Fatigue Damage Analysis Research Articles

Fatigue damage monitoring and analysis of aged asphalt concrete using acoustic emission technique

This paper presents an Acoustic Emission characterisation of the damage behaviour of asphalt concrete subjected to bending fatigue loading. An experimental campaign is carried out on an old asphalt concrete extracted from an in-service highway pavement, built-in 2001. Tests were performed in strain-controlled mode with an amplitude of 175 µstrain, a frequency of 25 Hz, and at 10°C. Failure criteria based on modulus decrease are analysed to determine the fatigue lifespan. Acoustic emission measurements are used to investigate the damage and failure processes. A network of eight piezoelectric sensors was used to acquire the acoustic signals. Therefore, different fatigue stages are identified based on the temporal evolution of acoustic activity. Hence, the event’s spatial location is presented to show the crack path propagation. The results show that sensors located at the bottom of the sample register more acoustic activity. The locations of acoustic events were in good agreement with the mechanical background calculations.

Evaluation of spectral methods for long term fatigue damage analysis of synthetic fibre mooring ropes based on experimental data

Two compact hybrid mooring concepts adopting top synthetic fibre rope (polyester or nylon), submerged buoy and bottom chain design are studied. In addition to these two mooring concepts, another concept that adds two clumped weights on the bottom segment of the hybrid mooring with nylon rope is also studied. The mooring tension RAOs are obtained from seventeen regular wave tests to a point absorber moored by these three mooring configurations. Five spectral methods, including Dirlik, Tovo-Benasciutti, Zhao–Baker, Wirsching–Light and α0.75 methods are applied to study mooring fatigue damage. Five irregular wave model tests are performed, the rainflow counting method in conjunction with measured mooring tension time series is applied to calculate mooring fatigue damage, and the values are used to calibrate the spectral methods. The spectral methods are then used to evaluate the long term fatigue damage of these three moorings in the application in the west Portuguese coast. The rainflow counting method is applied to the mooring tension series generated from estimated mooring tension spectra to analysis fatigue damage, and the results are acted as the reference values for checking the accuracy of spectral methods. Then the performance of spectral methods is evaluated based on the Akaike's Information Criterion.

Summary of fatigue durability analysis of whole vehicle

Technical characteristics and development trend of the fatigue durability analysis of the whole vehicle were reviewed in the directions. These existing research results were systematically summarized from the research status, signal acquisition, finite element analysis, load spectrum extraction and fatigue life. Wherein, the strengths and weaknesses of the virtual iteration technology was explained in detail, in which the result evaluation standard was mainly composed of relative damage value; and also the characteristics of fatigue damage theory and analysis method were summarized detailedly; additionally, the practical critical plane method possessed the advantages of the measurable component damage values, but this method still needed to be solved the problems of crack propagation direction. Moreover, according to the existing technology and achievements, reducing model errors and road conditions selection will become the development trends of vehicle fatigue durability technology in the future.

The strain characteristics and corresponding model of rock materials under uniaxial cyclic load/unload compression and their deformation and fatigue damage analysis

The fatigue characteristics of rock materials are usually studied by cyclic load–unload tests, and the deformation and damage development reflect their weakening characteristics. In this paper, according to the mechanical characteristics of rock materials during load/unload cycles, the total strain can be separated into three types, that is, elastic strain, viscoelastic strain, and viscoplastic strain. The elastic strain is linear with stress, and viscoelastic strain exhibits a special behavior after unloading, the viscoplastic strain also displays its own unique features and reflects the damage in rocks. Based on their unique characteristics, we establish elastic, viscoelastic, and viscoplastic submodels, then an elastic-visco-plastic model can be obtained by connecting three submodels in series, which can reflect the development of the law of different strains. In order to verify the reliability of the model, red sandstone samples are selected for cyclic load/unload tests. The results show that the collected strain–time data are well fitted by the model. In addition, the characteristics of strain–time curves imply the deformation and damage development of rocks during load/unload cycles.

