scholarly journals A Research on Fatigue Damage Constitutive Equation of Asphalt Mixture

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Yazhen Sun ◽  
Chenze Fang ◽  
Dong Fan ◽  
Jinchang Wang ◽  
Xuezhong Yuan
Keyword(s):  
Fatigue Damage ◽  
Damage Evolution ◽  
Damage Accumulation ◽  
Loading Rate ◽  
Damage Model ◽  
Asphalt Mixture ◽  
Fatigue Tests ◽  
Bending Fatigue ◽  
Three Point Bending ◽  
Three Stages

The laboratory investigations of fatigue damage constitutive equation of asphalt mixture were carried out by three-point bending fatigue tests. The three-point bending fatigue tests were performed at three levels of stress-strength ratio (SSR), temperature, and loading rate. The coupled multifactor (stress-strength ratio, temperature, and loading rate) fatigue life equation was established, which can well predict the fatigue life of the asphalt mixture. Both a damage model and a damage evolution equation have been established based on the E-N curve, which indicate that fatigue damage evolution is nonlinear and consists of three stages. The sensitivity analysis of damage model parameters indicates that each parameter has different effects on the three stages of damage evolution. Based on the researches above, the fatigue damage constitutive equations were finally built based on the σ-ε curves, which consist of two parts: the damage accumulation stage and the fatigue failure stage. The elasticity-power hardening model was used to describe the constitutive relation of damage accumulation stage. The elasticity-power hardening model and the Sidoroff damage model were used to describe the constitutive relation of damage failure stage. The constitutive equations can well characterize the fatigue damage performance of the asphalt mixtures under cyclic loading.

scholarly journals Energy-Based Approach to Predict Fatigue Life of Asphalt Mixture Using Three-Point Bending Fatigue Test

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1696 ◽  
Author(s):  
Yazhen Sun ◽  
Chenze Fang ◽  
Jinchang Wang ◽  
Zuoxin Ma ◽  
Youlin Ye
Keyword(s):  
Fatigue Life ◽  
Mathematical Models ◽  
Strain Energy ◽  
Asphalt Mixture ◽  
Fatigue Tests ◽  
Bending Fatigue ◽  
Three Point Bending ◽  
Average Value ◽  
Bending Fatigue Test ◽  
Fatigue Equation

The three-point bending fatigue tests were carried out in order to accurately predict the fatigue life of an asphalt mixture based on the plateau value (PV) of the dissipated strain energy ratio (DSER). The relations of the dissipated strain energy (DSE) to the stress-strength ratio, temperature and loading rate were studied, and the constructions of the mathematical models of DSE and DSER were completed based on the change laws of the DSE. The relation of the fatigue life to the PV was determined based on the analysis of damage evolution, based on which the fatigue equation was established and used to predict the fatigue life. The results show that the change laws of DSE and DSER can be well described by the proposed mathematical models. The PV is defined as the average value of the DSER in the second stage and the fatigue life decreases in power function with the increase of PV, based on which the fatigue equation of Nf = A(PV)B was established, and the established fatigue equation is very close to that is used in the MEPDG. The fatigue equation can well predict the fatigue life asphalt mixture.

scholarly journals Assessment Model and Virtual Simulation for Fatigue Damage Evolution of Asphalt Mortar and Mixture

2018 ◽  
Vol 2018 ◽  
pp. 1-14
Author(s):  
Danhua Wang ◽  
Xunhao Ding ◽  
Linhao Gu ◽  
Tao Ma
Keyword(s):  
Fatigue Damage ◽  
Damage Evolution ◽  
Damage Model ◽  
Fatigue Tests ◽  
Assessment Model ◽  
Virtual Simulation ◽  
Coarse Aggregates ◽  
Four Point Bending ◽  
Formula Derivation ◽  
Asphalt Mortar

