Editorial

Jump to: Research, Review

3 pages, 159 KiB

Open AccessEditorial

Fracture Mechanics and Fatigue Design in Metallic Materials

by Dariusz Rozumek

Metals 2021, 11(12), 1957; https://doi.org/10.3390/met11121957 - 06 Dec 2021

Cited by 1 | Viewed by 2129

Abstract

Devices, working structures and their elements are subjected to the influence of various loads [...] Full article

(This article belongs to the Special Issue Fracture Mechanics and Fatigue Design in Metallic Materials)

Research

Jump to: Editorial, Review

16 pages, 4395 KiB

Open AccessArticle

Research on the Corrosion Fatigue Property of 2524-T3 Aluminum Alloy

by Chi Liu, Liyong Ma, Ziyong Zhang, Zhuo Fu and Lijuan Liu

Metals 2021, 11(11), 1754; https://doi.org/10.3390/met11111754 - 01 Nov 2021

Cited by 3 | Viewed by 2176

Abstract

The 2524-T3 aluminum alloy was subjected to fatigue tests under the conditions of R = 0, 3.5% NaCl corrosion solution, and the loading cycles of 10⁶, and the S-N curve was obtained. The horizontal fatigue limit was 169 MPa, which is [...] Read more.

The 2524-T3 aluminum alloy was subjected to fatigue tests under the conditions of R = 0, 3.5% NaCl corrosion solution, and the loading cycles of 10⁶, and the S-N curve was obtained. The horizontal fatigue limit was 169 MPa, which is slightly higher than the longitudinal fatigue limit of 163 MPa. In addition, detailed microstructural analysis of the micro-morphological fatigue failure features was carried out. The influence mechanism of corrosion on the fatigue crack propagation of 2524-T3 aluminum alloy was discussed. The fatigue source characterized by cleavage and fracture mainly comes from corrosion pits, whose expansion direction is perpendicular to the principal stress direction. The stable propagation zone is characterized by strip fractures. The main feature of the fracture in the fracture zone is equiaxed dimples. The larger dimples are mixed with second-phase particles ranging in size from 1 to 5 μm. There is almost a one-to-one correspondence between the dimples and the second-phase particles. The fracture mechanism of 2524 alloy at this stage is transformed into a micro-holes connection mechanism, and the nucleation of micropores is mainly derived from the second-phase particles. Full article

(This article belongs to the Special Issue Fracture Mechanics and Fatigue Design in Metallic Materials)

► Show Figures

Figure 1

11 pages, 983 KiB

Open AccessArticle

Application of an Artificial Neural Network to Develop Fracture Toughness Predictor of Ferritic Steels Based on Tensile Test Results

by Kenichi Ishihara, Hayato Kitagawa, Yoichi Takagishi and Toshiyuki Meshii

Metals 2021, 11(11), 1740; https://doi.org/10.3390/met11111740 - 30 Oct 2021

Cited by 8 | Viewed by 1804

Abstract

Analyzing the structural integrity of ferritic steel structures subjected to large temperature variations requires the collection of the fracture toughness (K_J_c) of ferritic steels in the ductile-to-brittle transition region. Consequently, predicting K_J_c from minimal testing has been [...] Read more.

Analyzing the structural integrity of ferritic steel structures subjected to large temperature variations requires the collection of the fracture toughness (K_J_c) of ferritic steels in the ductile-to-brittle transition region. Consequently, predicting K_J_c from minimal testing has been of interest for a long time. In this study, a Windows-ready K_J_c predictor based on tensile properties (specifically, yield stress σ_YSRT and tensile strength σ_BRT at room temperature (RT) and σ_YS at K_J_c prediction temperature) was developed by applying an artificial neural network (ANN) to 531 K_J_c data points. If the σ_YS temperature dependence can be adequately described using the Zerilli–Armstrong σ_YS master curve (MC), the necessary data for K_J_c prediction are reduced to σ_YSRT and σ_BRT. The developed K_J_c predictor successfully predicted K_J_c under arbitrary conditions. Compared with the existing ASTM E1921 K_J_c MC, the developed K_J_c predictor was especially effective in cases where σ_B/σ_YS of the material was larger than that of RPV steel. Full article

(This article belongs to the Special Issue Fracture Mechanics and Fatigue Design in Metallic Materials)

► Show Figures

Figure 1

11 pages, 8809 KiB

Open AccessArticle

Fatigue Crack Growth Behaviour and Role of Roughness-Induced Crack Closure in CP Ti: Stress Amplitude Dependence

by Mansur Ahmed, Md. Saiful Islam, Shuo Yin, Richard Coull and Dariusz Rozumek

Metals 2021, 11(10), 1656; https://doi.org/10.3390/met11101656 - 19 Oct 2021

Cited by 5 | Viewed by 1851

Abstract

This paper investigated the fatigue crack propagation mechanism of CP Ti at various stress amplitudes (175, 200, 227 MPa). One single crack at 175 MPa and three main cracks via sub-crack coalescence at 227 MPa were found to be responsible for fatigue failure. [...] Read more.

This paper investigated the fatigue crack propagation mechanism of CP Ti at various stress amplitudes (175, 200, 227 MPa). One single crack at 175 MPa and three main cracks via sub-crack coalescence at 227 MPa were found to be responsible for fatigue failure. Crack deflection and crack branching that cause roughness-induced crack closure (RICC) appeared at all studied stress amplitudes; hence, RICC at various stages of crack propagation (100, 300 and 500 µm) could be quantitatively calculated. Noticeably, a lower RICC at higher stress amplitudes (227 MPa) for fatigue cracks longer than 100 µm was found than for those at 175 MPa. This caused the variation in crack growth rates in the studied conditions. Full article

(This article belongs to the Special Issue Fracture Mechanics and Fatigue Design in Metallic Materials)

► Show Figures

Figure 1

13 pages, 36722 KiB

Open AccessArticle

Fatigue Behavior of Nonreinforced Hand-Holes in Aluminum Light Poles

by Cameron R. Rusnak and Craig C. Menzemer

Metals 2021, 11(8), 1222; https://doi.org/10.3390/met11081222 - 30 Jul 2021

Cited by 2 | Viewed by 1795

Abstract

Hand-holes are present within the body of welded aluminum light poles. They are used to provide access to the electrical wiring for both installation and maintenance purposes. Wind is the main loading on these slender aluminum light poles and acts in a very [...] Read more.

