scholarly journals Study on Creep Behavior Of Asphalt Mixture Based on Discrete Element Method

2020 ◽  
Vol 15 (4) ◽  
pp. 174-195
Author(s):  
Youlin Ye ◽  
Yazhen Sun ◽  
Lin Gao ◽  
Zhuang Ma ◽  
Xingwei Xue
Keyword(s):  
Uniaxial Compression ◽  
Creep Behaviour ◽  
Viscoelastic Model ◽  
Asphalt Mixture ◽  
Discrete Element ◽  
Creep Tests ◽  
Burger Model ◽  
Air Voids ◽  
Compression Creep ◽  
Asphalt Mortar

A three-dimensional (3D) microstructure-based discrete element (DE) model was developed to study the creep behaviour of high viscoelastic asphalt sand (HVAS) with the uniaxial compression creep tests. The three-point bending creep tests of asphalt mortar were carried out in order to obtain the parameters of the Burger model, to determine the transformation method of macroscopic parameters and microscopic parameters of the model in theory, to obtain the parameters used in the discrete element model, and then establish the discrete element analysis model for the asphalt mixture. A 3D-DE digital specimen was composed of coarse aggregates, asphalt mortar and air voids, which could also take gradation, irregular shape, random distribution of aggregate and air voids into consideration, and the boundary conditions of the model were set through the simulation of the uniaxial compression creep tests. An accurate and extensive mapping model of HVAS was built by 3D-PFC (Particle Flow Code), which can provide a simple alternative to the laboratory tests. This method can simulate a series of numerical examples based on different stress levels, coarse aggregate homogenizations, mortar homogenizations and temperatures in a single factor method. Comparison of results of laboratory and numerical tests shows that the 3D-PFC-viscoelastic model can reflect the creep mechanical behaviour of asphalt mixture accurately. It provides the theoretical basis and auxiliary means for analysing the mechanical properties of asphalt mixtures using PFC software. The research on creep behaviour of the asphalt mixture by numerical simulation opens up a new way for the research on creep behaviour of the asphalt mixture, it is of considerable theoretical value and has broad application prospects.

Uniaxial Compression Creep Prediction of Asphalt Mixture Using the Eshelby Equivalent Inclusion Method

2014 ◽  
Vol 1061-1062 ◽  
pp. 410-413 ◽  
Author(s):  
Jun Wu
Keyword(s):  
Uniaxial Compression ◽  
Asphalt Mixture ◽  
Stress Conditions ◽  
Creep Tests ◽  
Two Phase ◽  
Asphalt Mastic ◽  
Compression Creep ◽  
Equivalent Inclusion Method ◽  
The Matrix ◽  
Constitutive Parameters

Asphalt mixture was simply treated as a two-phase composite, in which coarse aggregates are embedded into asphalt mastic matrix. According to the elastic-viscoelastic correspondence principle, an elastic micromechanical method is extended for predicting viscoelastic properties of asphalt mixture, which is simply treated as elastic coarse aggregate inclusions periodically and isotropically embedded into viscoelastic asphalt mastic matrix. The Burgers model is adopted for characterizing the matrix mechanical behavior, so that the homogenized relaxation modulus of asphalt mixture in compression creep is derived. After a series of uniaxial compression creep tests are performed on asphalt mastic in different stress conditions in order to determine the matrix constitutive parameters, the presented framework is validated by comparison with the experiment, and then some predictions to uniaxial compression creep behavior of asphalt mixture in different stress conditions are given.