Focused on the fatigue performance of the asphalt mortar, this study proposed an assessment model for fatigue damage evolution based on the continuum mechanics. From the perspective of the material scale rather than the macrostructure, the proposed damage model was set by concentrating on the stress-strain state of a tiny point which could characterize the material performance accurately. By the mechanical formula derivation and based on the four-point bending fatigue tests, the damage evolution law was determined and then the proposed model was verified. Based on the finite element method (FEM), a commercial software named ABAQUS was utilized to develop the random mixtures consisting of coarse aggregates, mortar, and voids. Eventually, combined with the damage model and virtual simulation of bending tests, the factors influencing the fatigue resistance of the whole asphalt mixtures were analyzed further.

scholarly journals Nonlinear Fatigue Damage Model of Asphalt Mixture Based on Dynamic Modulus and Residual Strength Decay

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2236 ◽  
Author(s):  
Hongfu Liu ◽  
Xinyu Yang ◽  
Chengdong Xia ◽  
Jianlong Zheng ◽  
Tuo Huang ◽  
...  
Keyword(s):  
Fatigue Damage ◽  
Residual Strength ◽  
Dynamic Modulus ◽  
Damage Model ◽  
Asphalt Mixture ◽  
Coupled Model ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Damage State ◽  
The Relationship

In order to describe the fatigue damage state of asphalt mixture more reasonably, direct tensile tests of the fatigue and the residual strength under stress levels of 1.00 MPa, 0.50 MPa and 0.25 MPa with five parallel tests were carried out. The trabecular specimens of AC-13C asphalt mixture (25 cm × 5 cm × 5 cm) were manufactured with Styrene-Butadiene-Styrene (SBS) modified asphalt, aggregate basalt and limestone mineral filler. The optimum asphalt-aggregate ratio was 5.2%. The dynamic modulus decay and the residual strength decay were termed as the damage variables to evaluate the fatigue damage process of asphalt mixtures, respectively. Based on the test results, the decay patterns of the dynamic modulus and the residual strength during fatigue tests under different stress states were revealed, and the model and the parameters of fatigue damage according to the corresponding decay patterns were obtained. Then, based on the assumption that the residual strength and dynamic modulus depend on the same damage state, the relationship between the two damage definitions was given, and the residual strength-dynamic modulus coupled model was established. The results showed that the residual strength-dynamic modulus coupled model could better describe the fatigue damage evolution law of asphalt mixture, and the parameter of this coupled model could be obtained by less residual strength tests. A modified formula for calculating the damage variables associated with residual strength and dynamic modulus was proposed based on the relationship between two kinds of damage variables.

X-Ray Diffraction Study of Microstructural Changes During Fatigue Damage in Steel Pipelines

2012 ◽  
Author(s):  
Bianca Pinheiro ◽  
Jacky Lesage ◽  
Ilson Pasqualino ◽  
Noureddine Benseddiq ◽  
Edoardo Bemporad
Keyword(s):  
Fatigue Damage ◽  
Fatigue Behavior ◽  
Ion Beam ◽  
Fatigue Tests ◽  
X Ray Diffraction ◽  
Microstructural Changes ◽  
X Ray ◽  
Steel Pipes ◽  
Damage Initiation ◽  
Three Stages

Steel pipes used for oil and gas exploitation undergo the action of cyclic loads that can cause their failure by fatigue. A consistent evaluation of the fatigue behavior should take into account the micromechanisms of fatigue damage initiation, which precede macroscopic cracking and macrocrack propagation. In this work, microstructural changes in terms of variations in microdeformations and residual stresses (macrostresses) are evaluated by X-ray diffraction in real time during alternating bending fatigue tests performed on samples taken from an API 5L X60 grade steel pipe. Three stages of microstructural changes are detected. It is found that their amplitudes and durations are proportional to the level of alternating stress applied. Changes in density and distribution of dislocations are observed by transmission electron microscopy combined with the technique of focused ion beam. To understand the role of the initial dislocation structure, fatigue tests on annealed samples are performed under the same test conditions. Again, three stages of changes are observed, but with an increase in microdeformations during the first stage instead of a decrease as found for as-machined samples, suggesting the influence of the initial state of the dislocation network. The results obtained are very encouraging for the consideration of microstructural evolutions in the development of an indicator of fatigue damage initiation in steel pipes.

