Predicting high cycle fatigue life with unified mechanics theory

Lee, Hsiao Wei; Basaran, Cemal

doi:10.1016/j.mechmat.2021.104116

Cited by 25 publications

(10 citation statements)

References 55 publications

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“…Under normal low-frequency tension-compression loading, the strain rate for high-cycle fatigue of DP600 steel is much lower than the transition strain rate over the entire stress amplitude range. Therefore, it is predicted that the deformation will take place in the athermal region, where slip bands in ferrite grains will be formed, causing a local stress and strain concentration that would initiate trans-granular cracks and, eventually, surface failure [62].…”

Section: Microstructural Mechanisms Of Fatigue Crack Initiationmentioning

confidence: 99%

“…Features at the micrometer length scale are often crucial, such as for microstructurally sensitive processes involved in fracture nucleation. This degree of detail is required to anticipate component performance [62]. Figure 4 shows the characteristic by using of scanning electron microscopy (SEM) micrographs of the area, and the results of the high-angular resolution electron backscatter diffraction technique (HR-EBSD) study show that changes in surface topography are microstructurally sensitive due to the evolution of surface slip and shear along the twin boundaries (revealing a stepped morphology with a frequency related to the twin structure), and that these features are observed after only two cycles.…”

Section: Microstructural Mechanisms Of Fatigue Crack Initiationmentioning

confidence: 99%

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Prediction of Fatigue Crack Initiation under Variable Amplitude Loading: Literature Review

Kedir

Lemu

2023

Metals

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Metallic materials are widely employed in engineering constructions, and one of the most common failure mechanisms in metals is fatigue failure. Even though metal fatigue has been studied for almost 160 years, many problems remain unsolved. Fatigue in metal occurs when the metallic material is subjected to varying loads, resulting in failure due to damage accumulation. The fatigue process consists of a buildup of damage that leads to crack initiation, followed by a period of crack growth until the critical flaw size is reached. The sum of a start phase and a propagation phase represents the total life. To better understand the fatigue phenomenon at its different stages and predict the fatigue life, various types of prediction models have been developed and reported in the literature. This paper reviewed the different models that include microstructure scale parameters that can be used to predict how fatigue cracks start under variable amplitude loading, including the Modified Tanaka-Mura Model, Acoustic Second Harmonic Generation, and the Probability of Crack Initiation on Defects. For perfect life prediction under variable amplitude loading, a stress-based approach, a strain-based approach, and a continuum damage mechanics approach are reviewed. The purpose of this paper is to get overview of the current state of approaches to the life prediction of fatigue crack initiation with variable amplitude. Finally, gaps in knowledge about the prediction of fatigue crack initiation under variable loading at high temperatures are pointed out.

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Section: Microstructural Mechanisms Of Fatigue Crack Initiationmentioning

confidence: 99%

Section: Microstructural Mechanisms Of Fatigue Crack Initiationmentioning

confidence: 99%

Prediction of Fatigue Crack Initiation under Variable Amplitude Loading: Literature Review

Kedir

Lemu

2023

Metals

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“…[34][35][36][37] On the other hand, some materials exhibit a high thermal conductivity, dissipating heat rapidly, which prevents a significant temperature rise. For these cases, entropy generation must be correlated with the microstructure of the material 34,38,39 through techniques such as lockin thermography or digital image correlation. Otherwise, the constant accumulation of entropy during a fatigue process would remain as a hypothesis only.…”

Section: Introductionmentioning

confidence: 99%

Comparative evaluation of fatigue life estimation under variable amplitude loading through damage models based on entropy

Rodríguez‐Reyes,

Abúndez‐Pliego,

Petatan‐Bahena

et al. 2024

Fatigue Fract Eng Mat Struct

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Three fatigue damage models based on entropy, originally developed for constant amplitude loading, were assessed and compared to each other aimed at stating whether its applicability can be extended towards variable amplitude loading conditions. A variable amplitude loading history, applied on a 2024‐T3 aluminum alloy reported in the literature, was processed using both rainflow cycle counting and spectral techniques to transform it into a distribution of simple processes with constant amplitudes, then the damage models were assessed under the new loading conditions. The results showed that the model by Khonsari, combined with the rainflow technique, exhibited the highest accuracy with regard to the referenced experimental results with a −0.67 standard deviation from the average data and a 16% error from the median. Therefore, it is possible to assess the fatigue damage accumulation in metallic materials under variable amplitude loading through a thermodynamic approach with models developed for constant amplitude loading.

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“…If one indeed speaks in a general manner about fatigue testing of a component or entire structure, whether subjected to monotonic cyclic loads or random vibrations, different methodologies are currently employed for the fatigue assessment [1,2]. For instance, the modern unified mechanics theory is used to derive a constitutive model for fatigue life prediction using a three-dimensional computational model [3,4].…”

Section: Introductionmentioning

confidence: 99%

Application of the Theory of Critical Distance (TCD) to the Breakage of Cardboard Cutting Blades in Al7075 Alloy

Morettini,

Landi,

Burattini

et al. 2024

Metals

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The study presented in this paper was undertaken in response to two instances of unexpected blade breakage in the cutting blade used in a Carton Wrap machine (CW). Failure of the Al7075 alloy blade occurred at an indentation during typical operational loading conditions. Subsequent metallographic examinations of the fractured samples confirmed that both cases were attributed to fatigue failure. The main objective of this study is to investigate potential causes of fatigue failure in the CW blade using simplified linear elastic static numerical simulations through Finite Element Analysis (FEA). In this research, we employed the well-established Theory of Critical Distance (TCD), and this case study provided a contextualization at an industrial level. Furthermore, the analysis focused on a second key aspect: proposing a new blade geometry aimed at mitigating the identified issues and eliminating possible causes of failure. In this context, the actual stress concentration at the indentation was determined using the TCD with Line Method (LM). The results from the numerical simulations indicated that the new blade geometry significantly reduced stress concentration, resulting in a risk factor reduction of approximately four compared to the original blade design, even under non-optimal operating conditions. Overall, in conjunction with simple linear static FEA, the proposed numerical approach provided substantial support for designers, especially in fault analysis and when comparing different industrial solutions.

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Predicting high cycle fatigue life with unified mechanics theory

Cited by 25 publications

References 55 publications

Prediction of Fatigue Crack Initiation under Variable Amplitude Loading: Literature Review

Prediction of Fatigue Crack Initiation under Variable Amplitude Loading: Literature Review

Comparative evaluation of fatigue life estimation under variable amplitude loading through damage models based on entropy

Application of the Theory of Critical Distance (TCD) to the Breakage of Cardboard Cutting Blades in Al7075 Alloy

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