New Mechanistic Procedure to Predict the Critical Cracking Temperature of Asphalt Concrete from Bending Beam Rheometer and Indirect Tension Test Data

2021 ◽  
pp. 036119812110237
Author(s):  
Md Amanul Hasan ◽  
Rafiqul A. Tarefder
Keyword(s):  
Thermal Stress ◽  
Strain Rate ◽  
Asphalt Concrete ◽  
Superposition Principle ◽  
Relaxation Modulus ◽  
Model Parameters ◽  
Creep Data ◽  
Bending Beam Rheometer ◽  
Indirect Tension ◽  
Critical Cracking Temperature

This study presents a new mechanistic procedure for determining the critical cracking temperature of asphalt concrete (AC) using data from bending beam rheometer (BBR) test of asphalt binder and indirect tension (IDT) test of AC. This new procedure uses BBR creep data to generate the mixture relaxation modulus mastercurve by utilizing the Hirsch model, time-temperature superposition principle, and Prony series-based interconversion method. The Hirsch model parameters are calibrated by comparing creep data from BBR and IDT creep tests performed at the same temperature. Boltzmann hereditary integral and second-order heat equation are then used to calculate thermal stress from the developed relaxation modulus mastercurve. IDT strength data is transferred from test strain rate to thermal strain rate using the viscoelastic continuum damage model. Since a strain gauge is not attached for traditional laboratory IDT strength testing, this study derived an analytical equation based on the Hondros solution to compute the horizontal strain rate from the applied vertical displacement rate. Finally, the critical cracking temperature is determined by coupling the thermal stress and strength profiles. Using the procedure presented in this paper, the critical cracking temperatures of four AC mixtures were predicted from BBR and IDT data. Their actual critical cracking temperatures were measured using thermal stress restrained specimen test performed in the laboratory to validate the method. The predicted critical cracking temperatures are found to be very close to the laboratory measured values. The developed procedure has substantial practical and technical importance in predicting the critical cracking temperature of AC because it utilizes widely available BBR and IDT tests.

Effect of Progressive Aging on the Viscoelastic Material Functions of Asphalt Concrete and its Binder

2017 ◽  
Author(s):  
A. S. M. Asifur Rahman ◽  
Hasan M. Faisal ◽  
Rafiqul A. Tarefder
Keyword(s):  
Shear Modulus ◽  
Viscoelastic Material ◽  
Asphalt Concrete ◽  
Complex Modulus ◽  
Superposition Principle ◽  
Asphalt Binder ◽  
Relaxation Modulus ◽  
Concrete Specimen ◽  
Material Functions ◽  
Four Levels

In this study, field collected loose asphalt-aggregate mixtures were used to prepare cylindrical asphalt concrete specimen using a Superpave gyratory compactor and samples were subjected to four levels of aging. Unaged and aged samples were then tested for complex modulus, relaxation modulus, and creep compliance in the laboratory at different temperatures and loading conditions. To determine broadband characteristics, mastercurves of related viscoelastic material functions were determined by applying time-temperature superposition principle. A comparison study showed that increasing levels of aging have significant effect on viscoelastic functions of asphalt concrete. In addition, liquid asphalt binder corresponding to the asphalt-aggregate mixture was tested for complex shear modulus at various levels of aged conditions, using a dynamic shear rheometer. Results showed that even though the binder shear modulus increases significantly with aging, asphalt concrete modulus does not necessarily show similar increment.

Investigation on the cooling medium effect in the characterization of asphalt binder with the bending beam rheometer (BBR)

2018 ◽  
Vol 45 (7) ◽  
pp. 594-604 ◽  
Author(s):  
Augusto Cannone Falchetto ◽  
Ki Hoon Moon ◽  
Di Wang ◽  
Chiara Riccardi
Keyword(s):  
Thermal Stress ◽  
Asphalt Binder ◽  
Asphalt Binders ◽  
Medium Effect ◽  
Bending Beam Rheometer ◽  
Cooling Medium ◽  
Performance Grade ◽  
Creep Stiffness ◽  
Critical Cracking Temperature ◽  
Huet Model

In this paper, the possibility of using air as an alternative cooling medium for testing asphalt binder in the bending beam rheometer (BBR) is considered and evaluated. For this purpose, five asphalt binders were characterized with the BBR; creep stiffness, m-value, performance grade (PG), thermal stress, and critical cracking temperature were computed both for ethanol and air. In addition, the rheological Huet model was fitted to the experimental measurements to further investigate the effect of the cooling medium. It was found that air measurements result in stiffer materials, with higher low PG, higher thermal stress, and critical cracking temperature. The parameters of the Huet model confirm such a stiffening effect when air is used. Based on the material response observed in this study, further research is recommended before potentially replacing ethanol with air in the BBR, as the latter appears to provide a substantially different material grading.

