scholarly journals Mechanistic and Economical Characteristics of Asphalt Rubber Mixtures

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Mena I. Souliman ◽  
Annie Eifert
Keyword(s):  
Fatigue Life ◽  
Fatigue Cracking ◽  
Advanced Characterization ◽  
Fatigue Tests ◽  
Modified Asphalt ◽  
State Highway ◽  
Asphalt Rubber ◽  
Mechanistic Analysis ◽  
Characterization Procedure ◽  
The Impact

Load associated fatigue cracking is one of the major distress types occurring in flexible pavement systems. Flexural bending beam fatigue laboratory test has been used for several decades and is considered to be an integral part of the new superpave advanced characterization procedure. One of the most significant solutions to prolong the fatigue life for an asphaltic mixture is to utilize flexible materials as rubber. A laboratory testing program was performed on a conventional and Asphalt Rubber- (AR-) gap-graded mixtures to investigate the impact of added rubber on the mechanical, mechanistic, and economical attributes of asphaltic mixtures. Strain controlled fatigue tests were conducted according to American Association of State Highway and Transportation Officials (AASHTO) procedures. The results from the beam fatigue tests indicated that the AR-gap-graded mixtures would have much longer fatigue life compared with the reference (conventional) mixtures. In addition, a mechanistic analysis using 3D-Move software coupled with a cost analysis study based on the fatigue performance on the two mixtures was performed. Overall, analysis showed that AR modified asphalt mixtures exhibited significantly lower cost of pavement per 1000 cycles of fatigue life per mile compared to conventional HMA mixture.

Improving Fatigue Life of Riveted Joints by Rivet Hole Sizing

2014 ◽  
Vol 598 ◽  
pp. 141-146
Author(s):  
Adam Lipski ◽  
Zbigniew Lis
Keyword(s):  
Fatigue Life ◽  
Fold Increase ◽  
Fatigue Tests ◽  
Aviation Industry ◽  
Lap Joint ◽  
Riveted Joints ◽  
Riveting Process ◽  
The Difference ◽  
Structural Connection ◽  
The Impact

The aim of this paper is to assess the impact of the rivet hole sizing process on the fatigue life based on the example of the structural connections characteristic for riveted joints used in aviation industry. Test specimens reflected the structural connection consisting in a riveted lap joint of an airplane plating stiffened with a T-bar. Connected plates and the T-bar are made of D16CzATW aluminum alloy. 3 mm diameter oval head solid rivets for aviation-related purposes were made of PA24 aluminum. During fatigue tests, individual specimens with non-sized holes and with sized holes were subjected to uniaxial, one-sided, fixed-amplitude loading (R = 0). It can be concluded from the fatigue life comparison that introduction of an additional operation in the riveting process, i.e. the hole sizing, results in significant, about two-fold increase of the fatigue life of the riveted structural connection, even at slight sizing degree. The difference of the specimen damage nature was observed between specimens with sized and non-sized holes.

A new model of multiaxial fatigue life prediction with the influence of different mean stresses

2019 ◽  
Vol 28 (9) ◽  
pp. 1323-1343 ◽  
Author(s):  
Bowen Liu ◽  
Xiangqiao Yan
Keyword(s):  
Fatigue Life ◽  
Equivalent Stress ◽  
Fatigue Tests ◽  
Multiaxial Fatigue ◽  
Stress Effect ◽  
Mean Stress ◽  
New Model ◽  
Von Mises ◽  
The Impact ◽  
Mean Stresses

In this paper, based on the thought of Modified Wöhler Curve Method (MWCM), a new general model for predicting multiaxial fatigue life with influence of mean stress is presented. Different from the MWCM, the expressions of multiaxiality effect and mean stress effect are located separately in the proposed fatigue equation, so that the new model can consider the impact of both axial and torsional mean stresses, and the equation form possesses excellent extendibility and variability. The wildly used von Mises equivalent stress is adopted as the fatigue parameter to improve computational efficiency. Finally, in conjunction with the Itoh criterion, the model can be trivially extended to perform non-proportional fatigue prediction with different mean stresses. Some representative fatigue tests published in the previous literature are used to verify this study.

