scholarly journals Discrete Element Analysis of Indirect Tensile Fatigue Test of Asphalt Mixture

2019 ◽  
Vol 9 (2) ◽  
pp. 327 ◽  
Author(s):  
Xuelian Li ◽  
Xinchao Lv ◽  
Xueying Liu ◽  
Junhong Ye
Keyword(s):  
Fatigue Test ◽  
Asphalt Mixture ◽  
Discrete Element ◽  
Particle Flow Code ◽  
Displacement Curve ◽  
Distribution Characteristics ◽  
Load Curve ◽  
Element Analysis ◽  
Tensile Fatigue ◽  
Indirect Tensile

In order to investigate the damage to microstructure and some other micromechanical responses during a fatigue test on asphalt mixture, Particle Flow Code (PFC) was used to reconstruct a two-dimensional discrete element model of asphalt mixture, based on computed tomography (CT) images and image-processing techniques. The indirect tensile fatigue test of asphalt mixture was simulated with this image-based microstructural model, and verified in the laboratory. It was found that there were four stages during the fatigue failure: no crack, crack initiation, crack developing, and interconnected crack. Cracks mainly developed between the aggregate and asphalt mortar, near the loading axis. The corresponding stages of failure, the developing trend and the distribution characteristics of the cracks matched well with those in the laboratory test. Furthermore, the trends of both the time-load curve and time-displacement curve from the simulation test were also consistent with those from the experimental test. In short, the distribution characteristics of cracks and internal forces of asphalt mixture show that it is feasible to simulate the fatigue performance of the asphalt mixture by a discrete element method (DEM).

scholarly journals Evaluation of Fatigue Life of CRM-Reinforced SMA and Its Relationship to Dynamic Stiffness

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Nuha Salim Mashaan ◽  
Mohamed Rehan Karim ◽  
Mahrez Abdel Aziz ◽  
Mohd Rasdan Ibrahim ◽  
Herda Yati Katman ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
Resilient Modulus ◽  
Dynamic Stiffness ◽  
Asphalt Mixture ◽  
Fatigue Cracking ◽  
Crumb Rubber ◽  
Fatigue Properties ◽  
Tensile Fatigue ◽  
Indirect Tensile

Fatigue cracking is an essential problem of asphalt concrete that contributes to pavement damage. Although stone matrix asphalt (SMA) has significantly provided resistance to rutting failure, its resistance to fatigue failure is yet to be fully addressed. The aim of this study is to evaluate the effect of crumb rubber modifier (CRM) on stiffness and fatigue properties of SMA mixtures at optimum binder content, using four different modification levels, namely, 6%, 8%, 10%, and 12% CRM by weight of the bitumen. The testing undertaken on the asphalt mix comprises the dynamic stiffness (indirect tensile test), dynamic creep (repeated load creep), and fatigue test (indirect tensile fatigue test) at temperature of 25°C. The indirect tensile fatigue test was conducted at three different stress levels (200, 300, and 400 kPa). Experimental results indicate that CRM-reinforced SMA mixtures exhibit significantly higher fatigue life compared to the mixtures without CRM. Further, higher correlation coefficient was obtained between the fatigue life and resilient modulus as compared to permanent strain; thus resilient modulus might be a more reliable indicator in evaluating the fatigue life of asphalt mixture.

scholarly journals Fatigue Resistance Characterization of Warm Asphalt Rubber by Multiple Approaches

2018 ◽  
Vol 8 (9) ◽  
pp. 1495 ◽  
Author(s):  
Jiangmiao Yu ◽  
Xianshu Yu ◽  
Zheming Gao ◽  
Feng Guo ◽  
Duanyi Wang ◽  
...  
Keyword(s):  
Fatigue Test ◽  
Fatigue Resistance ◽  
Crumb Rubber ◽  
Waste Recycling ◽  
Fatigue Performance ◽  
Four Point Bending ◽  
Asphalt Rubber ◽  
Shear Fatigue ◽  
Tensile Fatigue ◽  
Indirect Tensile

Warm asphalt rubber (WAR) mixture is a sustainable paving material with advantages including waste recycling and noise reducing. A comprehensive understanding of the fatigue performance of WAR specimens is helpful to its wide application. However, research on evaluating the fatigue performance of WAR binder and mixtures is very limited. This paper applies five fatigue analysis approaches to evaluate the fatigue life of WAR samples with three different warm mix asphalt (WMA) additives. The conventional G*sinδ, linear amplitude sweep (LAS), indirect tensile fatigue test (ITFT), and four-point bending beam (4PB) test were conducted based on available standards. In addition, a novel shear fatigue test was performed on WAR mortars. Test results indicated that the incorporation of crumb rubber has a significantly positive effect on fatigue resistance. WAR with chemical and foaming additives exhibited a poorer performance than asphalt rubber (AR), but their fatigue performance was still greatly superior to the non-rubberized samples. Finally, LAS as well as mortar shear fatigue and 4PB tests provided the same prediction of fatigue resistance, while the results of G*sinδ and the ITFT were inconsistent. It is recommended to use LAS, the mortar shear fatigue test, and the 4PB test for the fatigue resistance evaluation of rubberized specimens. The validation of the findings with more materials and field performances is recommended.

