Sample records for macrotexture
-
Assessing the role of pavement macrotexture in preventing crashes on highways.
Pulugurtha, Srinivas S; Kusam, Prasanna R; Patel, Kuvleshay J
2010-02-01
The objective of this article is to assess the role of pavement macrotexture in preventing crashes on highways in the State of North Carolina. Laser profilometer data obtained from the North Carolina Department of Transportation (NCDOT) for highways comprising four corridors are processed to calculate pavement macrotexture at 100-m (approximately 330-ft) sections according to the American Society for Testing and Materials (ASTM) standards. Crash data collected over the same lengths of the corridors were integrated with the calculated pavement macrotexture for each section. Scatterplots were generated to assess the role of pavement macrotexture on crashes and logarithm of crashes. Regression analyses were conducted by considering predictor variables such as million vehicle miles of travel (as a function of traffic volume and length), the number of interchanges, the number of at-grade intersections, the number of grade-separated interchanges, and the number of bridges, culverts, and overhead signs along with pavement macrotexture to study the statistical significance of relationship between pavement macrotexture and crashes (both linear and log-linear) when compared to other predictor variables. Scatterplots and regression analysis conducted indicate a more statistically significant relationship between pavement macrotexture and logarithm of crashes than between pavement macrotexture and crashes. The coefficient for pavement macrotexture, in general, is negative, indicating that the number of crashes or logarithm of crashes decreases as it increases. The relation between pavement macrotexture and logarithm of crashes is generally stronger than between most other predictor variables and crashes or logarithm of crashes. Based on results obtained, it can be concluded that maintaining pavement macrotexture greater than or equal to 1.524 mm (0.06 in.) as a threshold limit would possibly reduce crashes and provide safe transportation to road users on highways.
-
International Nuclear Information System (INIS)
Serna, Marilene Morelli
2002-01-01
The macrotexture is one of the main characteristics in metallic materials, which the physical properties depend on the crystallographic direction. The analysis of the macrotexture to middles of the decade of 80 was just accomplished by the techniques of Xray diffraction and neutrons diffraction. The possibility of the analysis of the macrotexture using, the technique of electron backscattering diffraction in the scanning electronic microscope, that allowed to correlate the measure of the orientation with its location in the micro structure, was a very welcome tool in the area of engineering of materials. In this work it was studied the theoretical aspects of the two techniques and it was used of both techniques for the analysis of the macrotexture of aluminum sheets 1050 and 3003 with intensity, measured through the texture index 'J', from 2.00 to 5.00. The results obtained by the two techniques were shown reasonably similar, being considered that the statistics of the data obtained by the technique of electron backscatter diffraction is much inferior to the obtained by the X-ray diffraction. (author)
-
Influence of pavement macrotexture on PM10 emissions from paved roads: A controlled study
China, Swarup; James, David E.
2012-12-01
This paper investigates influence of pavement macrotexture on paved road PM10 emissions. This study was conducted on different paved roadway types (local, collector and minor arterial) in the Las Vegas Valley, Nevada. Pavement macrotexture was measured using the ASTM E 965 sand patch method and the Digital Surface Roughness Meter™ (DSRM™). A controlled constant soil loading with known PM10 fraction was applied to cleaned road surfaces. The Desert Research Institute's (DRI) Mini-PI-SWERL™ (Portable In-Situ Wind ERosion Lab) was used to estimate PM10 mass emissions and cumulative mass emitted from pavement surfaces. PM10 mass emissions using controlled applied soil loadings generally declined with increasing pavement macrotexture at all applied shear levels. The relationships were statistically significant, and indicate that pavement macrotexture may need to be included in future development of revised paved road PM10 emissions factors. A change in the slope of emitted PM10 mass and pavement macrotexture occurred between 0.8 and 0.9 mm mean texture depth (MTD). Anomalies in PM10 mass emissions were observed at MTDs exceeding 1.2 mm. Two-way frequency distributions of pavement surface features obtained from DSRM measurements were analyzed to explain the observed anomalies. Results showed that pavement surface feature size distributions may influence on PM10 emissions from paved roads at similar MTDs. PM10 mass emissions were found to linearly depend on adjusted mode size of the pavement surface aggregate. A sharp decrease in friction velocities, computed from wind erosion theory, at MTDs above 0.9 mm matched an observed sharp decrease in PM10 emissions rates at MTDs above 0.9 mm, indicating that classical wind erosion theory could be adapted for non-erodible pavement surfaces and linearly relate PM10 emissions rates to applied shear stress at an aerodynamic roughness height of 0.075 mm.
-
Evolution of microstructure, macrotexture and microtexture during hot rolling of Ti-6Al-4V
International Nuclear Information System (INIS)
Ari-Gur, P.; Semiatin, S.L.
1998-01-01
The evolution of microstructure, macrotexture and microtexture during subtransus hot working of Ti-6Al-4V with two different types of transformed β starting microstructures (lamellar colony, acicular martensitic α) was investigated. Globularization of the transformed microstructures required heavy rolling reductions or moderate reductions coupled with near transus post-rolling heat treatment. Despite the sluggish dynamic globularization kinetics, noticeable macrotexture changes were noted after low reductions, an effect ascribed to the rotations associated with kinking and bending of the lamellar acicular plates. Noticeable microtextures, noted in samples with an initial lamellar colony microstructure, persisted through hot rolling suggesting that dynamic globularization does not involve recrystallization. In contrast, hot rolled material with a starting acicular α microstructure exhibited weak microtextures and strong macrotextures. The absence of microtexture in these latter cases was explained on the basis of multiple transformation variants within each colony/prior β grain following the β-annealing-and-water-quenching process used to obtain the microstructure. (orig.)
-
The evolution of microtexture and macrotexture during subtransus forging of Ti-10V-2Fe-3Al
International Nuclear Information System (INIS)
Raghunathan, S.L.; Dashwood, R.J.; Jackson, M.; Vogel, S.C.; Dye, D.
