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In this paper, the formulation to incorporate the used vibration profile, the stress generated by the product's application, mass, and the resonance frequency is given. After that, based on the vibration output data, the two-parameter Weibull distribution is used to predict the corresponding reliability indices. In the method, the mentioned stress is incorporated as acceleration response ( A r e s ), and by using a dynamic stress factor (σ d y n) . In addition, the Weibull parameters are determined based on the generated maximum and minimum principal vibration stress values. In the paper we show the efficiency of the fitted Weibull distribution to predict the reliability indices, by using its Weibull shape and scale parameters, it is always possible to reproduce the principal vibration stress values. Additionally, from the numerical application, we show how to use the Weibull analysis to determine the reliability index for a desired stress or desired cycle value. Finally, we also present the guidelines to apply the proposed method to any vibration fatigue analysis where the A r e s (used to determine the σ 1 and σ 2 values), and the σ d y n value are both known. [ABSTRACT FROM AUTHOR]

Copyright of Rolling Stock (1002-7602) is the property of Rolling Stock Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Steel–concrete composite box beams are widely used in bridge engineering, which might bear transverse and longitudinal bending moments simultaneously under vehicle loads. To investigate the fatigue performance of joints between the steel girders and the top reinforced concrete (RC) slabs under transverse bending moments, a reduced scale joint between the weathering steel girder with the corrugated steel web (CSW) and the top RC slab was designed and tested under constant amplitude fatigue loads. Test results show that the joint initially cracked in the weld metal connecting the CSW with the bottom girder flange during the fatigue loading process. The initial crack propagated from the longitudinal fold to the adjacent inclined folds after the specimen was subjected to 7.63 × 105 loading cycles and caused the final fatigue failure. Compared with the calculated fatigue lives in the methods recommended by EC3 and AASHTO, the fatigue performance of the details involved in the joint satisfied the demands of fatigue design. Meanwhile, finite element (FE) models of joints with different parameters were established to determine their effect on the stress ranges at the hot spot regions of the joints. Numerical results show that improving the bending radius or the thickness of the CSW helps to reduce the stress ranges in the hot spot regions, which is beneficial to enhance the fatigue resistance of the investigated fatigue details accordingly. [ABSTRACT FROM AUTHOR]

The present work presents a novel approach for semi‐analytic adjoint sensitivity‐based design optimization for nonproportional fatigue damage. In order to apply fatigue damage in sensitivity‐based design optimizations, an essential part is to calculate correct sensitivities. However, this is not straight forward since fatigue damage calculation typically include rainflow counting and critical plane search algorithms. Therefore, no derivatives are directly available for the fatigue damage calculation, only functional values given by numerical computation. In existing literature the considered fatigue damage calculation is simplified until a closed‐form differentiability is satisfied. However, these simplifications are not applicable for industrial examples where accurate fatigue life estimates are required. In the present work numerical differentiation of the fatigue damage values with respect to the stress tensor is applied to calculate semi‐analytical adjoint sensitivities at material points for multiple load cases. The proposed method is verified and demonstrated using different damage parameter types including critical plane analysis. Additionally, different academic and industrial numerical examples are compared to stress and stiffness optimized designs. The fatigue damage optimized designs show improved fatigue damage results for both the specific damage parameter types and when comparing to stress and stiffness optimized designs. Furthermore, it is successfully applied for different design variables (sizing, non‐parametric shape and bead) as well as different optimization formulations using fatigue damage either as objective or constraint. [ABSTRACT FROM AUTHOR]

Under fatigue loading, the stiffness decrease in short-fiber reinforced polymers reflects the gradual degradation of the material. Thus, both measuring and modeling this stiffness is critical to investigate and understand the entire fatigue process. Besides evolving damage, viscoelastic effects within the polymer influence the measured dynamic stiffness. In this paper, we study the influence of a linear viscoelastic material model for the matrix on the obtained dynamic stiffness and extend an elastic multiscale fatigue-damage model to viscoelasticity. Our contribution is two-fold. First, we revisit the complex-valued elastic models known in the literature to predict the asymptotic periodic orbit of a viscoelastic material. For small phase shifts in an isotropic linear viscoelastic material, we show through numerical experiments that a real-valued computation of an "elastic" material is sufficient to approximate the dynamic stiffness of a microstructure with a generalized Maxwell material and equal Poisson's ratios in every element as matrix, reinforced by elastic inclusions. This makes standard solvers applicable to fiber-reinforced thermoplastics. Secondly, we propose a viscoelastic fatigue-damage model for the thermoplastic matrix based on decoupling of the time scales where viscoelastic and fatigue-damage effects manifest. We demonstrate the capability of the multiscale model to predict the dynamic stiffness evolution under fatigue loading of short-fiber reinforced polybutylene terephthalate (PBT) by a validation with experimental results. [ABSTRACT FROM AUTHOR]

The high-resolution X-ray CT was applied to investigate the fatigue damage evolution of asphalt mixtures. The detailed Xray CT images in the centre of the samples were used to characterise the fatigue cracking and air voids increase at different vertical deformations. Air void content and surface area distribution before and after loading were also analysed. The results show that the main failure mode of asphalt mixtures at low temperature is debonding at the interface between aggregates and mastic, which is an adhesive failure. The maximum change of air void content due to fatigue damage often occurs near the middle of the sample. Cracks were observed in and around flat and elongated aggregates and on aggregates with insufficient fracture faces, demonstrating the effects of aggregate angularity and shape on fatigue cracking. The microcracks develop continuously throughout the entire fatigue process. [ABSTRACT FROM AUTHOR]

Indentation tests were used for early detection of deformation-induced damage of Inconel 718. Damage was produced in a controlled manner using specially designed specimens with a variable width of the gage part. Static tension, LCF, and HCF tests were performed to induce material damage. Accumulated plastic strain intensity was used as the reference measure of deformation-induced damage. Detection of damage progress in its early phase was based on the use of strain-hardening cross-effect. Experimentally determined correlation of hardness and indentation work with reference damage parameter was analyzed. The results of our analysis lead to the conclusion that the proposed experimental procedure is useful for the detection of deformation-induced damage in the early stage of the process. [ABSTRACT FROM AUTHOR]

