scholarly journals Comparative Analysis of Viscoelastic Properties of Open Graded Friction Course under Dynamic and Static Loads

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1250
Author(s):  
Liding Li ◽  
Chunli Wu ◽  
Yongchun Cheng ◽  
Yongming Ai ◽  
He Li ◽  
...  
Keyword(s):  
Dynamic Modulus ◽  
Viscoelastic Properties ◽  
Functional Relationship ◽  
Creep Compliance ◽  
Relaxation Modulus ◽  
Creep Tests ◽  
Static Loads ◽  
Burgers Model ◽  
Viscoelastic Parameters ◽  
Open Graded Friction Course

The viscoelastic properties of open graded friction course (OGFC) are closely related to anti-permanent deformation ability, noise reduction ability and durability. To study the viscoelastic parameters of OGFC under dynamic and static loads and to establish the functional relationship between them, uniaxial compression creep tests and dynamic modulus tests were performed to obtain the creep compliance and the dynamic modulus of OGFC. In addition, the Burgers model, modified Burgers model, second-order extensive Maxwell model, Scott-Blair model and modified Sigmoid model were employed to quantitatively analyze the dynamic and static viscoelastic properties of OGFC. Subsequently, the relaxation modulus of OGFC was deduced by the viscoelastic theory. Then, the dynamic modulus of OGFC was calculated according to the deduced relaxation modulus. Based on the calculated values and the measured values of dynamic modulus, the functional relationship of viscoelastic parameters of OGFC under dynamic and static loads was established. The results show that the increase in test temperature has adverse effects on the viscoelastic indexes of OGFC, such as creep compliance, relaxation modulus, and dynamic modulus; the dynamic modulus derived from static creep compliance has a good linear correlation with that obtained by dynamic modulus tests, but the correlation of the phase angle is poor.

Effects of Aging on Viscoelastic Properties of Asphalt-Aggregate Mixtures

1998 ◽  
Vol 1630 (1) ◽  
pp. 21-27 ◽  
Author(s):  
Jo Sias Daniel ◽  
Y. Richard Kim ◽  
Hyun-Jong Lee
Keyword(s):  
Asphalt Concrete ◽  
Material Properties ◽  
Dynamic Modulus ◽  
Viscoelastic Properties ◽  
Correspondence Principle ◽  
Creep Compliance ◽  
Relaxation Modulus ◽  
Fatigue Performance ◽  
Concrete Mixtures ◽  
Effects Of Aging

The effects of aging on asphalt-aggregate mixtures is a topic that has been gaining attention in recent years. Of special interest is how the fatigue performance of asphalt concrete mixtures changes with time because of changing material properties. The fatigue performance of a mixture is related to its viscoelastic material properties. An investigation of the effects of aging on viscoelastic properties of an asphalt-aggregate mixture, such as creep compliance, relaxation modulus, dynamic modulus, and phase angle, is discussed in this paper. The framework for including the effect of aging in an existing uniaxial constitutive model is established, and the applicability of Schapery’s elastic-viscoelastic correspondence principle to aged mixtures is validated.

Effect of Cure State on Stress Relaxation in 3501-6 Epoxy Resin

1997 ◽  
Vol 119 (3) ◽  
pp. 262-265 ◽  
Author(s):  
S. R. White ◽  
A. B. Hartman
Keyword(s):  
Stress Relaxation ◽  
Epoxy Resin ◽  
Creep Compliance ◽  
Numerical Technique ◽  
Matrix Material ◽  
Relaxation Modulus ◽  
Master Curves ◽  
Creep Tests ◽  
Three Point Bending ◽  
Direct Inversion

Little experimental work has been done to characterize how the viscoelastic properties of composite material matrix resins develop during cure. In this paper, the results of a series of creep tests carried out on 3501–6 epoxy resin, a common epoxy matrix material for graphite/epoxy composites, at several different cure states is reported. Beam specimens were isothermally cured at increasing cure temperatures to obtain a range of degrees of cure from 0.66 to 0.99. These specimens were then tested in three-point bending to obtain creep compliance over a wide temperature range. The master curves and shift functions for each degree of cure case were obtained by time-temperature superposition. A numerical technique and direct inversion were used to calculate the stress relaxation modulus master curves from the creep compliance master curves. Direct inversion was shown to be adequate for fully cured specimens, however it underpredicts the relaxation modulus and the transition for partially cured specimens. Correlations with experimental stress relaxation data from Kim and White (1996) showed that reasonably accurate results can be obtained by creep testing followed by numerical conversion using the Hopkins-Hamming method.

