scholarly journals Influence of Cracks on the Lifetime of Semi-Rigid Pavements

2016 ◽  
Vol 63 (2-3) ◽  
pp. 83-100
Author(s):  
Krystyna Kazimierowicz-Frankowska
Keyword(s):  
Finite Element ◽  
Theoretical Model ◽  
Numerical Simulations ◽  
Base Layer ◽  
Stress And Strain ◽  
Reflective Cracking ◽  
Single Crack ◽  
Traffic Loading ◽  
Rigid Pavements ◽  
Pavement Structure

AbstractThis paper focuses on a better understanding of the process of reflective cracking propagation through the pavement structure. A series of finite element numerical simulations were conducted to investigate the initial stress and strain states in typical semi-rigid pavements with and without reflective cracks under traffic loading. It was assumed that reflective-cracks propagate from the base layer to the pavement surface. The influence of selected parameters, such as the load position, overlay thickness, and subgrade quality on stress and strain concentrations was investigated. The behaviour of the pavement structure under repeated traffic loading was analyzed in terms of ground compaction. The original theoretical model proposed by Prof. Andrzej Sawicki was used to predict the deformation of a pavement subgrade subjected to traffic loading. The damaging effect of cracks appearing in the pavement structure was investigated. It was found that even a single crack in the pavement structure may significantly reduce the pavement lifetime.

Coupled Numerical Analysis of the Anti-Crack Mechanism for Open-Graded Large Stone Asphalt Mixes

2009 ◽  
Vol 79-82 ◽  
pp. 1149-1152
Author(s):  
Hong Bing Guo ◽  
Shuan Fa Chen
Keyword(s):  
Finite Element ◽  
Asphalt Concrete ◽  
Asphalt Pavement ◽  
Rigid Base ◽  
Reflective Cracking ◽  
Large Stone ◽  
Concrete Base ◽  
Test Road ◽  
Cracking Performance ◽  
Pavement Structure

The reflective cracking in asphalt surface is a technical problem that exists in the semi-rigid base asphalt pavement structure and the rigid base asphalt pavement structure, how to control its emergence and development is still a major problem for road engineering. At present, researches on the anti-cracking performance for Open-graded Large Stone asphalt Mix (OLSM) in China almost remain in the test road observations, very few study the mechanism of its anti-cracking from the mechanical point. Aiming at this problem, a method of using OLSM as the cracking relief layer is proposed, large mineral aggregate, low asphalt content and a great deal of void in OLSM can dissipate or absorb stress and strain around the crack. The 3-D finite element method is used to analyze the crack-alleviating layer of ordinary asphalt concrete and OLSM, and the large-scale commercial finite element software of ABAQUS is used to do numerical simulation analysis for the lean concrete base asphalt pavement structure with OLSM, the analysis result indicates that temperature-load coupling stress of OLSM are less than that of ordinary asphalt concrete. Depending on the test road on an expressway, research on the anti-crack mechanism of OLSM has been conducted. The investigation of the test road and the result of the theoretical calculation indicate that OLSM can prevent lean concrete base asphalt pavement from the reflective cracking effectively, OLSM has good anti-cracking performance, it is an effective material to alleviate the reflective cracking. As the crack-alleviating layer, OLSM can significantly enhance the anti-cracking ability of the semi-rigid base asphalt pavement structure and the rigid base asphalt pavement structure.

Analysis on the Traffic-Response of Asphalt Concrete Overlay on PCC-Slab

2012 ◽  
Vol 178-181 ◽  
pp. 1623-1627
Author(s):  
Wei Xu ◽  
Xuan Cang Wang ◽  
Shan Qiang Li
Keyword(s):  
Finite Element ◽  
Asphalt Concrete ◽  
Element Model ◽  
Concrete Pavement ◽  
Comprehensive Model ◽  
Reflective Cracking ◽  
Traffic Loading ◽  
Asphalt Overlay ◽  
Pavement Construction ◽  
Asphalt Concrete Pavement

Focusing on the severity of asphalt concrete pavement crack, the optimization analyzing finite element model(FEM) of typical asphalt overlay pavement was developed to address reflective cracking, in which the analysis of traffic-loading response were concentrated on the stress-intensive areas close to the joints or cracks. The FE sensitive analysis, evaluating the influence of pavement construction parameters, including modulus and thickness of pavement courses, is useful to establish comprehensive model of overlay pavement construction.