The uneven riverbed, and the impact and scour actions by water flow, make the underwater buried pipeline vulnerable to exposure and suspension, and endanger the pipeline operation safety. To investigate the mechanical properties and failure behaviors of the suspended pipeline section under water impact, according to the failure mechanism of the pipeline, the statics and dynamics analyses of the pipeline were carried out, and the graded safety evaluation technique for the buried pipeline with suspended sections was presented. First, a “static strength safety evaluation under static loads” (level 1) was conducted according to the mechanical features and stress states of the pipeline’s suspended section. Second, a “resonance safety evaluation under dynamic loads” (level 2) was conducted based on the correlation between the natural vibration frequencies of the suspended pipeline and the vortex emission frequencies of water flow. Finally, the periodical change process of the pipeline’s alternating stress was studied to solve the fatigue damage and fatigue life of the pipeline, and the “ fatigue strength safety evaluation under dynamic loads” (level 3) was performed. Thus, a 3-level safety assessment procedure for pipelines with suspended sections was proposed. The stabilizing measures for pipelines of poor safety were suggested, and through an example, a specific calculation process was provided. The work serves as a theoretical guide for the safety evaluation of the suspended sections of underwater buried pipelines. [ABSTRACT FROM AUTHOR]

In this paper, an aluminum foam sandwich (AFS) was prepared by the rolling composite-powder metallurgy method, and its fatigue properties were studied. It was compared with an AFS made by the adhesive method to study its fatigue properties more directly. In this experiment, the fatigue performance was investigated by studying the microscopic interface, fatigue life, deflection curve, and failure mode. The results show that the fatigue life of an AFS with the rolling composite-powder metallurgy method is much longer than that with the adhesive method. The failure mode of an AFS made by the rolling composite-powder metallurgy method is shear failure, and that of an AFS made by the adhesive method is shear failure and interface debonding. An AFS with the rolling composite-powder metallurgy method has better fatigue properties. This paper also explored the fatigue damage model using the fatigue modulus method, and the polynomial fitting method has a higher fitting degree. [ABSTRACT FROM AUTHOR]

To evaluate the fatigue-creep damage coupling effect of asphalt mixture under different loading frequencies, three tests—tension-compression fatigue, direct tensile fatigue, and static creep—were carried out with haversine cyclic loading at four loading frequencies of 5, 10, 20, and 50 Hz, respectively. In this research, the elastic modulus was selected as a damage variable for evaluation, and the evolution of fatigue damage and creep damage was analyzed by the Chaboche model and the Kachanov model, respectively. Then, based on haversine fatigue stress decomposition, tension-compression fatigue damage, direct tension fatigue damage, and creep damage under four loading frequencies were compared, and the fatigue-creep damage coupling model under those loading frequencies was established. The results indicated that, with the increase in loading frequency, the corresponding damage under the same standardized coordinate decreased, the growth rate of the damage evolution curve decreased, and the damage increased more rapidly when the asphalt mixture was damaged. It was found that the direct tensile fatigue damage of the asphalt mixture under repeated loads was not the direct superposition of pure fatigue and pure creep damage, but a coupling effect of fatigue-creep damage. In the direct tensile fatigue tests, the fatigue-creep damage coupling effect was negative and during the coupling effect the creep effect was more obvious. The model proposed in this result can better characterize the fatigue-creep damage coupling effect and damage evolution process of asphalt mixtures under different loading frequencies. [ABSTRACT FROM AUTHOR]

Benefitting from economic development and technological progress, long-span suspension bridges, with their superior span capacity and good economy, have been built in large numbers in recent decades. However, the excessive cumulative longitudinal displacement at the girder ends in the process of bridge operation leads to the degradation of, and fatigue damage to, the connecting components. This study aims to solve the problem with an effective parallel damping scheme of friction dampers and viscous dampers. Firstly, the phenomenon that quasi-static longitudinal displacement accounts for the majority of cumulative displacement is confirmed by the decomposition of measured displacement data at the girder end, which is caused by the asymmetric geometric deformation of the main cable induced by the moving vertical loads of a long-span suspension bridge. An efficient control performance analysis method is proposed based on the formation mechanism of the quasi-static longitudinal displacement. Secondly, the friction damper with a continuous damping model is employed to achieve an effective control performance with respect to the quasi-static longitudinal displacement. Thirdly, in order to realize the target of operational and seismic dual control, a parallel scheme of friction dampers and viscous dampers is proposed, aiming to reduce the cumulative value in the operational state, and maximum value in the seismic state, for longitudinal displacement at the girder ends of a long-span suspension bridge. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A constitutive model, which reflects the non-linear response association between microstructural motion and thermodynamic entropy production, is improved in this study. Two critical stress amplitudes associated with two microstructural movement mechanisms are considered in the improved constitutive model. The determination procedures for the parameters of the presented model are developed. Entropy generation data from three materials computed by two calculation methodologies, collected from the experiment and literature, are used to validate the improved model. Subsequently, a rapid fatigue life estimation method is proposed by using the accumulated entropy corresponding to fatigue damage, i.e. FFE, related to irreversible inelastic microstructural motion. Fatigue tests of welded joints fabricated by Q310NQL2 and Q345NQR2 steels, Q235 steel specimens, as well as experimental data, stainless steel specimens, collected from the literature, are employed to determine the values of the parameters of the developed model. The model is then used to forecast the S–N curve of butt joints with a 50% survival probability, and on this basis, the S–N curve with a certain confidence level is well estimated by the improved statistical method. This enhanced model may offer a fast forecast of the P–S–N curve at a certain confidence level within a limited set of tested data ranges. • An improved model is constructed to explain the response relationship between microstructural motion and entropy production. • The determination method for the coefficients of the improved model is proposed. • A rapid fatigue life prediction model is derived based on the improved model. • A fast estimation method of the P–S–N curve at a given confidence level is proposed. [ABSTRACT FROM AUTHOR]

ObjectiveIn order to improve the calculation accuracy of the influence of slamming load on ship fatigue damage, and evaluate ship fatigue life more effectively, a direct calculation method of ship fatigue damage which accounts for slamming load is proposed. MethodsFirst, the time domain calculation of nonlinear load is combined with the spectral analysis method of linear frequency domain, and the stress time history of the ship in a short-term sea state is obtained based on beam theory. Second, the damage of the check points is calculated using the rain flow counting method and S-N curve, the contribution and influence coefficients of nonlinear slamming load on fatigue damage are calculated with reference to the CCS guidelines, and the corresponding stress response transfer function is corrected by combining the spectral analysis method. Finally, the stress spectrum is calculated and fatigue damage accounting for nonlinear slamming is obtained. ResultsThe results show that compared with traditional spectral analysis method, it is found that the ship fatigue damage obtained by the direct calculation method accounting for slamming load is about 10%–50%. ConclusionThe proposed method can improve the accuracy of load calculation when evaluating the fatigue strength of ships sailing in harsh sea states.