2008-01-01
The macrotextures and microtextures produced during α+β forging of Ti-10V-2Fe-3Al were characterised using neutron, in situ synchrotron X-ray and ex situ electron backscatter diffraction (EBSD). The EBSD analysis showed that the measured misorientation distributions at a strain of 0.8 and strain rates of 0.1 and 0.01s -1 were similar, with an average misorientation of 2.2 deg. During forging, the moderate cube macrotexture inherited from the parent material was converted into a moderate fibre texture, with the major change occurring between strains of 0.4 and 0.6. The synchrotron diffraction studies allowed the orientation evolution of individual grains to be characterised. At the highest strain rate of 0.1s -1 , this indicated a change in behaviour from dispersion of the crystal mosaic (peak angular spread) at low strains, to convergence of the crystal mosaic at larger strains. At lower strain rates, only convergence of the crystal mosaic was observed. It is suggested that these results indicate a change in mechanism between deformation-controlled behaviour during the early stages of deformation and a strain rate of 0.1s -1 and diffusional, recovery-controlled behaviour at lower strain rates and higher strains
-
The double capsules in macro-textured breast implants.
Giot, Jean-Philippe; Paek, Laurence S; Nizard, Nathanael; El-Diwany, Mostafa; Gaboury, Louis A; Nelea, Monica; Bou-Merhi, Joseph S; Harris, Patrick G; Danino, Michel A
2015-10-01
Breast implants are amongst the most widely used types of permanent implants in modern medicine and have both aesthetic and reconstructive applications with excellent biocompatibility. The double capsule is a complication associated with textured prostheses that leads to implant displacement; however, its etiology has yet to be elucidated. In this study, 10 double capsules were sampled from breast expander implants for in-depth analysis; histologically, the inner capsular layer demonstrated highly organized collagen in sheets with delamination of fibers. At the prosthesis interface (PI) where the implant shell contacts the inner capsular layer, scanning electron microscopy (SEM) revealed a thin layer which mirrored the three-dimensional characteristics of the implant texture; the external surface of the inner capsular layer facing the intercapsular space (ICS) was flat. SEM examination of the inner capsule layer revealed both a large bacterial presence as well as biofilm deposition at the PI; a significantly lower quantity of bacteria and biofilm were found at the ICS interface. These findings suggest that the double capsule phenomenon's etiopathogenesis is of mechanical origin. Delamination of the periprosthetic capsule leads to the creation of the ICS; the maintained separation of the 2 layers subsequently alters the biostability of the macro-textured breast implant. Copyright © 2015 Elsevier Ltd. All rights reserved.
-
Surface friction measurements of fine-graded asphalt mixtures : final report, June 2008.
2008-06-01
Skid resistance is generated by the development of friction between the vehicle tire and : roadway surface, and is partially dependent upon the characteristics of the pavement : texture. Microtexture and macrotexture are the critical components of pa...
-
2017-04-01
Pavement skid resistance is primarily a function of the surface texture, which includes both microtexture and macrotexture. Earlier, under the Texas Department of Transportation (TxDOT) Research Project 0-5627, the researchers developed a method to p...
-
Solid Phase Extraction (SPE) for Biodiesel Processing and Analysis
2017-12-13
similar applications.[7] Nanoporous scaffolds within a macrotextured structure offered an alternative to currently available commercial dry wash...D) is an image of the hydrophilic (left) and hydrophobic (right) materials in water. METHODS Batch type experiments were used to characterize the...
-
The relation between surface texture of asphalt pavements and ...
African Journals Online (AJOL)
Traffic conditions, road variables, skid resistance, texture depth, and accident data for the period 2000 - 2004 were analysed to develop models to establish the inter-relationships between skid resistance, macrotexture and incidence of accidents. Poisson regression relating to accident frequency and exposure variables ...
-
Field investigation of skid resistance degradation of asphalt pavement during early service
Directory of Open Access Journals (Sweden)
Yinghao Miao
2016-07-01
Full Text Available This paper documents a field investigation into the skid resistance degradation of asphalt pavement during early service. Field tests were conducted 7 times during more than 2 years. There are 2 highway sections included in the field tests, which cover 4 asphalt surface types, i.e., dense asphalt concrete (DAC, rubber asphalt concrete (RAC, stone matrix asphalt (SMA, and ultra-thin wearing course (UTWC. Macrotexture and friction data were collected using the sand patch method and the dynamic friction tester respectively. The degradation of the mean texture depth (MTD and the friction coefficient at slip speed of 60 km/h (DFT60 were analyzed. The international friction index (IFI was also calculated using the friction coefficient at slip speed of 20 km/h (DFT20 with MTD to evaluate the skid resistance degradation. The UTWC has relatively good skid resistance even after 7.4 × 106 standard vehicle passes. The SMA has very stable friction performance which maintains almost the same friction level after 4.61 × 106 standard vehicle passes. The DAC and RAC have relatively poor friction performance while the RAC has better macrotexture. The changing trends of skid resistance with traffic wear can be fitted by a logarithmic model for all surface types. The SMA and UTWC have relatively clear relationship between DFT20 and MTD, while the RAC and the DAC show more complex. Keywords: Asphalt pavement, Skid resistance, Degradation, International friction index
-
An empirical model to predict road dust emissions based on pavement and traffic characteristics.
