and asperity aspect ratio (γ).

Roughness measurements of nonlinear optical polymer films by scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 22-23
Author(s):  
I. H. Musselman ◽  
R.-T. Chen ◽  
P. E. Russell
Keyword(s):  
Surface Roughness ◽  
Scanning Tunneling Microscopy ◽  
Nonlinear Optical ◽  
Polymer Surface ◽  
Light Extinction ◽  
Scanning Tunneling ◽  
Silicon Substrates ◽  
Tunneling Microscopy ◽  
Optical Polymer ◽  
Total Light

Scanning tunneling microscopy (STM) has been used to characterize the surface roughness of nonlinear optical (NLO) polymers. A review of STM of polymer surfaces is included in this volume. The NLO polymers are instrumental in the development of electrooptical waveguide devices, the most fundamental of which is the modulator. The most common modulator design is the Mach Zehnder interferometer, in which the input light is split into two legs and then recombined into a common output within the two dimensional waveguide. A π phase retardation, resulting in total light extinction at the output of the interferometer, can be achieved by changing the refractive index of one leg with respect to the other using the electrooptic effect. For best device performance, it is essential that the NLO polymer exhibit minimal surface roughness in order to reduce light scattering. Scanning tunneling microscopy, with its high lateral and vertical resolution, is capable of quantifying the NLO polymer surface roughness induced by processing. Results are presented below in which STM was used to measure the surface roughness of films produced by spin-coating NLO-active polymers onto silicon substrates.

Surface roughness measurements of vanadium-contaminated fluidized cracking catalysts by atomic force microscopy

1996 ◽  
Vol 54 ◽  
pp. 866-867
Author(s):  
H. Kinney ◽  
M.L. Occelli ◽  
S.A.C. Gould
Keyword(s):  
Surface Roughness ◽  
Zeolite Y ◽  
Atomic Level ◽  
Microporous Structure ◽  
Contact Mode ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After ◽  
Roughness Measurements ◽  
Cracking Catalysts

For this study we have used a contact mode atomic force microscope (AFM) to study to topography of fluidized cracking catalysts (FCC), before and after contamination with 5% vanadium. We selected the AFM because of its ability to well characterize the surface roughness of materials down to the atomic level. It is believed that the cracking in the FCCs occurs mainly on the catalysts top 10-15 μm suggesting that the surface corrugation could play a key role in the FCCs microactivity properties. To test this hypothesis, we chose vanadium as a contaminate because this metal is capable of irreversibly destroying the FCC crystallinity as well as it microporous structure. In addition, we wanted to examine the extent to which steaming affects the vanadium contaminated FCC. Using the AFM, we measured the surface roughness of FCCs, before and after contamination and after steaming.We obtained our FCC (GRZ-1) from Davison. The FCC is generated so that it contains and estimated 35% rare earth exchaged zeolite Y, 50% kaolin and 15% binder.

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