Study on Mechanics Properties of Automobile Rear Axle Shell and Optimization Design in Manufacturing System

2012 ◽  
Vol 252 ◽  
pp. 298-301
Author(s):  
Xin Li Bai ◽  
Ying Fang Zhang ◽  
Ya Wei Zhao
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Optimization Design ◽  
Manufacturing System ◽  
Rear Axle ◽  
Large Strain ◽  
Displacement Curve ◽  
Original Design ◽  
Load Curve ◽  
Element Analysis

The mechanics properties of a certain automobile rear axle shell were studied and a large displacement, large strain elastoplastic finite element analysis was carried out. and the followings were obtained: the load-displacement curve at loading point, elastoplastic strain-load curve at the maximum stress point, elastoplastic stress-load curve in dangerous cross-section, and the yielding load at which the dangerous cross-section overall yield. The results show that elastoplastic finite element simulation results are much closer to the experimental corresponding results. Through optimization design in manufacturing system, the weight of the rear axle shell is greatly reduced as compared with the original design. Optimal design not only saves materials and reduces cost, but also greatly reduces the design time. The calculation results provide the necessary data for automobile rear axle design, strength evaluation and fatigue life estimate.

scholarly journals Utilizing a Simple Numerical Model in Discrete Element Analysis to Simulate Flow Time and Number Tests of Asphalt Mixes

2014 ◽  
Vol 11 (2) ◽  
pp. 39
Author(s):  
A.M.A. Abdo
Keyword(s):  
Numerical Models ◽  
Discrete Element ◽  
Flow Time ◽  
Two Dimensions ◽  
Particle Flow Code ◽  
Test Results ◽  
Element Analysis ◽  
Asphalt Mixes ◽  
User Friendly ◽  
Simple Numerical Model

During the past decades, many numerical models have been used to predict responses of asphalt mixes under different types of loading. Some of these models were simple due to practicality but overestimated the response of asphalt mixes. On the other hand, sophisticated but effective numerical models have been developed to address the shortcomings of the simpler models, and were used mostly in finite element analysis (FEA). However, these models were complicated and not user friendly. Recently, the approach of the discrete element method (DEM) was adopted. Unlike traditional FEA, DEM can simulate crack propagation by allowing the separation of elements in the simulated models. Understanding these challenges, this study was initiated to investigate the utilization of a simple visco-elasto-plastic model that had been used successfully in predicting deformation in asphalt mixes using the DEM embedded in Particle Flow Code in Two Dimensions (PFC2D) software simulations. Simulation results, when compared to flow time (FT) and number (FN) test results, showed that this model could simulate actual tests, thus predicting deformation of asphalt mixes using the DEM on a larger scale. 

scholarly journals Influence of F-T Synthetic Wax on Asphalt Concrete Permanent Deformation

2013 ◽  
Vol 59 (3) ◽  
pp. 295-312
Author(s):  
M. Iwański ◽  
G. Mazurek
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
Asphalt Concrete ◽  
Permanent Deformation ◽  
Positive Influence ◽  
Test Results ◽  
Fischer Tropsch ◽  
Stiffness Modulus ◽  
Tensile Fatigue ◽  
Indirect Tensile

Abstract The paper presents the results of the study of the effect of a Fischer-Tropsch (F-T) synthetic wax on the resistance to permanent deformation of the AC 11S asphalt concrete. The synthetic wax was dosed at 1.5%, 2.5% and 3.5% by weight of bitumen 35/50. The compaction temperatures were 115°C, 130°C and 145°C. The criteria adopted for measuring the resistance to permanent deformation included the following parameters: stiffness modulus at 2, 10 and 20°C, permanent deformation (RTS), fatigue life determined using the indirect tensile fatigue test (ITFT) and resistance to rutting (WTSAIR, PRDAIR). The test results confirmed the positive influence of F-T synthetic wax on enhancing the permanent deformation resistance of asphalt concrete placed at lower compaction temperatures compared to that of standard asphalt concrete compacted at 140°C.

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