Types Of Surface Conditions Research Articles

Experimental and theoretical study on bond behavior of helically wound FRP bars with different rib geometry embedded in ultra-high-performance concrete

Fiber reinforced polymer (FRP) bar reinforced ultra-high-performance concrete (UHPC) members have attracted wide interest due to their excellent durability and mechanical properties. Determining bond strength is of great importance to the design of FRP bar reinforced UHPC members. This study investigates the effects of bar type, concrete type and rib geometry on the bond behavior of helically wound FRP bars embedded within UHPC. Pull-out tests on a total of 48 specimens with three types of concrete (0%, 1% and 2% steel fiber content), three types of bar (steel, basalt FRP and glass FRP) and three types of surface condition (smooth, shallow ribbed and deep ribbed) have been conducted. The results show that the bond strength of FRP bars embedded within UHPC is greatly affected by rib height. Indeed, FRP bars with deep ribs can reach a bond strength comparable to that of ribbed steel bars. A novel bond strength model for FRP bars embedded within UHPC, considering the effect of rib geometry, has been proposed and validated by the experimental results and existing data in the literature.

The Effecacy of Different Surface Conditioning on Shear Bond Strength of Orthodontic Bracket Bonded to Lithium Disilcate Crowns; An in Vitro Study

Background and objective: Lithium disilicate widely used, and it is important to correctly bond orthodontic brackets to such materials. This study aimed to assess the impact of various types of surface conditioning methods on the shear bond strength (SBS) of orthodontic metal brackets to lithium disilicate crown. Materials and methods: In this in vitro study, 30 lithium disilicate specimens were prepared based on the type of surface conditioning into three surface conditioning groups (n=10 for each group). First group the semi-crowns surface was conditioned with 10% hydrofluoric acid etching, the second group was micro-etched with sandblast particles (50 um aluminum oxide particles) and the last group was conditioned with ultrasonic scaler. Valo light cure was utilized with 3200mw/cm2 light intensity. SBS was measured using a universal testing machine. The findings were statistically examined. Result: The results showed significant difference among the three groups where the sandblasting group had the higher mean of SBS, while the hydrofluoric acid etching group had the lower value and in between, the mean of ultra-sonic intermediate.      Conclusions:  Although the means of the three types of surface conditioning were significantly different, shear bond strength was positively affected by all of them and subsequently all types may be considered recommended techniques for reliable shear bond strength

Evaluation Method of Soil Surface Roughness after Ditching Operation Based on Wavelet Transform

Soil surface roughness (SSR) is an important parameter affecting surface hydrology, erosion, gas exchange and other processes. The surface roughness of the farmland environment is directly related to the tillage process. In order to accurately characterize the random roughness (RR) parameters of the surface after ditching, a three-dimensional (3D) digital model of the surface was obtained by laser scanning under the conditions of an indoor ditching test, and the influence of oriented roughness components formed by removing ridge characteristics on the RR of the surface was analyzed by introducing the wavelet processing method. For this reason, four groups of ditching depths and two types of surface conditions (whether the surface was agglomerated or not) were designed in this paper. By comparing the root mean squared height (RMSH) and correlation length (CL) data calculated before and after wavelet processing under each group of tests, it was concluded that the RMSH values of the four groups before and after wavelet processing all change more than 200%, the change amplitude reached 271.02% under the treatment of 12 cm ditching depth, meanwhile, the average CL value of five cross-sections under each group of ditching depths decreased by 1.43–2.28 times, which proves that the oriented roughness component formed by furrows and ridges has a significant influence on the calculation of RR. By further analyzing the roughness value differences of clods and pits in different directions and local areas before and after wavelet transform, it was shown that the wavelet transform can effectively remove the surface anisotropy characteristics formed in the tillage direction and provide a uniform treatment method for the evaluation of surface RR at different ditching depths.