scholarly journals Influence Analysis and Optimization for Aggregate Morphological Characteristics on High- and Low-Temperature Viscoelasticity of Asphalt Mixtures

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2034 ◽  
Author(s):  
Yongchun Cheng ◽  
Wensheng Wang ◽  
Jinglin Tao ◽  
Meng Xu ◽  
Xiaoli Xu ◽  
...  
Keyword(s):  
Low Temperature ◽  
Viscoelastic Properties ◽  
Viscoelastic Model ◽  
Asphalt Mixture ◽  
Morphological Characteristics ◽  
Relaxation Modulus ◽  
Mixture Design ◽  
Asphalt Mixtures ◽  
Raw Material ◽  
Viscoelastic Parameters

Aggregate is an indispensable raw material for asphalt pavement construction. This study evaluates the influences of aggregate morphological characteristics on the high- and low-temperature viscoelasticity of asphalt mixtures. Based on simplex lattice mixture design (SLD), asphalt mix samples were designed and prepared with the same gradation but three different types of aggregates. Subsequently, three morphological characteristics of aggregate (roundness, perimeter index, and erosion-dilation area ratio) are presented to characterize fine and coarse aggregates. Then based on Burgers viscoelastic model, uniaxial compression static creep test was carried out to analyze the high-temperature viscoelastic properties for asphalt mortar and mixture. Meanwhile fitting Prony series models have been utilized to represent relaxation modulus conversed from creep compliance and the low-temperature relaxation characteristics can be also discussed. The experimental results indicated that morphological characteristics of aggregate, especially fine aggregates, are strongly correlated with the viscoelastic parameters of asphalt mixtures. However, the complex morphological characteristics of aggregates have opposite influences on the high- and low-temperature viscoelastic parameters. Therefore, when considering both high- and low-temperature viscoelastic properties, the aggregate proportion was optimized for the appropriate morphological characteristics, which will provide a reference for asphalt mixture design.

L-Curve Based Tikhonov’s Regularization Method for Determining Relaxation Modulus From Creep Test

2011 ◽  
Vol 78 (3) ◽  
Author(s):  
Yaoting Zhu ◽  
Lu Sun ◽  
Huilin Xu
Keyword(s):  
Regularization Method ◽  
Relaxation Modulus ◽  
Asphalt Mixtures ◽  
Parameter Estimates ◽  
Noise Levels ◽  
Creep Tests ◽  
Viscoelastic Parameters ◽  
Tikhonov’S Regularization ◽  
Numerical Case Study

A numerical method for directly obtaining discrete relaxation modulus from static creep tests data is developed for linear viscoelastic asphalt mixtures. To overcome the ill-posedness of interconversion between creep compliance and relaxation modulus, Volterra integral equations of the second kind and L-curve based Tikhonov’s regularization method are used to construct the computational scheme of parameter estimation. A numerical case study is presented to demonstrate the efficiency of the regularization method, which takes into account different step lengths and noise levels. It indicates that the computed results are accurate and robust at different noise levels. Compared with other existing methods, the L-curve based Tikhonov’s regularization method provides the best parameter estimates in dealing with both the numerical case study and the experiment data. The method can be used to extract viscoelastic parameters of asphalt mixtures from creep tests effectively and robustly.

scholarly journals A Combined Exponential-Power-Law Method for Interconversion between Viscoelastic Functions of Polymers and Polymer-Based Materials

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3001
Author(s):  
Vitor Dacol ◽  
Elsa Caetano ◽  
João R. Correia
Keyword(s):  
Mechanical Response ◽  
Creep Compliance ◽  
Viscoelastic Behavior ◽  
Relaxation Modulus ◽  
Creep Tests ◽  
General Applicability ◽  
Wide Range ◽  
Long Time ◽  
Linear Viscoelastic ◽  
The Time Domain

