Cumulative Damage Theory Research Articles

Fatigue performance and failure mechanism of ductile iron pipes with socket joints under traffic loads

Urban water supply pipelines experience repetitive traffic loads during their operational lifespan, potentially leading to fatigue failure. However, existing research focuses primarily on the static or dynamic mechanical responses of pipes, with limited studies on the fatigue performance of pipes. This study investigates the fatigue performance and failure mechanism of DN200 ductile iron (DI) pipes with socket joints under traffic loads and water pressure through bending fatigue tests. First, the mechanical responses of pipe joints under traffic loads derived from statistical data on highway traffic loads, soil pressure, and self-weight are calculated using ABAQUS to give the fatigue test load amplitude. Subsequently, tests are conducted on three DN200 DI pipes under a water pressure of 0.2 MPa: one for a monotonic test and two for fatigue tests under extra car and bus loads, respectively. The fatigue life of pipes under various traffic load combinations is analyzed using cumulative damage theory. Moreover, the relationship between fatigue load amplitude and number of cycles for DN200 DI pipes are obtained on the basis of the test data. Results show that the maximum rotation angle of joint is an important indicator of failure. Finally, a theoretical method for calculating the joint angle is proposed on the basis of geometric dimensions. A good agreement between the test and theoretical results is observed. Thus, the proposed method can obtain the fatigue performance of joints effectively.

Research on the service life of bearings in the gearbox of rolling mill transmission system under non-steady lubrication state

A rolling bearing plays a key role in the gearbox of the cold rolling mill transmission system. As a result, the degradation and failure of bearings can lead to unplanned shutdowns of the entire rolling mill system. Since on-site cold rolling mills work usually in non-steady lubrication rolling conditions originating form variations of multiple parameters, the uncertainty affecting bearing performance in a cold rolling mill transmission system increases, making it more difficult to assess health status and predict the remaining service life of bearings, Therefore, by establishing a coupling model describing the relationship for the rolling mill and normal /faulty gearboxes under non steady rolling conditions, quantitatively studies the influence of various rolling parameters of a rolling mill on the fatigue service life of bearings in the gearbox of the rolling mill transmission system, and verify the effectiveness of linear cumulative damage theory for bearing fatigue service life through experiments and on-site bearing vibration data. The results indicate that as the thickness of the strip steel inlet, lubricant viscosity, and rolling speed increase, or the thickness of the strip steel outlet and rolling roll radius decrease, the service life of bearings gradually decreases. As the fluctuation amplitude of various rolling parameters in the cold rolling mill increases, the service life of bearings in the gearbox of the rolling mill transmission system gradually shortens. Moreover, when the rolling parameter value or fluctuation amplitude increases to a specific values, the remaining service life of bearings will sharply decrease. Under the same rolling conditions, the service life of bearings in gearboxes with faults decreases more significantly than that in normal gearboxes.

Wind-Induced Response Analysis and Fatigue Reliability Study of a Steel–Concrete Composite Wind Turbine Tower

Taking an actual 3MW steel–concrete composite wind turbine tower as an example, a finite element model of the tower structure was established, and static bearing capacity and dynamic time history response analyses were performed to identify the locations where the structure is prone to failure. On this basis, the fatigue lives of the turbine tower at the most unfavorable locations were predicted using linear cumulative damage theory, and the fatigue reliability at the corresponding locations of the structure was calculated using the kriging–subset simulation method. The most dangerous locations of the tower that are most prone to failure are as follows: the bottom of the leeward side of the upper steel tube, the flange of the steel tube, the bolt-hole imprinting surface of the flange, the leeward side of the transition tube, and the top of the leeward side of the concrete tube. The failure risk of the flange and bolt-hole imprinting surface of the upper steel tube is relatively high, followed by that of the transition tube. This indicates that special attention should be given to the design and daily maintenance of this part. The fatigue resistance of the tower can be enhanced by improving the strength of the flange plate or increasing the number of bolts and strengthening the transition tube.