Padoan, Elio; Ajmone-Marsan, Franco; Querol, Xavier; Amato, Fulvio
2018-06-01
The relative impact of non-exhaust sources (i.e. road dust, tire wear, road wear and brake wear particles) on urban air quality is increasing. Among them, road dust resuspension has generally the highest impact on PM concentrations but its spatio-temporal variability has been rarely studied and modeled. Some recent studies attempted to observe and describe the time-variability but, as it is driven by traffic and meteorology, uncertainty remains on the seasonality of emissions. The knowledge gap on spatial variability is much wider, as several factors have been pointed out as responsible for road dust build-up: pavement characteristics, traffic intensity and speed, fleet composition, proximity to traffic lights, but also the presence of external sources. However, no parameterization is available as a function of these variables. We investigated mobile road dust smaller than 10 μm (MF10) in two cities with different climatic and traffic conditions (Barcelona and Turin), to explore MF10 seasonal variability and the relationship between MF10 and site characteristics (pavement macrotexture, traffic intensity and proximity to braking zone). Moreover, we provide the first estimates of emission factors in the Po Valley both in summer and winter conditions. Our results showed a good inverse relationship between MF10 and macro-texture, traffic intensity and distance from the nearest braking zone. We also found a clear seasonal effect of road dust emissions, with higher emission in summer, likely due to the lower pavement moisture. These results allowed building a simple empirical mode, predicting maximal dust loadings and, consequently, emission potential, based on the aforementioned data. This model will need to be scaled for meteorological effect, using methods accounting for weather and pavement moisture. This can significantly improve bottom-up emission inventory for spatial allocation of emissions and air quality management, to select those roads with higher emissions
-
International Nuclear Information System (INIS)
Choi, Shi-Hoon; Choi, Jae-Kwon; Kim, Hyoung-Wook; Kang, Seok-Bong
2009-01-01
The evolution of the macrotexture and r-value directionality of cold-rolled Al-5% Mg alloys during annealing at various temperatures was investigated to seek an optimum annealing condition to improve the formability of TRBs. The change of volume fractions for the typical texture components of Al-5% Mg alloys was calculated using a misorientation approach in 3-D Euler space. A visco-plastic self-consistent (VPSC) polycrystal model was used to predict r-value directionality of the cold-rolled and annealed Al-5% Mg alloys. The electron backscatter diffraction (EBSD) technique was used to investigate a rapid change of the initial deformation texture in the specimen deformed by a reduction of 9% during annealing. The results showed that an optimum annealing temperature for achieving the low planar anisotropy was strongly dependent on the rolling reduction ratio.
-
Directory of Open Access Journals (Sweden)
M. Sol-Sánchez
2017-07-01
Full Text Available Very Thin Asphalt Overlay (VTAO has been introduced as an alternative to traditional thick overlays, seal coats, and micro-surfacings. Nonetheless, there are some challenges that still remain regarding the application of VTAOs (such as mixture type, cohesiveness, wear resistance, cracking and durability, particularly in heavy traffic urban areas. Therefore, this paper presents an extensive comparative evaluation of the mechanical performance, durability and safety issues (cohesiveness, adhesiveness, ageing, cracking, plastic deformation, permeability, macrotexture, skid and wear resistance, and fuel resistance of a VTAO (20 mm thick and a high performance BBTM 11B (35 mm thick, commonly used as an open-graded mixture for pavement overlays. The results demonstrated that VTAO is an appropriate material for urban pavements as it provides good durability and resistance to the propagation of defects. Nonetheless, further studies are required to improve its behavior under distresses related to plastic deformations and safety properties.
-
Computational modeling of ring textures in mesophase carbon fibers
Directory of Open Access Journals (Sweden)
de Andrade Lima Luiz Rogério Pinho
2003-01-01
Full Text Available Carbon fibers are widely used in many industrial applications due the fact of their excellent properties. Carbonaceous mesophases are liquid crystalline precursor materials that can be spun into high performance carbon fibers using the melt spinning process, which is a flow cascade consisting of pressure driven flow-converging die flow-free surface extensional spinline flow that modifies the precursor molecular orientation structure. Carbon fiber property optimization requires a better understanding of the principles that control the structure development during the fiber formation processes and the rheological processing properties. This paper presents the elastic and continuum theory of liquid crystalsand computer simulations of structure formation for pressure-driven flow of carbonaceous liquid crystalline precursors used in the industrial carbon fiber spinning process. The simulations results capture the formation of characteristic fiber macro-textures and provide new knowledge on the role of viscous and elastic effects in the spinning process.
-
International Nuclear Information System (INIS)
Sol-Sánchez, M.; García-Travé, G.; Ayar, P.; Moreno-Navarro, F.; Rubio-Gámez, M.C.
2017-01-01
Very Thin Asphalt Overlay (VTAO) has been introduced as an alternative to traditional thick overlays, seal coats, and micro-surfacings. Nonetheless, there are some challenges that still remain regarding the application of VTAOs (such as mixture type, cohesiveness, wear resistance, cracking and durability), particularly in heavy traffic urban areas. Therefore, this paper presents an extensive comparative evaluation of the mechanical performance, durability and safety issues (cohesiveness, adhesiveness, ageing, cracking, plastic deformation, permeability, macrotexture, skid and wear resistance, and fuel resistance) of a VTAO (20 mm thick) and a high performance BBTM 11B (35 mm thick), commonly used as an open-graded mixture for pavement overlays. The results demonstrated that VTAO is an appropriate material for urban pavements as it provides good durability and resistance to the propagation of defects. Nonetheless, further studies are required to improve its behavior under distresses related to plastic deformations and safety properties. [es
-
Energy Technology Data Exchange (ETDEWEB)
Lee, K.M. [Department of Materials Science and Engineering, Korea University, 5-1, Anam-dong, Sungbuk-Gu, Seoul 136-701 (Korea, Republic of); Huh, M.Y., E-mail: myhuh@korea.ac.kr [Department of Materials Science and Engineering, Korea University, 5-1, Anam-dong, Sungbuk-Gu, Seoul 136-701 (Korea, Republic of); Lee, H.J.; Park, J.T.; Kim, J.S. [Electrical Steel Sheet Research Group, Technical Research Laboratories, POSCO, Goedong-dong, Pohang (Korea, Republic of); Shin, E.J. [Korea Atomic Energy Research Institute, Neutron Science Division, Daejeon 305-353 (Korea, Republic of); Engler, O. [Hydro Aluminium Rolled Products GmbH, Research and Development Bonn, P.O. Box 2468, D-53014 Bonn (Germany)
2015-12-15
The effect of hot band grain size on the development of crystallographic texture and magnetic properties in non-oriented electrical steel sheet was studied. After cold rolling the samples with different initial grain sizes displayed different microstructures and micro-textures but nearly identical macro-textures. The homogeneous recrystallized microstructure and micro-texture in the sample having small grains caused normal continuous grain growth. The quite irregular microstructure and micro-texture in the recrystallized sample with large initial grain size provided a preferential growth of grains in 〈001〉//ND and 〈113〉//ND which were beneficial for developing superior magnetic properties. - Highlights: • We produced hot bands of electrical steel with different grain size but same texture. • Hot band grain size strongly affected cold rolling and subsequent annealing textures. • Homogeneous recrystallized microstructure caused normal continuous grain growth. • Irregular recrystallized microstructure led to selective growth of <001>//ND grains. • Hot band with large grains was beneficial for superior magnetic properties.