A ballastless slab track, which is commonly used in the track structures of heavy-haul railway tunnels, was analysed based on field measurement data of the Fuyingzi Tunnel on the Zhangtang Railway. In accordance with the measured data, the dynamic load thresholds and distributions on the surface and bottom of the ballastless slab track were investigated. A fatigue damage analysis of the ballastless slab track was performed based on the dynamic load time–history curve. The results show that the ballastless slab track can accomplish train load attenuation and reduce the dynamic load from heavy-haul trains by 47.22% from the surface to the bottom. In addition, the distribution at the bottom of the ballastless slab track exhibited a triangular shape, and the dynamic load threshold at the line centre accounted for 78.67% of that at the track position. Meanwhile, the distribution at the surface was saddle-shaped; the dynamic load threshold at the track position accounted for 79.55% of that at the line centre position. The fatigue damage of the ballastless slab track was analysed effectively by combining the measured data and the linear fatigue damage theory. Moreover, the accuracy of the calculation results was verified based on the measured dynamic stress of the ballastless slab track structure. The dynamic action of the train load led to more-concentrated damage to the track bed, and the damage occurred earlier than that in the ordinary line. The axle load was the primary influencing factor of the track bed fatigue damage, and the damage mainly occurred in the track position. These results provide a theoretical basis for performing stress analysis and designing parameters for ballastless slab tracks in heavy-haul railway tunnels.

• Bending failure behaviors of sandwich panels under static and fatigue loadings were studied. • A bending fatigue fixture minimized longitudinal forces, enabling a negative load ratio. • A stiffness−degradation−based fatigue model depicted the entire failure process. • ·Differential evolution optimized model, aligned with experiments. Composite sandwich panels present a variety of damage modes due to their diverse components and variable structural parameters. This work conducted three-point bending static and fatigue tests on composite sandwich panels using specially designed fixtures to investigate their bending-shear characteristics and failure behaviors. The effects of core orientations, i.e., L -direction and W-direction, on the static strength, fatigue life, and fatigue crack initiation and propagation were compared. A stiffness-degradation-based fatigue damage model was constructed for the sandwich panels to describe the entire failure process from core cracking to core/plates debonding, achieving accurate modeling under the full load ratios. A differential evolution algorithm incorporating a penalty function was employed to optimize the model parameters under varying stresses. It was found that the designed fixture enables bi-directional fatigue loading and effectively avoids additional axial forces. Fatigue damage in sandwich panels resembles static but spans a wider area. While damage modes are similar in W-direction and L -direction, L -direction cores have higher stiffness and strength, and lower fatigue resistance in W-direction. Furthermore, the proposed fatigue damage model demonstrates excellent agreement with experimental results, achieving R2 = 0.968. [ABSTRACT FROM AUTHOR]

• A mathematical model of tube bundles subjected to two-phase cross-flow is developed. • The nonlinear dynamics of tubes considering the effects of two-phase cross-flow were investigated. • The relationships between fatigue damage and collision behavior are obtained. In this study, a mathematical model was developed to analyze the vibration of a simply supported tube with clearance restriction in an otherwise rigid rotated triangular tube array subjected to two-phase flow. The study evaluated the fatigue damage and collision behavior of the tube bundles system. The numerical results showed that the reduced velocity significantly affects the dominant frequency, collision frequency, and stable equilibrium position of the system. This suggests that the nonlinear dynamic characteristics of the simply supported tube with clearance restriction play a crucial role in determining fatigue damage. [ABSTRACT FROM AUTHOR]

The problem of vibration-based progressive fatigue damage detection and Fatigue State (FS) determination for thermoplastic coupons is experimentally addressed under significant population and experimental uncertainty. The study involves 13 coupons subjected to tension–tension fatigue testing with interruptions at 10,000-cycle intervals. Utilizing non-parametric random vibration analysis and a robust, uncertainty-tolerant methodology, the research employs Multiple Model Representations of uncertain dynamics through parametric ARMA(AutoRegressive-Moving Average)-type random vibration response modeling. Results, validated by ultrasonic C-Scan testing, reveal (a) the significance of uncertainties, (b) a resonant structural frequency indicating fatigue accumulation, (c) remarkable detection performance, achieving 100 % accuracy even at 10,000 cycles, and (d) FS determination with over 80 % accuracy across all coupons. This study offers promising avenues for automated fatigue damage detection and FS determination in thermoplastic structures, eliminating the need to interrupt their operational cycles. [ABSTRACT FROM AUTHOR]

As the scale of wind farms continues to expand, the impact of the wake on the power generation and load of wind turbines is becoming increasingly prominent. This study delves into the wake characteristics, power generation, load, and fatigue behavior of an ideal layout wind farm using a dynamic wake meandering model, accounting for diverse spacing configurations, inflow conditions, and yaw angles. The findings reveal that increasing the axial spacing facilitates superior wake recovery, promoting a more evenly distributed load and reducing fatigue damage throughout the wind farm. Moreover, higher inflow wind speed or turbulence intensity exacerbates fatigue damage, especially at elevated wind, where the damage accumulates exponentially. Under yaw conditions, the wake deviates, reducing its adverse impact on downstream turbines and subsequently boosting the overall power generation of the wind farm. However, this deflection simultaneously introduces intricate and detrimental effects on the fatigue load. Notably, optimal yaw achieves a 7.9 % improvement in power generation, also resulting in the most significant fatigue damage at the blade root and tower base. This study provides theoretical and technical underpinnings for the layout optimization and control strategies of wind farms or wind farm clusters. [ABSTRACT FROM AUTHOR]

Ship hulls advancing in level ice are exposed to considerable cyclic ice loadings, which might cause fatigue damage, threatening the structural integrity and endangering the crews' lives. Ice-induced fatigue problem is of significance to ice-going ships. In this paper, a fatigue analysis for ship structures in level ice is performed based on a dedicated 6-degree-of-freedom (6-DOF) numerical model of ice-ship interaction, founded on a circumferential crack assumption. The numerical procedure considers the time-varying instantaneous waterline and the couplings between ship motions and external forces. The local ice loads used for fatigue assessment can be obtained from numerical simulations, and the random load peaks are represented by Weibull distribution. A case study of fatigue calculation for designated transverse frames is carried out, of which the applied stress is converted from ice loads by means of structural beam theory. Eventually, according to a proper S-N curve, the fatigue damages are evaluated on the basis of Palmgren–Miner rule, respectively under the operational scenarios of laterally symmetrical and asymmetrical initial ice edges. • A fatigue calculation procedure based on numerical simulations is proposed for ship hulls operating in level ice. • A modification of coordinate transformation is made to the previous 6-DOF model. • The global and local ice loads are predicted and validated, and the statistical analyses of the numerical data are made. • The fatigue damages for both laterally symmetrical and asymmetrical ice edges are evaluated and discussed. [ABSTRACT FROM AUTHOR]

