Fatigue crack growth rate in CFRP reinforced constructional old steel

Pedrosa

Zięty

et al. 2020

Metals

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The paper deals with the subject of diagnostics and the quick repairs of long-term operated metallic materials. Special attention was paid to historical materials, where the structure (e.g., puddle iron) is different from modern structural steels. In such materials, the processes of microstructural degradation occur as a result of several decades of exposure, which could overpass 100 years. In some cases, their intensity can be potentially catastrophic. For this reason, the search for minimally invasive diagnostic methods is ongoing. In this paper, corrosion and fracture toughness tests were conducted, and the results of these studies were presented for two material states: post-operated and normalized (as a state “restoring” virgin state). Moreover, through the use of modern numerical methods, composite crack-resistant patches have been designed to reduce the stress intensity factors under cyclic loads. As a result, fatigue lifetime was extended (propagation phase) by more than 300%.

Section: Concept Of the Cfrp (Carbon Fiber Reinforced Polymer) Patches Strengthening And Numerical Analysismentioning

confidence: 99%

Minimal Invasive Diagnostic Capabilities and Effectiveness of CFRP-Patches Repairs in Long-Term Operated Metals

Pedrosa

Zięty

et al. 2020

Metals

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“…Many times in the range of linear fracture mechanics, integral J allows one to determine stress intensity factors where there are no closed-form analytical solutions. This has been demonstrated in the author’s and co-author’s works [25,26,27,28] devoted to mixed mode fatigue crack growth description. However, it is worth noting that the number of kinetic energy models based on integral J is still negligible.…”

Section: Introductionmentioning

confidence: 78%

Application of a New, Energy-Based ΔS* Crack Driving Force for Fatigue Crack Growth Rate Description

2019

Materials

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This paper presents the problem of the description of fatigue cracking development in metallic constructional materials. Fatigue crack growth models (mostly empirical) are usually constructed using a stress intensity factor ΔK in linear-elastic fracture mechanics. Contrary to the kinetic fatigue fracture diagrams (KFFDs) based on stress intensity factor K, new energy KFFDs show no sensitivity to mean stress effect expressed by the stress ratio R. However, in the literature there is a lack of analytical description and interpretation of this parameter in order to promote this approach in engineering practice. Therefore, based on a dimensional analysis approach, ΔH is replaced by elastic-plastic fracture mechanics parameter—the ΔJ-integral range. In this case, the invariance from stress is not clear. Hence, the main goal of this paper is the application of the new averaged (geometrically) strain energy density parameter ΔS* based on the relationship of the maximal value of J integral and its range ΔJ. The usefulness and invariance of this parameter have been confirmed for three different metallic materials, 10HNAP, 18G2A, and 19th century puddle iron from the Eiffel bridge.

“…Comparing the results achieved in laboratories with real conditions greatly helps in achieving the complete characteristics of the tested materials. Other studies mainly focus on fracture toughness [6][7][8] or focus on fatigue crack growth (FCG) [9]. For example, in [7] it was shown that the fracture toughness of very good quality pearlitic steels is at the level of 30.…”

Section: Introductionmentioning

confidence: 99%

“…Generally speaking, all methods are widely used as deceleration methods of fatigue crack growth. Carbon fiber-reinforced polymer (CFRP) patches are still of particular interest in various applications in civil engineering [9][10][11][12]. However, there are not many papers devoted to degradation problems in a real operational environment [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Deceleration Methods of Fatigue Crack Growth Rates under Mode I Loading Type in Pearlitic Rail Steel

Nykyforchyn

Zvirko

et al. 2021

Metals

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The paper presents a comparison of the results of the fatigue crack growth rate for raw rail steel, steel reinforced with composite material—CFRP—and also in the case of counteracting crack growth using the stop-hole technique, as well as with an application of an “anti-crack growth fluid”. All specimens were tested using constant load amplitude methods with a maximum loading of Fmax = 8 kN and stress ratio R = smin/smax = 0.1 in order to analyze the efficiency of different strategies of fatigue crack growth rate deceleration. It has been shown that the fatigue crack grows fastest in the case of the raw material and slowest in the case of “anti-crack growth fluid” application. Additionally, the study on fatigue fracture surfaces using light and scanning electron (SEM) microscopy to analyze the crack growth mechanism was carried out. As a result of fluid activity, the fatigue crack closure occurred and significantly decreased crack driving force and finally resulted in fatigue crack growth decrease.