RETROFITTING METHODS AGAINST FATIGUE CRACKING IN STEEL GIRDER WEB PENETRATION

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Chihiro Sakamoto ◽  
Masahiro Sakano ◽  
Hideyuki Konishi ◽  
Takashi Fujii
Keyword(s):  
Fatigue Life ◽  
Fatigue Cracking ◽  
Highway Bridges ◽  
Lower Surface ◽  
Strength Properties ◽  
Fatigue Tests ◽  
Stress Distributions ◽  
Steel Girder ◽  
Cracking Behavior ◽  
Weld Toe

Fatigue cracking in steel girder web penetration details is so dangerous that it can break steel girders. Since a number of highway bridges have such web penetration details in Japan, it is of urgent importance to grasp these fatigue strength properties and develop effective retrofitting methods. In a previous report, we investigated the stress distributions around web penetration details, and fatigue cracking behavior, using steel girder specimens with web penetration details. In this study, we investigate effects of retrofitting methods against fatigue cracking in web penetration details through fatigue tests using large girder specimens with web penetration details in which cross beam lower flanges are connected to lower surface of a slot by welding. Principal results obtained through this study are as follows: (1) Weld toe grinding can extend fatigue life more than 5 times, (2) Two-face attachment can extend fatigue life more than 10 times, and (3) Two-face attachment with weld toe grinding can extend fatigue life more than 25 times.

Effect of Residual Stress, Temperature and Adhesion on Wheel Surface Fatigue Cracking

2008 ◽  
Author(s):  
Daniel H. Stone ◽  
Scott M. Cummings
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Contact Stress ◽  
Fatigue Cracking ◽  
Fatigue Tests ◽  
Operating Conditions ◽  
Defect Prevention ◽  
Class C ◽  
Research Consortium

The Wheel Defect Prevention Research Consortium (WDPRC) conducted an analysis pertaining to the fatigue cracking of wheel treads by incorporating the effects of residual stresses, temperature, and wheel/rail contact stress. Laboratory fatigue tests were conducted on specimens of wheel tread material under a variety of conditions allowing the analysis to properly account for the residual stresses accumulated in normal operating conditions. Existing literature was used in the analysis in consideration of the effects of contact stress and residual stress relief. This project was performed to define a temperature range in which the life of an AAR Class C wheel is not shortened by premature fatigue and shelling. Wayside wheel thermal detectors are becoming more prevalent on North American railroads as a means of identifying trains, cars, and wheels with braking issues. Yet, from a wheel fatigue perspective, the acceptable maximum operating temperature remains loosely defined for AAR Class C wheels. It was found that residual compressive circumferential stresses play a key role in protecting a wheel tread from fatigue damage. Therefore, temperatures sufficient to relieve residual stresses are a potential problem from a wheel fatigue standpoint. Only the most rigorous braking scenarios can produce expected train average wheel temperatures approaching the level of concern for reduced fatigue life. However, the variation in wheel temperatures within individual cars and between cars can result in temperatures high enough to cause a reduction in wheel fatigue life.

Investigating Machining Impact on Fatigue Variance: A Machining Quality Perspective

2004 ◽  
Vol 127 (3) ◽  
pp. 492-502 ◽  
Author(s):  
Xiaoping Yang ◽  
C. Richard Liu
Keyword(s):  
Fatigue Life ◽  
Data Center ◽  
Room Temperature ◽  
Fatigue Tests ◽  
Machining Processes ◽  
Case Scenario ◽  
Bending Fatigue ◽  
Machining Quality ◽  
Four Point Bending ◽  
The Impact

Fatigue life of nominally identical structures under nominally identical loading conditions can scatter widely. This study has investigated the impact of machining processes on such scatters. After Ti 6Al-4V samples were surface ground and face turned, they were subject to constant amplitude four-point bending fatigue tests under room temperature. The best-case scenario of process capability ratios of fatigue for these samples were evaluated with assumed tolerances of fatigue life. Based on these ratios, the numbers of nonconforming parts were estimated. Under the machining conditions from the Machining Data Handbook (Machining Data Center, Cincinnati, 1980), up to 39% of samples due to one process are expected to be nonconforming, whereas only up to 0.6% of samples due to the other process are expected to be nonconforming. The ramifications in terms of cost for machining quality control due to the different capability ratios have been discussed. The current findings indicate an urgent need to further the study of this issue in a scientific manner.