-
Energy Technology Data Exchange (ETDEWEB)
Shi, Guoliang, E-mail: shigl@grinm.com; Zhang, Kui; Li, Xinggang; Li, Yongjun; Ma, Minglong; Yuan, Jiawei
2017-02-08
Precipitation behaviors, texture and tensile properties of an extruded Mg-7Y-1Nd-0.5Zr (wt%) (WE71) alloy bar with large cross-section of 230 mm×140 mm were investigated by hardness test, tensile test, optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD) macro-texture measurement. The bar was manufactured industrially through a procedure of “multi-direction forging (MDF)+extrusion+on-line quenching+T5 aging”. Totally different age-hardening behaviors are shown during T5 aging at 200 and 235 °C. In the first 100 h, T5 aging at 235 °C brings about 13% increases in hardness, while T5 aging at 200 °C results in 47% increase. During T5 aging at 200 °C, β′ precipitates homogeneously nucleate within the matrix with high number density; however, during T5 aging at 235 °C, β′ precipitates heterogeneously nucleate on discrete and sparse dislocations, resulting in chain-like arrangement of β′ precipitates with broad precipitate free zones in matrix. XRD macro-texture measurement illustrates that basal texture intensity of WE71 bar is much weaker than Mg-8Al-0.5Zn-0.15Mn (wt%) (AZ80) bar; the maximum basal texture intensities in the outer (O) and center (C) of WE71 bar are all about 3, while those of AZ80 bar are 17 and 14, respectively. EBSD micro-texture measurement demonstrates that the maximum texture intensities of C and O are 5.3 and 3.5, respectively. O has higher tensile properties than C because there are more un-dynamic-recrystallization (un-DRX) grains and thus larger average grain size in C. While stretching at room temperature (RT), extrusion direction (ED) in O has the best tensile properties, i.e. ultimate tensile strength (R{sub m})=368 MPa, elongation (A)=5%, and normal direction (ND) in C has the lowest tensile properties, i.e. R{sub m}=255 MPa, A=2%. While stretching at 200 °C, strength does not degrade much; ED in O still has
-
Fabrication and properties of strip casting 4.5 wt% Si steel thin sheet
Energy Technology Data Exchange (ETDEWEB)
Zu, Guoqing, E-mail: gz854@uowmail.edu.au [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, NSW 2522 (Australia); Zhang, Xiaoming [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Zhao, Jingwei [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, NSW 2522 (Australia); Wang, Yuqian [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Yan, Yi [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, NSW 2522 (Australia); Li, Chengang; Cao, Guangming [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Jiang, Zhengyi [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, NSW 2522 (Australia)
2017-02-15
Three 4.5 wt% Si steel thin sheets with different thicknesses were efficiently fabricated by twin-roll strip casting, warm rolling and cold rolling followed by final annealing. A comprehensive investigation from the workability of the as-cast strip to the magnetic property of the produces was performed to illustrate the superiority of the new materials. The results show that the as-cast strip, which has a much lower Vickers hardness than that of the 6.5 wt% Si steel, is suitable for rolling processing. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies confirm that no ordering phase exists in the as-cast strip. The cold-rolled thin sheets exhibit good surface quality without edge cracks. Furthermore, all the three 4.5 wt% Si steel thin sheets possess relative strong <100>//ND texture and present high magnetic inductions and low iron losses after finial annealing. - Highlights: • 4.5 wt% Si as-cast sheet with excellent workability was produced by strip casting. • Three 4.5 wt% Si thin sheets were effectively fabricated by warm and cold rolling. • The microstructure and macro-texture of the thin sheets were elucidated. • High magnetic inductions and low iron losses were achieved simultaneously.
-
Energy Technology Data Exchange (ETDEWEB)
Tomov, R I; Kursumovic, A; Majoros, M; Glowacki, B A; Evetts, J E; Tuissi, A; Villa, E; Zamboni, M; Sun, Y; Toenies, S; Weber, H W
2003-01-01
Pulsed laser deposition of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO)/buffer (Y{sub 2}O{sub 3}, YSZ, CeO{sub 2}) heterostructures have been performed in situ onto recently developed non-magnetic oxygenation resistant NiCrW tape. The influence of the critical processing parameters on texture development are investigated and the issues involved in NiO formation and relation to the substrate surface quality are discussed. The roles of Ni poisoning YBCO as well as local cation disorder are considered as possible current limiting factors. X-ray diffraction has been used for macro-texture evaluation. Both buffers and YBCO layers show good biaxial alignment with {omega} and {phi} scans having best YBCO FWHM values of 4.0 deg. and 6.5 deg. respectively. A comparison is made with results achieved on industrial Ni{sub 50}Fe{sub 50} tape. The film morphology has been characterized using atomic force microscopy and scanning electron microscopy. The cation disorder has been studied by Raman spectroscopy. Critical temperatures of 90 K ({delta}T{sub c}=5 K) have been measured. Direct transport as well as magnetic measurements shows the critical current density J{sub c} is 0.2 MA/cm{sup 2} in self-field at liquid nitrogen temperatures.