An efficient numerical method for meso-scopic fatigue damage analysis of heterogeneous concrete

A numerical method is developed to simulate effectively meso-scopic damage evolution of concrete subjected to cyclic fatigue loading based on considering its heterogeneous material constituents. In the developed method, a fatigue damage evolution gradient controlled procedure is developed to speed up fatigue damage simulation in a reasonable way by using the developed damage model. In the procedure, the block cycle jump strategy is used and the maximal fatigue damage accumulation for each block cyclic loading is controlled to be less than the pre-set value based on the condition of efficiency and precision. In addition, a heterogeneous concrete modeling strategy is developed and used to consider heterogeneous material constituents with lower computational cost, in which material parameters are assumed to obey some kinds of probability distribution such as Gaussian distribution. A representative numerical example supports the effectiveness of the developed numerical method, which illustrates its ability to simulate well fatigue damage evolution of heterogeneous concrete. From simulation results obtained from different finite element models with coarse and fine mesh. We can also find that fatigue analysis results are insensitive to gird mesh by using the developed numerical method.

Vibration Fatigue Damage Analysis of Compensator Reinforced by Wire Cloth with Preload

Vibration Fatigue Damage Analysis of Compensator Reinforced by Wire Cloth with Preload

Evaluating gantry crane-way pavement performance: An inverse approach

Gantry-crane pavements and foundations are significant assets within intermodal facilities. The performance of these pavements, which are subjected to highly-variable loads, is critical to safe operations. Traffic interruptions and costs associated with maintaining and rehabilitating distressed or failed pavements in associated areas are of particular importance. The purpose of this study was to evaluate structural behavior and improve design procedures for gantry crane way pavement used at intermodal facilities by assessing interactions among pavements, subgrades, and operational loading conditions. The performance of the gantry crane pavements and foundations was assessed using a finite-element (FE) model, while pavement structural response to a crane load was measured using strain gages installed in the field. Measuring material properties using in-situ/laboratory tests was not possible in this work due to the limited resources, restricted access to intermodal facilities, and tight schedule of rail freight transport(i.e. tight schedule of cranes). To verify the materials properties and ensure a consistent behavior of the developed FE model with respect to the field measurements, an inverse design approach was implemented. Because of the significant cost of FE simulation, the gradient-based solver used in this study is based on a trust region algorithm. The verified model was used to predict the critical responses of Portland cement concrete (PCC) layer, base course, and subgrade soil. These parameters were then used to conduct a pavement fatigue damage analysis, parametric analyses of material strength and slab geometry were carried out based on Model Code, and resulting fatigue-life recommendations for improved designs were made. The developed FE model along with the inverse approach create a framework that can be used in further health monitoring problems when a specific parameter cannot be directly observed.

Fatigue damage analysis of cement stabilized sub-base during construction period

When cement stabilized gravel materials are used as pavement base and sub-base, irreversible fatigue damage often occurs due to insufficient maintenance days during the construction period and overload of vehicle load. In order to obtain the fatigue damage caused by the construction load on the cement stabilized gravel sub-base, the flexural tensile strength test and the fatigue test are carried out based on Miner theory and ABAQUS software. Under 9 kinds of vehicle load, we analyze both the relationship between the maximum tensile stress of the sub-base layer and the substrate thickness when the substrate thickness is 16, 20, 24, 28, and 32 cm and the relationship between the maximum tensile stress of the sub-base layer and the modulus of the sub-base when the modulus of the subbase is 400, 800, 1 200, 1 600, and 2 000 MPa, respectively. The research results show that with the increase of the thickness of the sub-base layer, the tensile stress of the sub-base decreases gradually, and the maximum reduction rate is 8.8%. With the growth of the sub-base modulus, the bottom tensile stress of the sub-base layer increases gradually, but the growth rate continues to decrease. Relying on the actual engineering project, the fatigue prediction equation of the cement stabilized gravel sub-base can be obtained by using Miner theory to calculate the fatigue damage degree of the subbase caused by different construction loads under different working conditions, which provides guidance for the design and construction of the pavement.