Evaluation of select warm mix additives with polymer and rubber modified asphalt mixtures

2015 ◽  
Vol 42 (6) ◽  
pp. 377-388 ◽  
Author(s):  
Zahi Chamoun ◽  
Mena I. Souliman ◽  
Elie Y. Hajj ◽  
Peter Sebaaly
Keyword(s):  
Fatigue Testing ◽  
Research Effort ◽  
Fatigue Cracking ◽  
Moisture Damage ◽  
Asphalt Mixtures ◽  
Asphalt Binders ◽  
Experimental Program ◽  
Modified Asphalt ◽  
Warm Mix Additives ◽  
The Impact

Warm mix technologies are being increasingly investigated in an effort to conserve energy, reduce emissions, and extend paving season. Most of the laboratory research conducted to date on warm mix technologies has been concentrated on studying the impact of warm mix technologies on unmodified asphalt binders. This research effort evaluates the use of select warm mix additives with unmodified, polymer-modified, and terminal blend tire rubber asphalt mixtures from Nevada and California. The study evaluated two different warm mix asphalt (WMA) technologies: Sasobit and Advera. The experimental program evaluated the resistance to moisture damage and rutting of different mixtures with and without liquid anti-strip and lime. Additionally, fatigue resistance of modified and unmodified asphalt mixtures without anti-strip was conducted. In this research effort, the unmodified WMA mixtures were able to achieve mixing temperature reductions of 26.7 to 29.4 °C while the modified WMA mixtures were able to achieve mixing temperature reductions of 16.7 to 25.0 °C compared to their corresponding HMA control mixtures. The results showed that the use of modified binders with WMA technologies and anti-strip additives can result in mixtures with a better resistance to moisture damage compared to unmodified mixtures. Additionally, the combination of modified asphalt binders with lime will eventually generate better resisting mixtures to permanent deformation. Moreover, the resistance to fatigue cracking of HMA and WMA mixtures was also enhanced using modified asphalt binders. Furthermore, a mechanistic fatigue analysis using 3D-Move software confirmed the outcomes of fatigue testing.

Statistical Distributions of Pavement Damage Associated with Overweight Vehicles: Methodology and Case Study

2018 ◽  
Vol 2672 (9) ◽  
pp. 229-241 ◽  
Author(s):  
Dario Batioja-Alvarez ◽  
Seyed-Farzan Kazemi ◽  
Elie Y. Hajj ◽  
Raj V. Siddharthan ◽  
Adam J. T. Hand
Keyword(s):  
Probabilistic Method ◽  
Fatigue Cracking ◽  
The United States ◽  
Application Process ◽  
State Highway ◽  
Relative Damage ◽  
Gross Vehicle Weight ◽  
Pavement Damage ◽  
The Impact

The trucking industry is the primary mode of transporting for goods and commodities in the United States. Currently, there is an increasing trend in the use of overweight (OW) vehicles on the highway network. State highway agencies (SHAs) are challenged to address this increase, particularly relative to associated pavement damage. In this study, a probabilistic method was developed to evaluate rutting and fatigue cracking damage caused by OW vehicles under different road and environmental conditions. The influential input parameters in this analysis included gross vehicle weight (GVW), axle configuration, axle weight, pavement temperature, and vehicle-miles traveled (VMT). Necessary information was obtained by analyzing more than 170,000 entries of a Nevada Department of Transportation (NDOT) OW permit database. The developed model was based on mechanistic-empirical (ME) approach and considered asphalt concrete (AC) viscoelastic characterization. The results of this study were distributions of AC critical responses, load equivalency factors (LEFs), and relative damage factors (RDFs). The analysis showed that load equivalent factor (LEF) distributions could be incorporated in pavement design methods to account for OW vehicles. Furthermore, the damage induced by specific OW vehicles could be assessed using the relative damage factor (RDF) concept and may be efficiently used by SHAs during the permit application process. A case study was presented illustrating the impact of an OW axle configuration on pavement damage. Finally, a method was suggested for developing RDF tables with damage ranges corresponding to different axle configurations and the GVW that could be a tool for SHAs to evaluate and understand pavement damage induced by OW vehicles.

scholarly journals Fracture Areas Quantitative Investigating of Bending–Torsion Fatigued Low-Alloy High-Strength Steel

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1620
Author(s):  
Wojciech Macek
Keyword(s):  
Fatigue Life ◽  
Surface Topography ◽  
High Strength ◽  
Fatigue Loading ◽  
Fatigue Tests ◽  
Void Volume ◽  
Variation Method ◽  
Rupture Area ◽  
The Impact ◽  
Maximum Stresses

In this study, the impact of pseudo-random non-proportional bending-torsion fatigue loadings proportion on the fatigue life and the fracture surface topography was analyzed. Investigation was carried out for 24 specimens made of S355J2 steel with 11 different ratios of maximum stresses λ. For these cases, after the fatigue tests, the surface topography measurements were carried out using an optical profilometer, using the focus variation method. Three fracture zones were analyzed for each specimen: (1) total; (2) propagation; (3) rupture, taking into account the root average square height Sq and void volume Vv parameters. The results pointed that ratio of maximum stresses λ is the most influenced on volume surface parameters represented by void volume at a given height Vv, in the rupture area. A new fatigue loading parameter P was used, depending on fatigue life T and ratio of maximum stresses λ, which shows very good correlation in 4th degree type of fit, to void volume Vv parameter for the rupture area.