Intergranular Stress Corrosion Cracking Damage Model: An Approach and Its Development for Alloy 600 in High-Purity Water

CORROSION ◽  
1986 ◽  
Vol 42 (2) ◽  
pp. 99-105 ◽  
Author(s):  
Y. S. Garud ◽  
A. R. McIlree
Keyword(s):  
Strain Rate ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
High Purity ◽  
Corrosion Cracking ◽  
Model Parameters ◽  
Alloy 600 ◽  
Intergranular Stress Corrosion ◽  
Film Rupture ◽  
Intergranular Stress Corrosion Cracking

Abstract A logical approach to quantitative modeling of intergranular stress corrosion cracking (IGSCC) is presented. The approach is based on the supposition (supported partly by experimental and field observations, and by a related plausible underlying mechanism) that strain rate is a key variable. The approach is illustrated for the specific case of NiCrFe Alloy 600 in high-purity water. Model parameters are determined based on the constant stress IGSCC data (between 290 and 365 C) assuming a power law relation between the damage and the nominal strain rate. The model may be interpreted in terms of a film rupture mechanism of the corrosion process. The related mechanistic considerations are examined for the specific case. Resulting calculations and stress as well as temperature dependence are shown to be in good agreement with the data. More data are needed for further verification under specific conditions of interest.

Transferability of the Gurson Damage Model Parameters with Charpy and Tensile Tests with Different Constrain Level

2009 ◽  
Vol 65 ◽  
pp. 19-31
Author(s):  
Ruben Cuamatzi-Melendez ◽  
J.R. Yates
Keyword(s):  
Strain Rate ◽  
Damage Model ◽  
Rolling Direction ◽  
Fracture Initiation ◽  
Tensile Tests ◽  
Model Parameters ◽  
Gurson Model ◽  
Finite Element Program ◽  
Element Program ◽  
Gurson's Model

Little work has been published concerning the transferability of Gurson’s ductile damage model parameters in specimens tested at different strain rates and in the rolling direction of a Grade A ship plate steel. In order to investigate the transferability of the damage model parameters of Gurson’s model, tensile specimens with different constraint level and impact Charpy specimens were simulated to investigate the effect of the strain rate on the damage model parameters of Gurson model. The simulations were performed with the finite element program ABAQUS Explicit [1]. ABAQUS Explicit is ideally suited for the solution of complex nonlinear dynamic and quasi–static problems [2], especially those involving impact and other highly discontinuous events. ABAQUS Explicit supports not only stress–displacement analyses but also fully coupled transient dynamic temperature, displacement, acoustic and coupled acoustic–structural analyses. This makes the program very suitable for modelling fracture initiation and propagation. In ABAQUS Explicit, the element deletion technique is provided, so the damaged or dead elements are removed from the analysis once the failure criterion is locally reached. This simulates crack growth through the microstructure. It was found that the variation of the strain rate affects slightly the value of the damage model parameters of Gurson model.

Effects of asphalt concrete characteristics on cohesive zone model parameters of hot mix asphalt mixtures

2016 ◽  
Vol 43 (3) ◽  
pp. 226-232 ◽  
Author(s):  
S. Pirmohammad ◽  
H. Khoramishad ◽  
M.R. Ayatollahi
Keyword(s):  
Asphalt Concrete ◽  
Cohesive Energy ◽  
Cohesive Zone ◽  
Hot Mix Asphalt ◽  
Cohesive Zone Model ◽  
Experimental Tests ◽  
Model Parameters ◽  
Zone Model ◽  
Binder Type ◽  
Air Void

In this paper, the effects of the main asphalt concrete characteristics including the binder type and the air void percentage on the cohesive zone model (CZM) parameters were studied. Experimental tests were conducted on semi-circular bend (SCB) specimens made of asphalt concrete and the fracture behavior was simulated using a proper CZM. The CZM parameters of various hot mix asphalt (HMA) mixtures were determined using the SCB experimental results. Five types of HMA mixtures were tested and modeled to consider the effects of binder type and air void percentage on the CZM parameters. The results showed that as the binder in HMA mixture softened, the cohesive energy strength increased, whereas enhancing the air void percentage led to reduction of the cohesive energy and strength values. Among the studied HMA mixtures, the highest values of CZM parameters were found for the HMA mixture containing a copolymer called styrene-butadiene-styrene.