Analysis of probabilistic fatigue damage of mooring system for offshore fish cage considering long-term stochastic wave conditions

ABSTRACT This study deals with the probability distribution of fatigue damage of the mooring system for offshore fish cage considering the uncertainty of long-term wave conditions. A set of numerical simulations for offshore fish cage are performed to predict the fatigue damage of the mooring system. Through a virtual stochastic process model, the probability density function of the long-term fatigue damage of the mooring system is achieved by the generalized probability density evolution method, and the failure probability of the mooring system is predicted. The results demonstrate that the generalized probability density evolution method can effectively provide the fatigue damage distribution from the stochastic point of view. And the calibration of the engineering-based fatigue design factor of the current regulation can be conducted through the fatigue reliability analysis considering the uncertainty of the long-term wave conditions. This study provides a new understanding of the long-term fatigue damage distribution.

Prediction of Fatigue Strength of Extra-Large Container Ships Based on Spectrum Analysis

Wang, J.T.; Jiang, B.C., and Guo, Y.L., 2020. Prediction of fatigue strength of extra-large container ships based on spectrum analysis. In: Al-Tarawneh, O. and Megahed, A. (eds.), Recent Developments of Port, Marine, and Ocean Engineering. Journal of Coastal Research, Special Issue No. 110, pp. 146–149. Coconut Creek (Florida), ISSN 0749-0208.With the rapid development of maritime transportation industry, container ships have quickly become the mainstream ship model due to their advantages of fast shipping speed, high handling efficiency, and low operating costs. At the same time, their large-opening structure has resulted in poor performance in bending strength, torsional strength and other mechanical properties. In order to ensure the structural safety performance of extra-large container ships, it is necessary to conduct an in-depth research on its fatigue damage and strength life. Based on the spectrum analysis, this paper takes the model 8601ETP extra-large container ship as an example, and adopts finite element modeling to obtain distribution range of the alternating stress; it also uses SN curve and linear cumulative damage theory to predict the fatigue damage and strength life of the container ship. The research results show that the fatigue damage of the extra-large container ship at full load is significantly more severe than that at no load; the degree of structural damage at the position of the keyhole is greater than that at the position of the hatch corner, so it is the hotspot for the fatigue damage analysis and strength check of extra-large container ships. This study provides certain theoretical reference and data support for improving the safety performance of large container ships, and it also enriches the theory of fatigue strength evaluation.

Multi-scale damage mechanics method for predicting fatigue life of plain-braided C/SiC composites

In order to predict fatigue life of plain-braided C/SiC composites, a fiber bundle unit cell model and a braided unit cell model were established based on the meso-structure of two-dimensional braided C/SiC composites. First, different failure modes were considered and a progressive damage model of the two-dimensional braided C/SiC composite was established. Based on the results obtained by on-axis uniaxial tensile tests, the damage process of the unit cell model during off-axis tension was analyzed. In fatigue damage analysis, the uniaxial tensile fatigue experimental data of the plain-braided C/SiC composite standard specimen were used to fit the fatigue damage evolution equation of the fiber bundle. The fatigue damage results obtained by the model under uniaxial, biaxial, and shear loading were analyzed and fitted to obtain the equivalent stress equation and anisotropic macro-damage evolution equation. Finally, the life of the plain-braided C/SiC composite was estimated under random loading.

Analysis of fatigue damage of cemented carbide insert during the heavy-duty milling of water chamber head

According to the analysis of the damage morphology of the failure insert in the heavy-duty milling process of the water chamber head, fatigue damage is one of the main failure forms of the insert. Fatigue is the evolution process of inserts damage and impact fracture is the ultimate failure forms of inserts fatigue damage. According to the frequency that the insert cuts into and out workpiece, it is determined that insert is subjected to the low cycle load characteristic. Based on damage mechanics, the low cycle fatigue damage model is studied, and the fatigue evolution process of the insert material is numerically described. The damage parameters of cemented carbide material in the model are determined by simulation method. Fatigue simulation is carried out to determine the fatigue damage limit of the insert under cyclic loading, which provides theoretical basis and data foundation for the qualitative and quantitative research on the damage failure process of insert.