This study proposes a novel physics-guided metamodel to predict vertical bending-induced fatigue damage in a 2800TEU container vessel navigating the North Atlantic, based on data from the vessel's hull monitoring system. The metamodel combines two XGBoost-based base learners: a black-box model utilizing ship heave and pitch motion measurements, and a gray-box model using spectral moments from numerical analysis. Predictions from both models are refined through a meta learner Gaussian process regression to enhance accuracy. The metamodel was evaluated against black-box and gray-box models across various training data volumes. The proposed model adapts to varying data volumes, from months to over 2 years, effectively integrating the strengths of both base learners to provide reliable predictions in both seen and unseen scenarios. The model consistently demonstrated superior performance, enhancing fatigue damage accumulation accuracy by up to 35% over traditional machine learning methods. This advancement can aid the maritime industry in effectively monitoring ship fatigue and implementing predictive maintenance strategies, marking a significant step forward in applying data-driven techniques in shipping. • A novel physics-guided metamodel is proposed for fatigue damage monitoring in container vessels. • The metamodel integrates a purely data-driven BBM with a physics-guided GBM. • The proposed metamodel effectively adapts to varying available data volumes. • The proposed metamodel demonstrated up to 35% accuracy increase in fatigue damage accumulation than BBM. [ABSTRACT FROM AUTHOR]

This review provides a comprehensive analysis of the fatigue behaviour of cementitious materials, focusing on the characterisation, modelling, and mechanisms underlying their fatigue properties. It begins with a detailed exploration of how material composition and loading conditions influence fatigue performance, along with the underlying mechanisms that govern fatigue fracture processes. The review also synthesises current advanced experimental methods for characterising fatigue damage evolution, highlighting significant achievements and methodological innovations. It also examines theoretical approaches, summarising prominent models and emerging theories that deepen the understanding of fatigue behaviour in cementitious materials. Meanwhile, the paper reviews computational techniques based on fracture mechanics, damage mechanics, statistical analysis, machine learning algorithms and multiscale modelling, assessing their potential to improve the accuracy of fatigue predictions. Lastly, the review identifies crucial research gaps and outlines future directions, particularly in understanding fatigue-related coupling mechanisms to enhance the fatigue resistance and durability of cementitious materials. • This review paper systematically investigates the fatigue behaviour of cementitious materials, focusing on the characterisation, modelling and mechanisms of their fatigue properties. • Advanced experimental methods for characterising fatigue damage evolution are reviewed, highlighting significant achievements and methodological improvements. • The review identifies critical research gaps and proposes future directions aimed at improving the fatigue resistance of cementitious materials. [ABSTRACT FROM AUTHOR]

This study aims to investigate the nonlinear rheological response and fatigue performance of aged composited high viscosity modifier asphalt (CHVMA) under large strain amplitude condition. Firstly, the chemical composition and micro morphology of four types of CHVMA under different aging states were estimated through Fourier infrared spectroscopy (FTIR) and Fluorescence microscope (FM). Secondly, the nonlinear rheological-viscoelastic properties were analyzed based on the Lissajous curve and Fourier transform rheology (FTR) methods, respectively. Finally, the fatigue performance was evaluated through Linear amplitude sweep (LAS) tests. The results demonstrate that CHVMA with sufficient integration and resilient cross-linked structure could withstand the erosion and weakening effect of thermal and oxidative aging. The degradation of polymer modifier weakens the thermal stability while the oxidation of matrix asphalt phase strengthens the brittle damage resistance of CHVMA. With the continuous development of aging process, the Lissajous curves approach distorted ellipse, which would result in the earlier occurrence of critical damage failure. Besides, the nonlinear stress response characteristics of CHVMA are dependent on the dominant effect of modifier reinforcement or asphalt phase hardening erosion effect at different aging stage. Moreover, there exists obvious correlation between the fatigue performance and PI value of CHVMA, the higher PI values indicate greater fatigue life and lower deformation extent. In general, CHVMA-A has the best anti-aging ability, bonding capacity, nonlinear vehicle resistance and fatigue performance. • CHVMA with excellent cross-linked structure could withstand the erosion effect of aging. • Thermal and oxidative aging exhibit different weakening effect on CHVMA. • Nonlinear property depends on the dominant of modifier reinforcement or asphalt phase hardening erosion effect. • The fatigue performance of CHVMA is closely related to the effective polymer content in matrix asphalt phase. [ABSTRACT FROM AUTHOR]

• Efficient method for stress recovery using link flexibility for fatigue estimation. • New method estimates fatigue damage without simulating large number of cycles. • Analysis of contact forces, wear, and fatigue damage considering clearances. • Clearances greatly increase fatigue damage and make wear change its linear trend. • Wear affects fatigue damage distribution and can change critical zone location. Clearances and wear are present in almost all mechanisms. Their presence leads to degradation of the dynamic behavior of the mechanisms, involving the appearance of vibrations, noise, high forces at the joints, and an increasing fatigue damage. To simulate this problem, a flexible multibody model is proposed to efficiently determine the stresses involved, thus avoiding the high computational costs associated with the finite element method. The model considers the mechanical interactions and material degradation processes that affect the stress state, providing a more accurate estimation of fatigue damage. In this work, a methodology is proposed for estimating fatigue damage in mechanisms with clearance joints without the need of simulating all the cycles actually performed. The proposed methodology is applied to a planar slider-crank mechanism in which the fatigue undergone by the connecting rod is considered. Results show that clearances strongly affect the fatigue damage of the links. Furthermore, the effect of wear changes the linear behaviour of fatigue damage with respect to the number of cycles, generally producing a higher damage, and changing the critical damage zones in some cases. [ABSTRACT FROM AUTHOR]