Flexural behavior of eco-efficient and ultra-high durability concrete beams

The present paper describes an experimental study conducted to characterize the behavior of structural members produced with a new concept, consisting of using an ultra-high durability concrete (UHDC) in the cover of structural members, being the core produced with a low-binder concrete. This solution allows to build structures more durable and simultaneously eco-friendly because the UDHC that requires high dosages of Portland cement is applied only in the outer layer, where is most needed to protect the structure against the environmental actions. To reduce even more the cement consumption and the corresponding drawback regarding sustainability, the bulk of the members was produced with a concrete with a lower mechanical performance but also with lower cement dosage, only 125 kg/m3.Many of the previous studies were focused on the mixtures design, as well as on the shear strength of the interface between the cover and the bulk, considering different types of surface conditions. This work explores this concept in terms of structural behavior, particularly, on beams. With this aim eight beams with different longitudinal tensile reinforcement ratios were tested and the following parameters were analyzed: load-displacement relation; curvature in critical sections; flexural stiffness; ductility, cracking pattern, and failure mode. The tested eco-efficient high durability beams exhibited an excellent structural behavior, presenting both stiffness and flexural strength increase.

Experimental and numerical study of oxygen catalytic recombination of SiC-coated material

A combined experimental and numerical approach has been proposed to study the oxygen catalytic recombination coefficient of SiC-coated material for two different types of surface condition: roughened and pre-heated. For the experimental approach, the shock tube facility, which test gas consists of 21% oxygen and 79% argon by volume, is utilized to measure the oxygen catalytic recombination coefficient at near-room surface temperature. The coefficient is deduced from the local heat transfer measurement at the end-wall model of the shock tube via catalytic boundary layer theory. The experimental data indicated that the coefficient for the SiC-coated material varied between 0.0024 and 0.01, depending on the surface condition. The results suggested that even at low surface temperature, both the level of surface roughness and the oxidation due to the pre-heating should be considered carefully for the atomic recombination process. For the numerical approach, the finite rate catalytic modeling is elaborated in detail. The modeling is conducted to better understand the physical interaction for the recombination mechanism. Given the surface reactions considered in the modeling, the catalytic recombination coefficient was not significantly affected by the pressure at low wall temperature. Conversely, the variation in the coefficient was observed to be dependent on the activation energy and the number of active site concentrations at the surface.

Investigation on Surface Degradation of Wind Turbine Blades Surface Using Modified Surface Tracking Test as Part of Lightning Protection Improvement

This research work investigates the surface degradation of modified surface as part of wind turbine blade surface which is made from epoxy resin mixed with calcium carbonate (CaCO3) in different percentage as a filler elements. Accelerated test with AC voltage of 4.5 kV 50 Hz with a saline solution using flow rate of contaminant equals to 0.6 ml/min according to IEC 60587 standard [. It was found that ,the solid insulators which has a high percentage of calcium carbonate filler will slowdown the process of surface tracking. On the other hand, if the percentage of filler is more than 40% by weight ,it will lead to a faster tracking . In addition, researchers have tried to develop a type of surface condition by comparing the time to track between flatted and corrugated surfaces test sample. It was found that , the flatted surface can withstand the generated track than corrugated surface. Also, when the incline plane has been increased rather than 45 degrees, the breakdown process occurred slowly.

OS1545 スーパー二相ステンレス鋼の疲労強度に及ぼす表面性状の影響

To clarify the effect of surface conditions for fatigue strength of super duplex stainless steel, plane bending fatigue tests were conducted with four types of surface conditions; emery polished, machined, shot blasted and grinded surface. Furthermore, surface residual stress, hardness and roughness were measured. As the result, fatigue limits were varied by surface conditions and it was considered to be affected by not only surface roughness but also residual stress and work hardening. In this study, √<area> parameter model with a-phase stress gave a good prediction for fatigue limit of super duplex stainless steel.

Evaluation of crack nucleation site and mechanical properties for friction stir welded butt joint in 2024-T3 aluminum alloy

In this paper, metallographic observations, hardness measurement, and static and fatigue tests were conducted to investigate the discontinuity states which become crack nucleation sites in friction stir welded butt joints in 2-mm-thick 2024-T3 aluminum alloy and static and fatigue properties of the joint. Because different types of surface finish can be used depending on the application of the joint, several types of surface conditions were tested to evaluate their effect on crack nucleation sites and static and fatigue life. Indentation hardness tests revealed that typical hardness reduction is not necessarily observed on the section of the welding line. Based on fatigue test results, it was confirmed that there are several types of crack nucleation sites for friction stir welding (FSW) joints depending on the surface finish, and the features of the fracture surface also differ depending on the site. Furthermore, the type of discontinuity state affects the fatigue life of the FSW joint.