Structure and Fatigue Analysis of Semisubmersible Offshore Communication Platform

Xiao, Z., 2020. Structure and fatigue analysis of semisubmersible offshore communication platform. In: Gong, D.; Zhang, M., and Liu, R. (eds.), Advances in Coastal Research: Engineering, Industry, Economy, and Sustainable Development. Journal of Coastal Research, Special Issue No. 106, pp. 506–509. Coconut Creek (Florida), ISSN 0749-0208.As an important tool and means of marine oil and gas resources, a marine communication platform not only plays an important role in the development of marine high technology in China, but also plays an important role in marine environment monitoring. Therefore, it has become the current research hot spot. This paper first introduces the fatigue damage analysis method of a semisubmersible offshore communication platform, then calculates its structural design and hydrodynamic load, and finally analyzes the structural fatigue and maintenance of the semisubmersible offshore communication platform and gives maintenance advice.

Probabilistic Fatigue Damage Analysis of Long Span Suspension Bridge Due to Wind Induced Buffeting

In order to consider the fluctuating wind load induced fatigue problem of long span suspension bridge, fatigue reliability formula is modified by assuming the fatigue life is accord with the weibull distribution. Based on the accurate bridge buffeting analysis of time history, the stress time history of components of a suspension bridge in east sea China is simulated, and then the fatigue damages and reliabilities are calculated. The results indicate that the main cables and hangers have enough fatigue reliability under the fluctuating wind load, the fatigue failure will not occur; the stiffening girder has larger fatigue damage, under 40 / (m.s-1) mean wind speed action, the girder of mid-support section’s average fatigue life is only 3.103 years, so the girder’s damage under strong wind action should be taken seriously.

Mechanistic-empirical design of fibre reinforced concrete (FRC) pavements using inelastic analysis

Use of fibre reinforced concrete (FRC) for pavements is advocated since the higher crack resistance could lead to lower slab thickness and higher joint spacing. The post-cracking capacity of FRC allows pavements to be designed and analysed considering the response beyond the elastic regime. The current paper presents possible failure patterns in FRC pavement slabs, which are governed by the slab dimensions, loading type and boundary conditions, and the appropriateness of inelastic design methodologies for these failure patterns. Subsequently, a mechanistic-empirical design methodology developed for FRC pavements, based on yield line analysis incorporating fatigue in the moment calculation, is discussed. The proposed design methodology gives specific checks for the different failure patterns and the consequent design strategy to be adopted. The method incorporates material parameters, such as the first crack and post crack flexural strengths, and fatigue correction factors for the evaluation of the moment carrying capacity. Cumulative fatigue damage analysis is also done as a serviceability check. The final design solution satisfies both the inelastic moment capacity requirement and fatigue life required without excessive damage accumulation.

Fatigue tests and damage analyses in modified binders and gap-graded asphalt mixtures with Reacted and Activated Rubber – RAR

