Cumulative Damage Model Research Articles

Optimal Policies of Social Infrastructures Maintenance using Shock and Damage Model

Social infrastructures such as roads and bridges are indispensable for our lives. They have to be maintained continuously and such maintenance has become a big issue in Japan. Social infrastructures are maintained under strict restrictions such as decreasing in local finance revenue and scarcity of skilful engineers. Various kinds of factors such as inspection periods, maintenance costs, and degradation levels, are necessary to consider in establishing efficient maintenance plans of social infrastructures. Furthermore, the special circumstances of social infrastructures such as the delay of constructions which is caused by the scarcity of budget, must be discussed for the efficient maintenance plan. For such discussion, the stochastic cost model which contains preventive and corrective maintenances is useful. Although these models have been studied in mechanical and electronic systems, unique characteristics of social infrastructures such as their enormous scale and delays due to maintenance budget restrictions must be considered when such social infrastructure models are discussed. In this paper, we establish maintenance models of infrastructures which some of preventive maintenance must be prolonged. The expected maintenance cost rate is established using the cumulative damage model and optimal policies which minimizes them are considered. Three basic models and their extended models which consider natural disasters are discussed.

Study on Blasting Technology for Open-Pit Layering of Complex Mine Adjacent to High and Steep Slope

In China, mining blasting vibration has seriously threatened the safety and stability of high and steep rock slopes. In this paper, taking the east mining area of Jianshan Phosphorus Mine as the research background, combined with field survey, field blasting test, numerical simulation and theoretical analysis, we systematically studied the adjacent high-steep rock slope and the layered blasting technology of complex ore. Based on wide hole spacing blasting numerical simulation and field tests, the use of 8 × 4 m hole network parameters, oblique line hole-by-hole initiation method, detonator delay using 35 ms between holes, 65 ms between rows and 500 ms within the holes, the rock mass rate was reduced and the drilling workload was decreased. In addition, regression analysis was carried out on a large amount of vibration test data, and the attenuation law and propagation law of blasting vibration of adjacent high and steep slopes were predicted, which provided a reference for mine production blasting. By establishing a mathematical model of cumulative damage of rock mass blasting, it shows that the depth of impact of mining blasting on the slope of Jianshan open-pit was 0–3.6m, but the blasting did not cause overall damage to the adjacent high and steep slopes. In the future, this model can be used to predict rock damage caused by subsequent blasting.

A Nonlinear Fatigue Damage Model Based on Equivalent Transformation of Stress

It is rather difficult for engineers to apply many of the fatigue damage models for requiring a knee point, material-dependent coefficient, or extensive testing, and some of them are only validated by a fatigue test of two-stage loading rather than higher-stage loading. In this paper, we propose a new model of fatigue cumulative damage in variable amplitude loading, which just requires the information of the S-N curve determined from the fatigue experiment. Specifically, the proposed model defines a stress equivalent transformation way to translate the damage of one stress to another stress through simple calculation. Experimental data of fatigue including two-, three-, and four-block loading verify the superiority of the proposed model by comparing it with the Miner model and Manson model. The results show that the proposed model can be generalized to any type of loading and presents a better prediction. Therefore, the advantage of the proposed model can be easily used by an engineer.

A method for accurately assessing field performance degradation of PV modules in different geographical regions

Solar photovoltaic (PV) technologies have developed rapidly in recent years. As the core part of PV system, performance of PV modules largely determines the output of PV system. Module performance gradually degrades during operation, and the degradation is generally variant at different sites due to the differences in climatic stresses. Thus, it is necessary for sites selection of PV power stations and investment decisions to accurately assess field degradation of modules in different locations. In this work, an approach to assess and predict module field degradation in different regions through mathematical modeling and regional clustering was introduced. First, a mathematical model describing the relationship between climatic stresses and module performance degradation was established using cumulative damage model. Moreover, considering geographical region attribute of model parameters, a scientific method, namely regional clustering based on climatic stressors, was further developed to predict the module degradation at different locations, which guarantees its prediction accuracy. Compared to existing approach, cumulative fitting deviation of estimated degradation rates obtained by this model was reduced by 23.46%. Meanwhile, relative deviation of estimated degradation rates in different places was reduced to 1.61% and 0.4% with instruction of regional clustering result, which validated the effectiveness of the overall method.

A Bayes study of inverse Gaussian based strength models with accelerating stress

The survival probability of a composite material subject to external stress is governed by the condition that the strength of the material must exceed the applied stress. There are several models proposed in the literature for studying such stress-strength relationships, especially with reference to modeling failures in carbon fiber composites. A strong contender in this group is the inverse Gaussian based cumulative damage model. The present paper outlines the Bayes analysis of the four models of this family, two for each of additive and multiplicative stress functions. Further a comparative study, based on a real data set, has been carried out to propose the best model among them.