Spatial and temporal patterns of aeolian sediment transport on an inland parabolic dune, Bigstick Sand Hills, Saskatchewan, Canada

Topographic changes from erosion pins and on-site meteorological data document the spatial and temporal patterns of aeolian sediment transport at monthly to annual timescales across an active parabolic dune within a vegetation-stabilized inland, prairie dune field. Over two years, the sediment budget, calculated from digital elevation models, shows that the total volume of erosion (9890 m 3) is greater than the amount of deposition (6990 m 3), indicating a net loss of 2900 m 3 of sediment (or ∼ 29% of eroded sediment) from the dune. Sediment erosion occurred mainly on the stoss slope (3600 m 3; ∼ 36% of eroded sediment), but also on the south (2100 m 3; ∼ 21%) and north sides of the dune head (1700 m 3; ∼ 17%), the blowouts along the arms (1740 m 3, ∼ 18%) and the crest (650 m 3; ∼ 7%). Erosion from the deflation basin is limited by surface roughness and armoring effects of a gravel lag deposit (100 m 3; ∼ 1%). Thus, the blowouts currently contribute to maintaining dune mobility because no other sediment input occurs from upwind. Sediment deposition onto the dune occurred primarily beyond the brink on the south and southeast lee slopes (5500 m 3; ∼ 80%), coinciding with the southeasterly resultant transport direction for November 2004–05. The net loss of about 2900 m 3 (∼ 29%) may be attributed to sediment carried in suspension over and beyond the dune. Correlation analysis between sediment transport and meteorological variables suggests that monthly to seasonal changes of surface conditions (e.g., vegetation cover, ground freezing, moisture) buffer the relative importance of temperature and precipitation on rates of sediment transport. Conversely, wind correlates well on a monthly to seasonal basis because it is a driver of transport under all types of surface conditions. Seasonal effects produce a complex interaction between wind, climate and surface conditions. This leads to a dynamic range of threshold velocities, which in turn causes spatial and temporal variations in transport-limiting and supply-limiting conditions. Collectively, these findings have implications for modeling parabolic dune morphodynamics and sediment transport in mid- to high-latitude inland settings.

Influence of plastic anisotropy on the mechanical behavior of clinched joint of different coated thin steel sheets

This work describes an experimental and numerical study of the TOX®- clinching process and its mechanical strength due to different surface conditions (blank, electro galvanized, corrosion protection primer (CPP) coated). The main purpose of using different types of surface conditions is to analyze their influences on the geometry and mechanical strength of the clinched joint. Finite element analysis (ABAQUSExplicit) is used to model the clinching process as well as the subsequent loading of the joint in the shear and cross tension test. The influence of the plastic anisotropy of the material is analyzed by evaluation of the punch force-displacement curve and the strength of clinched joint under these loading conditions.

Image Requirements for Three-Dimensional Measurements of Pavement Macrotexture

This paper examines the effect of wavelength range on the estimation of pavement macrotexture quality from a three-dimensional (3-D) surface model. Macrotexture indicators computed from two-dimensional (2-D) profiles are compared with power spectrum energy computed from 3-D surface heights in the frequency domain. Pavement samples with different types of surface conditions were evaluated by means of a noncontact photometric stereo system. For each pavement sample, surface heights were recovered and a 3-D surface model was constructed. Surface profiles were also measured manually with a dial gauge. The surface heights in frequency domain were divided into 10 wavelength ranges. Power spectrum energy was computed for each wavelength range. The correlation between the 2-D indicators (mean profile depth and root mean square roughness) and the power spectrum energy was examined. It was found that the texture indicators computed from the 3-D recovered surface could represent the 2-D indicators adequately. Moreover, the power spectrum energy provided a good estimation of the 2-D indicators when it was computed from wavelength ranges of approximately 13 times the expected range of the 2-D indicators.