-
Investigation and modelling of rubber stationary friction on rough surfaces
International Nuclear Information System (INIS)
Le Gal, A; Klueppel, M
2008-01-01
This paper presents novel aspects regarding the physically motivated modelling of rubber stationary sliding friction on rough surfaces. The description of dynamic contact is treated within the framework of a generalized Greenwood-Williamson theory for rigid/soft frictional pairings. Due to the self-affinity of rough surfaces, both hysteresis and adhesion friction components arise from a multi-scale excitation of surface roughness. Beside a complete analytical formulation of contact parameters, the morphology of macrotexture is considered via the introduction of a second scaling range at large length scales which mostly contribute to hysteresis friction. Moreover, adhesion friction is related to the real area of contact combined with the kinetics of interfacial peeling effects. Friction experiments carried out with different rubbers on rough granite and asphalt point out the relevance of hysteresis and adhesion friction concepts on rough surfaces. The two scaling ranges approach significantly improves the description of wet and dry friction behaviour within the range of low sliding velocity. In addition, material and surface effects are predicted and understood on a physical basis. The applicability of such modelling is of high interest for materials developers and road constructors regarding the prediction of wet grip performance of tyres on road tracks
-
Masino, Johannes; Foitzik, Michael-Jan; Frey, Michael; Gauterin, Frank
2017-06-01
Tire road noise is the major contributor to traffic noise, which leads to general annoyance, speech interference, and sleep disturbances. Standardized methods to measure tire road noise are expensive, sophisticated to use, and they cannot be applied comprehensively. This paper presents a method to automatically classify different types of pavement and the wear condition to identify noisy road surfaces. The methods are based on spectra of time series data of the tire cavity sound, acquired under normal vehicle operation. The classifier, an artificial neural network, correctly predicts three pavement types, whereas there are few bidirectional mis-classifications for two pavements, which have similar physical characteristics. The performance measures of the classifier to predict a new or worn out condition are over 94.6%. One could create a digital map with the output of the presented method. On the basis of these digital maps, road segments with a strong impact on tire road noise could be automatically identified. Furthermore, the method can estimate the road macro-texture, which has an impact on the tire road friction especially on wet conditions. Overall, this digital map would have a great benefit for civil engineering departments, road infrastructure operators, and for advanced driver assistance systems.
-
Investigation and modelling of rubber stationary friction on rough surfaces
Energy Technology Data Exchange (ETDEWEB)
Le Gal, A; Klueppel, M [Deutsches Institut fuer Kautschuktechnologie, Eupener Strasse 33, D-30519 Hannover (Germany)
2008-01-09
This paper presents novel aspects regarding the physically motivated modelling of rubber stationary sliding friction on rough surfaces. The description of dynamic contact is treated within the framework of a generalized Greenwood-Williamson theory for rigid/soft frictional pairings. Due to the self-affinity of rough surfaces, both hysteresis and adhesion friction components arise from a multi-scale excitation of surface roughness. Beside a complete analytical formulation of contact parameters, the morphology of macrotexture is considered via the introduction of a second scaling range at large length scales which mostly contribute to hysteresis friction. Moreover, adhesion friction is related to the real area of contact combined with the kinetics of interfacial peeling effects. Friction experiments carried out with different rubbers on rough granite and asphalt point out the relevance of hysteresis and adhesion friction concepts on rough surfaces. The two scaling ranges approach significantly improves the description of wet and dry friction behaviour within the range of low sliding velocity. In addition, material and surface effects are predicted and understood on a physical basis. The applicability of such modelling is of high interest for materials developers and road constructors regarding the prediction of wet grip performance of tyres on road tracks.
-
Directory of Open Access Journals (Sweden)
Shengze Zhu
2017-01-01
Full Text Available Hydroplaning is a driving phenomenon threating vehicle’s control stability and safety. It happens when tire rolls on wet pavement with high speed that hydrodynamic force uplifts the tire. Accurate numerical simulation to reveal the mechanism of hydroplaning and evaluate the function of relevant factors in this process is significant. In order to describe the friction behaviors of tire-pavement interaction, kinetic friction coefficient curve of tire rubber and asphalt pavement was obtained by combining pavement surface power spectrum and complex modulus of tread rubber through Persson’s friction theory. Finite element model of tire-fluid-pavement was established in ABAQUS, which was composed of a 225-40-R18 radial tire and three types of asphalt pavement covered with water film. Mechanical responses and physical behaviors of tire-pavement interaction were observed and compared with NASA equation to validate the applicability and accuracy of this model. Then contact force at tire-pavement interface and critical hydroplaning speed influenced by tire inflation pressure, water film thickness, and pavement types were investigated. The results show higher tire inflation pressure, thinner water film, and more abundant macrotexture enhancing hydroplaning speed. The results could be applied to predict hydroplaning speed on different asphalt pavement and improve pavement skid resistance design.