Understanding and modeling the viscoelastic behavior of polymers and polymer-based materials for a wide range of quasistatic and high strain rates is of great interest for applications in which they are subjected to mechanical loads over a long time of operation, such as the self-weight or other static loads. The creep compliance and relaxation functions used in the characterization of the mechanical response of linear viscoelastic solids are traditionally determined by conducting two separate experiments—creep tests and relaxation tests. This paper first reviews the steps involved in conducting the interconversion between creep compliance and relaxation modulus in the time domain, illustrating that the relaxation modulus can be obtained from the creep compliance. This enables the determination of the relaxation modulus from the results of creep tests, which can be easily performed in pneumatic equipment or simple compression devices and are less costly than direct relaxation tests. Some existing methods of interconversion between the creep compliance and the relaxation modulus for linear viscoelastic materials are also presented. Then, a new approximate interconversion scheme is introduced using a convenient Laplace transform and an approximated Gamma function to convert the measured creep compliance to the relaxation modulus. To demonstrate the accuracy of the fittings obtained with the method proposed, as well as its ease of implementation and general applicability, different experimental data from the literature are used.

Experimental Study on the Viscoelastic Properties of Asphalt Concrete under Chloride Corrosion

2013 ◽  
Vol 668 ◽  
pp. 645-649
Author(s):  
Jin Zhi Zhou ◽  
Jie Dai ◽  
Jian Hua Zheng
Keyword(s):  
Experimental Study ◽  
Asphalt Concrete ◽  
Viscoelastic Properties ◽  
Chloride Solution ◽  
Creep Tests ◽  
Chloride Corrosion ◽  
Viscoelastic Parameters ◽  
Compression Creep ◽  
Creep Stiffness ◽  
Diurnal Temperature Variation

In the paper, uniaxial compression creep tests were carried out at 25°C after the asphalt concrete corroded by different chloride solution concentrations, suffering different times of diurnal temperature variation cycle. Creep stiffness module and the ratio of residual strain were employed to evaluate the viscoelastic properties of asphalt concrete. According to the winter in Wuhan district, the viscoelastic properties of asphalt concrete under the action of chloride corrosion together with day-night cycle were preliminarily studied, and the corresponding viscoelastic parameters were determined with the help of Burgers model. The results show that chloride corrosion and day-night cycle can separately affect the viscoelastic properties of asphalt concrete, and the influence becomes severer while they act together.

scholarly journals Research of Method for Solving Relaxation Modulus Based on Three-Point Bending Creep Test

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2021 ◽  
Author(s):  
Yazhen Sun ◽  
Zhangyi Gu ◽  
Jinchang Wang ◽  
Xuezhong Yuan
Keyword(s):  
Creep Test ◽  
Relaxation Modulus ◽  
High Viscosity ◽  
Transcendental Equation ◽  
Creep Tests ◽  
Three Point Bending ◽  
Viscoelastic Parameters ◽  
Relaxation Experiments ◽  
Laboratory Investigations ◽  
Relaxation Characteristics

A method was developed for solving the relaxation modulus of high viscosity asphalt sand (HVAS) based on the three-point bending creep test, and was verified by comparison with experimental results. In this method, firstly, a transcendental equation was obtained by the convolution, and then equations were obtained by Taylor’s formula, which were solved by Mathmatica to obtain the relaxation modulus by Newton’s method. Subsequently, the laboratory investigations of the viscoelastic parameters of the Burgers model for the HVAS by three-point bending creep tests were carried out. In addition, the method was verified by comparing the relaxation moduli with the indoor relaxation experiments. Results showed that the numerical calculation and the test data were in good agreement, and the relaxation characteristics of the HVAS were reflected more accurately. The method can be used to study the relaxation characteristics of the asphalt mixtures effectively. In addition, this study provides a research basis for road crack prevention.

scholarly journals Study on Mechanical and Viscoelastic Properties of Asphalt Mixture Modified by Diatomite and Crumb Rubber Particles

2020 ◽  
Vol 10 (23) ◽  
pp. 8748
Author(s):  
Chunyu Liang ◽  
Hao Zhang ◽  
Zhengwei Gu ◽  
Xin Xu ◽  
Jinxin Hao
Keyword(s):  
Viscoelastic Properties ◽  
Rubber Particle ◽  
Asphalt Mixture ◽  
Maxwell Model ◽  
Crumb Rubber ◽  
Asphalt Mixtures ◽  
Creep Tests ◽  
Aggregate Gradation ◽  
Burgers Model ◽  
Rubber Particles