Random Vibration Fatigue Life Prediction of Nano-Silver Solder Joint

Nano-silver is a very potential electronic interconnection material. It’s excellent physical and chemical properties, high thermal conductivity and good electrical conductivity make it very suitable for high power electronic devices. In practical engineering, 20% of the failure of electronic products is caused by vibration load, so it is necessary to study the vibration reliability of interconnected materials. In this paper, the modal and random vibration finite element analysis of nano-silver solder joints were analyzed with workbench software. Predicting random vibration fatigue life of nano-silver solder joint by Coffin-Manson high cycle fatigue empirical formula, Miner’s linear cumulative damage theory and Steinberg model. The random vibration fatigue life of the nanosilver solder joint is 8342 h. It is found that the vibration reliability of nano-silver is inferior to Sn3.0Ag0.5Cu and Sn63Pb37 and the diameter of solder joints and PCB thickness are proportional to the vibration fatigue life, and the PCB thickness has a greater effect on the vibration life than the solder joint diameter. Solder joint height and pad thickness are inversely proportional to vibration fatigue life, and pad thickness has little effect on vibration fatigue life.

Fatigue Damage Assessment of Turbine Runner Blades Considering Sediment Wear

The wear phenomenon that occurs on the blades during operation has a significant impact on the fatigue life of the blades. To address the issue of fatigue life assessment for turbine runner blades subjected to increased dynamic stress due to sediment wear, taking a specific high-head hydropower unit’s mixed-flow turbine as the research subject, a hydraulic model of the turbine was established. The wear zones of the runner blades are determined based on the distribution of the flow field’s velocity and the sediment volume fraction. According to the wear rate formula for runner blade material, the amount of wear on the blades is determined, and the dynamic stress data for the dangerous areas of the blades under different degrees of wear are calculated using a unidirectional fluid–structure coupling method. The load spectrum of the time–stress history data for the dangerous area at different levels of wear was compiled using the rain-flow counting statistical method. The operating time ratios for the flood season and the non-flood season are combined. Based on the fatigue cumulative damage theory, the total fatigue damage at the maximum stress part of the runner blade was calculated for different stages of wear, providing a reference for the life calculation of mixed-flow hydraulic turbines.

Analysis and Zonation of Freeze–Thaw Action in the Chinese Plateau Region Considering Spatiotemporal Climate Characteristics

Concerns about the durability of transportation infrastructure due to freeze–thaw (F–T) cycles are particularly significant in the Chinese plateau region, where concrete aging and performance deterioration pose substantial challenges. The current national standards for the frost resistance design of concrete structures are based predominantly on the coldest monthly average temperature and do not adequately address the comprehensive effects of the spatiotemporal variance, amplitude, and frequency of F–T cycles. To address this issue, this study introduced a spatiotemporal distribution model to analyze the long-term impact of F–T action on concrete structures by employing statistical analysis and spatial interpolation techniques. Cluster analysis was applied to create a nationwide zonation of F–T action level from data on the freezing temperature, temperature difference, and the number of F–T cycles. Furthermore, this study explored the similarity between natural environmental conditions and laboratory-accelerated tests using hydraulic pressure and cumulative damage theories. A visualization platform that incorporates tools for meteorological data queries, environmental characteristic analyses, and F–T action similarity calculations was designed. This research lays theoretical groundwork and provides technical guidance for assessing service life and enhancing the quantitative durability design of concrete structures in the Chinese plateau region.

Acoustic and Vibration Response and Fatigue Life Analysis of Thin-Walled Connection Structures under Heat Flow Conditions

Thin-walled connection structures are commonly used in the hot-end components of aerospace vehicles. Large deflection nonlinear responses and fatigue failure occur due to their discontinuous mass distribution and prominent cross-sectional changes under the action of complex thermal, aerodynamic, and noise loads. A thermoacoustic fatigue test was carried out to obtain the acoustic and vibration responses and fatigue life changes of the connection structure under heat flow conditions in engineering applications. The high-temperature acoustic fatigue test system of aviation thin-walled structures was used, taking the high-temperature alloy thin-walled plate-load-bearing frame bolted connection structure as the research object. As a result, the vibration response and fatigue life under different thermoacoustic loads were obtained. The contact finite element method was used to simulate the connection pre-tightening force, and the coupled finite element/boundary element method was used to calculate the acoustic and vibration response of the heat flow conditions. The changing rules of the frequency response peak value at the critical point of the thin-walled connection structure under the effects of different temperature fields, fluid fields, and sound fields were obtained through the processing and analysis of the calculation results. Considering the structural vibration fatigue damage mechanism, this study employed an improved rainflow counting method to compute the rainflow circulation matrix (RFM) and rainflow damage matrix (RFD) of the vibration stress time history at critical points within the structure framework. Said method was combined with Miner’s linear cumulative damage theory to estimate the fatigue life under various thermal-fluid-acoustic coupled loads. A comprehensive analysis validates the accuracy of the established numerical simulation calculation model in identifying critical connection points within structures subjected to pre-tightening forces. This model effectively characterizes thermal, aerodynamic, and acoustic loads on high-temperature alloy thin-walled-load-bearing frame bolted connection structures. It delineates the relationship between vibration response and fatigue life while assessing the impact of three distinct load parameters.