-
Directory of Open Access Journals (Sweden)
Alberti Susanna
2017-09-01
Full Text Available Deterioration models are the key factor for effective Pavement Management Systems, helping out road agencies to assess the actual pavement condition and forecast future performance of the asset. Among pavement condition characteristics, friction should be taken into account due to its important effect on user safety, while roughness could be used to express user comfort. The purpose of this study was to provide a reasonable case study for future improvements of Italian road management, even if the length of the analyzed highways was not intended to be representative of the overall Italian network.This research studied the friction trend (Side Force Coefficient depending on traffic levels (ESALs and pavement aging for Italian highways, combining the data with roughness and macrotexture. Surface characteristics were monitored during a seven-year time span. A selection of different road sections with homogeneous traffic levels, similar environmental conditions and surface material was performed and high-speed/high-quality road surveys were used for distress data collection. Pavement deterioration models for Italian road sectors were developed at project level, as starting point to advance pavement management practices in Italy. Degradation curves showed the same trends for similar pavement structures, materials and traffic levels; on the other hand, differences in pavement characteristics, increased ESALs and various maintenance treatments significantly altered those trends. Keywords: Pavement Management System, Deterioration models, Friction, Roughness, MPD, High-speed monitoring
-
Experimental study of tyre/road contact forces in rolling conditions for noise prediction
Cesbron, Julien; Anfosso-Lédée, Fabienne; Duhamel, Denis; Ping Yin, Hai; Le Houédec, Donatien
2009-02-01
This paper deals with the experimental study of dynamical tyre/road contact for noise prediction. In situ measurements of contact forces and close proximity noise levels were carried out for a slick tyre rolling on six different road surfaces between 30 and 50 km/h. Additional texture profiles of the tested surfaces were taken on the wheel track. Normal contact stresses were measured at a sampling frequency of 10752 Hz using a line of pressure sensitive cells placed both along and perpendicular to the rolling direction. The contact areas obtained during rolling were smaller than in static conditions. This is mainly explained by the dynamical properties of tyre compounds, like the viscoelastic behaviour of the rubber. Additionally the root-mean-square of the resultant contact forces at various speeds was in the same order for a given road surface, while their spectra were quite different. This is certainly due to a spectral influence of bending waves propagating in the tyre during rolling, especially when the wavelength is small in comparison with the size of the contact patch. Finally, the levels of contact forces and close proximity noise measured at 30 km/h were correlated. Additional correlations with texture levels were performed. The results show that the macro-texture generates contact forces linearly around 800 Hz and consequently noise levels between 500 and 1000 Hz via the vibrations transmitted to the tyre.
-
Microstructure and crystallographic texture evolution during TIG welding of zircaloy-2 material
International Nuclear Information System (INIS)
Jha, S.K.; Singh, R.P.; Singh, V.K.; Ramanathan, R.; Samjdar, I.; Srivastava, D.; Tewari, R.; Dey, G.K.
2005-01-01
Zirconium and its alloys are extensively used as structural materials in nuclear reactors, because of better neutron economy, good corrosion resistance in water and good mechanical properties at operating temperature. Zircaloy-2 and zircaloy-4 are widely used in both pressurized water reactors (PWR) and boiling water reactors (BWR) as fuel cladding materials and as calandria tube and pressure tube materials in pressurized heavy water reactors (PHWR). The satisfactory performance and the life of the reactor components depend mainly upon their mechanical properties, corrosion properties and dimensional stability in the reactor condition, which are strong function of metallurgical parameters such as microstructure and texture. Therefore, for best performance of the reactor components these parameters are optimized during their fabrication. The microstructure and texture of the zircaloy-2 components are expected to get modified during the welding of the components. In this study the evolution of the microstructure and texture has been investigated as a function of the welding parameters. Heat input was varied the current and welding time. A variety of analytical techniques have been applied for the study on microstructure and texture of the welds. Optical microscopy and electron microscopy were used to evaluate the detailed microstructure. X-ray diffraction (XRD) was used investigate the crystallographic textures among the base metal, heat affected zone and fusion zone. Particular attention was focused on the determination of microtexture in weld by using electron backscatter diffraction (EBSD) technique. After that, an effort was put to compare the results of X-ray macro-texture and EBS-microtexture. (author)
-
Impact of Volcanic Ash on Road and Airfield Surface Skid Resistance
Directory of Open Access Journals (Sweden)
Daniel M. Blake
2017-08-01
Full Text Available Volcanic ash deposited on paved surfaces during volcanic eruptions often compromises skid resistance, which is a major component of safety. We adopt the British pendulum test method in laboratory conditions to investigate the skid resistance of road asphalt and airfield concrete surfaces covered by volcanic ash sourced from various locations in New Zealand. Controlled variations in ash characteristics include type, depth, wetness, particle size and soluble components. We use Stone Mastic Asphalt (SMA for most road surface experiments but also test porous asphalt, line-painted road surfaces, and a roller screed concrete mix used for airfields. Due to their importance for skid resistance, SMA surface macrotexture and microtexture are analysed with semi-quantitative image analysis, microscopy and a standardised sand patch volumetric test, which enables determination of the relative effectiveness of different cleaning techniques. We find that SMA surfaces covered by thin deposits (~1 mm of ash result in skid resistance values slightly lower than those observed on wet uncontaminated surfaces. At these depths, a higher relative soluble content for low-crystalline ash and a coarser particle size results in lower skid resistance. Skid resistance results for relatively thicker deposits (3–5 mm of non-vesiculated basaltic ash are similar to those for thin deposits. There are similarities between road asphalt and airfield concrete, although there is little difference in skid resistance between bare airfield surfaces and airfield surfaces covered by 1 mm of ash. Based on our findings, we provide recommendations for maintaining road safety and effective cleaning techniques in volcanic ash environments.
-
Using a constructive pavement texture index for skid resistance screening
Directory of Open Access Journals (Sweden)
Chia-Pei Chou
2017-07-01
Full Text Available Skid resistance measurement is one of the major measurements used to assess road safety. Typical devices used for measuring skid resistance include single point checking type and continuous measurements type. However, conducting periodic full roadway network skid resistance survey can be a relatively time consuming and difficult task because of the limited water carrying capacity used by all kinds of devices, including the continuous types. On the contrary, measurement of pavement surface texture can be conducted easily and continuously by most profilers. This research investigates the relation between pavement skid resistance and surface texture. The focus is on the development of a texture index that can serve as a screening indicator to filter out the high-risk pavement sections for further skid resistance measurement. Two measuring devices, GripTester (GT and National Taiwan University laser profiler (NTU Profiler, were used to collect data on pavement skid resistance and texture in a network of 555 sections, respectively. The pavement texture index of the mean difference of elevation (MDE is calculated at a 1 mm profile interval, which is a very promising indicator to represent pavement skid resistance. Through a sensitivity study, the MDE threshold of 0.15 mm is observed to provide a relatively reasonable screening function that filters out 29.01% of the entire surveyed network for further skid resistance inspection. It averted more than 70% skid resistance measurement capacity of the entire network. The accuracy of correct judgment by the selected threshold is about 80%, only 3.78% of roadway sections considered for further inspection of the recommended list are not included. Keywords: Skid resistance, Pavement texture, Macrotexture, Laser profiler, GripTester
-
Development of Ultra-Fine-Grained Structure in AISI 321 Austenitic Stainless Steel
Tiamiyu, A. A.; Szpunar, J. A.; Odeshi, A. G.; Oguocha, I.; Eskandari, M.