To optimize the properties of asphalt mixtures and make full use of waste rubber tires, diatomite and crumb rubber particles were applied to reinforce the asphalt mixtures in this study. The rutting tests, the three-point bending tests, the freeze-thaw splitting tests, and the uniaxial compression creep tests were performed to analyze the effects of asphalt types and aggregate gradation on the pavement properties of diatomite and crumb rubber particles reinforced asphalt mixtures (DRPAM). Subsequently, the creep and relaxation characteristics of DRPAM were analyzed by the Burgers model, the modified Burgers model, the second-order extensive Maxwell model, and the Scott–Blair model. The results show that rubber particles and diatomite can reinforce the high temperature, low temperature, and viscoelastic properties of asphalt mixtures, although the improvement effect is weaker than styrene-butadiene-styrene (SBS). Consequently, it is concluded that rubber particle and diatomite compound modified asphalt mixture with suspension dense gradation and SBS binder will have better performance.

EXPERIMENTAL RESEARCH ON VISCOELASTICITY PROPERTY OF DIFFERENT LAYERS PERIODONTAL LIGAMENT UNDER COMPRESSION

2021 ◽  
pp. 2150050
Author(s):  
JINLAI ZHOU ◽  
YANG SONG ◽  
CHENGUANG XU ◽  
CHUNQIU ZHANG ◽  
XUE SHI
Keyword(s):  
Elastic Modulus ◽  
Periodontal Ligament ◽  
Creep Compliance ◽  
Relaxation Modulus ◽  
Maxwell Model ◽  
Kelvin Model ◽  
Generalized Maxwell Model ◽  
Relaxation Stress ◽  
Generalized Kelvin Model ◽  
Fitting Accuracy

The periodontal ligament (PDL) exhibits different material mechanical properties along the long axis of the teeth. To explore the creep and the relaxation effects of dissimilar layers of PDL, this paper took the central incisors of porcine mandibular as experimental subjects and divided them perpendicular to the teeth axis into five layers. Creep experiments and relaxation experiments on five layers were conducted to obtain the creep compliance and relaxation modulus at different layers. Linear elastic model, generalized Kelvin model, and generalized Maxwell model were used to describe the major characteristics of the PDL: Instantaneous elasticity, creep and relaxation. Fitting accuracy of three-parameter, five-parameter, and seven-parameter of the model was compared, and the constitutive equations of different layers were established by the least square method. The results presented that the creep strain and the relaxation stress of PDL were exponentially correlated with time under different loading conditions. Different layers showed a significant effect on the creep strain and relaxation stress of PDL. Along the long axis of the teeth, the changing rule of the creep compliance and relaxation modulus of each layer showed quite the contrary, and the instantaneous elastic modulus first decreased to the minimum, then increased to the maximum. Higher instantaneous elastic modulus led to lower creep compliance and higher relaxation modulus. The generalized Kelvin model and the generalized Maxwell model well characterized the creep and relaxation properties of PDL. Fitting accuracy increased with the number of model parameters. The relaxation time of PDL was about one order of magnitude shorter than the creep retardation time, which indicated that the relaxation effect lasted shorter than the creep effect.

Novel Approach for the Lifetime Prediction of Composite Materials under Static Loads

2019 ◽  
Vol 809 ◽  
pp. 620-624
Author(s):  
Stefan Gloggnitzer ◽  
Gerald Pilz ◽  
Christian Schneider ◽  
Gerald Pinter
Keyword(s):  
Composite Materials ◽  
Creep Rupture ◽  
Stress Rate ◽  
Testing Time ◽  
Creep Tests ◽  
Static Loads ◽  
Rate Dependent ◽  
R Ratio ◽  
Structural Applications ◽  
Load Rate

Composite materials in structural applications that are subjected to static loads for several decades tend to change material performance over their lifetime. Classical creep tests with constant static loading are quite simple tests with low demands on the test equipment. Unfortunately, these tests require uneconomically long test times, which is why a shortening of the test times with various accelerated approaches is being researched. Within this work two approaches for reduction of the testing time were investigated. On the one hand a fatigue test with the variation of R-ratio and following extrapolation to an R-ratio of 1 was done. On the other hand a Stress Rate Accelerated Creep Rupture Test (SRCR) was developed, where a defined initial stress σi is applied at the beginning of the loading process, followed by an increase load with a constant rate instead of the static stress segment of the classic creep rupture tests. Changing the load rate in several individual tests leads to stress rate-dependent fracture strengths with associated fracture times, which allows extrapolation to a fracture time at a load rate of zero. In particular, the approach of the SRCR offers great potential for greatly reducing test times with an acceptable prediction quality.

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