scholarly journals Experimental verification of a numerical surface roughness model for metallic bodies under large plastic strain

2019 ◽  
Vol 252 ◽  
pp. 05005
Author(s):  
Paweł Sidun
Keyword(s):  
Surface Roughness ◽  
Plastic Strain ◽  
Experimental Verification ◽  
Surface Profile ◽  
Surface Force ◽  
Numerical Calculations ◽  
Real Surface ◽  
Friction Process ◽  
Arithmetic Average ◽  
The Impact

The present work describes selected aspects of numerical modelling of the process of bonding metal alloys with consideration for micro-roughness, as well as experimental verification. The plastic-elastic contact between two deformable bodies was investigated in a DEFROM FEM environment, and verified at the test stand. The present paper demonstrates selected results of contact modelling investigated using aluminium-copper samples, in relation to their elastic-plastic range. The real surface profile helped to create a mathematical model of surface roughness measured using a laser microscope. Dependency between a blade of a tool and a feed was used to build a numerical model of roughness based on the arithmetic average value of the roughness profile. The work presents also a process of simplification of real surface roughness for the needs of numerical calculations. The paper investigates an impact of wave roughness at obtained values on effective plastic strain and stress. Additionally, numerical analysis shows a need to enter a new roughness wave correction factor assuming a zero value of the coefficient of friction. This is due to the interaction of metallic surfaces within the plastic contact zone. The obtained results allow the estimation of the impact of surface force interaction expressed by the wave coefficient factor. The experimental verification of numerical calculations allowed the estimation of the actual impact of the micro-cutting process in the entire friction process. Further analysis of obtained results permits the author to explain the surface phenomena occurring during the friction process, such as adhesion or diffusion, and outline the development direction of numerical methods.

Bridge Surface Roughness Identified from the Displacement Influence Lines of the Contact Points by Two Connected Vehicles

2020 ◽  
pp. 2043003
Author(s):  
Y. B. Yang ◽  
B. Q. Wang ◽  
Z. L. Wang ◽  
K. Shi ◽  
H. Xu ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Surface Roughness ◽  
Dynamic Properties ◽  
Surface Profile ◽  
Connected Vehicles ◽  
The Finite Element Method ◽  
Contact Points ◽  
Continuous Beams ◽  
Static Correlation ◽  
The Impact

In this study, a new, effective procedure is proposed for identifying the surface roughness from the responses recorded of two connected test vehicles moving over the bridge. Central to this study is the proposal of a simple static correlation formula for relating the dynamic deflections of the two vehicles’s contact points on the bridge, via the displacement influence lines (DILs). With the aid of this relation, the roughness formula for estimating the bridge surface profile is derived using the responses of the leading and following vehicles. It does not require any prior knowledge of the dynamic properties of the bridge. The efficacy of the proposed procedure is validated for both the simple and three-span continuous beams by the finite element method (FEM). Also, a parametric study is conducted for various physical properties of the test vehicles. It is confirmed that the roughness profiles back-calculated from the proposed formula agree excellently with the assumed ones for both the simple and continuous beams. For use in practice, the two connected test vehicles should not be designed too heavy and not to move at too fast speeds, in order to reduce the impact on the bridge.

CFD Modelling Strategies for the Simulation of Roughness Effects on Friction and Heat Transfer in Additive Manufactured Components

2020 ◽  
Author(s):  
Lorenzo Mazzei ◽  
Riccardo Da Soghe ◽  
Cosimo Bianchini
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Thermal Performance ◽  
Accurate Estimation ◽  
Real Surface ◽  
Cfd Modelling ◽  
Roughness Effects ◽  
Modelling Strategies ◽  
The Impact ◽  
Grain Roughness

Abstract It is well-known from the literature that surface roughness affects significantly friction and heat transfer. This is even more evident for additive manufactured (AM) components, which are taking an increasingly important role in the gas turbine field. However, the exploitation of numerical approaches to improve their design is hindered by the lack of dedicated correlations and CFD model developed for such high roughness conditions. Usually the additive manufactured components are simulated considering the surfaces as smooth or applying an equivalent sand-grain roughness (ks) that results in a velocity shift in the boundary layer. However, determining a priori the most appropriate value of ks is challenging, as dozens of correlations are available, returning scattered and uncertain results. The aim of this work is to benchmark some existing modelling strategies (among which the equivalent sand grain roughness) and test a numerical approach capable of narrowing the existing gap between simulated and tested thermal performance of additive manufactured devices. The technology enabler is represented by higher-fidelity CFD simulations accounting for the impact of real surface roughness on pressure drop and heat transfer. At this purpose, an existing literature model for rough walls has been implemented in ANSYS Fluent and tested on a variety of AM mini-channels so as to determine the best-fitting values of ks and corrected wetted surface ratio Scorr that match the experimental data in terms of friction factor and Nusselt number. Knowing also the measured roughness descriptors of each component, it has been possible to derive valuable guidelines for an effective exploitation of CFD on additive manufactured components, thus allowing a more accurate estimation of the thermal performance in additive manufactured components.

