Characteristics of fatigue crack propagation behaviour as identified by hysteresis loop at the crack tip

Xiong, Ying; Katsuta, Junichi; Kawano, K.; Sakiyama, T.

doi:10.1111/j.1460-2695.2006.01016.x

Cited by 6 publications

(3 citation statements)

References 15 publications

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“…2. For the measurement result, a hysteresis loop is calculated by subtracting the unloading elastic strain from the fatigue crack tip strain 25 . From the above results, it is observed that there are two types of hysteresis loop patterns show in Fig.…”

Section: Test Methods and Resultsmentioning

confidence: 99%

“…Using a high‐precision load cell and a digital dynamic strain meter as well as self‐design program, strains both near the crack tip and on the back face and load are measured within 1 msec. In the fatigue test, three steps that are automatically carried out by a program are sampling data ( P and ɛ), smoothing compliance curve and calculating the hysteresis loop during the test 25 . The test process is monitored and recorded by a computer.…”

Section: Test Methods and Resultsmentioning

confidence: 99%

“…In the fatigue test, three steps that are automatically carried out by a program are sampling data (P and ε), smoothing compliance curve and calculating the hysteresis loop during the test. 25 The test process is monitored and recorded by a computer. Fatigue crack length is measured by the bake face strain (BFS) method.…”

Section: Test Materials and Conditionsmentioning

confidence: 99%

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Examination of fatigue crack driving force parameter

Xiong

Katsuta

Kawano

et al. 2008

Fatigue Fract Eng Mat Struct

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A B S T R A C T Most of the previous parameters that utilized as a crack driving force were established in modifying the parameter K op in Elber's effective SIF range K eff ( = K max − K op ). However, the parameters that replaced the traditional parameter K op were based on different measurements or theoretical calculations, so it is difficult to distinguish their differences. This paper focuses on the physical meaning of compliance changes caused by plastic deformation at the crack tip; the tests were carried out under different amplitude loading for structural steel. Based on these test results, differences of several parameter K eff in literature are analysed and an improved two-parameter driving force K drive ( =(K max ) n ( K ∧ ) 1−n ) has been proposed. Experimental data for several different types of materials taken from literature were used in the analyses. Presented results indicate that the K drive parameter was equally effective or better than K(=K max − K min ), K eff (=K max − K op ) and K * ( = (K max ) α ( K + ) 1−α ) in correlating and predicting the R-ratio effects on fatigue crack growth rate. BCAL = block constant amplitude loading BFS = back face strain CAL = constant amplitude loading CPLM = crack growth load measurement K * = two-parameter crack driving force k = unified two-parameter crack driving force K + = tensile part of the stress intensity range K = applied SIF range K appl = applied stress intensity range K CF = stress intensity factor range corresponding to P CF ( = P max − P CF ) K CF , P CF = stress intensity factor corresponding to P CF , crack flanks contact load K cl , P cl = closure stress intensity factor, closure load K drive = improved two-parameter crack driving force K eff,th , K th = the effective or threshold stress intensity factor range K max,appl = applied maximum stress intensity factor K max,tot = resultant maximum stress intensity factor K max , P max = maximum stress intensity factor, maximum load K min,act = actual stress intensity transmitted to the crack tip at externally applied stress 754

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Section: Test Methods and Resultsmentioning

confidence: 99%

Section: Test Methods and Resultsmentioning

confidence: 99%

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Examination of fatigue crack driving force parameter

Xiong

Katsuta

Kawano

et al. 2008

Fatigue Fract Eng Mat Struct

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Fatigue behaviour of reinforcing steel under going corrosion

Gehlen¹,

Weirich²

2011

Materialwissenschaft Werkst

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In der 2001 grundlegend überarbeiteten Version der DIN 1045-1, vgl. hierzu auch [1], ist erstmalig ein expliziter Nachweis gegen Ermüdung, d. h. ein Betriebsfestigkeitsnachweis, verankert worden. Eine Dauerschwingfestigkeit ab einer Schwingspielzahl von zwei Mio. Lastwechseln, so wie sie noch bis vor wenigen Jahren im Bauwesen üblich war, ist nicht mehr gebräuchlich. Der Einfluss von Korrosion auf das Ermüdungsverhalten wurde bisher nur unzureichend untersucht. Er kann damit als noch nicht hinreichend abgeklärt gelten. Um in diesem Bereich den Kenntnisstand zu erweitern, wurde ein Forschungsprogramm aufgelegt, in dem Dauerschwingversuche an Stahlproben u. a. mit einem Durchmesser von 16 mm unter gleichzeitig wirkender korrosiver Beanspruchung durchgeführt wurden. Insgesamt vier unterschiedliche korrosive Medien wurden überprüft. Es zeigte sich, wie erwartet, dass die Wöhler-Linien, die sich aus den Dauerschwingversuchen ergeben, expositionsbedingt recht unterschiedliche Verläufe aufweisen. Aus werkstofftechnologischer Sicht, interessierte dazu die Fragestellung, inwieweit die Anteile der Risseinleitung-und Rissausbreitungsphase expositionsabhängig getrennt voneinander erfasst werden können. Diesbezüglich kamen verschiedene Prüfverfahren zur Risserkennung zum Einsatz, die sich insbesondere bezüglich ihrer Methodik unterschieden. Im Aufsatz wird der Einsatz der verwendeten Prüfmethoden zur Risserkennung kurz geschildert, die Dauerschwingversuche mit den korrosiven Medien erläutert und beschrieben, sowie deren Ergebnisse diskutiert. Schlüsselwörter: Betonstahl / Ermüdung / Korrosion /In the 2001 completely revised version of DIN 1045-1 for the first time an explicit proof against fatigue, more a fatigue analysis, have been published. A limit on the fatigue strength at two million cycles, as it was formerly common in civil engineering, is no longer in use. The influence of corrosion on the fatigue behaviour has been investigated insufficiently. It is thus not satisfyingly clarified. To fill this gap of knowledge, a research program was launched, in which fatigue tests at steel samples with a diameter of 16 mm were performed under going corrosion. The fatigue behaviour of the reinforcing steel was determined for four different corrosive media. The aim of the investiagtions was to show that the SN lines, which are the result of the fatigue tests, have exposure caused very different patterns. On the other hand it is examined, whether crack initiation and crack growth of the steel specimen can be recorded separately from each other. Therefore, different testing methods for crack detection were used. They differ especially with respect to their methodology. The article briefly describes the use of the testing methods for crack detection, explains the fatigue tests with the different corrosive liquids and discusses the test results.

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