Modelling of rapid pressure—strain in Reynolds-stress closures

1994 ◽  
Vol 269 ◽  
pp. 143-168 ◽  
Author(s):  
Arne V. Johansson ◽  
Magnus Hallbäck
Keyword(s):  
Strain Rate ◽  
Reynolds Stress ◽  
Sudden Change ◽  
Model Parameters ◽  
Rapid Distortion Theory ◽  
Flow Parameters ◽  
Turbulent Reynolds Number ◽  
Principal Axes ◽  
Anisotropy Tensor ◽  
Rapid Pressure

The most general form for the rapid pressure—strain rate, within the context of classical Reynolds-stress transport (RST) closures for homogeneous flows, is derived, and truncated forms are obtained with the aid of rapid distortion theory. By a classical RST-closure we here denote a model with transport equations for the Reynolds stress tensor and the total dissipation rate. It is demonstrated that all earlier models for the rapid pressure—strain rate within the class of classical Reynolds-stress closures can be formulated as subsets of the general form derived here. Direct numerical simulations were used to show that the dependence on flow parameters, such as the turbulent Reynolds number, is small, allowing rapid distortion theory to be used for the determination of model parameters. It was shown that such a nonlinear description, of fourth order in the Reynolds-stress anisotropy tensor, is quite sufficient to very accurately model the rapid pressure—strain in all cases of irrotational mean flows, but also to get reasonable predictions in, for example, a rapid homogeneous shear flow. Also, the response of a sudden change in the orientation of the principal axes of a plane strain is investigated for the present model and models proposed in the literature. Inherent restrictions on the predictive capability of Reynolds-stress closures for rotational effects are identified.

The Viscoelastic Characteristics of the Asphalt Concrete Modified with Different Synthetic Waxes Using a Modified Huet- Sayegh Model

2017 ◽  
Author(s):  
Grzegorz Mazurek
Keyword(s):  
Asphalt Concrete ◽  
Dynamic Modulus ◽  
Complex Modulus ◽  
Model Parameters ◽  
Fischer Tropsch ◽  
Stiffness Modulus ◽  
Molecular Weights ◽  
Cole Diagram ◽  
Sinusoidal Load ◽  
Viscoelastic Characteristics

The article presents the results of dynamic modulus tests carried on the asphalt concrete (AC16W). The sinusoidal load was applied to the samples in accordance with DTC-CY method. The neat bituminous binder (penetration grade 35/50) was modified by means two synthetic waxes, coming from the Fischer-Tropsch raction, with various molecular weights and softening point temperature results (hard and softer). The relaxation phenomenon in terms of changes in complex modulus and phase angle was evaluated using the modified Huet-Sayegh (2S2P1D). Estimated model parameters pointed out that the addition of the synthetic wax with the high (hard wax) and the low (softer wax) molecular weight raised the stiffness of the bituminous binder in relation to the reference bitumen 35/50. The application of the modified Huet-Sayegh model showed that the presence of the synthetic wax in the bitumen significantly affected the stiffness modulus of considered asphalt concretes. Basing analysis on Cole-Cole diagram it was found significant differences in the viscoelastic behaviour between the reference asphalt concrete and the asphalt concretes with synthetic waxes. In contrast, there were no significant differences between viscoelastic properties of tested asphalt concretes modified, used in the experiment, synthetic waxes. Furthermore, the sensitivity to the loading time of asphalt concretes containing both synthetic waxes was marginal.

scholarly journals Theoretical and Experimental Study on Hot-Embossing of Glass-Microprism Array without Online Cooling Process

Micromachines ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 984
Author(s):  
Manfeng Hu ◽  
Jin Xie ◽  
Wei Li ◽  
Yuanhang Niu
Keyword(s):  
Thermal Stress ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Optical Glass ◽  
Low Cost ◽  
Hot Embossing ◽  
Control Device ◽  
Grinding Wheel ◽  
Cooling Process ◽  
Low Strain Rate

Optical glass-microprism arrays are generally embossed at high temperatures, so an online cooling process is needed to remove thermal stress, but this make the cycle long and its equipment expensive. Therefore, the hot-embossing of a glass-microprism array at a low strain rate with reasonable embossing parameters was studied, aiming at reducing thermal stress and realizing its rapid microforming without online cooling process. First, the flow-field, strain-rate, and deformation behavior of glass microforming were simulated. Then, the low-cost microforming control device was designed, and the silicon carbide (SiC) die-core microgroove array was microground by the grinding-wheel microtip. Lastly, the effect of the process parameters on forming rate was studied. Results showed that the appropriate embossing parameters led to a low strain rate; then, the trapezoidal glass-microprism array could be formed without an online cooling process. The standard deviation of the theoretical and experimental forming rates was only 7%, and forming rate increased with increasing embossing temperature, embossing force, and holding duration, but cracks and adhesion occurred at a high embossing temperature and embossing force. The highest experimental forming rate reached 66.56% with embossing temperature of 630 °C, embossing force of 0.335 N, and holding duration of 12 min.

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