Surface Roughness Effects on Fluid Flow between Two Rotating Cylinders

2015 ◽  
Vol 642 ◽  
pp. 275-280
Author(s):  
Sutthinan Srirattayawong ◽  
Shian Gao
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Reynolds Equation ◽  
Surface Profile ◽  
Fluid Film ◽  
Real Surface ◽  
Contact Center ◽  
Roughness Effects ◽  
Fluid Film Thickness ◽  
Lubricant Viscosity

In general, the thin fluid film problems are explained by the classical Reynolds equation, but this approach has some limitations. To overcome them, the method of Computational Fluid Dynamics (CFD) is used in this study, as an alternative to solving the Reynolds equation. The characteristics of the two cylinders contact with real surface roughness are investigated. The CFD model has been used to simulate the behavior of the fluid flows at the conjunction between two different radius cylinders. The non-Newtonian fluid is employed to calculate the lubricant viscosity, and the thermal effect is also considered in the evaluation of the lubricant properties. The pressure distributions, the fluid film thickness and the temperature distributions are investigated. The obtained results show clearly the significance of the surface roughness on the lubricant flow at the contact center area. The fluctuated flow also affects the pressure distribution, the temperature and the lubricant viscosity in a similar pattern to the rough surface profile. The surface roughness effect will decrease when the film thickness is increased.

Influence of Surface Roughness Effects on the Lubrication Performance of External Gear Machines

2017 ◽  
Author(s):  
Divya Thiagarajan ◽  
Andrea Bratto ◽  
Andrea Vacca
Keyword(s):  
Surface Roughness ◽  
Surface Profile ◽  
Operating Conditions ◽  
Gap Model ◽  
Roughness Effects ◽  
Lateral Plate ◽  
Surface Finishes ◽  
Lubrication Performance ◽  
Wide Range ◽  
The Impact

In pressure compensated external gear machines (EGMs), lateral lubricating interfaces exist between floating lateral bushings and gears. These interfaces are primarily responsible for supporting the high pressure bearing loads in these gaps and promoting good operating efficiencies of these units. A fully coupled fluid-structure-thermal interaction lateral gap model has been developed previously in the authors’ research team which considers this highly coupled physical phenomena to predict the lubrication performance of the interface under full film as well as mixed film conditions. In the current work, capabilities of the lateral gap model are utilized in studying the impact of the variations in surface finishes on the performance of a commercially available EGM chosen for this study. Lateral plate designs of varying surface roughness are chosen for the same EGM unit, to analyze their influence on the lubricating performance of the unit. Detailed surface profile measurements were carried out on these lateral plates under study to determine precise inputs to the lateral gap model. Resulting numerical simulations from the gap model over different operating conditions are used to examine the significant performance features associated with the lateral interface which are affected by such surface variations. Furthermore, the paper compares the simulated leakages obtained directly from the lateral gap model for each of the lateral plate designs, with corresponding experimental data over a wide range of operating conditions.

Paper 6: Assessment of Face Seal Performance Based on the Parameters of a Statistical Representation of Surface Roughness

1967 ◽  
Vol 182 (11) ◽  
pp. 101-107 ◽  
Author(s):  
L. A. Mitchell ◽  
M. D. Rowe
Keyword(s):  
Surface Roughness ◽  
Standard Deviation ◽  
Surface Profile ◽  
Real Surface ◽  
Face Seal ◽  
Statistical Representation ◽  
Adequate Information ◽  
Centre Line ◽  
Sealing Performance ◽  
The Mean

Most methods commonly used to describe real surface roughness do not provide adequate information to enable predictions to be made of fluid leakage between two surfaces. To carry out such an analysis it is essential to know the depths of the remaining valleys at all stages of compression. It is shown that, when the distributions of peak and valley levels are defined, load-compression and load-leakage relationships can be derived if wedge-shaped asperities of constant apex semi-angle are assumed. The results suggest that a convenient quantity for specifying the form of a surface profile is the ratio of the distance between the mean peak and mean valley levels to the standard deviation of the distributions ( d/σ). For the best sealing performance d/σ should be as large as possible, whilst the centre-line average (c.l.a.), which provides a measure of the scale of the roughness, should be as small as possible.

scholarly journals Fractal analysis for biosurface comparison and behaviour prediction