Recommendations for the Use of an Atomic Force Microscope as an In-Fab Stiction Monitor

An atomic force microscope (AFM) can be used to monitor stiction (by measuring the work of adhesion) at different stages of manufacture, which then might be correlated to device performance. The four main challenges to using the AFM as an in-fab stiction monitor are calibration, effects from the angle of repose of the cantilever, surface roughness, and material properties. We measured the work of adhesion between different AFM tips and samples. There were 17 tips of four different types, with radii from 200 nm to 60, covering the range of typical microelectromechanical systems (MEMS) contacts. The samples were unpatterned amorphous silicon dioxide MEMS die with two types of surface conditions (untreated and treated with a few angstroms of vapor-deposited diphenylsiloxane). A simple correction for the surface roughness resulted in the expected linear dependence for work of adhesion on radius, but the magnitudes were higher than expected. Commercial and heat-treated AFM tips have minimal surface roughness and result in magnitudes that were more reliable. In this paper, we review the four main challenges and show their influence on the measured work of adhesion, from which we develop a set of recommendations for the use of an AFM as an in-fab stiction monitor.

Evaluation of the electric force in electrophoresis

A new expression for the evaluation of the electric force acting on a colloidal particle in an applied electric field is derived under the condition of weak applied electric field. The expression derived, which is based on the Maxwell stress tensor, is applicable to both rigid and soft particles for various types of surface conditions and to both symmetric and asymmetric geometries. We show that, depending upon the electrophoresis conditions, the electric force evaluated by the methods commonly used in the literature can be overestimated, thereby leading to incorrect electrophoretic mobility.

ACTUAL SURFACE CONDITIONS OF AIRPORT ASPHALT PAVEMENTS

Actual surface conditions of airport asphalt pavements have been surveyed and the changes of them with time have also been investigated with the accumulated survey data. The following primary findings are obtained. 1) The current surface conditions of runways are evaluated better than those of taxiways, that leads to higher PRI for the runways. 2) The current surface conditions are rated good as a whole, but those of runways are evaluated worse compared with those of taxiways. 3) Annual changes of surface conditions depend on airports, and the influencing factors are different in types of surface conditions and pavement facilities. 4) Annual changes of surface conditions for runways could be roughly estimated with multiple linear regression analysis.

Experimental Study of Wear Behaviour of Hot Forging Tool Steels Under Dry Conditions: 40CrMoV13 Against C35E

The dimensions and quality of forged-steel components are significantly affected by the action of friction and wear. The thermal and mechanical operating conditions of hot forging tools provoke serious degradation, such as oxidative wear, thermal fatigue, plastic damage and mechanical cracking. This slowly causes the tools to lose their original geometry and thus they must be either reformed or discarded [1]. The knowledge and control of this damage is essential and must be taken into consideration, both in die design and in the choice of tool material and the type of surface conditioning. The degradation has direct effects on the lifespan of the tools, and consequently on the cost of the components. This paper deals with the sliding wear behaviour of 40CrMoV13 Steel against C35E in the 700 to 850 °C temperature range under ambient conditions. This steel is used frequently as hot forging die material. This study focuses on the effect of the test temperature and the role of the oxide scales. The purpose of these experiments was to obtain tribological data (friction coefficient, wear rate, etc.), in order to include it in numerical simulations of damage to hot forging tools for the purpose of optimizing the tools' lifespan.