• Fatigue damage experiments on coal are conducted by applying multi step and cyclic loads. • AE is utilized to characterize the time–space-energy evolution and fracturing nature of microcracks. • Power-law scaling relation of acoustic activity near the catastrophic failure of coal is investigated. • Clustering fractal structure in temporal, spatial and energic domains of microcracks are analyzed. During the deep mining process, coal mass encounter intricate geo-environmental stress, such as periodic weighting loading and repeatedly excavation unloading–reloading cycles, which weakens coal's mechanical integrity and predisposing it to severe coalburst accidents. To investigate the microcracking damage mechanisms and predictive indicators in coal failure under in-situ stress analogs, the multistage step and cyclic loading experiments are conducted on cubic coal specimens. Acoustic emission (AE) technology is employed to track the spatiotemporal-energy evolution of stress-induced damages and discern the microcracking nature through AF/RA assessments, and the power-law scaling relation of AE activity near the catastrophic failure of coal is investigated. Then the clustering fractal structures of microcracking events in the stressed coal are quantified across temporal, spatial and energetic domains, utilizing correlation integral methodologies and b-value derivations from magnitude-frequency relation. Findings indicate that irrespective of the loading mode (step or cyclic), escalating stress triggers an intensification of irreversible fatigue deformations. AE characteristic parameters manifest a gradual rise, culminating in a precipitous peak coinciding with the critical failure point. This escalation adheres to a power-law correlation between AE occurrence frequency and time to failure, observable in the immediate pre-failure seconds, reflecting a universal attribute of coal fracture. Prior to ultimate failure, a marked increase in shear microcracks is discernible, despite tensile-dominated cracks (constituting about 80 % of total microcracks) prevailing as inferred from the variation of AF/RA values, aligning with an inferred "X" conjugate wedge splitting pattern from AE event density and energy mapping. The microcracking events in the loaded coal exhibit a clustering fractal structure that spans across temporal, spatial, and energetic (or magnitude) domains. Notably, the temporal fractal dimension, spatial fractal dimension, and b-value (i.e., a parameter characterized the energetic fractal dimension) all follow a parallel decrease pattern as the loading stress escalates, with a pronounced diminution becoming especially evident as the specimen approaches its catastrophic failure threshold. This insight offers fresh perspectives for predicting rock/coal dynamic disasters, emphasizing the necessity of concurrently monitoring the shift from diffuse microcracking to localized failure across time, space and energy domains. These research findings contribute to a deeper understanding of microcracking damage evolution and failure mechanism of loaded coal, and provide a foundational basis for early warning of rock failure such as the coalburst disasters. [ABSTRACT FROM AUTHOR]

In this paper, a fatigue-creep damage model that can take into account the interaction of fatigue and creep damage is proposed under high temperature cyclic loading. In the proposed model, the effect of temperature on creep damage, the variation of creep damage under different high temperature cyclic loading conditions, and fatigue-creep interaction damage are considered. In addition, in order to accurately describe the creep behavior of unidirectional laminates with different orientations, the damage mechanism of unidirectional laminates was also analyzed. The creep and fatigue test results at different temperatures showed that the proposed creep rupture time model and the fatigue-creep damage model considering the damage mechanisms can successfully predict the creep and fatigue lives of unidirectional laminates at high temperature, and the prediction results are in good agreement with the experimental data. [Display omitted] [ABSTRACT FROM AUTHOR]

Lumbar disc herniation is usually caused by the accumulation of long-term mechanical loads and sudden overload damage. Therefore, this study aims to illustrate how fatigue failure in lumbar spine segments is influenced by both cyclic loading magnitude and pre-existing damage. Eighty-six sheep intervertebral disc samples were divided into four groups to test the fatigue responses in healthy and damaged intervertebral discs. Both before and after fatigue loading, the specimens were performed on loading–unloading tests to analyze the viscoelasticity changes, while the specimens were performed on MRI examination to analyze the geometric and morphological changes. The Stress-Failure curve (SN curve) was examined, while the number of cycles to failure of damaged specimens was much smaller than that of healthy specimens at the same stress level during cyclic loading, and the relationship was approximately linear on a logarithmic scale. In addition, the healthy specimens will not accumulate fatigue failure if the compression force remains below 50% of the ultimate compressive tolerance (UTC). Before and after fatigue loading, the loading–unloading curves do not coincide and show obvious strain-rate-dependent viscoelastic characteristics, while the elastic modulus of the damaged specimen is significantly smaller. For magnetic resonance imaging, morphological changes included the changes of nucleus pulposus (NP) shape and area, while fatigue has a more significant effect on ruptured and herniated disc specimens. The dissipated energy of the intervertebral discs under cyclic loading was then calculated based on viscoelastic constitutive equations, which show that the load and preexisting damage both have significant effects on the dissipation rate. [ABSTRACT FROM AUTHOR]

Fatigue performance tests on concrete specimens were conducted using a three-point equal amplitude loading method. As the number of fatigue loadings increased, microcracks inside the concrete extended and expanded, forming through-cracks that gradually developed into macroscopic, large cracks that rapidly propagated across the entire cross-section. Under different stress levels, the specimens exhibited a relatively stable ultimate residual strain value when fatigue failure occurred, while the maximum strain varied significantly. The development of bending fatigue deformation followed a three-stage pattern. Microscopic testing methods such as SEM electron microscope scanning and mercury intrusion porosimetry (MIP) were employed to analyze the whole process of deterioration and evolution of microcracks and pore structures in fatigue-damaged concrete. Fatigue loading damage resulted in a significant reduction in harmless and less harmful pores, or micropores, inside the concrete, while the proportion of harmful and more harmful pores increased substantially. Macroscopically, this was manifested as further intensification of fatigue performance deterioration. The entire fatigue development pattern is a process of continuous damage accumulation, culminating in instantaneous brittle fatigue fracture at failure. Based on the fundamental theory of continuum damage mechanics, the damage degree D was determined by quantifying the cumulative damage of concrete using residual strain. A fatigue damage evolution equation was derived from theoretical deductions, and a calculation model for the fatigue damage degree of concrete was proposed. [ABSTRACT FROM AUTHOR]