Influence of Intermediate Course Gradation Type on Anti-Fatigue Performance of the Asphalt Pavement Structure

2014 ◽  
Vol 684 ◽  
pp. 191-194
Author(s):  
Zhao Hui Sun ◽  
Li Guang Chen ◽  
Guo Feng Yang ◽  
Bao Yang Yu
Keyword(s):  
Finite Element ◽  
Asphalt Mixture ◽  
Fatigue Analysis ◽  
Base Layer ◽  
Rigid Base ◽  
Course Materials ◽  
Finite Element Software ◽  
Calculation Results ◽  
Pavement Structure ◽  
Asphalt Concrete Pavement

Three grading types of asphalt mixture are designed and respectively placed in intermediate course of asphalt concrete pavement with a typical semi-rigid base layer, the pavement structure model is established by the application of finite element software, the tensile stress at the bottom of intermediate course is analyzed under the wheel pressure of 1.5MPa, the finite element calculation results are led to the fatigue analysis software nSoft, the fatigue analysis results of intermediate course materials are obtained. The results show that the design gradation AC-20 mixture has excellent fatigue resistance in the pavement structure layer.

scholarly journals Research on the Anti-Reflective Cracking Performance of a Full-Depth Asphalt Pavement

2021 ◽  
Vol 13 (17) ◽  
pp. 9499
Author(s):  
Fujin Hou ◽  
Tao Li ◽  
Xu Li ◽  
Yunliang Li ◽  
Meng Guo
Keyword(s):  
Finite Element ◽  
Asphalt Pavement ◽  
Mode Ii ◽  
Reflective Cracking ◽  
Direct Tension ◽  
Propagation Process ◽  
Loading Mode ◽  
Cracking Performance ◽  
Pavement Structure ◽  
Reflection Crack

In order to analyze the anti-reflective cracking performance of a full-depth asphalt pavement and study the propagation process of a reflection crack and its influencing factors, a mechanical model of pavement structural crack analysis was established based on the ABAQUS finite element software and the extended finite element method (XFEM). Based on two different loading modes of three-point bending and direct tension, the propagation process of a reflection crack is analyzed. The results show that the anti-reflective cracking performance of a full-depth asphalt pavement is better than that of a semi-rigid base pavement structure, and the loading mode II based on direct tension is more consistent with the propagation mechanism of pavement reflection cracks, while the loading mode II is more suitable for analyzing the anti-reflective cracking performance of the pavement structure. Appropriately reducing the elastic modulus of the stress-absorbing layer can significantly improve the anti-reflective cracking performance of the full-depth asphalt pavement.

Modulation instability in nonlinear chiral fiber

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Demissie Jobir Gelmecha ◽  
Ram Sewak Singh
Keyword(s):  
Theoretical Model ◽  
Numerical Simulations ◽  
Pulse Propagation ◽  
Modulation Instability ◽  
Constitutive Relations ◽  
Gain Spectrum ◽  
Circularly Polarized ◽  
Left Handed ◽  
Simulation Results ◽  
The Difference

AbstractIn this paper, the rigorous derivations of generalized coupled chiral nonlinear Schrödinger equations (CCNLSEs) and their modulation instability analysis have been explored theoretically and computationally. With the consideration of Maxwell’s equations and Post’s constitutive relations, a generalized CCNLSE has been derived, which describes the evolution of left-handed circularly polarized (LCP) and right-handed circularly polarized (RCP) components propagating through single-core nonlinear chiral fiber. The analysis of modulation instability in nonlinear chiral fiber has been investigated starting from CCNLSEs. Based on a theoretical model and numerical simulations, the difference on the modulation instability gain spectrum in LCP and RCP components through chiral fiber has been analyzed by considering loss and chirality into account. The obtained simulation results have shown that the loss distorts the sidebands of the modulation instability gain spectrum, while chirality modulates the gain for LCP and RCP components in a different manner. This suggests that adjusting chirality strength may control the loss, and nonlinearity simultaneously provides stable modulated pulse propagation.