Effect of Equal-Channel Angular Pressing (ECAP) on Creep in Aluminium Alloys

2007 ◽  
Vol 539-543 ◽  
pp. 2904-2909 ◽  
Author(s):  
Vàclav Sklenička ◽  
Jiří Dvořák ◽  
Marie Kvapilová ◽  
Milan Svoboda ◽  
Petr Král ◽  
...  
Keyword(s):  
Equal Channel Angular Pressing ◽  
Aluminium Alloys ◽  
Creep Resistance ◽  
Room Temperature ◽  
Creep Behaviour ◽  
Coarse Grained ◽  
Pure Aluminium ◽  
Creep Tests ◽  
Angular Pressing ◽  
Compression Creep

This paper examines the effect of equal-channel angular pressing (ECAP) on creep behaviour of pure aluminium, binary Al-0.2wt.%Sc alloy and ternary Al-3wt.%Mg-0.2wt.%Sc alloy. The ECAP was conducted at room temperature with a die that had a 90° angle between the channels and 8 repetitive ECAP passes followed route BC. Constant stress compression creep tests were performed at 473 K and stresses ranging between 16 to 80 MPa on ECAP materials and, for comparison purposes, on the initial coarse-grained materials. The results showed that the creep resistance of the ECAP processed Al-Sc and Al-Mg-Sc alloys was markedly deteriorated with respect to unpressed coarse-grained materials.

Discrete Element Modelling of Rock Creep Behaviour using Rate Process Theory

2020 ◽  
Author(s):  
José G. Gutiérrez-Ch ◽  
Salvador Senent ◽  
Eduardo Estebanez ◽  
Rafael Jimenez
Keyword(s):  
Creep Behavior ◽  
Creep Behaviour ◽  
Element Model ◽  
Discrete Element ◽  
Process Theory ◽  
Discrete Element Modelling ◽  
Rate Process ◽  
Creep Tests ◽  
Rock Creep ◽  
Rate Process Theory

Rock creep behavior is crucial in many rock engineering projects. Different approaches have been proposed to model rock creep behavior; however, many cannot reproduce tertiary creep (i.e., accelerating strain rates leading to rock failure). In this work, a discrete element model (DEM) is employed, in conjunction with the rate process theory [Kuhn MR, Mitchel JK. Modelling of soil creep with the discrete element method. Eng Computations. 1992;9(2):277–287] to simulate rock creep. The DEM numerical sample is built using a mixture of contact models between particles that combines the Flat Joint Contact Model and the Linear Model. Laboratory uniaxial compression creep tests conducted on intact slate samples are used as a benchmark to validate the methodology. Results demonstrate that, when properly calibrated, DEM models combined with the rate process theory can reproduce all creep stages observed in slate rock samples in the laboratory, including and without using constitutive models that incorporate an explicit dependence of strain rate with time. The DEM results also suggest that creep is associated to damage in the samples during the laboratory tests, due to new micro-cracks that appear when the load is applied and maintained constant at each loading stage.

scholarly journals An investigation on the effects of flaky particles on the properties of asphaltic mixtures

2015 ◽  
Vol 42 (11) ◽  
pp. 865-871 ◽  
Author(s):  
Babak Kazemi Darabadi ◽  
Hasan Taherkhani
Keyword(s):  
Creep Behaviour ◽  
Permanent Deformation ◽  
Asphaltic Concrete ◽  
Test Results ◽  
Creep Tests ◽  
Air Voids ◽  
Static Creep ◽  
Different Types ◽  
Creep Stiffness ◽  
Marshall Stability

Flaky particles, because of their shape, are considered as inferior aggregates in asphaltic mixtures, and specifications usually set limits on the amount of flaky particles in asphaltic mixtures. In this study, the effects of flaky particles content on the volumetric properties, Marshall Stability and creep behaviour of hot mixed asphaltic concrete have been investigated. Specimens with two different types of gradation and specified amounts of flaky particles were made and used for Marshall Stability and static creep tests. Test results show that the Marshall Stability decreases and the air voids content of asphaltic mixture and the voids in mineral aggregate increase as the flaky particles content increases. It is also found that flaky particles cause increase in permanent deformation and decrease in creep stiffness. The creep tests also show that the recoverable deformation of the mixtures decreases as the flaky particles content increases.