Understanding the fatigue failure mechanisms in concrete is complex and remains an area of ongoing investigation. Material heterogeneity, along with the size effect, plays a significant role in specifying the crack propagation behaviour and fatigue life in case of repetitive loading conditions. In this study, the influence of material heterogeneity on the fatigue behaviour of concrete has been examined. Three different-size beam specimens with varying heterogeneity (aggregate sizes) have been considered to investigate various fracture characteristics under repetitive load conditions. Acoustic emission and digital image correlation techniques have been employed to analyse crack growth behaviour. The results revealed that stiffness degradation and crack propagation rates are faster for the specimens with smaller aggregate sizes compared to the larger aggregate size specimens of the same depth. Moreover, the fatigue life and effective crack length at failure are also higher in the case of larger aggregate sizes compared to smaller ones. Therefore, a heterogeneity-adjusted, analytical model of fatigue crack growth has been proposed. Further, the AE parameters have been utilized to characterize the tensile and shear crack dominance in different stages of fatigue crack propagation. The outcome of this study can be utilized to anticipate the crack propagation behaviour and residual fatigue life for any combination of specimen size and aggregate size. • The present study focuses on fatigue analysis in concrete considering material heterogeneity. • The work considers three different specimen sizes and aggregate sizes to demonstrate its influence. • The research proposes a heterogeneity adjusted fatigue crack growth model for concrete. • AE parameters have been utilized to characterize the tensile and shear crack dominancy. [ABSTRACT FROM AUTHOR]

The heat alternation and bending during the service process of the pipeline structure are the key issues affecting its residual strength. The nonuniform plastic deformation of its cross-section causes nonlinear damage to the structure, which makes it difficult to calculate the residual strength of the overall structure. This study proposed a novel variable-strength material damage model with damage accumulation, which achieved the coupling analysis of structural damage and material fatigue residual strength, making the structural strength of nonlinear damage cross-section computable. Based on this, a theoretical ultimate load model for nonlinear damage cross-section and a finite element analysis model for dynamic material strength with damage accumulation were established. The analysis was conducted on the repeated banding damage to coiled tubing. The results showed that the residual yield strength of nonlinear damaged coiled tubing showed a trend of first rapid decrease and then slow decrease with damage accumulation, and the tensile displacement showed an increasing trend with damage accumulation. The ultimate internal pressure strength of nonlinear damaged structures showed a similar downward trend to the yield strength. The nonlinear damage coupling analysis model proposed in this study has significant practical engineering application value.

Wind turbines and floating platform upsizing are major trends in the current offshore wind development. However, harsh environmental conditions increase the risk of anchor dragging and mooring failure when deploying large offshore floating wind turbines. Therefore, it is necessary to design a mooring system for the specific deployment site. This study aims to perform the mooring system design of a floating offshore wind turbine (FOWT) operated in the South China Sea, which is a combination of the IEA 15 MW wind turbine and UMaine VolturnUS-S floating platform. Hydrodynamic coefficients were calculated based on the potential flow theory, considering the environmental loads in the South China Sea. Additionally, the hydrodynamic coefficients were imported into AQWA to calculate the time-domain mooring tension. The mooring design parameters, such as mooring line length, nominal sizes, and anchor point, were determined using the criterion of anchor uplift, maximum breaking strength, and fatigue life, respectively. The design criterion required that the anchor uplift is not more than the allowable value, the long-term breaking limit of mooring with a 100-year return period should be less than the maximum breaking limit, and the fatigue damage accumulation in 50 years should be safe. The mooring design procedure provides a reference for mooring system design and safe operation of large floating wind turbines in the South China Sea.

In the present work, the results of acoustic nonlinear response of ultrasonic wave propagation when monitoring the progress of damage induced by fatigue on notched C45 carbon steel specimens have been reported. Two ultrasound probes were fixed to the specimens during the tests. The input signal was sinusoidal type, while the corresponding ultrasound response signal was acquired and recorded at each stage of the test by means of a digital oscilloscope. A nonlinear frequency study was performed on the acquired data to evaluate the change in the second- and third-order nonlinearity coefficients of β1 and β2, respectively, on the tested specimens. Ultrasonic results were correlated to plastic strain at the notch tip in the initial phases of fatigue and stiffness degradation. The results showed a significant increase in second-order nonlinearity β1 in the early stages of fatigue life. Subsequently, starting from about 30–40% of the fatigue life, the nonlinearity of β1 increases. Before final failure, from 80 to 85% of fatigue life, the second-order nonlinearity further increases in the crack propagation stages. The nonlinear parameter of the third-order β2 was less sensitive to damage than the parameter β1, showing a rapid increase only starting from approximately 80 to 85% of the fatigue life. The proposed method proved to be valid for detective damage induced by fatigue and to predict the lifetime of metal materials.

Current research on the fatigue properties of degradable zinc alloy stents has not yet considered the issue of the fatigue life changing with material properties during the dynamic degradation process. Therefore, in this paper, we established a fatigue damage algorithm to study the fatigue problem affected by the changing of material properties during the dynamic degradation process of the stent under the action of pulsating cyclic loading. Three models: the dynamic degradation model, the dynamic degradation model under pulsating cyclic loading, and the coupled model of fatigue damage and dynamic degradation, were developed to verify the effect of fatigue damage on stent life. The results show that fatigue damage leads to a deeper degree of inhomogeneous degradation of the stent, which affects the service life of the stent. Fatigue damage is a factor that cannot be ignored. Therefore, when studying the mechanical properties and lifetime of degradable stents, incorporating fatigue damage into the study can help more accurately assess the lifetime of the stents.

A series of creep–fatigue tests of Gr.91 steel were performed at 600 °C. Fatigue life was reduced by tensile strain holding. The minimum life reduction factor was approximately 0.3. The creep–fatigue life could not be estimated properly via the conventional linear summation rule of the fatigue damage and creep damage. Since this material is considered to have a large creep–fatigue interaction, it was proposed that the creep–fatigue life should be estimated using the improved linear summation rule of the fatigue damage, the creep damage and the creep–fatigue interaction damage. In the future, it will be necessary to clarify the creep–fatigue interaction mechanism and define its damage value. On the other hand, a series of creep–fatigue tests for Gr.91 steel welded joints were also performed in the strain range of 0.5% at 600 °C. Again, the fatigue life was shortened by the tensile strain holding. The minimum fatigue life reduction factor was approximately 0.2. All the test pieces fractured in the fine-grained HAZ of the welded joints. The creep–fatigue life could not be estimated properly using the linear summation rule of the fatigue damage and creep damage in the HAZ. One possible reason was thought to be the effects of the elastic follow-up phenomena peculiar to welded joints. The creep strain of the HAZ might increase due to the transfer of the elastic strain from both the base metal and the weld metal, according to the elastic follow-up phenomena during strain holding. In the future, it will be important to quantitatively estimate the effects of the elastic follow-up phenomena.

