Calculation of Roughness Parameters during Ultrasonic Hobbing from the Viewpoint of the Theory of Elastic-Plastic Contact

2019 ◽  
Vol 973 ◽  
pp. 170-173
Author(s):  
Sergey I. Agapov ◽  
Yuriy I. Sidyakin ◽  
Oleg F. Korpelyanskiy
Keyword(s):  
Surface Roughness ◽  
Analytical Solutions ◽  
Roughness Parameter ◽  
Regression Equations ◽  
Ultrasonic Machining ◽  
Roughness Parameters ◽  
Elastic Plastic ◽  
Fine Pitch

This article analyses the process of occurrence of the surface roughness during the ultrasonic hobbing of the fine pitch gears from the viewpoint of the theory of elastic-plastic contact, and suggests analytical solutions and regression equations to estimate the roughness parameter Ra in both conventional and ultrasonic machining.

scholarly journals Predictability of Microbial Adhesion to Dental Materials by Roughness Parameters

Coatings ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 456 ◽  
Author(s):  
Andrea Schubert ◽  
Torsten Wassmann ◽  
Mareike Holtappels ◽  
Oliver Kurbad ◽  
Sebastian Krohn ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Titanium Alloy ◽  
Biofilm Formation ◽  
Dental Materials ◽  
Roughness Parameter ◽  
In Vitro Study ◽  
Mean Deviation ◽  
Roughness Parameters ◽  
Microbial Adhesion

Microbial adhesion to intraoral biomaterials is associated with surface roughness. For the prevention of oral pathologies, smooth surfaces with little biofilm formation are required. Ideally, appropriate roughness parameters make microbial adhesion predictable. Although a multitude of parameters are available, surface roughness is commonly described by the arithmetical mean roughness value (Ra). The present study investigates whether Ra is the most appropriate roughness parameter in terms of prediction for microbial adhesion to dental biomaterials. After four surface roughness modifications using standardized polishing protocols, zirconia, polymethylmethacrylate, polyetheretherketone, and titanium alloy specimens were characterized by Ra as well as 17 other parameters using confocal microscopy. Specimens of the tested materials were colonized by C. albicans or S. sanguinis for 2 h; the adhesion was measured via luminescence assays and correlated with the roughness parameters. The adhesion of C. albicans showed a tendency to increase with increasing the surface roughness—the adhesion of S. sanguinis showed no such tendency. Although Sa, that is, the arithmetical mean deviation of surface roughness, and Rdc, that is, the profile section height between two material ratios, showed higher correlations with the microbial adhesion than Ra, these differences were not significant. Within the limitations of this in-vitro study, we conclude that Ra is a sufficient roughness parameter in terms of prediction for initial microbial adhesion to dental biomaterials with polished surfaces.

Considerations Regarding Some Surface State Parameters Characterized by a more Restricted Use

2015 ◽  
Vol 809-810 ◽  
pp. 93-98
Author(s):  
Ionuţ Urzică ◽  
Ciprian Râznic ◽  
Mihai Apostol ◽  
Corina Mihaela Pavăl ◽  
Mihai Boca ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Roughness Parameter ◽  
Cutting Speed ◽  
Roughness Parameters ◽  
Turning Process ◽  
Nose Radius ◽  
Machined Surface ◽  
Surface Roughness Parameter ◽  
Surface Roughness Parameters ◽  
Restricted Use

Frequently, on the drawings of mechanical parts, only indications concerning the surface roughness parameter Ra and, relatively rarely, the surface roughness parameter Rz are included. However, the study of the machined surface roughness highlights the necessity to use yet other surface roughness parameters, in order to have a clearer image on the state of the machined surface. Some other surface roughness parameters possible to be used and presenting importance, without the parameters Ra and Rz, were highlighted. One took into consideration the possibility of measuring parameters Rsk and Rmr by means of the available surface roughness testers. Experimental researches of turning by applying the method of full factorial experiment were developed. As input factors in turning process, the cutting speed, the feed rate and the tool nose radius were used. The experimental results were mathematically processed, being determined empirical mathematical models that highlight the influence of certain input factors of turning process on the values of some surface roughness parameters characterized by a more restricted use

