Assessment of crack tip plastic zone size and shape and its influence on crack tip shielding

Vasco-Olmo, J.M.; James, M.N.; Christopher, Colin; Patterson, E. A.; Díaz, F.A.

doi:10.1111/ffe.12436

Cited by 85 publications

(34 citation statements)

References 18 publications

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“…Similar data have been obtained using the displacement solution of the CJP model and DIC techniques on 25 x 24 x 1 mm Grade 5 titanium CT specimens [5] (see Fig. 4).…”

Section: Characterising Plasticity-induced Closuresupporting

confidence: 78%

“…Recent work on the CJP model has been aimed at investigating how it might characterise the growth of inclined cracks subject to biaxial loading [4], comparing its ability to characterise plastic zone size and shape with that of the Williams and Westergaard models of elastic crack tip stresses [5], and with a comparison of the interpretation of plasticity-induced closure obtained from trends observed in K R and K F with values obtained via traditional strain gauge determination. This paper will briefly review some of this work, in particular the ability of the CJP model to characterise plasticity-induced fatigue crack closure.…”

Section: Introductionmentioning

confidence: 99%

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Interpretation of Plasticity Effects Using the CJP Crack Tip Field Model

James

Christopher

Garrido

et al. 2016

SSP

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This paper will outline the development of a model of crack tip fields that represents an innovation in incorporate the influences on crack tip displacement and stress fields of the zone of local plasticity that envelops a growing fatigue crack. The model uses assumed distributions of elastic stresses induced at the elastic-plastic boundary via wake contact and compatibility requirements, and defines a set of modified elastic stress intensity factors to characterise the crack stress or displacement tip field. In particular, recent work will be presented that compares the interpretation of plasticity-induced shielding obtained from trends observed in K R and K F with values of so-called 'crack closure' obtained via traditional strain gauge determination.

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“…Similar data have been obtained using the displacement solution of the CJP model and DIC techniques on 25 x 24 x 1 mm Grade 5 titanium CT specimens [5] (see Fig. 4).…”

Section: Characterising Plasticity-induced Closuresupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Interpretation of Plasticity Effects Using the CJP Crack Tip Field Model

James

Christopher

Garrido

et al. 2016

SSP

View full text Add to dashboard Cite

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“…COD measurements obtained with high magnification DIC were used to evaluate crack growth and closure mechanisms for different thicknesses on 6082T6 aluminium alloy . The plastic zone ahead of the crack as a way to control the rate of crack growth was assessed with DIC on specimens with artificial cracks and on specimens with real fatigue cracks . In this work, we show for the first time a DIC methodology for continuous monitoring of the effective SIF under a range of different cyclic loads.…”

Section: Introductionmentioning

confidence: 99%

Stress intensity factor monitoring under cyclic loading by digital image correlation

Mokhtarishirazabad

López-Crespo

Zanganeh

2018

Fatigue Fract Eng Mat Struct

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In the present work, a methodology for structural health monitoring based on a combination of digital image correlation and an analytical elastic solution is presented. To this end, full‐field displacement around a crack tip in a CT sample made of 2024‐T351 Al alloy under cyclic loading was monitored at different load levels. An analytical solution based on Williams' model was used to evaluate the experimental value of the stress intensity factor (SIF) in a continuous fashion during cyclic loads. It was observed that by increasing the loading amplitude in the cyclic loading, the difference between nominal and experimental estimation of SIF increased due to the crack tip plasticity effect, which was not considered in the nominal evaluations. To consider the plasticity effect, Irwin's approach was employed. The results showed that the proposed method can successfully monitor the evolution of SIF of a sample under cyclic loading until the sudden fracture of the sample.

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“…When an elastic-plastic body with crack is subjected to load, the crack tip will produce a plastic zone. J M VascoOlmo [32] used DIC technique to quantitatively characterize the shape and size of the plastic zone at the crack tip of pure titanium. Firstly, the displacement and strain fields of crack tip region are obtained by DIC method, and the stress field is obtained according to generalized Hooke law.…”

Section: Determination Of Crack Tip Plastic Zone Based On Dicmentioning

confidence: 99%

Deformation Fields Measurement of Crack Tip under High‐Frequency Resonant Loading Using a Novel Hybrid Image Processing Method

Gao

Zhang

Jiang

et al. 2018

Shock and Vibration

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A novel hybrid image processing method is proposed to obtain the crack tip location, crack propagation path, displacement, strain fields, and plastic zone size of crack tip region under high-frequency resonant loading in this paper. An ordinary CCD camera is used to collect a series of crack images on one side of the compact tension (CT) specimen; meanwhile, a high-speed digital camera is used to acquire a series of digital speckle images of the other side of the specimen under the loading conditions at regular time intervals. Digital image processing (DIP) method is used to determine the macroscopic crack position. Digital image correlation (DIC) method is applied to obtain the displacement, strain fields, and plastic zone size of crack tip region. The characteristic digital speckle images of one stress cycle are obtained by data fitting and image matching method. Accordingly, the displacement/strain fields of crack tip region within one stress cycle and the displacement and strain amplitude fields with different crack lengths are obtained and analyzed. The obtained results are compared with the measured results of ordinary methods and show a good match. The success of this method will help to obtain better insight into and understanding of the fatigue and failure behavior of metal material with mode I crack under high-frequency resonant loading.

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Assessment of crack tip plastic zone size and shape and its influence on crack tip shielding

Cited by 85 publications

References 18 publications

Interpretation of Plasticity Effects Using the CJP Crack Tip Field Model

Interpretation of Plasticity Effects Using the CJP Crack Tip Field Model

Stress intensity factor monitoring under cyclic loading by digital image correlation

Deformation Fields Measurement of Crack Tip under High‐Frequency Resonant Loading Using a Novel Hybrid Image Processing Method

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