Linking fatigue response of asphalt binders, mastics, and asphalt concrete mixture modified by nano-silica and synthesized polyurethane

2020 ◽  
Vol 30 (1) ◽  
pp. 103-122
Author(s):  
Mana Motamedi ◽  
Gholamali Shafabakhsh ◽  
Mohammad Azadi
Keyword(s):  
Fatigue Life ◽  
Asphalt Concrete ◽  
Damage Mechanics ◽  
Asphalt Binder ◽  
Continuum Damage Mechanics ◽  
Fatigue Performance ◽  
Concrete Mixture ◽  
Asphalt Binders ◽  
Continuum Damage ◽  
Nano Silica

Asphalt concrete is composed of stone, sand, filler, and asphalt binder. Fatigue can be considered as a phenomenon affecting both the binder (asphalt binder or mastic) and the mixture. The purpose of this study was to investigate the fatigue damage response in asphalt binders, mastics, and asphalt concrete mixtures modified with nano-silica and synthesized polyurethane. The continuum damage mechanics method and phenomenological approaches in this study were used to investigate the fatigue performance. Obtained results indicated that the effect of the synthesized polyurethane on improving the fatigue life was far greater than that of nano-silica. The damage process in asphalt binders differed from that in the mastic and asphalt concrete mixture. Damage intensity parameter is an appropriate criterion for evaluating fatigue performance of asphalt binders and mastics. Concerning the fatigue of asphalt concrete mixture, the results of this study indicated a better convergence between the fatigue parameters of mastics and asphalt concrete mixture compared to asphalt binders, especially with increasing aging. Also, there was greater convergence between the fatigue life of the asphalt concrete mixture and asphalt binder and mastics in the method of continuum damage mechanics as compared to the phenomenological approach.

Fatigue Life of the Human Teeth: A Continuum Damage Approach

2019 ◽  
Vol 43 ◽  
pp. 1-19
Author(s):  
Theddeus Tochukwu Akano
Keyword(s):  
Fatigue Life ◽  
Damage Mechanics ◽  
Stress Amplitude ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Elastoplastic Model ◽  
Human Teeth ◽  
Proposed Model ◽  
Number Of Cycles ◽  
Cycles To Failure

Normal oral food ingestion processes such as mastication would not have been possible without the teeth. The human teeth are subjected to many cyclic loadings per day. This, in turn, exerts forces on the teeth just like an engineering material undergoing the same cyclic loading. Over a period, there will be the creation of microcracks on the teeth that might not be visible ab initio. The constant formation of these microcracks weakens the teeth structure and foundation that result in its fracture. Therefore, the need to predict the fatigue life for human teeth is essential. In this paper, a continuum damage mechanics (CDM) based model is employed to evaluate the fatigue life of the human teeth. The material characteristic of the teeth is captured within the framework of the elastoplastic model. By applying the damage evolution equivalence, a mathematical formula is developed that describes the fatigue life in terms of the stress amplitude. Existing experimental data served as a guide as to the completeness of the proposed model. Results as a function of age and tubule orientation are presented. The outcomes produced by the current study have substantial agreement with the experimental results when plotted on the same axes. There is a notable difference in the number of cycles to failure as the tubule orientation increases. It is also revealed that the developed model could forecast for any tubule orientation and be adopted for both young and old teeth.

Life Prediction of Solder Joints by Damage and Fracture Mechanics

1996 ◽  
Vol 118 (4) ◽  
pp. 193-200 ◽  
Author(s):  
S. H. Ju ◽  
B. I. Sandor ◽  
M. E. Plesha
Keyword(s):  
Fatigue Life ◽  
Fracture Mechanics ◽  
Crack Growth ◽  
Damage Mechanics ◽  
Solder Joints ◽  
Continuum Damage Mechanics ◽  
Computer Time ◽  
Initial Crack ◽  
Continuum Damage ◽  
Growth Path

Much research has been done on Surface Mount Technology (SMT) using the Finite Element Method (FEM). Little of this, however, has employed fracture mechanics and/or continuum damage mechanics. In this study, we propose two finite element approaches incorporating fracture mechanics and continuum damage mechanics to predict time-dependent and temperature-dependent fatigue life of solder joints. For fracture mechanics, the J-integral fatigue formula, da/dN = C(δJ)m, is used to quantify fatigue crack growth and the fatigue life of J-leaded solder joints. For continuum damage mechanics, the anisotropic creep-fatigue damage formula with partially reversible damage effects is used to find the initial crack, crack growth path, and fatigue life of solder joints. The concept of partially reversible damage is especially novel and, based on laboratory tests we have conducted, appears to be necessary for solder joints undergoing cyclic loading. Both of these methods are adequate to predict the fatigue life of solder joints. The advantage of the fracture mechanics approach is that little computer time is required. The disadvantage is that assumptions must be made on the initial crack position and the crack growth path. The advantage of continuum damage mechanics is that the initial crack and its growth path are automatically evaluated, with the temporary disadvantage of requiring a lot of computer time.