Fatigue assessment of a 100-year-old riveted truss railway bridge

Fatigue is one of the most common reasons for failure in existing steel railway bridges, particularly with a riveted structure. Therefore, fatigue assessment is always the most important part of the complex evaluation of existing steel railway bridges. Additionally, a reliable fatigue assessment is often decisive in estimating the remaining service life of a bridge. The purpose of the presented research is to assess the fatigue of a 100-year-old riveted truss railway bridge. The assessment was carried out to decide whether the existing truss superstructure is still suitable for rehabilitation in the context of the ongoing modernisation of the railway line. The fatigue assessment procedure is based on the safe life method in the convention of nominal stresses. The Miner linear cumulative damage theory and the S-N curves according to the relevant European recommendations were also applied. Bridge evaluation revealed that the fatigue life of the steel superstructure was almost exhausted and that its remaining service life is too short to be considered for rehabilitation. It was also confirmed by the presence of fatigue cracks in the deck joints, detected during bridge inspection. Taking into account the assessment results, it was revealed that the existing riveted truss superstructure was not suitable for further use, which was intended to extend the bridge service life by the next 50 years after the modernisation of the railway line.

Study on fatigue damage and frequency attenuation characteristics of carbon fiber composite

Fatigue analysis and life prediction are the key and challenging issues in the mechanics research of composite material. In this paper, based on the progressive damage analysis method and fatigue cumulative damage theory, a three-dimensional fatigue cumulative damage numerical model is constructed by introducing the orthotropic constitutive equation, 3D-Hashin fatigue criterion, and material performance degradation scheme. Two loading conditions of tension–tension fatigue and compression–compression fatigue of Carbon Fiber composite laminates were investigated. In the tension–tension fatigue experiments, when the cycle is [Formula: see text] times, the experiment and the numerical simulation all not completely destroyed. However, progressive degradation of stiffness and strength was observed in certain elements, accompanied by some internal damage. On the other hand, the experimental and predicted values for compression–compression fatigue were within a triple error band. Then the cumulative damage evolution law of each laminate under fatigue load was analyzed. Compression–compression fatigue damage initiated from the center of the hole and expanded to both sides of the composite laminate, and its fatigue life increased with the increase of the compression–compression fatigue load. Considering the degradation of stiffness in composite materials under fatigue loading, which leads to frequency attenuation in the structure, this paper established a connection between the fatigue state and frequency to obtain the frequency attenuation curve under fatigue loading. The relationship between frequency and fatigue life was revealed, allowing for the prediction of remaining fatigue life in practical engineering based on the rate of inherent frequency reduction.

Study on biaxial bending fatigue performance of Engineered Cementitious Composites (ECC)

Structural components such as bridge deck, highway pavement and thin-walled roof dome often are subjected to the biaxial and even multi-axis stress state due to the external load. Also, the fatigue effect cannot be ignored due to the moving vehicle load in the design of these structures. If engineering cementitious composites (ECC) is used in the above traditional concrete structures, their performance, such as easy cracking and short service life can be greatly improved. However, the biaxial bending fatigue performance of ECC should be analyzed in detail. At present, the biaxial bending test methods of cement-based materials include biaxial bending test (BFT) and centrally loaded round panel test (RPT). This study used both RPT and BFT test methods to analyze the biaxial fatigue performance of ECC and used four-point bending test (4PBT) uniaxial fatigue test as a reference. The stress levels S were set as 0.5, 0.6 and 0.7. The uniaxial and biaxial bending fatigue failure procedures of ECC were analyzed by plotting the three-stage deflection development curve, the fatigue damage and strain relationship curve based on the linear cumulative fatigue damage theory, and the S–N curve. The fatigue life of ECC biaxial bending specimens was greater than that of uniaxial bending specimens. At S = 0.5, the fatigue life: BFT > RPT. At S = 0.6, the fatigue life of BFT and RPT specimens was close. At S = 0.7, the fatigue life: BFT < RPT. With increasing stress level, the fatigue life of BFT specimen decreases more than that of RPT specimen. The lognormal distribution model and Weibull distribution model were used to fit the uniaxial and biaxial bending fatigue life of ECC, respsectively. Using the double logarithmic fatigue equation, fatigue life under the failure probability PF of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 was derived. The survival rate represents the level of safety reservation, which could provide reference and basis for the design of ECC bridge deck and highway pavement with different safety reservation requirements.