Applying a Stepwise Load for Calculation of the S-N Curve for Trabecular Bone Based on the Linear Hypothesis for Fatigue Damage Accumulation

2012 ◽  
Vol 726 ◽  
pp. 39-42 ◽  
Author(s):  
Tomasz Topoliński ◽  
Artur Cichański ◽  
Adam Mazurkiewicz ◽  
Krzysztof Nowicki
Keyword(s):  
Trabecular Bone ◽  
Fatigue Damage ◽  
Damage Accumulation ◽  
Applied Load ◽  
Fatigue Tests ◽  
Bone Sample ◽  
Linear Hypothesis ◽  
Fatigue Damage Accumulation

In this work were presented calculated fatigue curves based on fatigue tests of trabecular bone under stepwise load with the application of a linear hypothesis accumulation of fatigue damage. The investigation was performed on 61 cylindrical bone samples obtained from the neck of different femur heads. The bone sample fatigue tests were carried out under compression with stepwise increases of the applied load. The fatigue calculation assumed the Palmgren-Miner (P-M) linear hypothesis accumulation of fatigue damage and the associated modified formulae. The obtained mean fatigue curves were based on the modified stress σ/E0 (E0 – initial stiffnes) for the assumed rule-determined slope or y-intercept. The highest agreement with the literature was obtained for Σn/N=10.

Mechanical Characterizations of Saxidomus purpuratus Shells

2010 ◽  
Vol 434-435 ◽  
pp. 601-604 ◽  
Author(s):  
W. Yang ◽  
Y. Jiang ◽  
G.P. Zhang ◽  
Y.S. Chao ◽  
Xiao Wu Li
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Bending Strength ◽  
Target Material ◽  
Organic Matrix ◽  
Fatigue Tests ◽  
Bending Fatigue ◽  
Three Point Bending ◽  
Saxidomus Purpuratus ◽  
Scanning Electron

A sort of biological shells (Saxidomus purpuratus), which belongs to Bivalve, was selected as the target material, and hardness and dynamic three point bending fatigue tests were conducted to examine its mechanical properties. Microhardness measurements showed that the inner layer is the hardest. The indentation on the specimen with a lower bending strength was damaged more seriously by the same load. Three point bending fatigue tests demonstrated that this kind of the shells with a special structure comprising mineral and organic matrix can experience the repeated loads instead of immediate breaking. The fatigue results on a single shell investigated here indicated that the fatigue strength is usually less than the static bending strength. Most of the fatigue lives of the specimens are less than 2105 cycles. In addition, fatigue fracture surfaces are observed by scanning electron microscopy.

Analysis on High Cycle Fatigue Properties and Fatigue Damage Evolution of TC25 Titanium Alloy

2016 ◽  
Vol 697 ◽  
pp. 658-663
Author(s):  
Rong Guo Zhao ◽  
Ya Feng Liu ◽  
Yong Zhou Jiang ◽  
Xi Yan Luo ◽  
Qi Bang Li ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Fatigue Life ◽  
Strain Hardening ◽  
Fatigue Damage ◽  
Damage Evolution ◽  
High Cycle Fatigue ◽  
Damage Model ◽  
Fatigue Properties ◽  
Test Machine ◽  
Cycle Fatigue

The high cycle fatigue tests for smooth specimens of TC25 titanium alloy under different stress ratios are carried out on a MTS 809 Material Test Machine at a given maximum stress level of 917MPa at ambient temperature, the high cycle fatigue lifetimes for such alloy are measured, and the effects of stress amplitude and mean stress on high cycle fatigue life are analyzed. The initial resistance is measured at the two ends of smooth specimen of TC25 titanium alloy, every a certain cycles, the fatigue test is interrupted, and the current resistance values at various fatigue cycles are measured. The ratio of resistance change is adopted to characterize the fatigue damage evolution in TC25 titanium alloy, and a modified Chaboche damage model is applied to derive the fatigue damage evolution equation. The results show that the theoretical calculated values agree well with the test data, which indicates that the modified Chaboche damage model can precisely describe the accumulated damage in TC25 titanium alloy at high cycle fatigue under unaxial loading. Finally, the high cycle fatigue lifetimes for TC25 titanium alloy specimens at different strain hardening rates are tested at a given stress ratio of 0.1, the effect of strain hardening on fatigue life is investigated based on a microstructure analysis on TC25 titanium alloy, and an expression between fatigue life and strain hardening rate is derived

scholarly journals A 3D progressive damage model for fatigue analysis of woven fabric composites

