Fatigue damage analysis in asphalt concrete mixtures using the dissipated energy approach

2006 ◽  
Vol 33 (7) ◽  
pp. 890-901 ◽  
Author(s):  
Khalid A Ghuzlan ◽  
Samuel H Carpenter
Keyword(s):  
Asphalt Concrete ◽  
Fatigue Testing ◽  
Fatigue Curve ◽  
Theoretical Background ◽  
Energy Approach ◽  
Dissipated Energy ◽  
Initial Stiffness ◽  
Fatigue Damage Analysis ◽  
Concrete Damage ◽  
Highly Correlated

An asphalt concrete damage–energy fatigue approach based on the concept of change in dissipated energy is presented in this paper. The damage–energy based fatigue approach is simple and based on a sound theoretical background. The central concept of the energy approach is the energy fatigue curve, which is based on two key elements, namely the plateau value (PV) and the number of load cycles to true failure (Ntf). The plateau value represents the constant value of the percentage of dissipated energy that produces damage to the material under cyclic loading. Failure is defined as the number of load cycles at which this percentage of dissipated energy begins to increase rapidly, indicating instability. Flexural fatigue testing was used to test hundreds of asphalt concrete beams, mainly under controlled-strain testing conditions. It was found that PV is highly dependent on the initial loading conditions, stress, strain, and dissipated energy. As a result, it can be used conveniently in pavement design. The number of load cycles to 50% reduction in initial stiffness was found to be highly correlated with the new failure point (Ntf). Using the dissipated energy concepts in fatigue analysis makes it possible to account for damage accumulation in a straightforward manner.Key words: fatigue of asphalt concrete, dissipated energy, damage, energy ratio.

Energy-Derived, Damage-Based Failure Criterion for Fatigue Testing

2000 ◽  
Vol 1723 (1) ◽  
pp. 141-149 ◽  
Author(s):  
Khalid A. Ghuzlan ◽  
Samuel H. Carpenter
Keyword(s):  
Fatigue Testing ◽  
Fatigue Loading ◽  
Constant Stress ◽  
Material Behavior ◽  
Dissipated Energy ◽  
Initial Stiffness ◽  
Repeated Load ◽  
Definition Of ◽  
Selection Of

Determination of the failure limit in a repeated-load fatigue test in the laboratory has relied entirely on the arbitrary selection of a fixed criterion. The constant strain and constant stress modes of fatigue loading have been described by a consistent definition of failure in flexural fatigue testing because of the distinctly different application of energy during the loading history. The most widely accepted definition is a decrease in initial stiffness by 50 percent. Procedures examining energy input and dissipated energy have required different schemes for each mode in an attempt to describe similar states of damage in the mixture. A proposed method is presented for examining dissipated energy to select a consistent level of material behavior that is indicative of the damage accumulation in the mixture. This procedure shows the similarity between the constant stress and constant strain modes of testing and is shown to provide the potential for unifying the now phenomenological description of fatigue with a more rational energy-based description.

scholarly journals Parasitic-Based Active Gate Driver Improving the Turn-On Process of 1.7 kV SiC Power MOSFET

2021 ◽  
Vol 11 (5) ◽  
pp. 2210
Author(s):  
Bartosz Lasek ◽  
Przemysław Trochimiuk ◽  
Rafał Kopacz ◽  
Jacek Rąbkowski
Keyword(s):  
Gate Voltage ◽  
Drain Current ◽  
Theoretical Background ◽  
Dissipated Energy ◽  
Feedback Signal ◽  
Power Losses ◽  
Turn On ◽  
Speed Up ◽  
Gate Driver ◽  
The Right

This article discusses an active gate driver for a 1.7 kV/325 A SiC MOSFET module. The main purpose of the driver is to adjust the gate voltage in specified moments to speed up the turn-on cycle and reduce the amount of dissipated energy. Moreover, an adequate manipulation of the gate voltage is necessary as the gate current should be reduced during the rise of the drain current to avoid overshoots and oscillations. The gate voltage is switched at the right moments on the basis of the feedback signal provided from a measurement of the voltage across the parasitic source inductance of the module. This approach simplifies the circuit and provides no additional power losses in the measuring circuit. The paper contains the theoretical background and detailed description of the active gate driver design. The model of the parasitic-based active gate driver was verified using the double-pulse procedure both in Saber simulations and laboratory experiments. The active gate driver decreases the turn-on energy of a 1.7 kV/325 A SiC MOSFET by 7% comparing to a conventional gate driver (VDS = 900 V, ID = 270 A, RG = 20 Ω). Furthermore, the proposed active gate driver lowered the turn-on cycle time from 478 to 390 ns without any serious oscillations in the main circuit.

