On the Applicability of Laser Scanning for Evaluation of the Pavement Serviceability Parameters

Pavement performance is influenced by man factors such as climate and environmental conditions, traffic and operational conditions and type of pavement. These factors cause a pavement deterioration what leads to the restriction of the pavement serviceability or pavement efficiency. The pavement serviceability is the ability of the pavement to fulfil the service function represented by the actual values of variable parameters such as pavement surface roughness, surface evenness, pavement surface condition. The state of the pavement is assessed using different performance indicators when International Roughness Index (IRI) is most used. This approach allows to classify the state of the pavement in the pavement management system as a most used indexing, generalizes the pavement surface to the response of the testing car tire and the pavement. Laser scanning presented in this paper is able to bring the knowledge about the real pavement surface considering the accuracy of the method and equipment. Realized laser scanning proved the applicability of this method for the measurement of the pavement surface. Because of the complex knowledge of the pavement surface morphology, we can evaluate the pavement serviceability in terms of roughness, surface evenness or even pavement surface condition (rutting or cracks).

Correlation Analysis of Roughness Surface Height Distribution Parameters and Maximum Mises Stress

Roughness surfaces contact analysis is an advanced research topic in interface design. The 3D rough surface amplitude distribution characterized by height distribution parameters(Sq (root mean square), Ssk (skewness), Sku (kurtosis)) has a great influence on the extreme value and distribution of the interface contact stress. However, the relationship between height distribution parameters and surface maximum mises stress (σmax) is still unclear and lacks of in-depth study. With the assistance of roughness surface reconstruction and contact stress algorithm proposed by the research group, σmax under a large sample was calculated and used as the data support for correlation analysis. Through BP neural network, global sensitivity qualitative (Morris) and quantitative (Sobol) analysis methods, the relationship between Sq, Ssk, Sku and σmax under different loads is studied. Based on complete polynomial and permutation combination method, the optimal correlation model between height distribution parameters and σmax was established, and particle swarm algorithm was introduced to analyze σmax extreme values under different Sq. The results show that: (1) Under different loads, the order about height distribution parameters influence on surface contact stress is: Sq> Ssk > Sku, and as the load increases, the influence of Ssk and Sku gradually decreases. (2) In different roughness surfaces, the influence of Ssk and Sku on the contact performance is significantly full of discrepancy. The research results provide reference and technical support for active design of rough surface microstructure to improved contact performance.

Analysis of the best roughness surface based on the bearing area curve theory

An in-depth study of friction and wear requires analysis of the surface morphologies and contact status of friction pairs in mechanical systems. The bearing area curve is introduced for the calculation of wear, and combined with the concept of repositioning. The application of fast calculation of wear amount and improved three-dimensional characterization of a bearing area curve is achieved by this new method. The best roughness surface is used as the target surface to extract the target bearing area curve. The influence of microtexture parameters on the bearing area curve is studied to determine the optimal microtexture parameters. The test results show that a matching texture surface has a short run-in time and the lowest friction coefficient after stabilization among the surfaces studied herein, and the presence of a texture changes the wear mechanism from the original adhesive wear to abrasive wear and improves the tribological performance. The best texture parameters and laser process parameters are determined, which provide new ideas for the optimal design of surface topography.

Effects of Surface Irregularities and Coatings on Thermal Emittance of Selected Metals Between 373 and 1073 K

In many areas of engineering, radiation heat transfer plays an important role and it is of great importance the knowledge of the thermal radiative properties of the surfaces involved. Radiation properties of solid materials are highly dependent on surface characteristics, e.g., surface roughness, surface damage, oxide layers, and deposited thin films, and cannot be assumed as those of pure materials, typically referred to optically smooth surfaces (OS). An experimental investigation of the thermal emittance of some metals (nickel, titanium, silver, and stainless steel) is presented. Experiments were conducted by using a radiometric apparatus able to measure the total normal emittance under different temperature and pressure conditions. The aim of this paper was to identify the separate roles of surface microgeometry alterations (surface roughness), surface damage, and surface coatings (i.e., presence of either thin films deposited onto a smooth surface or oxide layers formed on both smooth and rough surfaces) by undertaking carefully selected sets of experiments covering a relatively large temperature range.

The Effects of Food-Simulating Liquids on Surface Roughness, Surface Hardness, and Solubility of Bulk-Fill Composites

Aim: To investigate the surface roughness, surface hardness, and solubility of bulk-fill composites after exposure to food-simulating liquids (FSLs). Materials and Methods: A total of 200 disc-shaped samples (8 mm diameter × 4 mm depth) were prepared using four bulk-fill composites (SonicFillTM, Tetric® EvoCeram Bulk Fill, Beautifil-Bulk Restorative, FiltekTM Bulk Fill Posterior Restorative) and a microhybrid composite (FiltekTM Z250) ( n = 40). Following the measurement of initial weights of the samples ( m1), the surface roughness measurements were gauged using a contact-profilometer. The samples were stored in four different FSLs for 7 days, and then the second surface roughness values were recorded. The samples were stored in a desiccator to reach the constant mass and the values were recorded as m2, then the solubility levels were calculated. The Vickers microhardness values of the samples were determined. A total of 20 specimens were evaluated in terms of surface morphology with a scanning electron microscope (SEM). Data were statistically analyzed with the two-way ANOVA and Bonferroni tests ( P < .05). Results: Beautifil-Bulk Restorative was affected at most in terms of surface roughness after storage in FSLs and citric acid caused the highest values in this group ( P < .005). Beautifil-Bulk Restorative and Filtek Z250 showed the highest surface hardness values, while the Tetric EvoCeram group had the lowest. The highest solubility values were found in Beautifil-Bulk Restorative, and citric acid and ethanol yielded the highest solubility values for all of the composites. Conclusion: Beautifil-Bulk Restorative is the most affected group in all parameters evaluated and also affected overly by citric acid among the FSLs in consequence of its prereacted glass ionomer fillers.

Controllable magnetic roughness surface with sustainable superhydrophobicity based on magnetorheological colloid

In this article, magnetorheological colloid was adopted to coat a stainless steel substrate, which was cured under magnetic field to form magnetic roughness surface. Superhydrophobicity had been verified in the experiments, and the influential factors on the hydrophobic performance had been explored. A regular sawtooth structure model was proposed to relate the hydrophobicity with the formed surface microstructure. With the self-cleaning and bonding strength testing, the magnetic roughness surface is promising to keep sustainable superhydrophobicity in the self-cleaning or drag reduction applications.