An improved nonlinear cumulative damage model for strength degradation considering loading sequence

2020 ◽  
pp. 105678952096486
Author(s):  
Changjie Jiang ◽  
Xintian Liu ◽  
Minghui Zhang ◽  
Xu Wang ◽  
Yansong Wang
Keyword(s):  
Fatigue Damage ◽  
Residual Life ◽  
Damage Model ◽  
Degradation Process ◽  
Strength Degradation ◽  
Cumulative Damage ◽  
Degradation Model ◽  
Cumulative Damage Model ◽  
Metal Materials ◽  
Loading Sequence

In order to determine the effect of different loads on fatigue damage, a strength degradation model is proposed according to the law of residual strength degradation of metal materials. The model is verified with the strength degradation test data, and the results show that the model can describe the strength degradation process of general metal materials well. Combined with the strength degradation model, an improved equivalent damage model for different loading sequences is proposed. On this basis, a nonlinear fatigue cumulative damage model based on strength degradation is derived. The cumulative damage model is applied to the estimation of fatigue residual life under two-, three-, and four-stage loads to investigate the effects of different loading sequence on fatigue damage under various loading conditions. Combining with experimental data, it is verified that the cumulative damage model can accurately estimate the fatigue life under two-, three-, and four-stage loads.

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

2021 ◽  
Author(s):  
Phalguni Nanda ◽  
Prajamitra Bhuyan ◽  
Anup Dewanji
Keyword(s):  
Damage Model ◽  
Strength Degradation ◽  
Cumulative Damage ◽  
Expected Cost ◽  
Replacement Strategy ◽  
Optimal Replacement ◽  
Poisson Arrival ◽  
Cumulative Damage Model ◽  
The Cost ◽  
Minimum Expected Cost

AbstractIn 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.

A Modified Cumulative Damage Model for Fatigue Life Prediction under Variable Amplitude Loadings

2016 ◽  
Vol 853 ◽  
pp. 62-66 ◽  
Author(s):  
Peng Yue ◽  
Qiang Lei ◽  
Cheng Lin Zhang ◽  
Shun Peng Zhu ◽  
Hong Zhong Huang
Keyword(s):  
Fatigue Damage ◽  
Life Prediction ◽  
Damage Accumulation ◽  
Damage Model ◽  
Cumulative Damage ◽  
Mean Stress ◽  
Stress Model ◽  
Proposed Model ◽  
Fatigue Damage Accumulation ◽  
Cumulative Damage Model

To evaluate the fatigue damage accumulation and predict the residual life of components at different stress levels, this paper proposed a modified cumulative damage model based on the strain energy density parameter. Noting that mean stress and load interaction under uniaxial fatigue loading exhibit significant effects on fatigue damage accumulation and life prediction. According to this, a new model based on damaged stress model which considers the effects of mean stress and load interaction was presented in this paper. The proposed model was verified by using four experimental data sets of aluminium alloys and steels. The experimental results are compared with those of the Miner’s rule, damaged stress model (DSM) and damaged energy model (DEM). Results show that the proposed model agrees better with the experimental observations than others.

A Multi-Level Low Cycle Fatigue Damage Model for Forging Die Material

2006 ◽  
Vol 514-516 ◽  
pp. 804-809
Author(s):  
S. Gao ◽  
Ewald Werner
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Low Cycle Fatigue ◽  
Damage Model ◽  
Fatigue Loading ◽  
Cycle Fatigue ◽  
Die Material ◽  
Multi Level ◽  
Loading Sequence ◽  
Forging Die

The forging die material, a high strength steel designated W513 is considered in this paper. A fatigue damage model, based on thermodynamics and continuum damage mechanics, is constructed in which both the previous damage and the loading sequence are considered. The unknown material parameters in the model are identified from low cycle fatigue tests. Damage evolution under multi-level fatigue loading is investigated. The results show that the fatigue life is closely related to the loading sequence. The fatigue life of the materials with low fatigue loading first followed by high fatigue loading is longer than that for the reversed loading sequence.

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