2018 ◽  
Author(s):  
DC Pham
Keyword(s):  
Fatigue Damage ◽  
Test Data ◽  
Damage Accumulation ◽  
Damage Model ◽  
Peak Load ◽  
Woven Fabrics ◽  
Woven Fabric ◽  
Stress Criterion ◽  
Damage Initiation ◽  
Fatigue Damage Accumulation

A new 3D damage model is developed to predict the progressive failure and accumulated fatigue damage of woven fabric composite materials. Stress-based failure criteria are used to predict the damage initiation in x-tow, y-tow, and matrix constituent. An S-N based damage accumulation model is implemented to characterize the cycle dependent strength of the x- and y- fiber tows and matrix subjected to axial tension, compression, or in-plane share loading. A curve-fit non-linear shear model is also employed based on the static coupon test data of (+45/-45) woven fabric laminates. A static failure progression module is used to predict the damage and failure at the peak load prior to fatigue cycling. Stiffness degradation, fatigue damage accumulation, and failure mode detection are performed during the fatigue marching process. The developed user-defined material model for Abaqus features: 1) description of initial nonlinear shear before the damage initiation; 2) characterization of failure initiation based on a maximum stress criterion; and 3) performance of fatigue damage accumulation using a phenomenological model based on S-N test data. The predictive capabilities of the developed model are demonstrated using tension-tension fatigue of SYNCOGLAS R420 E-glass woven fabrics.

Fatigue Analysis of the Asphalt Mixture Beam Using Damage Evolution Equations

2010 ◽  
Vol 163-167 ◽  
pp. 3332-3335 ◽  
Author(s):  
Ding Han ◽  
Bing Gen Zhan ◽  
Xiao Ming Huang
Keyword(s):  
Fracture Toughness ◽  
Damage Evolution ◽  
Life Prediction ◽  
Evolution Equations ◽  
Asphalt Mixture ◽  
Fatigue Tests ◽  
Toughness Index ◽  
Residual Fatigue ◽  
Stress Damage ◽  
Fully Coupled

Damage evolution equations of asphalt mixture specimen beams were analyzed using the fracture toughness index and the ultimate tension strain index, respectively. The fracture toughness of the asphalt mixture was calculated by FEM. Damage evolution equations controlled apart by the stress and the strain were given. Their coefficients were back-calculated using partial fatigue tests data. The fully coupled stress-damage method and the fully coupled strain-damage method were used. The life prediction precision of each equation was verified by residual fatigue tests data. The results show that FEM is effective to calculate the fracture toughness of the asphalt mixture. Two damage evolution equations have better life prediction abilities comparing with the S-N equation used usually.

Local Viscoelastic Properties of a Thermoplastic/Carbon Laminate as an Indicator of Fatigue Damage

2014 ◽  
Vol 606 ◽  
pp. 237-240
Author(s):  
Jiří Minster ◽  
Martin Šperl ◽  
Jaroslav Lukeš
Keyword(s):  
Fatigue Damage ◽  
Viscoelastic Properties ◽  
Damage Accumulation ◽  
Mechanical Characteristics ◽  
Young Modulus ◽  
Time Dependent ◽  
Three Point Bending ◽  
Thermoplastic Matrix ◽  
Microindentation Testing ◽  
Cycling Loading

The paper is aimed at an assessment of influence of damage accumulation in a thermoplastic/carbon laminate during a tensile cycling loading on durability, Young modulus and both instant and time-dependent local mechanical characteristics of a thermoplastic matrix, analysed by means of instrumented microindentation. Standard mechanical data from three-point bending are compared with results of the local microindentation testing.

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