scholarly journals Evaluation of Bone–Implant Interface Stress and Strain Using Heterogeneous Mandibular Bone Properties Based on Different Empirical Correlations

2021 ◽  
Author(s):  
Mostafa Omran Hussein ◽  
Mohammed Suliman Alruthea
Keyword(s):  
Finite Element ◽  
Group Iv ◽  
Von Mises Stress ◽  
Patient Specific ◽  
Dental Arch ◽  
Stress And Strain ◽  
Bone Implant ◽  
Bone Properties ◽  
Group I ◽  
Von Mises

Abstract Objective The purpose of this study was to compare methods used for calculating heterogeneous patient-specific bone properties used in finite element analysis (FEA), in the field of implant dentistry, with the method based on homogenous bone properties. Materials and Methods In this study, three-dimensional (3D) computed tomography data of an edentulous patient were processed to create a finite element model, and five identical 3D implant models were created and distributed throughout the dental arch. Based on the calculation methods used for bone material assignment, four groups—groups I to IV—were defined. Groups I to III relied on heterogeneous bone property assignment based on different equations, whereas group IV relied on homogenous bone properties. Finally, 150 N vertical and 60-degree-inclined forces were applied at the top of the implant abutments to calculate the von Mises stress and strain. Results Groups I and II presented the highest stress and strain values, respectively. Based on the implant location, differences were observed between the stress values of group I, II, and III compared with group IV; however, no clear order was noted. Accordingly, variable von Mises stress and strain reactions at the bone–implant interface were observed among the heterogeneous bone property groups when compared with the homogenous property group results at the same implant positions. Conclusion Although the use of heterogeneous bone properties as material assignments in FEA studies seem promising for patient-specific analysis, the variations between their results raise doubts about their reliability. The results were influenced by implants’ locations leading to misleading clinical simulations.

Effect of Healing on Fatigue Law Parameters of Asphalt Binders

2012 ◽  
Vol 2293 (1) ◽  
pp. 96-105 ◽  
Author(s):  
Arianna Stimilli ◽  
Cassie Hintz ◽  
Zhijun Li ◽  
Raul Velasquez ◽  
Hussain U. Bahia
Keyword(s):  
Fatigue Life ◽  
Asphalt Binder ◽  
Rest Period ◽  
Power Laws ◽  
Asphalt Binders ◽  
Traffic Loading ◽  
Damage Level ◽  
Rest Periods ◽  
Pavement Structure ◽  
Number Of Cycles

Asphalt binder has the ability to self-heal during rest periods when repetitive loading is applied. Studying the effect of rest on fatigue law parameters provides useful insight into the healing capabilities of asphalt binders. Currently, standard testing and analysis procedures to quantify asphalt binder healing capability are limited and difficult to implement in practice. Fatigue is known to depend on both traffic loading and pavement structure. Power law relations (e.g., Nf = Aγ−B) are commonly used for fatigue analysis of pavement materials. Power laws are used to estimate fatigue life (i.e., number of cycles to failure, Nf) as a function of load amplitude (e.g., strain, γ), which is a reflection of the pavement structure. In this study, testing consisted of strain-controlled time sweeps in the dynamic shear rheometer with a single rest period inserted at a specified damage level. With the selected test, the effect of healing on the relationship between fatigue life and strain was investigated. Nine neat and modified binders were tested. Healing testing was conducted at multiple age levels and strains. Healing that resulted from a single rest period had an insignificant effect on fatigue performance compared with modification and oxidative aging. Although this paper highlights the challenges of using few rest periods to predict healing potential, preliminary results of testing with multiple rest periods show the importance of healing. Further investigation is needed to verify the effect of multiple rest periods on binder fatigue.

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