Fracture mechanics as a tool in failure analysis — Prospects and limitations

Zerbst, Uwe; Klinger, Christian; Clegg, Richard

doi:10.1016/j.engfailanal.2015.07.001

Cited by 50 publications

(19 citation statements)

References 41 publications

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“…[40] and Figure 32 in Ref. [41], where a stretch region is presented). Diffusion creep is identified as the main creep mechanism for creep-fatigue damage in the present work.…”

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confidence: 97%

“…A defected-related state, such as intrinsic defects, around the crack tip may also promote crack growth (negative to fatigue resistance), where the weakest zone of atomic bonds is represented. An example of presenting a defected-related effect is shown in Figure 32 from [41], where the crack is promoted due to void coalescence and the bridges between voids are sheared off. In addition, precipitates may also be considered to be defected-related effects, but ones which are normally beneficial to fatigue resistance.…”

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confidence: 99%

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Crack Propagation Mechanisms for Creep Fatigue: A Consolidated Explanation of Fundamental Behaviours from Initiation to Failure

Liú

Pons

2018

Metals

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Background-Creep-fatigue damage is generally identified as the combined effect of fatigue and creep. This behaviour is macroscopically described by crack growth, wherein fatigue and creep follow different principles. Need-Although the literature contains many studies that explore the crack-growth path, there is a lack of clear models to link these disparate findings and to explain the possible mechanisms at a grain-based level for crack growth from crack initiation, through the steady stage (this is particularly challenging), ending in structural failure. Method-Finite element (FE) methods were used to provide a quantitative validation of the grain-size effect and the failure principles for fatigue and creep. Thereafter, a microstructural conceptual framework for the three stages of crack growth was developed by integrating existing crack-growth microstructural observations for fatigue and creep. Specifically, the crack propagation is based on existing mechanisms of plastic blunting and diffusion creep. Results-Fatigue and creep effects are treated separately due to their different damage principles. The possible grain-boundary behaviours, such as the mismatch behaviour at grain boundary due to creep deformation, are included. The framework illustrates the possible situations for crack propagation at a grain-based level, particularly the situation in which the crack encounters the grain boundary. Originality-The framework is consistent with the various creep and fatigue microstructure observations in the literature, but goes further by integrating these together into a logically consistent framework that describes the overall failure process at the microstructural level.

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“…[40] and Figure 32 in Ref. [41], where a stretch region is presented). Diffusion creep is identified as the main creep mechanism for creep-fatigue damage in the present work.…”

mentioning

confidence: 97%

mentioning

confidence: 99%

Crack Propagation Mechanisms for Creep Fatigue: A Consolidated Explanation of Fundamental Behaviours from Initiation to Failure

Liú

Pons

2018

Metals

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“…A review of the emergence of fracture mechanics in failure analysis projects is comprehensively attempted in [37]. It is noteworthy that the utilization of fracture mechanics in FA creates some issues related with conservatism, originating mainly from different sources, such as uncertainties and a lower number of data, critical stress intensity factor estimation (K Ic ), and the consideration of an extremely sharp crack tip size (zero-tip radius).…”

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confidence: 99%

A Short Review on Fracture Mechanisms of Mechanical Components Operated under Industrial Process Conditions: Fractographic Analysis and Selected Prevention Strategies

Pantazopoulos¹

2019

Metals

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An insight of the dominant fracture mechanisms occurring in mechanical metallic components during industrial service conditions is offered through this short overview. Emphasis is given on the phenomenological aspects of fracture and their relationships with the emergent fracture mode(s) with respect to the prevailed operating parameters and loading conditions. This presentation is basically fulfilled by embracing and reviewing industrial case histories addressed from a technical expert viewpoint. The referenced case histories reflected mainly the author's team expertise in failure analysis investigation. As a secondary perspective of the current study, selected failure investigation and prevention methodological approaches are briefly summarized and discussed, aiming to provide a holistic overview of the specific frameworks and systems in place, which could assist the organization of risk minimization and quality enhancement.

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“…Mechanics approach. An improved joint design can be achieved allowing for possible fabrication 85 defects by, for example, specifying larger thicknesses, higher toughness steels, post weld heat 86 treatment, etc (Zerbst et al, 2015). 87 New welding processes: There are always efforts to improve structural resistance, fabrication 88 efficiency and weld quality by developing and implementing new welding technologies.…”

Section: Introduction 28mentioning

confidence: 99%

A fracture mechanics framework for optimising design and inspection of offshore Wind Turbine support structures against fatigue failure

Amirafshari¹,

Brenan²,

Kolios³

2020

Preprint

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Abstract. Offshore Wind Turbine (OWT) support structures need to be designed against fatigue failure under cyclic aerodynamic and wave loading. The fatigue failure can be accelerated in a corrosive sea environment. Traditionally, a stress-life approach called the S-N curve method has been used for design of structures against fatigue failure. There are a number of limitations in S-N approach related to welded structures which can be addressed by the fracture mechanics approach. In this paper the limitations of the S-N approach related to OWT support structure are addressed, a fatigue design framework based on fracture mechanics is developed. The application of the framework to a monopile OWT support structure is demonstrated and optimisation of in-service inspection of the structure is studied. It was found that both the design of the weld joint and Non-destructive testing techniques can be optimised to reduce In-service frequency. Furthermore, probabilistic fracture mechanics as a form of risk-based design is outlined and its application to the monopile support structure is studied. The probabilistic model showed to possess a better capability to account for NDT reliability over a range of possible crack sizes as well as providing a risk associated with the chosen inspection time which can be used in inspection cost benefit analysis. There are a number of areas for future research. including better estimate of fatigue stress with a time-history analysis, the application of framework to other types of support structures such as Jackets and Tripods, and integration of risk-based optimisation with a cost benefit analysis.

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Fracture mechanics as a tool in failure analysis — Prospects and limitations

Cited by 50 publications

References 41 publications

Crack Propagation Mechanisms for Creep Fatigue: A Consolidated Explanation of Fundamental Behaviours from Initiation to Failure

Crack Propagation Mechanisms for Creep Fatigue: A Consolidated Explanation of Fundamental Behaviours from Initiation to Failure

A Short Review on Fracture Mechanisms of Mechanical Components Operated under Industrial Process Conditions: Fractographic Analysis and Selected Prevention Strategies

A fracture mechanics framework for optimising design and inspection of offshore Wind Turbine support structures against fatigue failure

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