A dissipated energy approach for flow number determination

2020 ◽  
pp. 347-350
Author(s):  
Hamzeh Saqer ◽  
Munir D. Nazzal ◽  
Mohammad Al-Khasawneh ◽  
Ala Abbas ◽  
Sang Soo Kim
Keyword(s):  
Energy Approach ◽  
Dissipated Energy ◽  
Flow Number

scholarly journals Gauge-Strain-Controlled Air and PWR Fatigue Life Data for 304 Stainless Steel—Some Effects of Surface Finish and Hold Time

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1248
Author(s):  
Marc Vankeerberghen ◽  
Michel De Smet ◽  
Christian Malekian
Keyword(s):  
Fatigue Life ◽  
Surface Finish ◽  
Fatigue Testing ◽  
Hold Time ◽  
Ground Surface ◽  
Fatigue Curve ◽  
304 Stainless Steel ◽  
Polished Surface ◽  
Water Reactor ◽  
Primary Water

We performed environmental fatigue testing in simulated primary water reactor (PWR) primary water and reference fatigue testing in air in the framework of an international, collaborative project (INCEFA-PLUS), where the effects of mean strain and stress, hold time, strain amplitude and surface finish on fatigue life of austenitic stainless steels in light water reactor environments are being studied. Our fatigue lives obtained on machined specimens in air at 300 °C lie close to the NUREG/CR6909 mean air fatigue curve and are in line with INCEFA-PLUS air fatigue lives. Our environmental fatigue lives obtained in simulated PWR primary water at 300 °C lie relatively close to the NUREG/CR6909 mean fatigue curve; derived from the NUREG/CR6909 mean air fatigue curve and the applicable environmental correction factor (Fen). The PWR results show that (1) a polished surface finish has a slightly higher and a ground surface finish a slightly lower fatigue life than the NUREG/CR6909 prediction; (2) the ratio of polished to ground specimen life is ~1.37 at 300 °C and ~1.47 at 230 °C; (3) holds—at zero strain after a positive strain-rate—have a slightly detrimental effect on fatigue life. These results are in line with the INCEFA-PLUS PWR fatigue lives. A novel gauge-strain extensometer was deployed in order to perform a true gauge-strain-controlled fatigue test in simulated PWR primary water.

Probabilistic Analysis of 60-Year Environmental Fatigue Effects for Reactor Components

2003 ◽  
Author(s):  
Arthur F. Deardorff ◽  
Dilip Dedhia ◽  
Stan T. Rosinski ◽  
David O. Harris
Keyword(s):  
Environmental Effects ◽  
Fatigue Testing ◽  
Fatigue Curve ◽  
Light Water Reactor ◽  
Operating Period ◽  
Detailed Review ◽  
Core Damage ◽  
Fatigue Initiation ◽  
Mechanics Analysis ◽  
Stress Variance

In NUREG/CR-6674, a probabilistic fracture mechanics analysis was conducted to assess the effects of light water reactor environmental effects on the probability of fatigue initiation and subsequent crack growth leading to leakage and possible core damage. The results were based on stresses for typical locations in BWR and PWR reactors as determined from an analysis reported in NUREG/CR-6260. Although environmental effects were shown to have an insignificant effect on core damage frequency, the study concluded that there could be a significant increase in probability of leakage. A detailed review of the methodology and input conditions used in NUREG/CR-6674 has been completed, including use of an altered probabilistic fatigue curve with more representative high-cycle stress variance and consideration of results from more recent environmental fatigue testing. This revised analysis indicates that environmental effects on the probability of leakage and core damage frequency in an extended nuclear plant operating period are significantly less than previously reported in NUREG/CR-6674. This paper summarizes the analysis performed and the results obtained.