In this study, we proposed a non-destructive testing and evaluation (NDT&E) method for assessing the micro-scale fatigue damage of carbon-fiber-reinforced plastic (CFRP) structures. The process involves evaluating the thermophysical properties of the material, specifically the thermal diffusivity D and specific heat capacity Cp. To measure these properties, we employed the laser-induced periodic heating method using lock-in thermography, which is suitable for anisotropic composite materials. Our fatigue experiments revealed that the thermal diffusivity D decreased and the specific heat capacity Cp increased with the increase in fatigue cycles. We attribute these trends to the thermal resistance caused by the change in composite microstructure and the degradation of the matrix resin. These findings are discussed in detail, with implications for assessing CFRP structures and potential future research directions.

Offshore environment contains rich and high-quality wind resource with higher wind speed and lower turbulence intensity. In the offshore wind farm, the wake flows of different wind turbines will interact with each other, which will cause the energy loss and fatigue damage increase on wind turbines, namely wake effect. To alleviate the wake effect in the wind farm, several control methodologies have been proposed. The previous researchers have made a great progress on the power-augmentation effect. However, the fatigue damage from the wake control was not fully quantified in most current research. As a result, in this study, the fatigue damage of wind turbine blade from the wake control will be researched based on the coupled model of structural dynamics model and large-eddy-simulation-based CFD model. The flow field and dynamic loading for the wind turbine blades are simulated and analyzed. The equivalent fatigue damage (DEL) caused by the wake control for the upstream and downstream wind turbines has been calculated. It was found that the yaw-based wake control can cause 50% fatigue damage increase with increasing yaw angle. This research will provide guidelines for the design of both large wind turbine and wind farm. [ABSTRACT FROM AUTHOR]

The effect of matrix and fibre cracks on the static strength and stiffness of uni-directional plies and cross-ply laminates under tensile loads was examined with the goal of understanding the main damage mechanisms. The size of matrix cracks emanating from cracked fibres was determined and found to be in excellent agreement with test results. This was used to predict static tensile failure of uni-directional laminates and was shown to be in good to excellent agreement with test results for six different materials. The approach was extended to fatigue loading by determining the number of cycles for the plastic zone ahead of a matrix crack tip to fail. It was combined with an approach to quantify the effect of matrix cracks under any in-plane loading previously developed by the authors to predict changes in laminate stiffness as a function of cycles. Comparisons with test results showed good to excellent agreement between predicted and measured laminate stiffness as a function of fatigue cycles. [ABSTRACT FROM AUTHOR]

Combined analysis of roadway, truck axle loads and the service life of concrete bridges The increasing need for rehabilitation of road bridges in Germany results in a growing importance of planning their maintenance and new constructions. The more accurate the knowledge about impacts is, the more precise forecasts of the service life of structures can be. This is not only relevant for bridge construction, but also for the automotive industry, where detailed, time‐varying axle loads are measured and simulated with the aim of vehicle optimisation. Using these data and simulation methods, the question of a possible connection between road quality and the service life of road bridges arises for civil engineering. By setting higher requirements for the pavement quality in the area of bridges, dynamic loads could be reduced and extensive renovations of the load‐bearing structure could be avoided or delayed. In order to investigate a possible correlation, a procedure for determining the influence of the pavement quality on the service life of road bridges is presented below. For this purpose, realistic road surfaces are generated and used to trigger a forced vibration at the simplified axle and vehicle models on a coupled structure‐vehicle system. Based on this, the time varying internal forces of the structure can be calculated and analysed for their damage potential. Finally, this methodology is illustrated by means of an example. It can be demonstrated that in this case a clear correlation between surface quality and service life can be identified. [ABSTRACT FROM AUTHOR]

The fatigue damage behavior and the failure characteristics of the T300/QY8911 laminate and 7050-T7451 aluminum single-bolt bolted joints were investigated by test and progressive damage analysis (PDA) in this article. The manufactured composites-to-metal bolted joints (CMBJs) with different thickness metal plates and lap-patterns have been tested in static and fatigue load case and the failure characteristics are compared. A modified Lemaitre fatigue damage model and a phenomenological composite fatigue damage model were proposed and applied simultaneously to capture the damage evolution in the laminate and the metal parts. The competition of the fatigue damage of the laminate and the metal parts in affecting the joint stiffness and the coupling of the damage accumulation were studied by PDA, and the results indicates that: the failing sequence of the CMBJs constructive parts may change between the static load case and the fatigue load case; the fatigue damage of the metal parts has little effect on the joint stiffness of the CMBJs, nevertheless, there is certain coupling of the laminates fatigue damage and metal fatigue damage in the CMBJs, the harden or soften of the metal parts by fatigue hardening or crack progression would promote or slow down the damage accumulation in laminate. [ABSTRACT FROM AUTHOR]

It is urgent to study the damage mechanism of corn kernels and find ways of reducing the rate of kernel breakage in mechanical threshing. This paper, by studying the mechanical curves and deformation characteristics of corn kernels with different moisture contents, points out the brittle mechanical characteristics of corn kernel damage fracture with low moisture content, and clarifies the variation law of mechanical properties of kernels with moisture contents. The experimental data of fatigue load - fatigue life curves of corn kernels with different moisture contents were described by the power function equation. At the same time, the fatigue life and damage characteristics of kernel with different moisture content were analyzed, and the accuracy of the fitting equation was verified. Through mathematical statistical analysis, the normal distribution curve of fatigue life was fitted, and the variation law of normal distribution curve with moisture content and fatigue load was determined. [ABSTRACT FROM AUTHOR]

The fatigue damage assessment of laser-repaired components is critical to their service safety. However, since laser repairing is an advanced green remanufacturing technology, the current research on its fatigue mechanical behavior and fatigue damage evaluation methods is still immature. In addition, the relevant models used for the fatigue damage evaluation can only indicate the fatigue limit of components, which cannot describe the damage accumulation process of the components during the fatigue testing. Therefore, there is an urgent need to develop a fatigue damage evaluation method that can describe the fatigue damage accumulation and evolution to reveal the damage evolution mechanism during the fatigue test. In this study, based on the 3D-DIC technique, new damage parameters, i.e., strain average value and strain standard deviation, are proposed to quantitatively describe the damage status of the nickel-based components during the stress-based fatigue process. Then, based on the new damage parameters, a strain average value/strain standard deviation damage curve method is proposed to describe the damage status evolution of the components during the fatigue testing and evaluate its fatigue damage. For example, in the tensile fatigue test, the strain average value/strain standard deviation damage curves of the substrate component and the laser-repaired component can be divided into two damage stages. In the first damage stage, the damage increases slowly with the increase in the cycle number, whereas in the second damage stage, the damage increases rapidly with the increase in the cycle number. At this time, there is a demarcation point between the first damage stage and second damage stage in the strain average value damage curve and strain standard deviation damage curve. The cycle number of the demarcation point can be used as a reference value for the fatigue failure of the laser-repaired component. In addition, the electron backscatter diffraction (EBSD) technique was used to verify the validity of the evaluation results from the novel damage parameters. [ABSTRACT FROM AUTHOR]