An Improved Nonlinear Cumulative Damage Model Considering the Influence of Load Sequence and Its Experimental Verification

According to the change characteristics in the toughness of the metal material during the fatigue damage process, the fatigue tests were carried out with the standard 18CrNiMo7-6 material. Scanning the fracture with an electron microscope explains the lack of linear cumulative damage in the mechanism. According to the obtained results, a nonlinear damage accumulation model which considered the loading sequence state under the toughness dissipation model was established. The recursive formula was devised under two-level. The fatigue test data verification of three metal materials showed that using this model to predict fatigue life is satisfactory and suitable for engineering applications.

Fatigue Design of Steel Bridge Deck Asphalt Pavement Based on Nonlinear Damage Accumulation Theory

Based on the nonlinear damage theory, this paper aims to explore the fatigue performance of steel bridge deck asphalt pavement under multistage fatigue load. Manson–Halford cumulative damage model and the modified model were introduced to describe loading sequence effects, and interactions between multiple loads were represented in stress ratio. The fatigue life prediction method of steel bridge deck asphalt pavement was put forward, considering loading sequence effects and load interactions. The fatigue design of steel bridge deck asphalt pavement was investigated with the fatigue life prediction model. The effects of different load levels and loading sequence on the fatigue design parameters stress ratio of steel bridge deck asphalt pavement were studied. The design results were compared with experimental results, and the prediction results were based on traditional Miner’s theory. The analysis results showed that the fatigue life prediction method based on the nonlinear cumulative damage theory can effectively design and analyze the fatigue characteristics of asphalt pavement of steel bridge deck with high accuracy and reliability. The fatigue life prediction model of steel bridge deck asphalt pavement can well reflect loading sequence effects and load interactions. In addition, the design model has relatively few parameters; therefore, it can be applied to practical engineering design.

Continuum Damage Mechanics Approach for Modeling Cumulative-Damage Model

In this study, we propose a novel cumulative-damage model based on continuum damage mechanics under situations where the mechanical components are subjected to variable loading. The equivalent completely reversed stress amplitude accounting for the effect of mean stress, stress gradients, loading history, and additional hardening behavior related to nonproportional loading paths on high-cycle fatigue under variable loading is elaborated. The effect of mean stress, stress gradients, loading history, and additional hardening behavior related to nonproportional loading paths is considered by averaging the superior limit of the intrinsic damage dissipation work in the critical domain. We developed a novel cumulative-damage model by introducing the equivalent completely reversed stress amplitude into the damage-evolution model. For better comparison, existing cumulative-damage models, including the Palmgren–Miner law, corrected Palmgren–Miner law, Morrow’s plastic work interaction rule, and Wang’s rule, were employed to predict the fatigue life under variable loading. The proposed model performed better, considering the error scatter band obtained by plotting the predicted and experimental fatigue life on the same coordinate system. The model precisely predicts fatigue life under variable loading and easily identifies its material constants.

On classes of life distributions based on the mean time to failure function

AbstractThe performance and effectiveness of an age replacement policy can be assessed by its mean time to failure (MTTF) function. We develop shock model theory in different scenarios for classes of life distributions based on the MTTF function where the probabilities $\bar{P}_k$ of surviving the first k shocks are assumed to have discrete DMTTF, IMTTF and IDMTTF properties. The cumulative damage model of A-Hameed and Proschan [1] is studied in this context and analogous results are established. Weak convergence and moment convergence issues within the IDMTTF class of life distributions are explored. The preservation of the IDMTTF property under some basic reliability operations is also investigated. Finally we show that the intersection of IDMRL and IDMTTF classes contains the BFR family and establish results outlining the positions of various non-monotonic ageing classes in the hierarchy.

Theoretical study on fatigue cumulative damage model of nanometer concrete

In order to follow-up nano concrete freeze-thaw damage model can have a solid theoretical foundation, this paper elaborates the concrete damage theory and fatigue damage model, and analyzes the characteristic and law of development of concrete fatigue cumulative damage, in order to fully understand the deteriorating law of the fatigue damage of concrete freezing and thawing, guide the establishment of concrete freeze-thaw damage model.

