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1

On the Estimation of Fatigue Crack Initiation Life of H62 Brass

Zheng M., Zhang S., Peng Xiao Jian, Wang Yi

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 1

31--35

EN

In the present paper, the excavation of the energetic approach that estimates the fatigue crack initiation life of metal is conducted for H62 brass. The benefit of the energetic approach is the division of the actual applied strain range Δε into two parts, that is, a damage strain range Δεd that induces fatigue damage within the metal, and an undamaged strain range Δεc, which does not produce fatigue damage of the metal and corresponds to theoretical strain fatigue limit. The brightness of this approach is that the undamaged strain range Δεc can be estimated by the fundamental conventional parameters of metal in tensile test. The result indicated that the fatigue crack initiation life of H62 brass can be estimated by this approach successfully.

2

Experimental analysis and modelling of fatigue crack initiation mechanisms

Ustrzycka A., Mróz Z., Kowalewski Z. L.

Journal of Theoretical and Applied Mechanics

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2017

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Vol. 55 nr 4

1443--1448

EN

The present work is devoted to simulation of fatigue crack initiation for cyclic loading within the nominal elastic regime. It is assumed that damage growth occurs due to action of mean stress and its fluctuations induced by crystalline grain inhomogeneity and the free boundary effect. The macrocrack initiation corresponds to a critical value of accumulated damage. The modelling of damage growth is supported by Electronic Speckle Pattern Interferometry (ESPI) apparatus using coherent laser light.

3

Badania inicjacji i propagacji pęknięć zmęczeniowych próbek krzyżowych w stali 18G2A

Karolczuk A., Lachowicz C. T., Rozumek D., Słowik J.

Zeszyty Naukowe Politechniki Świętokrzyskiej. Nauki Techniczne

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2007

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Z. 4

53-55

PL

Praca zawiera wyniki badań eksperymentalnych dotyczące wyznaczania liczby cykli do inicjacji oraz rozwoju pęknięć zmęczeniowych w próbkach krzyżowych. Próbki krzyżowe wykonano ze stali 18G2A z koncentratorem naprężeń w postaci centralnego otworu o trzech średnicach (d = 2,4; 2,5; 3 mm). Próbki zostały przebadane na stanowisku MZPK100, którego konstrukcja oraz system sterowania zostały opracowane przez Katedrę Mechaniki i Podstaw Konstrukcji Maszyn Politechniki Opolskiej. Stanowisko MZPK100 umożliwia prowadzenie badań przy kontroli sił (Fx, Fy) oraz utrzymania stałego położenia punktu przecięcia kierunków działania sił w osiach próbki.

EN

The paper presents the experimental results concerning fatigue life to crack initiation and crack growth in the cruciform specimens. The specimens made of 18G2A steel with stress concentrator in shape of central hole of three diameters (d = 2.4, 2.5, 3.0 mm) were used. Biaxial fatigue tests were performed under antiphase sinusoidal loading with forces control applied to the specimen arms. Depending on loading level different numbers of fatigue cracks with different behaviours were observed.

4

Probabilistic micromechanical description of fatigue crack initiation

Sobczyk K., Spencer B., Trębicki J.

Archives of Mechanics

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2000

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Vol. 52, nr 4-5

761-777

EN

In this paper the Mura-Nakasone model for fatigue crack initiation is extended to the situation where randomness in material microstructure (e.g. in grain size) and in the applied stress are important factors. The analysis and formulae presented provide a quantitative characterization of the effect of statistical scatter in grain size of the metals on the crack initiation time. Also, crack initiation time is analyzed for the situation where the applied stress is a narrow-band stationary stochastic process. The mean value, variance and probability distribution of the time to crack initiation are derived, and the results are illustrated graphically for real empirical data.