Algorithms for the estimation of fatigue crack growth using energy method

Szata, M.; Lesiuk, Grzegorz

doi:10.1016/s1644-9665(12)60045-4

Cited by 26 publications

(23 citation statements)

References 2 publications

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“…In comparison to the force approach and K basis in fatigue fracture diagrams, the CTOD is more sensitive for degradation changes in kinetics of fatigue crack growth in the puddled steel. In the light of the experimental results and deliberations in the works [7][8][9], it seems that energy description for the fatigue crack growth rate and microstructural degradation influence is a promising approach. …”

Section: Discussionmentioning

confidence: 99%

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Kinetics of fatigue crack growth and crack paths in the old puddled steel after 100-years operating time

Lesiuk

Szata

2015

Frattura Ed Integrità Strutturale

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ABSTRACT. The goal of the authors' investigations was determination of the fatigue crack growth in fragments of steel structures (of the puddled steel) and its cyclic behavior. Tested steel elements coming from the turn of the 19 th and 20 th were gained from still operating ancient steel construction (a main hall of Railway Station, bridges etc.). This work is a part of investigations devoted to the phenomenon of microstructural degradation and its potential influence on their strength properties. The analysis of the obtained results indicated that those long operating steels subject to microstructure degradation processes consisting mainly in precipitation of carbides and nitrides inside ferrite grains, precipitation of carbides at ferrite grain boundaries and degeneration of pearlite areas [1,2]. It is worth noticing that resistance of the puddled steel to fatigue crack propagation in the normalized state was higher. The authors proposed the new kinetic equation of fatigue crack growth rate in such a steel. Thus the relationship between the kinetics of degradation processes and the fatigue crack growth rate also have been shown. It is also confirmed by the materials research of the viaduct from 1885, which has not shown any significant changes in microstructure. The non-classical kinetic fatigue fracture diagrams (KFFD) based on deformation () or energy (W) approach was also considered. In conjunction with the results of low-and high-cycle fatigue and gradual loss of ductility as a consequence (due to the microstructural degradation processes) -it seems to be a promising construction of the new kinetics fatigue fracture diagrams with the energy approach.

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Section: Discussionmentioning

confidence: 99%

“…In several studies (i.e. [7,8,9]), the relationship between low-cycle fatigue properties and the kinetics of fatigue crack growth in metals has been proposed. The base of consideration is always the dissipated energy during the cyclic loading.…”

Section: Fatigue Crack Growth Rate and Analytical Descriptionmentioning

confidence: 99%

Kinetics of fatigue crack growth and crack paths in the old puddled steel after 100-years operating time

Lesiuk

Szata

2015

Frattura Ed Integrità Strutturale

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“…The tested rotor is made of the AISI 416 (EN X12Crl3) stainless steel, for which the following parameters are assumed C = 2x 10-", m = 3, and A/fu, = 9.15 MPa [41]. Note that Eq.…”

Section: Ak -mentioning

confidence: 99%

“…Here, diag(v) denotes the diagonal matrix with the components of vector v on the main diagonal. The stiffness/damping coefficients of tapered elements (3,4,40,41) are calculated by replacing each element with six prismatic elements of equal length and gradually decreasing diameter, as it is recommended in Refs. [33] and [34].…”

Section: Introductionmentioning

confidence: 99%

New Finite Element Modeling Approach of a Propagating Shaft Crack

Kulesza

Sawicki

2013

Journal of Applied Mechanics

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Transverse shaft cracks are one of the most dangerous malfunctions of the rotating machines, including turbo-and hydrogenerators, high-speed machine tool spindles, etc. The undetected crack may grow slowly and not disturb normal machine operation. However, if it extends to a critical depth, the immediate shaft fracture may completely damage the machine, resulting in a catastrophic accident. Therefore, in-depth knowledge of the crack propagation process is essential to ensure reliable and safe operation of rotating machinery. The article introduces a new model of the propagating shaft crack. The approach is based on the rigid finite element (RFE) method, which has previously proven its effectiveness in the dynamical analysis of numerous complicated machines and structures. The crack is modeled using several dozen spring-damping elements (SDEs), connecting the faces of the cracked section of the shaft. By controlling the exact behavior of individual SDEs, not only the breathing mechanism, but also the crack propagation process can be simply introduced. In order to accomplish this, the stress intensity factors (SIFs) along the crack edge are calculated using the novel approach based on the modified virtual crack closure technique (VCCT). Based on the SÍF values, the crack propagation rate is calculated from the Paris law. If the number of load cycles is greater than the constantly updated threshold number, then the crack edge is shifted by a small increment. This way, starting from the first initially cracked SDE, the crack is extended little by little, continuously changing its shape. The approach is illustrated with numerical results, demonstrating the changes in the rotor vibration response and in the crack shape and also explaining some issues about the breathing mechanism due to the propagating shaft crack. The increasing amplitude of the 2X harmonic component is recognized as an evident propagating crack signature. The numerical results correspond well with the data reported in the literature. The REE model of the rotor is validated by comparing the vibration responses obtained experimentally and numerically. A good agreement between these data confirms the correctness and accuracy of the proposed model. The suggested approach may be utilized for a more reliable dynamic analysis of the rotating shafts, having the potential to experience propagating transverse cracks.

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“…The logical symbiosis of stress and strain approaches is energy one [17][18][19][20]. The known parameters of the last are based on the area of the hysteresis loop and, in relation to the fatigue of materials, are studied in detail for smooth specimens.…”

Section: Introductionmentioning

confidence: 99%

The diagnostics and ways heat treatment optimization of a railway wheels steel

Vira¹,

Kulyk²,

Chepil³

et al. 2019

Diagnostyka

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A high resolution sensor of linear displacements has been elaborated for diagnosing the size of the crack tip opening in standard test specimens. Based on the data measured during fatigue crack growth resistance tests of a wheel steel heat treated after various modes, calculations of the strain and energy parameters of local fracture were performed for the corresponding variants of treatment, and fatigue crack growth rate diagrams were constructed using different approaches of fatigue fracture mechanics. It was established that the diagrams obtained using the strain and energy approaches are more sensitive to material microstructure and its mechanical properties than the traditional diagrams obtained using the stress approach. Based on the parameters of the fatigue crack growth resistance estimated using the strain and energy approaches, the effective diagnostics and the best heat treatment mode for the wheel steel was developed. It comprises the stages of isothermal quenching and tempering at a temperature of 500 °С, providing the highest fatigue fracture toughness of the steel.

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Algorithms for the estimation of fatigue crack growth using energy method

Cited by 26 publications

References 2 publications

Kinetics of fatigue crack growth and crack paths in the old puddled steel after 100-years operating time

Kinetics of fatigue crack growth and crack paths in the old puddled steel after 100-years operating time

New Finite Element Modeling Approach of a Propagating Shaft Crack

The diagnostics and ways heat treatment optimization of a railway wheels steel

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