Optimal replacement policy under cumulative damage model and strength degradation with applications

In many real-life scenarios, system failure depends on dynamic stress-strength interference, where strength degrades and stress accumulates concurrently over time. In this paper, we consider the problem of finding an optimal replacement strategy that balances the cost of replacement with the cost of failure and results in the minimum expected cost per unit time under cumulative damage model with strength degradation. In the most general setting, we propose to find optimal choices of three thresholds on operation time, number of arriving shocks and amount of cumulative damage such that replacement of the system due to failure or reaching any of the three thresholds, whichever occurs first, results in the minimum expected cost per unit time. The existing recommendations are applicable only under the assumption of Exponential damage distribution including Poisson arrival of shocks and/or with fixed strength. As theoretical evaluation of the expected cost per unit time turns out to be very complicated, a simulation-based algorithm is proposed to evaluate the expected cost rate and find the optimal replacement strategy. The proposed method is easy to implement having wider domain of application including non-Poisson arrival of shocks and non-Exponential damage distributions. For illustration, the proposed method is applied to real case studies on mailbox and cell-phone battery experiments.

An improved strength degradation model for fatigue life prediction considering material characteristics

Experimental results show that when the loading sequence of fatigue loads changes, the fatigue cumulative damage prediction based on Miner's rule will have a large error, even as high as 252.83%. In an effort to improve the fatigue life predictions, based on the residual strength degradation rule, a power exponential fatigue equivalent damage model is presented in this paper, which contains two material parameters. Experimental data were cited to verify the residual strength model, and the statistical results showed that this model is capable of describing the residual strength degradation of materials. Furthermore, a fatigue cumulative damage model based on residual strength is established to predict the fatigue life. The Miner's rule and other models were compared to validate the model by referring to the test data of different materials under different loading stress levels. And the accuracy of the fatigue life predicted by this model is twice as good as that predicted by others models.

A Novel Probabilistic Fatigue Life Prediction Method for Welded Structures Based on gPC

The traditional fatigue life prediction methods based on the S-N curve all believe that the parameters in the model are deterministic constants and can be categorized to the deterministic life prediction. However, in practice, it is difficult to carry out a large number of experiments due to the limitation of time or the possible shortage of funds. In addition, the specimens used in the experiments are not exactly the same, and the test operations and data reading depend on the accuracy of the test equipment as well as the subjective judgment of the testers, which result to the uncertainty of the S-N curve. Therefore, the uncertainty should be considered in order to improve the accuracy of the fatigue life prediction. In this paper, the uncertain factors affecting the fatigue life of welded joints are summarized, and the generalized polynomial chaos (gPC) is introduced into fatigue life prediction. A novel probabilistic fatigue life prediction method combined with the nonlinear cumulative damage model considering the uncertainty of the S-N curve is constructed. An illustrative example is presented to demonstrate the advantages of the proposed approach.

Fatigue deformation and damage characteristics of bolting system under stress-controlled cyclic pullout

This study explored the fatigue mechanical properties and acoustic emission (AE) characteristics of bolting system under cyclic pullout tests controlled by different upper stress levels. A novel compression-pull load conversion device was designed to precisely apply cyclic pullout load on bolting system. Strain gauges and AE sensors were employed to capture the surface strain variations of rock bolts and microfracture development during static and cyclic testing. The fatigue strength, deformation, axial/shear stress distributions and AE characteristics of the bolting system were comprehensively investigated. Fatigue threshold, an important value determining the service life of a bolting system, was supposed to be lower than 85% of the static strength in this study. The bolt residual slip strain curve was S-shaped and comprised three stages: the initial stage, constant-velocity stage and acceleration stage. The constant-velocity stage accounted for most of the fatigue life and was the main stage of fatigue development. The fatigue failure of the anchorage system was presumably controlled by the entire static stress–strain process, and the residual strain at fatigue failure corresponded to the peak strain at the peak stress under static loading. The anchorage fatigue damage development completely coincided with the residual strain evolution, and the turning points were identical between the different deformation stages. Based on the residual slip strain development, nonlinear inverted S-shaped cumulative fatigue damage models were proposed for different upper stress levels. A comparison of the results from different samples revealed that the damage evolution was highly dependent on the upper stress level. The fatigue life of the bolting system decreased as the upper stress level increased due to the increased steepness of the second stage and the decreased proportion of the second stage to the entire fatigue process.

Experimental study on the cumulative damage constitutive model of high-performance steel Q345GJ under cyclic loading

GJ series steel is a new type of high-performance structural steel, which has emerged in China steel construction, and it has been widely utilized in steel-framed building structures. To investigate the low cycle fatigue performance and cumulative damage behaviors and find a suitable constitutive relationship of GJ series steel under cyclic loading, a total of eighteen Q345GJ steel low cycle fatigue experiments have been carried out. The mechanical behavior of Q345GJ steel were discussed, including monotonic loading behavior, hysteresis loading behaviors and energy dissipation capacity. Based on the cyclic behavior of GJ series steel, a modified cumulative damage model was recommended. Then, with comparison of the Q345GJ tests data (including the data in public papers) under various loading systems, the model proposed in this paper is proved correct and can be used to simulate the cyclic behavior of Q345GJ members.