2017-12-01
Ultra-fine-grained (UFG) structure was developed in AISI 321 austenitic stainless steel (ASS) using cryogenic rolling followed by annealing treatments at 923 K, 973 K, 1023 K, and 1073 K (650 °C, 700 °C, 750 °C, and 800 °C) for different lengths of time. The α'-martensite to γ-austenite reversion behavior and the associated texture development were analyzed in the cryo-rolled specimens after annealing. The activation energy, Q, required for the reversion of α'-martensite to γ-austenite in the steel was estimated to be 80 kJ mol-1. TiC precipitates and unreversed triple junction α'-martensite played major roles in the development of UFG structure through the Zener pinning of grain boundaries. The optimum annealing temperature and time for the development of UFG structure in the cryo-rolled AISI 321 steel are (a) 923 K (650 °C) for approximately 28800 seconds and (b) 1023 K (750 °C) for 600 seconds, with average grain sizes of 0.22 and 0.31 µm, respectively. Annealing at 1023 K (750 °C) is considered a better alternative since the volume fraction of precipitated carbides in specimens annealed at 1023 K (750 °C) are less than those annealed at 923 K (650 °C). More so, the energy consumption during prolonged annealing time to achieve an UFG structure at 923 K (650 °C) is higher due to low phase reversion rate. The hardness of the UFG specimens is 195 pct greater than that of the as-received steel. The higher volume fraction of TiC precipitates in the UFG structure may be an additional source of hardening. Micro and macrotexture analysis indicated {110}〈uvw〉 as the major texture component of the austenite grains in the UFG structure. Its intensity is stronger in the specimen annealed at low temperatures.
-
Energy Technology Data Exchange (ETDEWEB)
Sol-Sánchez, M.; García-Travé, G.; Ayar, P.; Moreno-Navarro, F.; Rubio-Gámez, M.C.
2017-07-01
Very Thin Asphalt Overlay (VTAO) has been introduced as an alternative to traditional thick overlays, seal coats, and micro-surfacings. Nonetheless, there are some challenges that still remain regarding the application of VTAOs (such as mixture type, cohesiveness, wear resistance, cracking and durability), particularly in heavy traffic urban areas. Therefore, this paper presents an extensive comparative evaluation of the mechanical performance, durability and safety issues (cohesiveness, adhesiveness, ageing, cracking, plastic deformation, permeability, macrotexture, skid and wear resistance, and fuel resistance) of a VTAO (20 mm thick) and a high performance BBTM 11B (35 mm thick), commonly used as an open-graded mixture for pavement overlays. The results demonstrated that VTAO is an appropriate material for urban pavements as it provides good durability and resistance to the propagation of defects. Nonetheless, further studies are required to improve its behavior under distresses related to plastic deformations and safety properties. [Spanish] Las capas bituminosas ultra delgadas para rehabilitación superficial de carreteras son una alternativa a las tradicionales capas asfálticas, riegos bituminosos y micro-aglomerados. No obstante, aún son numerosos los aspectos a estudiar para la generalización de su uso, particularmente en zonas urbanas con elevado tráfico. Así, este artículo recoge un análisis comparativo del comportamiento mecánico, durabilidad y factores de seguridad (evaluando parámetros como cohesividad, adhevisvidad, envejecimiento, fisuración, deformaciones, permeabilidad, macrotextura, y resistencia al deslizamiento, al desgaste y a los combustibles) entre una capa delgada de 20 mm de espesor, y una mezcla discontinua de altas prestaciones (BBTM-11B con 35 mm), comúnmente utilizada en capas de rodadura. Los resultados indican que puede ser una adecuada solución para pavimentos urbanos dada su durabilidad y resistencia a la propagación de
-
Effect of aggregate graining compositions on skid resistance of Exposed Aggregate Concrete pavement
Wasilewska, Marta; Gardziejczyk, Wladysław; Gierasimiuk, Pawel
2018-05-01
The paper presents the evaluation of skid resistance of EAC (Exposed Aggregate Concrete) pavements which differ in aggregate graining compositions. The tests were carried out on concrete mixes with a maximum aggregate size of 8 mm. Three types of coarse aggregates were selected depending on their resistance to polishing which was determined on the basis of the PSV (Polished Stone Value). Basalt (PSV 48), gabbro (PSV 50) and trachybasalt (PSV 52) aggregates were chosen. For each type of aggregate three graining compositions were designed, which differed in the content of coarse aggregate > 4mm. Their content for each series was as follows: A - 38%, B - 50% and C - 68%. Evaluation of the skid resistance has been performed using the FAP (Friction After Polishing) test equipment also known as the Wehner/Schulze machine. Laboratory method enables to compare the skid resistance of different types of wearing course under specified conditions simulating polishing processes. In addition, macrotexture measurements were made on the surface of each specimen using the Elatexure laser profile. Analysis of variance showed that at significance level α = 0.05, aggregate graining compositions as well as the PSV have a significant influence on the obtained values of the friction coefficient μm of the tested EAC pavements. The highest values of the μm have been obtained for EAC with the lowest amount of coarse aggregates (compositions A). In these cases the resistance to polishing of the aggregate does not significantly affect the friction coefficients. This is related to the large areas of cement mortar between the exposed coarse grains. Based on the analysis of microscope images, it was observed that the coarse aggregates were not sufficiently exposed. It has been proved that PSV significantly affected the coefficient of friction in the case of compositions B and C. This is caused by large areas of exposed coarse aggregate. The best parameters were achieved for the EAC pavements
-
Directory of Open Access Journals (Sweden)
Paweł Raczyński
2017-07-01