Effect of Loading Waveform Pattern and Rest Period on Fatigue Life of Asphalt Concrete Using Viscoelastic Continuum Damage Model

2018 ◽  
Vol 2672 (28) ◽  
pp. 451-461 ◽  
Author(s):  
Waleed Abdelaziz Zeiada ◽  
Padmini P. Gudipudi ◽  
B. Shane Underwood ◽  
Mena I. Souliman
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
Asphalt Concrete ◽  
Rest Period ◽  
Test Method ◽  
Concrete Mixture ◽  
Continuum Damage ◽  
Viscoelastic Continuum Damage ◽  
Loading Waveform ◽  
Waveform Pattern

Fatigue cracking is one of the most critical types of distress in asphalt pavements and is due to actions of repetitive traffic loading over time. The fatigue life of asphalt concrete is often estimated from laboratory experiments where the performance depends directly on the test method, loading conditions, temperature, rest period, and aging in addition to the composition and properties of the mixture itself. The uniaxial fatigue test has become a popular method for developing constitutive models that describe the fatigue behavior of asphalt concrete mixture owing to the uniform states of stress across the specimen section. This study investigates the effect of the loading waveform (sinusoidal versus haversine) and rest period (continuous versus intermittent) on the laboratory fatigue life of asphalt concrete mixtures. The fatigue analysis was performed using the simplified viscoelastic continuum damage (S-VECD) approach where the damage characteristic (C-S) curves were established for all the cases, and then used to estimate the fatigue laws through simulated predictions. The proposed uniaxial fatigue test and analysis method were able to determine the fatigue life relationships of asphalt concrete mixture at different waveform and rest period conditions with a reduced testing time compared to other traditional testing and analysis methods. Overall, both rest period and waveform pattern were found to affect the laboratory fatigue life of asphalt concrete mixture. Model predictions show that pulse-rest loading yields an equivalent fatigue life to continuous loading at strain values that are approximately four times greater.

scholarly journals A Review on Fatigue Life Prediction Methods for Metals

2016 ◽  
Vol 2016 ◽  
pp. 1-26 ◽  
Author(s):  
E. Santecchia ◽  
A. M. S. Hamouda ◽  
F. Musharavati ◽  
E. Zalnezhad ◽  
M. Cabibbo ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Prediction Model ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Fatigue Life Prediction ◽  
Continuum Damage ◽  
Metallic Materials ◽  
Variable Amplitude Loading ◽  
Variable Amplitude

Metallic materials are extensively used in engineering structures and fatigue failure is one of the most common failure modes of metal structures. Fatigue phenomena occur when a material is subjected to fluctuating stresses and strains, which lead to failure due to damage accumulation. Different methods, including the Palmgren-Miner linear damage rule- (LDR-) based, multiaxial and variable amplitude loading, stochastic-based, energy-based, and continuum damage mechanics methods, forecast fatigue life. This paper reviews fatigue life prediction techniques for metallic materials. An ideal fatigue life prediction model should include the main features of those already established methods, and its implementation in simulation systems could help engineers and scientists in different applications. In conclusion, LDR-based, multiaxial and variable amplitude loading, stochastic-based, continuum damage mechanics, and energy-based methods are easy, realistic, microstructure dependent, well timed, and damage connected, respectively, for the ideal prediction model.

The Effect of Asphalt Binder Aging on Fatigue Performance of Evotherm WMA

2012 ◽  
Vol 535-537 ◽  
pp. 1686-1692
Author(s):  
Yong Chun Qin ◽  
Sui Yuan Wang ◽  
Wei Zeng ◽  
Xiao Pei Shi ◽  
Jian Xu ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Warm Mix Asphalt ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Asphalt Binders ◽  
Different Temperatures ◽  
Binder Aging ◽  
Lower Production

One of the main benefits advertised with the use of warm mix asphalt (WMA) is the decreasing aging of the asphalt binder resulting from the lower production temperature compared to conventional hot mix asphalt (HMA). Some tests were performed to determine the asphalt binder aging properties from WMA and HMA. Asphalt binders were recovered by extraction and distillation from asphalt mixtures premixed at different temperatures (140°C, 160°C, 180°C for HMA, 100°C and 120°C for WMA) in the mixing plant. Penetration@25°C, softening point (R&B) and rotational Brookfield viscosity tests were carried out. Results show that the aging of asphalt binder increases as the mixing temperature is elevated, and remarkably accelerates at the temperatures higher than 150°C. Warm mix asphalt (for example, mixing temperature at 100°Cor 120°C) can greatly reduce the aging of asphalt. Aging of the asphalt binder is one of the factors that would affect the mixture’s fatigue life. Four-point beam fatigue test samples were mixed and compacted at 140°C for HMA and 120°C for WMA, and fatigue tests with a frequency of 10 Hz and three constant strain levels (150 micro-strain, 300 micro-strain, 450 micro-strain, respectively) were performed. Results show that WMA’s fatigue life was higher than the control HMA, which indicates that it may reduce aging of asphalt binder and improve fatigue performance of asphalt mixture at lower production temperatures.

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