An Energy Approach for Helping the Selection of Solid Lubrication Coatings Under Fretting Conditions

2009 ◽  
Author(s):  
D. B. Luo ◽  
V. Fridrici ◽  
Ph. Kapsa ◽  
M. Taillandier ◽  
C. Prud’homme
Keyword(s):  
Master Curve ◽  
Initial Energy ◽  
Energy Approach ◽  
Friction Reduction ◽  
Solid Lubrication ◽  
Dissipated Energy ◽  
Test Parameters ◽  
Definition Of ◽  
Energy Dissipated ◽  
Fretting Damage

Employing friction reduction coatings is one of the most effective methods to palliate the fretting damage. However, facing numerous available coatings, how to compare them and select the optimum one for a specific application is still a challenging task. In this paper, based on the investigation of the fretting behaviors of several bonded solid lubricant coatings, an energy approach in terms of “initial maximal dissipated energy density” was suggested to compare the tribological response of coatings. According to test results, the lifetime of each coating under different test parameters can be fitted by one master curve. The definition of this master curve for a given coating may be used for the prediction of the coating lifetime only by knowing the initial energy dissipated in the contact. The comparison of different master curves for different coatings can be employed to help the coating selection.

Constitutive Modeling of Asphalt Bound Granular Materials: Theoretical Background

2002 ◽  
Author(s):  
J. Murali Krishnan ◽  
K. R. Rajagopal
Keyword(s):  
Creep Test ◽  
Asphalt Concrete ◽  
Constitutive Modeling ◽  
Hot Mix Asphalt ◽  
Constitutive Models ◽  
Companion Paper ◽  
Theoretical Background ◽  
Asphalt Mixtures ◽  
Unified Approach ◽  
Multiple Natural Configurations

Different kinds of hot mix asphalt mixtures are used in highway and runway constructions. Each of these mixtures cater to specific needs and differ from each other in the type and percentage of aggregates and asphalt used, and their response can be markedly different. Constitutive models used in the literature do not differentiate between these different kinds of mixtures and use models which treat them as if they are one and the same. In this study, we propose constitutive models for two different kinds of hot mix asphalt, viz., asphalt concrete and sand asphalt. We use a framework for materials that possess multiple natural configurations for deriving the constitutive equations. While asphalt concrete is modeled as a two constituent mixture, sand asphalt is modeled as a single constituent mixture due to the peculiarity in its makeup. In this study, we present a unified approach for deriving models for these different kind of mixtures. In a companion paper, we compare the predictions of the model for a compressive creep test with available experimental results.

scholarly journals Investigation of the Effect of Induction Heating on Asphalt Binder Aging in Steel Fibers Modified Asphalt Concrete

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1067 ◽  
Author(s):  
Hechuan Li ◽  
Jianying Yu ◽  
Shaopeng Wu ◽  
Quantao Liu ◽  
Yuanyuan Li ◽  
...  
Keyword(s):  
Induction Heating ◽  
Asphalt Concrete ◽  
Asphalt Binder ◽  
Steel Fibers ◽  
Asphalt Binders ◽  
Carbonyl Index ◽  
Modified Asphalt ◽  
Concrete Damage ◽  
The Difference ◽  
Binder Aging

Induction heating is a valuable technology to repair asphalt concrete damage inside. However, in the process of induction heating, induced particles will release a large amount of heat to act on asphalt binder in a short time. The purpose of this paper was to study the effect of induction heating on asphalt binder aging in steel fibers modified asphalt concrete. The experiments were divided into two parts: induction heating of Dramix steel fibers coated with asphalt binder (DA) and steel wool fibers modified asphalt concrete. After induction heating, the asphalt binders in the samples were extracted for testing aging indices with Fourier Transform Infrared (FTIR), Dynamic Shear Rheometer (DSR), and Four-Components Analysis (FCA) tests. The aging of asphalt binder was analyzed identifying the change of chemical structure, the diversification of rheological properties, and the difference of component. The experiments showed that the binder inside asphalt concrete began aging during induction heating due to thermal oxygen reaction and volatilization of light components. However, there was no peak value of the carbonyl index after induction heating of ten cycles, and the carbonyl index of DA was equivalent to that of binder in asphalt concrete after three induction heating cycles, which indicated the relatively closed environment inside asphalt concrete can inhibit the occurrence of the aging reaction.

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