The benefits of employing the virtual simulation tools tend to be amplified when applied at the initial stages of the project. In order to predict the loads acting on a component, a load generation methodology is used. The suspension loads generated depend on a series of suspension and body characteristics. These characteristics are refined to suit ride, handling and fuel consumption targets. The focus of the present study is to evaluate the effects of these variations on the rear suspension durability using load generation DOE and Fatigue analyses. Through this understanding, an initial virtual prototype can be idealized. [ABSTRACT FROM AUTHOR]

Only by using accurate material data can precise simulation results be achieved. This principle also and especially applies in the field of crash simulation. However, in the simulation of short-fibre reinforced thermoplastics, material parameters are usually used that originate from the material testing of as-new samples. In order to get closer to the condition on the roads, where not only new vehicles are driving, the influence of service loads on the crashworthiness has to be investigated. This paper reports on studies of PBT GF30, a polybutylene terephthalate reinforced with 30% glass fibres, in which fatigue damage was induced in the material by cyclic loading. The residual strength was then determined in a high-speed experiment and compared with the strength of virgin samples. In order to enable the usability of the findings in the simulation, a modified failure criterion was implemented that takes the previous fatigue damage into account. The prediction quality of the simulation model was compared with the experimental findings and it can be concluded that there is good agreement. [ABSTRACT FROM AUTHOR]

A7N01P-T4 aluminum alloy plates for high-speed trains will experience a certain amount of fatigue damage under alternating loads. Three groups of samples, P0 (no fatigue damage), P1 (loading stress 30 MPa), and P2 (loading stress 70 MPa), were created, and corrosion fatigue crack growth (CFCG) tests were conducted in 3.5 wt.% NaC1 solution. The crack growth rate was found to increase after fatigue damage as the damage degree increased. In addition, the A7N01P-T4 aluminum alloy base metal exhibited obvious secondary cracks and crack bifurcations after fatigue damage. It is believed that fatigue damage causes stress concentration in the material, while a certain degree of stress corrosion cracking occurs during the CFCG growth process. This is because hydrogen (H) easily accumulates and diffuses along the grain boundary, which reduces the strength of the grain boundary, thereby becoming the preferred orientation for crack growth. This explains why the CFCG rate of the material is accelerated following fatigue damage to a certain extent. [ABSTRACT FROM AUTHOR]

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Very high cycle fatigue (VHCF) tests were carried out under variable amplitude loading for TC21 titanium alloy. The first level of high amplitude loading was set as 950 MPa close to yield strength, and the second level of low amplitude loading was determined between 435 MPa and 500 MPa where fatigue cracks initiated at the specimen subsurface under constant amplitude. The results indicate that the high/low stress block significantly reduced the cumulative fatigue life of low stress amplitude, and the fatigue crack initiation site changed from the specimen subsurface under constant loading to the specimen surface under stress block. Based on continuum damage mechanics, the fatigue damage model of two-step stress block was established to estimate the fatigue damage process. The prediction of cumulative fatigue life generally agreed with the experimental data. The cumulative fatigue damage of the stress block was related to the stress amplitude and the cycle ratio, which determined the stress fatigue damage and its interaction damage. The surface crack initiation in the stress block accelerated fatigue damage of low stress amplitude, reducing the cumulative life. [ABSTRACT FROM AUTHOR]

When ceramic-matrix composites (CMCs) are under tension-tension cyclic fatigue loading, stochastic matrix cracking evolves with applied cycles and the closure of cracks occurs upon unloading. Evolution, opening, and closure of matrix cracking affect the reliability and safety of CMC components during operation. The objective of this paper is to establish the relationship between the hysteresis loops, cracking evolution, opening, and closure based on a new hysteresis constitutive model. Multiple micro damage parameters, e.g., unloading/reloading inverse tangent modulus (UITM/RITM), interface reverse slip ratio (IRSR), and interface new slip ratio (INSR), are developed to characterize the hysteresis loops with cracking evolution and closure. Upon unloading, the closure of matrix cracking decreases the UITMs and IRSR of the tension-tension fatigue hysteresis loops; upon reloading, the opening of matrix cracking increases the RITMs and IRSR of the tension-tension fatigue hysteresis loops. Experimental tension-tension fatigue hysteresis loops in different CMCs are predicted for different peak stresses and cycles. Effects of fiber volume, interface properties, peak stress, and stress ratio on ITM, IRSR, and IRSR are discussed. The developed approach can be used for cracking evolution, opening, and closure identification in CMCs. [ABSTRACT FROM AUTHOR]

In order to reveal the galloping mechanism of ice-coated conductors on transmission lines, the galloping wind tunnel test of ice-coated conductors was carried out. The galloping characteristics of flexible ice-coated conductors were studied by changing wind speed, wind direction, sag and other parameters. Research shows that the ice-coated wire deforms to an equilibrium position under wind load, and vibrates in multiple modes around the equilibrium position. The average deformation and amplitude of the ice-coated wire in the downwind direction are the largest, and increase with the increase of wind speed. A three-tower four-line coupled system model is established by numerical simulation, and the galloping response of the tower-line system is given. The calculation results show that the icing wire begins to dance at the equilibrium position at 2 m from the initial position, the wire amplitude continues to increase, the trajectory of the dance is elliptical, and the vertical amplitude of the wire is significantly greater than the horizontal amplitude. At the same time, based on the fatigue cumulative damage criterion, the galloping fatigue damage and fatigue life of the key nodes of the transmission tower are further evaluated. The study found that the intersection of the upper and lower curved arms of the wineglass tower line system is the key node that is most prone to fatigue failure during the galloping process. The fatigue damage of the components at the intersection of the upper and lower curved arms should be fully considered in the design process of the transmission tower. Finally, the galloping fatigue life of the main key nodes of the transmission tower is given. [ABSTRACT FROM AUTHOR]