The fatigue behavior of polymeric sulfur-modified asphalt mixtures subjected to freeze-thaw conditioning

2019 ◽  
pp. 089270571988998 ◽  
Author(s):  
Amir Kavussi ◽  
Mehdi Azarnia ◽  
Pooyan Ayar ◽  
Makan Pedram
Keyword(s):  
Fatigue Life ◽  
Fatigue Behavior ◽  
Fatigue Cracking ◽  
Crumb Rubber ◽  
Asphalt Mixtures ◽  
Experimental Results ◽  
Moisture Sensitivity ◽  
Modified Asphalt ◽  
Freeze Thaw ◽  
Brittle Behavior

Abundance, affordability, and also the usability of sulfur as a part of the binder are the main reasons for using this additive in asphalt mixtures. However, lack of proper adhesion and brittle behavior of sulfur-modified asphalt mixtures could make them susceptible to moisture damage and fatigue cracking. In this regard, anti-stripping agents and some polymers like crumb rubber may be used to overcome these types of distresses. This research aimed at investigating the effects of polymeric sulfur and crumb rubber on the moisture sensitivity and fatigue behavior of asphalt mixtures. To this end, asphalt mixtures were subjected to 1 and 3 freeze-thaw cycles. Then, an indirect tensile fatigue test was carried out. Moreover, the response surface method (RSM) was used to assess the interaction between various parameters in samples containing polymeric sulfur and crumb rubber. Results showed that with an increase in polymeric sulfur content, the fatigue life was reduced and the moisture sensitivity was increased. Additionally, the RSM was found to be effective in ranking parameters influencing the performance of asphalt mixtures. According to the experimental results, a crumb rubber-modified binder could improve the fatigue life of the polymeric sulfur-modified mixture up to 70%. Furthermore, experimental results and RSM analysis indicated that crumb rubber would be more effective in higher numbers of freeze-thaw cycles and raised temperatures, in which polymeric sulfur-modified asphalt mixtures are probably prone to moisture damages (i.e. the lack of adequate cohesion and adhesion).

scholarly journals Effect of Weather Aging on Viscoelasticity and Fatigue Performance of Asphalt Mastic

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6163
Author(s):  
Gang Xu ◽  
Yixin Zhou ◽  
Yu Zhu ◽  
Rui Wang ◽  
Xianhua Chen
Keyword(s):  
Fatigue Life ◽  
High Strain ◽  
Asphalt Mixture ◽  
Strain Level ◽  
Fatigue Performance ◽  
Modified Asphalt ◽  
Asphalt Mastic ◽  
Sbs Modified Asphalt ◽  
The Impact

The long-term effect of climate factors, such as sunlight, oxygen, and water, leads to the performance degradation of the asphalt mastic, which is the binding part in the asphalt mixture. It is not conducive to satisfy the long-term performance requirements of long-life asphalt pavement. In this study, five kinds of base asphalt mastic and styrene-butadiene-styrene (SBS) modified asphalt mastic were prepared with the filler-asphalt ratio of 0.6, 0.8, 1.0, 1.2, and 1.4. The indoor simulated weather aging tests were carried out considering multi-factors including sunlight, oxygen, and water. The master curves of the complex shear modulus and phase angle of the asphalt mastic with different aging degrees were obtained by the frequency sweep test. The curves of fatigue damage characteristics and fatigue life were fitted based on the viscoelastic continuum damage (VECD) model. The influence of weather aging on the viscoelasticity and fatigue performance of asphalt mastic were analyzed. Results indicated that the effect of weather aging increases the elastic component and decreases the viscous component. The fatigue performance of SBS modified asphalt mastic was better than that of base asphalt mastic. As the aging degree deepens, the brittle failure characteristics of asphalt mastic with a higher filler–asphalt ratio were more obvious. The base asphalt mastic becomes more sensitive to the strain level due to weather aging, and its fatigue life increased under the low strain loading and decreased under the high strain loading. The fatigue performance of SBS modified asphalt mastic was less sensitive to the strain level. The fatigue life reduced after aging under low and high strain load. Taking the impact of weather aging on the fatigue performance into consideration, the optimal filler–asphalt ratios of the base asphalt mastic SBS modified asphalt mastic are 1.0 and 1.2, respectively.

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