Several types of modifiers are currently studied, and among them, polymers and ground scrap tyre rubber stand out. The Reacted and Activated Rubber (RAR) is a new type of asphalt rubber that improves the engineering properties of the binder and mixtures. This research studied the rheological behaviour and fatigue performance of binders and gap-graded mixtures with RAR in quantities of 25% and 30%. The rheological characterisation tests were based on the Linear Viscoelasticity Theory and the principle of time-temperature superposition, which made it possible to elaborate the master curves. The fatigue performance was evaluated based on Continuum Damage Theory (CDT), getting the C-D curves and, in classic approach, getting the traditional Whöler curves. The tests on the binders were performed using the Dynamic Shear Rheometer (DSR) and asphalt mixtures tested in the Four-Point Bending (4PB) beam equipment. Modifications in AC 50/70 by RAR resulted in increased in PG, in softening point, rotational viscosity and density, and it reduced the penetration. Lower susceptibility to the frequency and temperature conditions of AB-R30 resulted in high fatigue life due to less sensitivity to the damage parameter. Comparison between the 4PB tests results of RAR produced mixtures tested at 20°C (MAB-R-25 and MAB-R30-1) and a field blend (MAB-RJ-122), expressed that the RAR modified mixtures exhibited superior fatigue life to the field blend, obtaining the MAB-R30-1 mix the highest performance. Tests with different temperatures for the same composition (MAB-R30-1, MAB-R30-2 and MAB-R30-3) and the same temperature for different compositions (MAB-R25 e MAB-R30-1) showed α parameter (CDT approach, C-D curves) with the similar behaviour of the parameter k2 (traditional approach, Whöler curves). Analysing the results, considering the research conditions (base binder, temperatures, tests, and methodologies performed) binder and mixture modifications using 30% RAR, proved to be more satisfactory.

Cyclic behavior and strain energy-based fatigue damage analysis of mooring chains high strength steel

This study investigates the low-cycle fatigue behavior of mooring chains high-strength steel grade R4 under different strain amplitudes and strain ratios at room temperature. A fatigue test program has been carried out on small low cycle fatigue specimens cut from large mooring chains. The experimental results characterize the cyclic stress-strain relationship, the mean stress relaxation behavior, and the cyclic plasticity parameters of the material. Strain energy density is correlated with fatigue life through a simple power-law expression and very well represented by Basquin-Coffin-Mansion relationship. Further, a non-linear elastic-plastic material model is calibrated to the experimental stress-strain curves and used for the estimation of energy dissipation in the specimens under applied cyclic loads. The predicted fatigue life using the calibrated material parameters demonstrates a close agreement with the experimental fatigue life. Numerical simulations are carried out to analyze local plastic straining and assess crack initiation at the pit site of corroded mooring chains considering the multiaxial stress state. An energy-based approach is employed to estimate the number of cycles needed for a crack to initiate from an existing corrosion pit.

Fatigue Damage Evaluation of Pile‐Supported Bridges under Stochastic Ice Loads

The Bohai Sea is the sea area with the worst ice condition in China, and the ice loads significantly threaten the safety of structures in the sea. The intense vibrations of the pile‐supported bridge under stochastic ice loads will increase the fatigue damage of a bridge structure and reduce the fatigue life of a bridge structure. In the present study, a comprehensive analysis model is presented to study fatigue damage for pile‐supported bridges under ice loads in Bohai Sea. On the basis of measured statistical data of ice parameters and stochastic ice loads spectrum of Bohai Sea, the time histories of the stochastic ice loads of Bohai Sea are simulated. Fatigue damage analysis is carried out in time domain utilizing the finite element method considering soil and bridge structure interaction. The effect of soil conditions and water depth on the cumulative fatigue damage of the pile‐supported bridges is studied. Numerical results indicate that in comparison with stiff soil conditions, pile‐supported bridges in soft oil conditions can increase the cumulative fatigue damage substantially; pile‐supported bridges in deep water also can increase the cumulative fatigue damage obviously. The study presented the first danger position of cumulative damage of the pile cross section under stochastic ice loads. The findings of this study can be used to fatigue damage evaluation and bridge construction in the ice‐covered sea area.

Vibration Response and Cumulative Fatigue Damage Analysis of Overlapped Subway Shield Tunnels

AbstractOverlapped subway shield tunnels are subjected to the dynamic impacts caused by running trains and are damaged during their long-term service life. In this paper, the dynamic response and c...

Mesoscale Analysis of Fatigue Damage through Aggregate–Mortar Bond Cracks in Cementitious Composites

AbstractA micromechanics-based model is developed to study the fatigue response of cementitious composites. Microcrack growth, which is the predominant mechanism responsible for fatigue damage, is ...