A cumulative fatigue damage model of polysilicon films for MEMS resonator under repeated loadings

Prior work is primarily focused on observation and analysis of experimental results of fatigue loadings, while an insightful damage model describing the evolvement of distributed micro/nano cracks before they can be readily observed is still missing. A fatigue damage model is developed to quantify the damage due to micro/nano cracking in crystalline silicon structure and the native oxide layer. From the physical point of view, the developed model links the fatigue life to average crack length, maximum applied stress, resonant frequency and stiffness. The effectiveness of the proposed damage model is verified through simulations and experimental results from previous work.

The accumulated stress damage and residual life prediction of unreinforced concrete pavement with electric heating pipes

The unreinforced concrete pavement with electric heating pipes (UCP-EHP) has been widely used to melt the snow and ice on the pavement because the melting process is easy to conduct and control. However, the stress damage caused by the internal elevated-temperature is totally different from other situations, and its cumulative effects would cause severe structural failures to the unreinforced concrete pavement. To reduce stress damage, this paper investigates the above-mentioned damage characteristics under different pavement structures and working conditions through numerical simulations and develops the cumulative stress damage model to predict the residual life of the UCP-EHP. Firstly, the numerical model of the UCP-EHP was established to investigate the stress damage caused by internal thermal stress, and then it was verified by the validation experiments. Secondly, to reduce the stress damage, the stress damage characteristics were investigated under different pavement structures and working conditions through numerical modeling. Afterward, the optimum pavement structure with minimum stress damage was recommended based on the above analysis. Finally, the cumulative stress damage prediction model was derived, and the corresponding residual life of the UCP-EHP is predicted. Based on the prediction model, the residual life ratio of the UCP-EHP can be calculated when the number of cyclic heating is within 100. The conclusions of this paper can enrich the structural design of the UCP-EHP in terms of stress damage analysis.

Improved numerical model for fatigue cumulative damage of mechanical structure considering load sequence and interaction

To more accurately predict the fatigue life of components under the action of random loads, it is necessary to explore the influence of the interaction between the load sequence and the load on the life prediction. Based on the Manson-Halford method and Corten-Dolan model, this paper establishes a fatigue cumulative damage model that takes into account both the load order and the interaction between loads, and also takes into account the loads near the fatigue limit. The fatigue life of mechanical parts under random load can be calculated through this model, which provides a theoretical basis for life prediction under random load spectrum. The fatigue life of mechanical parts under random load can be calculated through this model, which provides a theoretical basis for life prediction under random load spectrum. Comparing the calculation results of the proposed model with the results of Palmgren Miner, Manson-Halford method, and Corten-Dolan model, it is found that the fatigue damage model established can reasonably predict the fatigue life of parts. Comparison and verification of examples further prove the accuracy and reliability of the proposed model.

Remaining Useful Life Prediction on Wind Turbine Gearbox

This research proposes a methodology to estimate the reliability of gearbox using life data analysis and predict the Lifetime Use Estimation (LUE). Life data analysis involves collection of historical field replacements of gearbox and perform statistical analysis such as Weibull analysis to estimate the reliability. Remaining useful life is estimated by using Cumulative damage model and data-driven methods. The first approach is based on the physics of failure models of degradation and the second approach is based on the operational, environmental & loads data provided by the design team which is translated into a mathematical model that represent the behavior of the degradation. Data-driven method is used in this research, where the different performance data from components are exploited to model the degradation’s behavior. LUE is used to make key business decisions such as planning of spares, service cost and increase availability of wind turbine. Gearbox is the heart of the wind turbine and it is made up of several stages of helical/planetary gears. Performance data is acquired separately for each of these stages and LUE is calculated individually. The individual LUE is then rolled up to estimate the overall Lifetime Use Estimation of gearbox. This will identify the weak link which is going to fail first and the failure mode which is driving the primary failure can be identified. Finally, corrective measures can be planned accordingly. The cumulated damage and LUE are estimated by using Inverse power law damage model along with Miner’s rule.

Cumulative Damage and Life Prediction Models for High-Cycle Fatigue of Metals: A Review

Fatigue design of engineering structures is typically based on lifetime calculation using a cumulative damage law. The linear damage rule by Miner is the universal standard for fatigue design even though numerous experimental studies have shown its deficiencies and possible non-conservative outcomes. In an effort to overcome these deficiencies, many nonlinear cumulative damage models and life prediction models have been developed since; however, none of them have found wide acceptance. This review article aims to provide a comprehensive overview of the state-of-the art in cumulative damage and lifetime prediction models for endurance based high-cycle fatigue design of metal structures.