Study on fatigue life estimation method of welded structure of lifting machinery

The fatigue strength of lifting machinery structure has always been an important issue in ensuring safety. In order to effectively and accurately evaluate the fatigue life of lifting machinery structure, this paper based on Miner linear cumulative damage theory and S-N curve in British BS 7608 standard, the fatigue life calculation of metal welded structure is carried out. Taking the large-scale bridge crane of hydropower station as an example, the nominal stress of the corresponding key parts is obtained by applying the actual load in the finite element model, and the stress time history is calculated, and then the safe service life of the structure is estimated, which provides an effective and feasible method for evaluating the fatigue residual life of the crane. The example analysis shows that the calculation method is convenient and reliable, which provides a scientific basis for accurately estimating the fatigue life of welded structure of lifting machinery.

Numerical modeling and fatigue analysis of the dynamic response of main pump cable in nuclear power plant

Abstract The structural temperature rise and thermal stress caused by operation current and ambient temperature are some of the main factors affecting cable fatigue life. Combined with the operating and environmental conditions of the main cooling pump of the nuclear power plant, the thermal-structural coupling field numerical modeling and fatigue analysis of the 6kV single-core and three-core cable of the main pump is carried out. Based on obtaining the steady-state operating current, the motor start-up transient current, and the circulating ambient temperature, the thermal-structural coupling field numerical model of the main pump cable is established using the load transfer method to obtain the thermal and stress field distribution of the internal structural layer. The load history of one cycle is extracted for the fatigue numerical simulation of the main pump cable. The stress time history of the cable structure layer was constructed by the stress calculation results and the load time history of a single period, and the fatigue life of the main pump cable was obtained based on the S-N curve of the main insulation material and the Miner’s linear cumulative damage theory. The simulation results show that the force acting on the main pump cable by the operating current and ambient temperature is an approximately symmetric cyclic load of constant amplitude. The life cycle of the cable can reach 2.235*e4 times, and the overall life of the cable is about 63.97 years. This study can provide theoretical guidance for the safety and reliability design and state operation and maintenance of the main pump cable of the nuclear power plant.

Analytical modeling and analysis of the low-velocity penetration and non-penetration behaviors of fiber-reinforced composite cylindrical shells based on critical impact velocity criterion

An analytical model is developed to predict the impact characteristic parameters of composite cylindrical shells when low-velocity penetration and non-penetration damage are considered. The critical impact velocity criterion for judging the penetrating failure of such structures is also proposed. The impact contact force, displacement, and load-displacement curve of the structure subjected to oblique non-penetrating impact loading are solved using the improved Hertz contact theory, cumulative damage theory, stiffness degradation method, etc. Based on the formula derivation of critical impact velocity, the key impact parameters are solved, such as the residual velocity of the projectile and damage area of the structure with penetrating impact, which takes into account three energy absorption mechanisms, such as delamination, laminating crushing and linear momentum transfer. A series of non-penetrating and penetrating impact tests are conducted using a low-velocity drop hammer rig and a light gas gun. The prediction results of the proposed model are compared to both experimental and literature results. One can find out that the largest prediction errors of the peaks of impact contact force and displacement deformation are 12.3 and 9.2 %, respectively, and the counterparts of residual velocity and damage area are 12.0 and 6.2 %, respectively. Hence, the present model is trustworthy for predicting these impact parameters. Moreover, it is advised to adopt an appropriate stacking sequence, a high ratio of structural thickness to radius, a large oblique impact angle of the projectile, and a small mass ratio of the projectile to such a structure to enhance its impact resistance or reduce impact response. In addition, it is worth noting that the current model probably has a big prediction error of the high-velocity impact behaviors involving the material heating and soft effects caused by penetration damage since high strain rate and temperature effects are not considered.