Full Text Available The Bonikowo Reef occurs in the central part of the Zechstein Limestone Basin in western Poland and was growing on the topmost edges of tilted blocks and/or on the top of uplifted horsts of the Brandenburg–Wolsztyn–Pogorzela High. Its size is ca. 1.6 km2. The Bonikowo Reef shows the thickest reef section (90.5 m recorded in the High. The Zechstein Limestone unit is represented mostly by limestones, often thoroughly recrystallized, although the macrotextures and biota of the boundstone are identifiable in most cases. The drillcore section is a mixture of boundstones (microbial and bryozoan, wackestones, packstones and grainstones, which often co-occur. The δ13C and δ18O values for both calcite (avg. 3.8 ± 0.8‰ and −3.4 ± 1.7‰, respectively and dolomite (avg. 3.5 ± 0.7‰ and −5.2 ± 1.3‰, respectively are transitional between the values previously reported for condensed sequences of the basinal facies and larger reef complexes. The biofacies of the Bonikowo Reef are very similar to those recognized in other reefs of the Brandenburg–Wolsztyn–Pogorzela High, which owe their origin to the destruction of bryozoan boundstones. The biota composition is typical and characteristic of other Zechstein Limestone reefs. However, the Bonikowo Reef demonstrates the importance of microbialites, laminar and nodose encrustations, in the growth and cohesion of the Zechstein Limestone reefs. Such encrustations abound within the Zechstein Limestone although, in many cases, the real nature of the encrustations is difficult to ascertain. These laminated encrustations show great similarity to Archaeolithoporella that is one of the most important Permian reef-building organisms. The encrustations considered to represent Archaeolithoporella were also previously recorded in the Zechstein Limestone of western Poland and in its stratigraphic equivalent, the Middle Magnesian Limestone of Northeast England. The lower part of the sequence shows
-
Does osteoporosis reduce the primary tilting stability of cementless acetabular cups?
von Schulze Pellengahr, Christoph; von Engelhardt, Lars V; Wegener, Bernd; Müller, Peter E; Fottner, Andreas; Weber, Patrick; Ackermann, Ole; Lahner, Matthias; Teske, Wolfram
2015-04-21
Cementless hip cups need sufficient primary tilting stability to achieve osseointegration. The aim of the study was to assess differences of the primary implant stability in osteoporotic bone and in bone with normal bone density. To assess the influence of different cup designs, two types of threaded and two types of press-fit cups were tested. The maximum tilting moment for two different cementless threaded cups and two different cementless press-fit cups was determined in macerated human hip acetabuli with reduced (n=20) and normal bone density (n=20), determined using Q-CT. The tilting moments for each cup were determined five times in the group with reduced bone density and five times in the group with normal bone density, and the respective average values were calculated. The mean maximum extrusion force of the threaded cup Zintra was 5670.5 N (max. tilting moment 141.8 Nm) in bone with normal density and.5748.3 N (max. tilting moment 143.7 Nm) in osteoporotic bone. For the Hofer Imhof (HI) threaded cup it was 7681.5 N (192.0 Nm) in bone with normal density and 6828.9 N (max. tilting moment 170.7 Nm) in the group with osteoporotic bone. The mean maximum extrusion force of the macro-textured press-fit cup Metallsockel CL was 3824.6 N (max. tilting moment 95.6 Nm) in bone with normal and 2246.2 N (max. tilting moment 56.2 Nm) in osteoporotic bone. For the Monoblock it was 1303.8 N (max. tilting moment 32.6 Nm) in normal and 1317 N (max. tilting moment 32.9 Nm) in osteoporotic bone. There was no significance. A reduction of the maximum tilting moment in osteoporotic bone of the ESKA press-fit cup Metallsockel CL was noticed. Results on macerated bone specimens showed no statistically significant reduction of the maximum tilting moment in specimens with osteoporotic bone density compared to normal bone, neither for threaded nor for the press-fit cups. With the limitation that the results were obtained using macerated bone, we could not detect any restrictions for
-
Estructura y textura de un meteorito metálico de tipo octaedrita (Gibeon
Directory of Open Access Journals (Sweden)
Gil Sevillano, J.
2000-06-01
Full Text Available A sample from the meteoritic iron Gibeon (fine octahedrite has been studied combining optical and scanning electron microscopy, crystallographic microtexture by EBSP (Electron Back Scattered Patterns and macrotexture by X-ray diffraction. The sample (approx. 24x23x3 mm, 14.3 g shows the classical Widmastätten structure of intersecting ferrite (kamacite plates grown along {111}γ octahedric previous austenite (taenite planes. Residual layers of austenite are also seen between the ferrite plates as well as larger domains of more complex structures of bainitic type (plessite produced by the last fraction of austenite transformed during extra-terrestrial cooling. The sample structure shows few signs of impact modifications (Neumann bands, etc.. Kamacite plates are divided in weakly misoriented (< 2º subgranular domains. The measurement of individual orientations by EBSP or the macroscopic texture measurement show a single austenite orientation (although with a non-negligible dispersion around the average orientation and a limited number of ferrite orientations compatible with the variants of the Kurdjumov-Sachs orientation relationship.
Se ha estudiado un fragmento del hierro meteorítico Gibeon (Namibia, 1847, con estructura de octaedrita fina, combinando técnicas de microscopía óptica, microscopía electrónica de barrido, análisis EDX, medida de orientaciones cristalográficas mediante EBSP (Electron Back Scattered Patterns y difracción de rayos X. La muestra (aprox. 24x23x3 mm, 14.3 g presenta la clásica estructura de Widmanstätten, producto de la intersección de placas lenticulares de ferrita (kamacita, orientadas según planos octaédricos, con la sección metalográfica de la muestra. Se observan también una fracción residual de austenita (taenita retenida entre las placas ferríticas y estructuras más complejas (plesita, producto de la descomposición extraterrestre de la última fracción de austenita. La muestra