The potential drop method for monitoring crack growth in real components subjected to combined fatigue and creep conditions: application of FE techniques for deriving calibration curves

Gandossi, L; Summers, Steve; Taylor, Nigel; Hurst, Roger Christopher; Hulm, Belinda J.; Parker, J.D.

doi:10.1016/s0308-0161(01)00103-x

Cited by 37 publications

(24 citation statements)

References 6 publications

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“…Direct methods are based on measuring the crack length visually, optically, or by employing X‐ray radiographic testing, while indirect crack length measurements are based on monitoring a change in a physical or mechanical property of the material due to the extension of the crack. For example, the change in the material electric resistance or material stiffness, due to crack growth, has led to the development of electrical potential technique and the compliance methods for crack growth measurement, respectively. In the same manner, other methods such as infrared and thermal testing, acoustic emission, eddy current, and ultrasonic have been successfully employed to monitor the defect size.…”

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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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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“…Some investigated the relationship between potential drop as a function of crack size by performing FEA [20,21]. The detectability of cracks in the pipe using DCPD was also predicted by FEA [22].…”

Section: Validation Of Esap-dcpd Against Theoretical Solution and Finmentioning

confidence: 99%

On-Line Monitoring of Environment-Assisted Cracking in Nuclear Piping Using Array Probe Direct Current Potential Drop

et al. 2015

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A direct current potential drop method utilizing array probes with measurement ends maintaining an equalized potential designated as equi-potential switching array probe direct current potential drop (ESAP-DCPD) technique has been developed earlier at Seoul National University. This paper validates ESAP-DCPD technique by showing consistency among experimental measurements, analytical solution and numerical predictions using finite element analysis (FEA) of electric field changes with crack growth in metals. In order to examine its viability as an on-line monitoring of environment assisted crack growth at the inner surface of piping welds, artificial inner surface cracks were introduced in a full-scale weldment mockup pipe and stainless steel metal mockup pipe. The weldment was joined by low alloy steel and stainless steel pipes. The pipes were monitored by using ESAP-DCPD in laboratory environments. Optimization of electrical wiring configuration has produced results with significantly reduced noise for adequately long period of time. Then optimized experimental results were compared with the FEA prediction results for the mockup to show a good agreement. Also a round-robin measurement has been made at three laboratories. It has been found that the developed ESAP-DCPD can detect circumferential cracks with a depth of 40 % of wall thickness in stainless steel with a good detectability for further growth behaviors. For axial cracks, however, the measurements showed poor detectabil-B J. Y. Yoon

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“…The numerical calibration by using the 2-D or 3-D finite element method also offers multiple advantages and has been used in many cases for fatigue tests with particular geometries or loading conditions [29][30][31]. This method, however, is not adapted to our testing conditions due to the contact configuration where the fretting pad conducts part of the current.…”

Section: Principle Of the Potential Drop Techniquementioning

confidence: 99%

Characterization of crack nucleation in TA6V under fretting–fatigue loading using the potential drop technique

Meriaux

Fouvry

Kubiak

et al. 2010

International Journal of Fatigue

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In this work, the crack nucleation under fretting and fretting fatigue loading was investigated experimentally on a Ti-6Al-4V alloy. The geometry considered is a cylinder on flat contact in stick slip conditions. A new dual actuator fretting fatigue device was presented and an original interrupted test expertise methodology was proposed. In order to quantify the crack nucleation, the fretting fatigue set-up was equipped with a potential drop technique device. A proper calibration, presented in this paper, allowed a crack nucleation detection threshold of 50 µm with an error threshold of 10% at the maximum. Three parallel studies have been carried out: fretting loading tests (optical expertise), fretting fatigue test for a lifetime of 100 000 (optical expertise) and fretting fatigue interrupted tests (potential drop technique).These tests have shown that the addition of a fatigue load can provide a fall of 45% of the tangential threshold of crack nucleation compared to simple fretting loading. It has been identified that the crack nucleation is influenced by the fretting and the fatigue forces in two ways: increasing the fatigue load leads to a decrease of the tangential force nucleation threshold whereas raising the fretting load leads to a decrease of the nucleation and fracture fatigue lifetime. All tests curried out with the potential drop technique system have shown that this technique is very efficient in the case of a fretting fatigue test.

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The potential drop method for monitoring crack growth in real components subjected to combined fatigue and creep conditions: application of FE techniques for deriving calibration curves

Cited by 37 publications

References 6 publications

Stress intensity factor monitoring under cyclic loading by digital image correlation

Stress intensity factor monitoring under cyclic loading by digital image correlation

On-Line Monitoring of Environment-Assisted Cracking in Nuclear Piping Using Array Probe Direct Current Potential Drop

Characterization of crack nucleation in TA6V under fretting–fatigue loading using the potential drop technique

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