2009 ◽  
Vol 63 (3) ◽  
pp. 239-245 ◽  
Author(s):  
Bozica Bojovic ◽  
Zoran Miljkovic ◽  
Bojan Babic ◽  
Djuro Koruga
Keyword(s):  
Surface Roughness ◽  
Fractal Dimension ◽  
Fractal Analysis ◽  
Surface Profile ◽  
Scanning Probe ◽  
Real Surface ◽  
Behavior Prediction ◽  
Functional Behavior ◽  
Probe Microscope ◽  
The Given

Fractal analysis was used in previous authors' researches for characterizations of grinded ceramics surface textures by surface profile fractal dimension. In this paper the 'skyscrapers' method was chosen for calculating fractal dimension of surface, using the image processing toolbox, as well as a custom-developed algorithm of Matlab environment. This method entails recording the surface as an image, by using a scanning probe microscope. In the given contact lens case, fractal dimension values confirm changes of the surface roughness during the cleaning and wearing processes. Examination of real surface roughness could provide comparison and functional behavior prediction.

Automated system for creating training programs for mass professional users

2020 ◽  
pp. 21-27
Author(s):  
V.K. Grigoriev ◽  
A.A. Biryukova ◽  
A. Yu. Volk ◽  
A.S. Ilyushechkin
Keyword(s):  
Experimental Verification ◽  
Training Programs ◽  
Automated System ◽  
Software Product ◽  
Learning Programs ◽  
E Learning ◽  
The Creation ◽  
The Impact

The article discusses the automation of the creation and use of e-learning programs. The impact of automating the learning of a large number of users on the effectiveness of the introduction of a new software product is analyzed. The methods and algorithms that increase the efficiency of creating electronic training programs on example of the author’s automated system “Tutor Builder” are described. The results of experimental verification of the automated system are provided.

scholarly journals Smoothing additive manufactured parts using ns-pulsed laser radiation

2021 ◽  
Author(s):  
Florian Kuisat ◽  
Fernando Lasagni ◽  
Andrés Fabián Lasagni
Keyword(s):  
Surface Roughness ◽  
Mechanical Performance ◽  
State Of The Art ◽  
Pulsed Laser ◽  
Industrial Applications ◽  
Laser Source ◽  
Pulsed Laser Radiation ◽  
Current State ◽  
The Impact

AbstractIt is well known that the surface topography of a part can affect its mechanical performance, which is typical in additive manufacturing. In this context, we report about the surface modification of additive manufactured components made of Titanium 64 (Ti64) and Scalmalloy®, using a pulsed laser, with the aim of reducing their surface roughness. In our experiments, a nanosecond-pulsed infrared laser source with variable pulse durations between 8 and 200 ns was applied. The impact of varying a large number of parameters on the surface quality of the smoothed areas was investigated. The results demonstrated a reduction of surface roughness Sa by more than 80% for Titanium 64 and by 65% for Scalmalloy® samples. This allows to extend the applicability of additive manufactured components beyond the current state of the art and break new ground for the application in various industrial applications such as in aerospace.

scholarly journals The Surface Condition of Ni-Cr after SiC Abrasive Blasting for Applications in Ceramic Restorations

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5824
Author(s):  
Weronika Czepułkowska-Pawlak ◽  
Emilia Wołowiec-Korecka ◽  
Leszek Klimek
Keyword(s):  
Surface Condition ◽  
Abrasive Particle ◽  
Surface Profile ◽  
Abrasive Particles ◽  
Dental Restorations ◽  
Large Width ◽  
Ceramic Restorations ◽  
The Impact ◽  
Abrasive Size ◽  
Abrasive Blasting

Abrasive blasting is a process widely used in dentistry. One of the uses is the development of metal surfaces for connections with ceramics in fixed prosthetic restorations. The purpose of this paper was to check how the rough surface profile (width, height, and depth on unevenness) impacts the surface’s condition, like its wettability and percentage of stuck abrasives. The Ni-Cr alloy surface was abrasive blasted by silicon carbide with the various pressure parameters (0.2, 0.4, and 0.6 MPa) and abrasive particle sizes (50, 110, and 250 µm). Cleaned surfaces were examined for roughness, wettability, and percentage of stuck abrasive particles on the surface. The surface after abrasive blasting using 110 µm of abrasive size and 0.4 MPa pressure has the best wettability results. The width of unevenness may cause it. When the unevenness has too small or too large width and depth, the fluids may not cover the entire cavities because of locking the air. The surface condition of dental alloys directly affects metal–ceramic connection strength. The knowledge about the impact of the abrasive blasting parameters on the bond strength will allow one to create durable dental restorations.

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