Measurements and Evaluation of Internal Wall Surface Roughness of Small Diameter Pipes for High Pressure Natural Gas Systems

2014 ◽  
Author(s):  
C. Hartloper ◽  
K. K. Botros ◽  
J. Geerligs ◽  
H. Golshan ◽  
K. Jensen
Keyword(s):  
Surface Roughness ◽  
Pipe Wall ◽  
Large Diameter ◽  
Roughness Parameter ◽  
Small Diameter ◽  
Wall Roughness ◽  
Roughness Parameters ◽  
Internal Wall ◽  
Effective Roughness ◽  
Pipe Size

The default roughness parameter values used in industry to determine the pressure loss through small diameter pipeline systems are much higher than the values employed in typical large diameter gas transmission and lateral systems. It is uncertain whether these higher roughness values are due to higher topological roughness of the internal wall of the small diameter pipes or if they are a result of other factors. Measurements were taken on 17 small diameter pipe samples in order to evaluate the pipe-wall roughness parameter. A model to calculate the effective roughness parameter, which takes into account pressure losses due to the measured roughness as well as internal welds and scaling, has been developed. The effective roughness parameter of these samples is found to range from 20.4μm to 62.9μm, an increase of 11.0μm to 23.3μm over the measured pipe-wall roughness parameter. This range of effective roughness parameters agrees well with the default range of 35μm to 65μm used in industry, as well as the literature quoted range for clean pipe of 40μm to 100μm. The measured roughness parameter on average increases with increasing nominal pipe size, a result that may be a characteristic of the extrusion or hot-rolling processes used to manufacture small diameter pipes. Additionally, there is a large variation in the measured roughness parameters of pipe samples of the same nominal pipe size, indicating that surface roughness can vary depending on the manufacturing source of these pipes.

scholarly journals The influence of technological parameters on surface roughness during turning and roughness prediction using artificial neutral networks

Mechanik ◽  
2018 ◽  
Vol 91 (10) ◽  
pp. 898-900 ◽  
Author(s):  
Ireneusz Zagórski ◽  
Monika Kulisz ◽  
Tomasz Warda
Keyword(s):  
Neural Network ◽  
Surface Roughness ◽  
Artificial Neural Network ◽  
Aluminum Alloy ◽  
Roughness Parameter ◽  
Cutting Speed ◽  
Roughness Parameters ◽  
Technological Parameters ◽  
Surface Roughness Parameters ◽  
Roughness Prediction

The purpose of this investigation was to determine whether and to what extent the technological parameters of turning (feed, cutting speed) affect selected surface roughness parameters of aluminum alloy EN-AW 7075 (AlZn5.5MgCu). The principal findings indicate a significant impact of feed and show on the surface roughness and simultaneously show that cutting speed has no effect on the value of surface roughness parameters under investigation. An artificial neural network was employed to evaluate the prediction of surface roughness parameter Rz in turning.

Numerical analysis of high-speed wheel/rail adhesion under interfacial liquid contamination using an elastic-plastic asperity contact model

2016 ◽  
Vol 231 (1) ◽  
pp. 63-74
Author(s):  
Bing Wu ◽  
Tao Wu ◽  
Zefeng Wen ◽  
Xuesong Jin
Keyword(s):  
Surface Roughness ◽  
High Speed ◽  
Present Model ◽  
Temperature Fields ◽  
Elastic Model ◽  
Asperity Contact ◽  
Roughness Parameters ◽  
Slip Ratio ◽  
Elastic Plastic ◽  
Train Speed

The objective of this paper is to investigate the high-speed wheel/rail adhesion under interfacial liquids contamination using a numerical model. This model considers the rheological property of interfacial liquids, elastic-plastic deformation of microasperities contact and the temperature across the film thickness. The pressure and the temperature fields can be obtained. The effects of train speed, surface roughness parameters, characteristic shear stress, and the slip ratio are investigated. Furthermore, the present model is compared with the elastic model and the elastic-plastic model without considering the thermal effect. The numerical results show that the train speed and temperature affects the wheel/rail adhesion significantly.