Study on wind-induced fatigue performance of large-span transmission tower-line system considering the combined distribution probability of wind direction and speed

To accurately evaluate the fatigue life of transmission line structures under wind loads, this study proposes a multivariate member fatigue damage analysis method for investigating the wind-induced fatigue performance of a large-span transmission tower-line with full consideration of the combined distribution effects of wind direction and speed in the actual wind field. With the background of in-service transmission line project, a refined finite element model of the large-span transmission tower-line system is established, and the wind load is simulated and generated based on the linear filtering method. According to the meteorological statistics of the project site in the past 50 years, the wind-induced fatigue sensitivity analysis of the tower-line system is performed through considering the combined distribution probability of wind direction and speed. The wind-induced fatigue damage of the tower-line system is calculated based on the rain-fall counting method and Miner's fatigue cumulative damage theory, and its wind-induced fatigue life is further analyzed. The analysis results show that the sensitive members of the tower-line system are mainly distributed in the 2nd, 6th, 8th and 9th segments by combining the effects of wind attack angle and wind speed. The fatigue damage of the sensitive members decreases gradually with the increase of wind attack angle (0° wind attack angle damage is the largest), and the effect of wind speed on the vertical main member is larger than that of the crossarm upper chord member. Moreover, the fatigue damage at the end of the member is significantly larger than that in the center, and even at small wind speeds, the member's end can produce a stress amplitude larger than the fatigue cut-off limit. The fatigue life of crossarm upper chord members is 72.89 years, and that of the vertical main member is 77.60 years. In particular, the vertical main member should be employed as the control member for the structural fatigue life when considering extreme wind loads.

Cumulative fatigue damage theories for metals: review and prospects

PurposeScholars mainly propose and establish theoretical models of cumulative fatigue damage for their research fields. This review aims to select the applicable model from many fatigue damage models according to the actual situation. However, relatively few models can be generally accepted and widely used.Design/methodology/approachThis review introduces the development of cumulative damage theory. Then, several typical models are selected from linear and nonlinear cumulative damage models to perform data analyses and obtain the fatigue life for the metal.FindingsConsidering the energy law and strength degradation, the nonlinear fatigue cumulative damage model can better reflect the fatigue damage under constant and multi-stage variable amplitude loading. In the following research, the complex uncertainty of the model in the fatigue damage process can be considered, as well as the combination of advanced machine learning techniques to reduce the prediction error.Originality/valueThis review compares the advantages and disadvantages of various mainstream cumulative damage research methods. It provides a reference for further research into the theories of cumulative fatigue damage.

Micro-Scale Numerical Simulation of Fatigue Failure for CFRP Subjected to Multiple-Amplitude Cyclic Loadings Based on Entropy Damage Criterion.

Fatigue failure of carbon fiber-reinforced plastics (CFRPs) under cyclic loadings has attracted the attention of researchers recently. In this study, the entropy-based failure criterion is proposed to investigate the fatigue lifetime of unidirectional CFRPs subjected to multiple-amplitude cyclic loadings. Due to the heterogeneity of CFRPs, a micro-finite element model considering matrix resin and fibers independently is developed, and the entropy-based damage criterion is implemented into a user-subroutine of Abaqus to model the progressive damage of matrix resin. The fatigue lifetime of CFRPs under typical loading sequences consisting of two stages, such as varying from low to high (L-H) or from high to low (H-L) loading sequence, is estimated with the proposed failure criterion. Numerical results show that the initial damage occurs near the area between two fibers, and a transverse crack propagates progressively under the cyclic loading. The difference in predicted lifetime to final failure in L-H and H-L stress levels is 6.3%. Thus, the effect of loading sequence on the fatigue lifetime can be revealed via the proposed entropy-based damage criterion. Comparisons with the conventional linear cumulative damage (LCD) and kinetic crack growth (KCG) theories are also conducted to demonstrate the validity of the proposed method. The entropy-based failure criterion is a promising method to predict the residual strength and fatigue lifetime of CFRP components.