Effect of surface conditioning and restorative material on the shear bond strength and resin–dentin interface of a new one-bottle nanofilled adhesive

Objectives: To determine the effect of different combinations of surface conditioning (DeTrey Conditioner 36, NRC, no etching) and restorative materials (Dyract AP, Spectrum TPH) on the shear bond strength of Prime and Bond NT to enamel and dentin, and to characterize the resin–dentin interface produced by these combinations. Methods: Shear bond strength was tested on 30 enamel and 30 dentin flat labial surfaces of extracted bovine teeth. The enamel and dentin specimens were randomly assigned to six groups of five teeth each and treated using different combinations of surface conditioners and restorative materials with Prime and Bond NT. Scanning electron microscope (SEM) observation of argon-ion-etched specimens was done to evaluate the resin–dentin interface. Results: The type of surface conditioning and restorative material had significant effects on dentin bond strengths. Etching the dentin prior to application of Prime and Bond NT significantly increased bond strength and caused formation of a hybrid layer for Spectrum TPH. For Dyract AP, dentin etching generally did not improve bond strength despite the formation of a hybrid layer. On enamel, Prime and Bond NT had consistently high bond strengths on etched specimens. Significance: The results showed that Dyract AP and Spectrum TPH, when used with Prime and Bond NT have different bonding mechanisms and the effect of surface conditioning on their shear bond strength differs. Clinicians should be aware of these effects in order to optimize bonding.

Chloride Corrosion Threshold of Reinforcing Steel in Alkaline Solutions—Open-Circuit Immersion Tests

Abstract Reinforcing steel bars with three types of surface conditions (as-received mill scale, prerusted in 3.5% sodium chloride [NaCl] solution, or sandblasted) were exposed in open-circuit immersion (OCI) tests in pH 12.6 saturated calcium hydroxide (Ca[OH]2) solution (SCS) and pH 13.3 (SPS1) and pH 13.6 (SPS2) simulated concrete pore solutions. These solutions were free of chlorides at the beginning of the test to allow the steel specimens to passivate. Then the chloride concentration ([Cl−]) was increased in several steps. The corrosion potential was monitored, and electrochemical impedance spectroscopy tests were performed periodically on selected specimens. It was found that active corrosion for all three surface conditions tookplace in the pH 12.6 SCS andpH 13.3 SPS1, when the [Cl−] reached threshold levels. However, sustained active corrosion of steel was not found inpH 13.6 SPS2 in a testing period of ∼ 2 years, although the final [Cl−] in that solution reached 3.0 M. Removing the mill scale or ...

Unsteady mixed convection from a sphere in water-saturated porous media with variable surface temperature/heat flux

Mixed convection about a sphere buried in a porous medium saturated with water is numerically investigated using a Chebyshev-Legendre spectral method. Both Darcy's law and the Boussinesq approximation together with effects due to nonlinear dependence of density on temperature are used to formulate the governing equations. Two types of surface condition are considered including variable surface temperature and surface heat flux which are modeled by Legendre expansions. Calculated results for the nonuniform heating and the nonuniform surface temperature cases demonstrate that the flow structures are not much different from the non-porous medium except for the recirculation zones which appear when the direction of the free stream velocity is opposite to the direction of the buoyancy force. Effects of nonuniform surface temperature are seen to dictate the heat flux distribution along the sphere surface and vice versa.

Analysis of an asymmetrical model for boundary diffusion

An asymmetrical version of the Fisher model, in which bulk diffusivities on both sides of the boundary are different, is analyzed. Five regimes of boundary diffusion (C,B1, B3 and B4) are distinguished. They progressively change each other as the temperature or/and time of diffusion anneal increase. Asymptotic solutions corresponding to the regimes are obtained, three types of surface conditions (constant source, Suzuoka's conditions, fast surface diffusion) being considered. In B2-regime, which is the most widely spread, only the product D′δ can be determined, while in B1-regime the boundary diffusivity D′ and width δ can be determined separately. Due to introducing an effective bulk diffusion coefficient, analytical solutions for C, B1 and B2-regimens are applicable to interphase boundary diffusion. The results can be used in designing diffusion experiments and treating measured penetration curves.

Corrosion of Silicate Glasses: An Overview

ABSTRACTThe corrosion of silicate glasses is described in terms of four stages of surface attack which result in six types of surface conditions depending upon the glass composition and various environmental and physical factors. Type I and II surfaces correspond to durable glasses which have a very high surface SiO2 content whereas Type IV and V surfaces are unstable. Type IIIA surfaces include bioactive glasses which chemically bond to bone and Type IIIB surfaces are characteristic of the alkali borosilicate nuclear waste glasses which form multiple layers of precipitated surface films.