scholarly journals Characterization of the surface of formworks – Influence of the surface energy and surface texture parameters on the demolding forces

2021 ◽  
Vol 272 ◽  
pp. 121947
Author(s):  
Calypso Chadfeau ◽  
Safiullah Omary ◽  
Essia Belhaj ◽  
Christophe Fond ◽  
Françoise Feugeas
1975 ◽  
Vol 97 (1) ◽  
pp. 190-195 ◽  
Author(s):  
T. S. Sankar ◽  
M. O. M. Osman

This paper discusses a new approach for describing accurately the typology of manufactured surfaces. The method employs the theory of stochastic excursions to characterize the surface texture in the amplitude and lengthwise directions. The mathematical principle behind the approach is briefly explained, and it is shown that an accurate description of the roughness can be obtained from the knowledge of the intercept probabilities of the crest and valley excursions of the surface texture about any given level, say the CLA value, specified with respect to the mean line. Based on the preceding excursion probability densities, new surface texture parameters are proposed. These parameters may be computed directly from the surface roughness data obtained from commercially available measuring devices. On the basis of this investigation, it is feasible to develop a low-cost measuring device for “on-line” surface evaluation in production. It is also shown that the sampling length provides a geometrically well-defined filter characteristic similar to that of the rolling circle radius in the E-system.


Author(s):  
Timothy Miller ◽  
Daniel Swiertz ◽  
Laith Tashman ◽  
Nader Tabatabaee ◽  
Hussain U. Bahia

This paper presents improved analysis methods for characterizing asphalt pavement surface texture and focuses on the use of laser profiling techniques to estimate friction characteristics. Derived from signal processing theories, texture spectral analysis methods show promise for improving characterization of the tire–pavement interface. Texture parameters measured with spectral analysis techniques represent a means for quantifying surface properties. Current methods to analyze frictional properties rely on the mean profile depth (MPD) and mean texture depth (MTD) texture parameters. Although these parameters are used widely, they do not capture the range and distribution of surface asperities on the pavement surface. Knowing the distribution of surface asperities is critical for assessing friction characteristics. Thus, texture spectral analysis methods are anticipated to improve on the MPD and MTD parameters by capturing relevant texture-level distributions. This study investigates the applicability of laser profiling systems for measuring pavement surface texture and subsequent relationships to friction. Models accounting for aggregate and mixture properties are developed and related to texture parameters through analysis of constructed field sections and corresponding laboratory samples. Results indicate that stationary laser profiling systems can capture the microtexture and macrotexture spectrum and suggest that a comprehensive friction characterization of asphalt mixtures can be obtained in a laboratory setting. With this analysis system, it is believed that asphalt mixture designers will have an improved tool by which to estimate pavement surface texture and frictional properties.


Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 758
Author(s):  
Cibi Pranav ◽  
Minh-Tan Do ◽  
Yi-Chang Tsai

High Friction Surfaces (HFS) are applied to increase friction capacity on critical roadway sections, such as horizontal curves. HFS friction deterioration on these sections is a safety concern. This study deals with characterization of the aggregate loss, one of the main failure mechanisms of HFS, using texture parameters to study its relationship with friction. Tests are conducted on selected HFS spots with different aggregate loss severity levels at the National Center for Asphalt Technology (NCAT) Test Track. Friction tests are performed using a Dynamic Friction Tester (DFT). The surface texture is measured by means of a high-resolution 3D pavement scanning system (0.025 mm vertical resolution). Texture data are processed and analyzed by means of the MountainsMap software. The correlations between the DFT friction coefficient and the texture parameters confirm the impact of change in aggregates’ characteristics (including height, shape, and material volume) on friction. A novel approach to detect the HFS friction coefficient transition based on aggregate loss, inspired by previous works on the tribology of coatings, is proposed. Using the proposed approach, preliminary outcomes show it is possible to observe the rapid friction coefficient transition, similar to observations at NCAT. Perspectives for future research are presented and discussed.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Junru Wang ◽  
Quandai Wang ◽  
Yueyan Li ◽  
Meiling Guo ◽  
Pengyang Li ◽  
...  

Purpose The purpose of this paper is to investigate the effects of surface texture with roughness orientation considered on tribological properties under a mixed lubrication state numerically and experimentally. Design/methodology/approach Based on the average Reynolds equation and asperity contact model, the impacts of surface texture parameters and roughness orientation on lubrication properties have been calculated using finite difference method. Tin–bronze samples with various prescribed surface texture geometric parameters and roughness orientation were fabricated by laser surface texturing technique, and the tribology performance of the textured surface was studied experimentally. Findings The effects of surface geometric parameters and roughness orientation parameters have been discerned. The experimental observations are in good agreement with the numerical prediction, which suggests that the numerical scheme adopted in this work is suitable in capturing the surface texture and roughness effect under mixed lubrication state. Originality/value By meticulously controlling the surface roughness and surface texture geometric characteristics based on the laser surface texturing process, samples with prescribed surface texture parameters and roughness orientation consistent with that in theoretical studies were fabricated and the theoretical model and results were verified experimentally.


2019 ◽  
Vol 799 ◽  
pp. 71-76
Author(s):  
Oskars Linins ◽  
Ernests Jansons ◽  
Armands Leitans ◽  
Irina Boiko ◽  
Janis Lungevics

The paper is aimed to the methodology for estimation of service life of mechanical engineering components in the case of elastic-plastic contact of surfaces. Well-known calculation methods depending on physics, theory of probability, the analysis of friction pair’ shape and fit include a number of parameters that are difficult or even impossible to be technologically controlled in the manufacturing of mechanical engineering components. The new approach for wear rate estimation using surface texture parameters as well as physical-mechanical properties and geometric parameters of components is proposed. The theoretical part of the calculations is based on the 3D surface texture principles, the basics of material fatigue theory, the theory of elasticity and the contact mechanics of surfaces. It is possible to calculate the service time of the machine, but the process of running-in of the components is relatively short (less than 5%), therefore, the service time is mainly determined by a normal operating period, which also was used to evaluate this period. The calculated input parameters are technologically and metrologically available and new method for calculating the service time can be used in the design process of the equipment. The results of approbation of the method for estimation service time of mechanical engineering, which prove the applicability of mentioned method, are offered as well.


Author(s):  
Turker Oktay

Surface texture of engine components such as crankshafts and camshafts is one of the most important factors that determine the performance, efficiency and the operating life of an internal combustion engine. Current practices and the challenges faced by design engineers in specifying the target surface topography to meet these goals have been reviewed. Once specified, the surface texture must be measured fast, accurately and repeatably in the rough environment of an engine manufacturing plant. The key components of an automated skidded surface finish measuring gage designed with these criteria in mind are described in this paper. The gage has 7 axes of motion and 3 stylus probes oriented in the axial and radial directions to take axial and facial measurements on journal and cam lobe surfaces and thrust bearing surfaces. The selection of surface texture parameters to best describe the desired surface texture of these engine components was investigated. The final stage of surface preparation is often the superfinishing process. The measurement gage must be able to provide the sensitivity and repeatability that are required for measuring the finely finished surfaces generated by this process. Typical surface texture results of a superfinishing process achieved on crankshafts are described. The results of a Gage Repeatability and Reproducibility (R&R) study performed on the surface texture measuring gage are presented.


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