Performance study of a back-depression mechanical dry gas seal

1998 ◽  
Vol 212 (4) ◽  
pp. 279-290 ◽  
Author(s):  
T. A. Stolarski ◽  
Y Xue
Keyword(s):  
Finite Element Analysis ◽  
Surface Roughness ◽  
Finite Element ◽  
Roughness Parameter ◽  
Design Procedure ◽  
Control Parameters ◽  
Roughness Parameters ◽  
Performance Study ◽  
Element Analysis ◽  
Dry Gas Seal

An aerostatic mechanical dry gas seal is described in this paper. The seal has shallow depression grooves (compensators) on the back and annular grooves on one of the working faces. With the help of the back depression grooves, a hydrostatic pressure and thereby a separating force with satisfactory stiffness are produced within the sealing gap. A model which takes surface roughness into account was used to predict the performance of the seal. Relationships between the control parameters (the recess position, rG, the nominal film thickness, h0, the depth, hv, of depression grooves and the surface roughness parameter, a) are investigated against various pressure ratios, pe/ pi. The analysis provides a simple optimum design procedure. A finite element analysis was carried out to account for the effect of face deformation during operation of the seal. Experiments for various speeds, pressures and roughness parameters were carried out and the results from the experiments were used to validate the analysis performed. Analysis and experiment revealed the importance of the surface roughness and deformation of the faces for the creation and retention of the gap.

scholarly journals Roughness parameters as the elements of surface condition and deformation assessment based on the results of TLS scanning

2017 ◽  
Vol 49 (1) ◽  
pp. 29-41
Author(s):  
Maria E. Kowalska ◽  
Janina Zaczek-Peplinska
Keyword(s):  
Surface Roughness ◽  
Laser Scanning ◽  
Surface Condition ◽  
Roughness Parameter ◽  
Terrestrial Laser Scanning ◽  
Point Clouds ◽  
Arithmetic Mean ◽  
Roughness Parameters ◽  
Small Surface ◽  
Alternative Approach

Abstract Roughness parameters as the elements of surface condition and deformation assessment based on the results of TLS scanning. Roughness is the attribute of a surface that can be defined as a collection of small surface unevennesses that can be identified optically or detected mechanically which do not result from the surface’s shape and their size depends on a material type as well as on undergone processing. The most often utilised roughness parameters are: Ra - mean distance value of the points on the observed profile from the average line on the sampling length, and Rz - difference between arithmetic mean height of the five highest peaks and arithmetic mean depth of the five deepest valleys regarding to the average line on the length of the measured fragment. In practice, roughness parameters are most often defined for surface elements that require relevant manufacturing or processing through grinding, founding or polishing in order to provide the expected surface roughness. To measure those parameters for the produced elements profilometers are used. In this paper the authors present an alternative approach of determining and utilising such parameters. Instead of the utilising methods based on sampling length measurement, roughness parameters are determined on the basis of point clouds, that represent a surface of rough concrete, obtained through terrestrial laser scanning. The authors suggest using the surface roughness parameter data acquired in this way as a supplementary data in the condition assessment (erosion rate) of surfaces being a part of engineering constructions made of concrete.

scholarly journals Tribological Properties of PVD Ti/C-N Nanocoatnigs

2017 ◽  
Vol 54 (2) ◽  
pp. 64-71
Author(s):  
A. Leitans ◽  
J. Lungevics ◽  
J. Rudzitis ◽  
A. Filipovs
Keyword(s):  
Surface Roughness ◽  
Wear Resistance ◽  
Friction Coefficient ◽  
Wear Rate ◽  
Tribological Properties ◽  
Roughness Parameter ◽  
Surface Wear ◽  
Roughness Parameters ◽  
Coating Deposition ◽  
2D And 3D