scholarly journals Effects of Aggregate Mesostructure on Permanent Deformation of Asphalt Mixture Using Three-Dimensional Discrete Element Modeling

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3601 ◽  
Author(s):  
Deyu Zhang ◽  
Linhao Gu ◽  
Junqing Zhu
Keyword(s):  
Surface Texture ◽  
Deformation Behavior ◽  
Negative Impact ◽  
Permanent Deformation ◽  
Asphalt Mixture ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Discrete Element ◽  
Asphalt Mixtures ◽  
Creep Tests

This paper investigated the effects of aggregate mesostructures on permanent deformation behavior of an asphalt mixture using the three-dimensional (3D) discrete element method (DEM). A 3D discrete element (DE) model of an asphalt mixture composed of coarse aggregates, asphalt mastic, and air voids was developed. Mesomechanical models representing the interactions among the components of asphalt mixture were assigned. Based on the mesomechanical modeling, the uniaxial static load creep tests were simulated using the prepared models, and effects of aggregate angularity, orientation, surface texture, and distribution on the permanent deformation behavior of the asphalt mixtures were analyzed. It was proven that good aggregate angularity had a positive effect on the permanent deformation performance of the asphalt mixtures, especially when approximate cubic aggregates were used. Aggregate packing was more stable when the aggregate orientations tended to be horizontal, which improved the permanent deformation performance of the asphalt mixture. The influence of orientations of 4.75 mm size aggregates on the permanent deformation behavior of the asphalt mixture was significant. Use of aggregates with good surface texture benefitted the permanent deformation performance of the asphalt mixture. Additionally, the non-uniform distribution of aggregates had a negative impact on the permanent deformation performance of the asphalt mixtures, especially when aggregates were distributed non-uniformly in the vertical direction.

scholarly journals Creep Behaviour Under Compressive Stresses of Calcium and Barium Containing Mg-Al-based Die Casting Alloys

2013 ◽  
Vol 765 ◽  
pp. 69-73 ◽  
Author(s):  
Hajo Dieringa ◽  
Daniela Zander ◽  
Mark A. Gibson
Keyword(s):  
Creep Behaviour ◽  
Die Casting ◽  
Creep Tests ◽  
Alloying Additions ◽  
Casting Alloys ◽  
Compression Creep ◽  
Compressive Stresses ◽  
Property Evaluation ◽  
Pressure Die Casting ◽  
Applied Stresses

The development of creep resistant high pressure die casting (HPDC) alloys is one of the main focuses in magnesium research. Alloying elements like rare earths, calcium, strontium or scandium added to the necessary aluminium for die casting have already been introduced. Newly developed barium containing magnesium alloys with three levels of alloying additions were processed via HPDC and their compression creep response at 200 °C was evaluated. DieMag633 (Mg-6Al-3Ba-3Ca) displays the best creep resistance followed by DieMag422 (Mg-4Al-2Ba-2Ca) and then DieMag211 (Mg-2Al-1Ba-1Ca). Stress exponents from tests at different applied stresses were calculated. The creep tests were also accompanied by microstructural investigations and mechanical property evaluation.

scholarly journals Does the Permanent Creep-Rate of Polycrystalline Ice Increase with Crystal Size?

1980 ◽  
Vol 25 (91) ◽  
pp. 151-158 ◽  
Author(s):  
Paul Duval ◽  
Hugues Le Gac
Keyword(s):  
Grain Size ◽  
Creep Rate ◽  
Uniaxial Compression ◽  
Crystal Size ◽  
Size Range ◽  
Transient Creep ◽  
Creep Tests ◽  
Compression Creep ◽  
Polycrystalline Ice

AbstractUniaxial compression creep tests were performed on artificial and natural polycrystalline ices at temperatures near –7°C. The grain-size range investigated was from 1 to 10 mm. Contrary to previous results, the permanent creep-rate was not found to increase with crystal size. Only the transient creep appears to be sensitive to variations in crystal size.

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