Experimental study on residual monotonic mechanical properties of high-performance Q690 steel with pre-fatigue damage

In this paper, we conduct an experimental study of the fatigue performance and monotonic tensile properties with pre-fatigue damage of seismic and corrosion resistant Q690 structural steel (abbreviation high-performance Q690 steel). Based on fatigue cumulative damage theory, S-N curves and fatigue cumulative damage curves of high performance Q690 steel were obtained. According to the static mechanical properties with different degree of fatigue damage, the related curves between fatigue damage degree and residual mechanical properties were proposed. Finally, based on the Rambeger-Osgood constitutive relationship, a constitutive model for high performance Q690 steel considering fatigue damage is proposed. The results indicated that the high performance Q690 steel showed good fatigue performance. Its limit fatigue strength is 630 MPa (0.86fy) approximately, which is higher than fatigue limit values specified in steel design standards. In addition, the fatigue crack propagation stage and transient fracture stage accounted for a relatively small proportion of fatigue life. The static mechanical properties with pre-fatigue damage of high performance Q690 steel is similar to the AISI 1045 steel. As the fatigue damage degree increases, the elasticity modulus of high performance Q690 steel decreases and yield strength increases. Whereas, pre-fatigue damage has little effect on ultimate strength and elongation. Finally, a new constitutive model considering fatigue damage was proposed, which was found better simulating tensile curves with different fatigue damage.

Fatigue Life Analysis of Railway Axles under Pre-crack Conditions

This paper takes the wheelset of a certain type of EMU as the research object and checks the strength of the axle according to the standard, and the most dangerous section of the axle is determined to be 35 mm away from the inner edge of the wheel seat. A crack with a depth of 1.2 mm was prefabricated by an electric spark in this position, and the crack was extended to a semi-elliptic crack with a depth of 2 mm by a fatigue test. The remaining service life of the non-damaged axle and the defective axle were analyzed based on the cumulative damage theory and the damage tolerance design method.

Fatigue condition assessment of subsea pipelines under vortex induced vibration and cyclical lateral displacement

ABSTRACT Subsea pipeline may suffer from vortex-induced vibration (VIV) and cyclical lateral displacement (CLD), which can result in fatigue failure of subsea pipeline. This paper presents a fatigue damage assessment of subsea pipelines under VIV and CLD. A finite element model of pipeline considering the pipe–soil coupling action is developed, and dynamic response of subsea pipeline under VIV and CLD is implemented to obtain time history of equivalent stress. The integrated fatigue damage of subsea pipeline under VIV and CLD is estimated using Palmgren–Miner linearly cumulative fatigue damage theory. The effect of pipe diameter, span length, pipe length and tidal period on fatigue damage of subsea pipelines under CLD is analyzed. A case study of a subsea pipeline in the strong tide area is performed. The results show the fatigue life of pipeline under VIV and CLD is 14.1 years, which is 2.3 years lower than the pipeline under VIV alone. The study can support more accurate estimation of fatigue life of subsea pipelines.

A Reliability-Based Robust Design Optimization Method for Rolling Bearing Fatigue under Cyclic Load Spectrum

Reliability-based robust design methods have been widely used in the field of product design; however, they are difficult to apply to the fatigue reliability design process of rolling bearings due to the problems of determining fatigue accumulated damage caused by the internal cyclic time-varying load distribution of rolling bearings and the computational cost of time-varying reliability. Therefore, a reliability-based robust design method for rolling bearing fatigue failure is proposed, which derives the formula for fatigue accumulated damage of a rolling bearing under cyclic load spectrum and significantly reduces the computational cost of rolling bearing time-varying reliability compared with existing methods. First, the state response of a rolling bearing under random design parameters is obtained by finite element simulation. Then, the adaptive kriging method is used to characterize the correlation between the random parameters and the state response. The Miner fatigue cumulative damage theory is improved and the rolling bearing fatigue time-varying equation of state under cyclic load spectrum is derived. Subsequently, a fatigue time-varying reliability model based on an improved fourth-order moment method is developed, and a reliability robust optimization design method is proposed. Finally, a rolling bearing example is presented to demonstrate that the method achieves time-varying fatigue reliability design under cyclic load spectrum and effectively improves the reliability and robustness of the product design.