Abstract The present paper discusses and analyses tribological properties of various coatings that increase surface wear resistance. Four Ti/C-N nanocoatings with different coating deposition settings are analysed. Tribological and metrological tests on the samples are performed: 2D and 3D parameters of the surface roughness are measured with modern profilometer, and friction coefficient is measured with CSM Instruments equipment. Roughness parameters Ra, Sa, Sz, Str, Sds, Vmp, Vmc and friction coefficient at 6N load are determined during the experiment. The examined samples have many pores, which is the main reason for relatively large values of roughness parameter. A slight wear is identified in all four samples as well; its friction coefficient values range from 0,.21 to 0.29. Wear rate values are not calculated for the investigated coatings, as no expressed tribotracks are detected on the coating surface.

Application of Surface Roughness Parameters to the Evaluation of Low Cycle Fatigue Damage in Austenitic Stainless Steel

2013 ◽  
Author(s):  
Nao Fujimura ◽  
Takashi Nakamura ◽  
Hiroyuki Oguma
Keyword(s):  
Surface Roughness ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Crack Detection ◽  
Low Cycle Fatigue ◽  
Roughness Parameter ◽  
Strain Range ◽  
Maximum Height ◽  
Roughness Parameters ◽  
Number Of Cycles

Changes in the surface roughness of SUS316NG during cyclic loadings were investigated, and the relations between those changes and the crack initiation and propagation processes are discussed on the basis of microscopic observations and cellulose acetate replica observations. Strain-controlled fatigue tests were conducted at three constant strain ranges. Surface roughness was measured periodically during the tests, and three roughness parameters were calculated: arithmetic mean roughness Ra, surface profile maximum height Rmax, and maximum valley depth Rv. Until the middle of fatigue life, all three increased linearly with the number of cycles regardless of the strain range, and their rates of increase became smaller with decreasing strain range. Surface observation revealed that small cracks initiated very early in fatigue life, propagated slowly until the middle of fatigue life, and then grew rapidly. Changes in surface roughness are therefore sensitive to fatigue loading even when cracks are very small and crack detection is difficult. The results suggest that surface roughness can probably be used to assess fatigue damage because until the middle of fatigue life it increases linearly with the number of cycles. The definition of each roughness parameter and the changes show that Rmax and Rv are suitable for damage assessment.

scholarly journals Internal surface roughness of plastic pipes for irrigation

2017 ◽  
Vol 21 (3) ◽  
pp. 143-149 ◽  
Author(s):  
Hermes S. da Rocha ◽  
Patricia A. A. Marques ◽  
Antonio P. de Camargo ◽  
José A. Frizzone ◽  
Ezequiel Saretta
Keyword(s):  
Surface Roughness ◽  
Roughness Parameter ◽  
Internal Surface ◽  
Low Density Polyethylene ◽  
Pipe Diameter ◽  
Roughness Parameters ◽  
Pressure Losses ◽  
Plastic Pipes ◽  
Irrigation Pipes ◽  
Surface Irregularities

ABSTRACT Assuming that a roughness meter can be successfully employed to measure the roughness on the internal surface of irrigation pipes, this research had the purpose of defining parameters and procedures required to represent the internal surface roughness of plastic pipes used in irrigation. In 2013, the roughness parameter Ra, traditional for the representation of surface irregularities in most situations, and the parameters Rc, Rq, and Ry were estimated based on 350 samples of polyvinyl chloride (PVC) and low-density polyethylene (LDPE) pipes. Pressure losses were determined from experiments carried out in laboratory. Estimations of pressure loss varied significantly according to the roughness parameters (Ra, Rc, Rq, and Ry) and the corresponding pipe diameter. Therefore, specific values of roughness for each pipe diameter improves accuracy in pressure losses estimation. The average values of internal surface roughness were 3.334 and 8.116 μm for PVC and LDPE pipes, respectively.

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