Hand-holes are present within the body of welded aluminum light poles. They are used to provide access to the electrical wiring for both installation and maintenance purposes. Wind is the main loading on these slender aluminum light poles and acts in a very cyclic way. In the field, localized fatigue cracking has been observed. This includes areas around hand-holes, most of which are reinforced with a cast insert welded to the pole. This study is focused on an alternative design, specifically hand-holes without reinforcement. Nine poles with 18 openings were fatigue tested in four-point bending at various stress ranges. Among the 18 hand-holes tested, 17 failed in one way or another as a result of fatigue cracking. Typically, fatigue cracking would occur at either the 3:00 or 9:00 positions around the hand-hole and then proceed to propagate transversely into the pole before failure. Finite element analysis was used to complement the experimental study. Models were created with varying aspect ratios to see if the hand-hole geometry had an effect on fatigue life. Full article

(This article belongs to the Special Issue Fracture Mechanics and Fatigue Design in Metallic Materials)

► Show Figures

Figure 1

12 pages, 9563 KiB

Open AccessArticle

Fatigue Variability of Alloy 625 Thin-Tube Brazed Specimens

by Seulbi Lee, Hanjong Kim, Seonghun Park and Yoon Suk Choi

Metals 2021, 11(8), 1162; https://doi.org/10.3390/met11081162 - 22 Jul 2021

Cited by 2 | Viewed by 1598

Abstract

As an advanced heat exchanger for aero-turbine applications, a tubular-type heat exchanger was developed. To ensure the optimum performance of the heat exchanger, it is necessary to assess the structural integrity of the tubes, considering the assembly processes such as brazing. In this [...] Read more.

As an advanced heat exchanger for aero-turbine applications, a tubular-type heat exchanger was developed. To ensure the optimum performance of the heat exchanger, it is necessary to assess the structural integrity of the tubes, considering the assembly processes such as brazing. In this study, fatigue tests at room temperature and 1000 K were performed for 0.135 mm-thick alloy 625 tubes (outer diameter of 1.5 mm), which were brazed to the grip of the fatigue specimen. The variability in fatigue life was investigated by analyzing the locations of the fatigue failure, fracture surfaces, and microstructures of the brazed joint and tube. At room temperature, the specimens failed near the brazed joint for high σ_max values, while both brazed joint failure and tube side failure were observed for low σ_max values. The largest variability in fatigue life under the same test conditions was found when one specimen failed in the brazed joint, while the other specimen failed in the middle of the tube. The specimen with brazed joint failure showed multiple crack initiations circumferentially near the surface of the filler metal layer and growth of cracks in the tube, resulting in a short fatigue life. At 1000 K, all the specimens exhibited failure in the middle of the tube. In this case, the short-life specimen showed crack initiation and growth along the grains with large through thickness in addition to multiple crack initiations at the carbides inside the tube. The results suggest that the variability in the fatigue life of the alloy 625 thin-tube brazed specimen is affected by the presence of the brazed joint, as well as the spatial distribution of the grain size and carbides. Full article

(This article belongs to the Special Issue Fracture Mechanics and Fatigue Design in Metallic Materials)

► Show Figures

Figure 1

13 pages, 47751 KiB

Open AccessArticle

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

by Grzegorz Lesiuk, Hryhoriy Nykyforchyn, Olha Zvirko, Rafał Mech, Bartosz Babiarczuk, Szymon Duda, Joao Maria De Arrabida Farelo and Jose A.F.O. Correia

Metals 2021, 11(4), 584; https://doi.org/10.3390/met11040584 - 02 Apr 2021

Cited by 4 | Viewed by 2416

Abstract

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 [...] Read more.

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 F_max = 8 kN and stress ratio R = σ_min/σ_max = 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. Full article

(This article belongs to the Special Issue Fracture Mechanics and Fatigue Design in Metallic Materials)

► Show Figures

Figure 1

13 pages, 3663 KiB

Open AccessArticle

The Evaluation of Front Shapes of Through-the-Thickness Fatigue Cracks

by Behnam Zakavi, Andrei Kotousov and Ricardo Branco

Metals 2021, 11(3), 403; https://doi.org/10.3390/met11030403 - 01 Mar 2021

Cited by 5 | Viewed by 1637

Abstract

Fatigue failure of structural components due to cyclic loading is a major concern for engineers. Although metal fatigue is a relatively old subject, current methods for the evaluation of fatigue crack growth and fatigue lifetime have several limitations. In general, these methods largely [...] Read more.

Fatigue failure of structural components due to cyclic loading is a major concern for engineers. Although metal fatigue is a relatively old subject, current methods for the evaluation of fatigue crack growth and fatigue lifetime have several limitations. In general, these methods largely disregard the actual shape of the crack front by introducing various simplifications, namely shape constraints. Therefore, more research is required to develop new approaches to correctly understand the underlying mechanisms associated with the fatigue crack growth. This paper presents new tools to evaluate the crack front shape of through-the-thickness cracks propagating in plates under quasi-steady-state conditions. A numerical approach incorporating simplified phenomenological models of plasticity-induced crack closure was developed and validated against experimental results. The predicted crack front shapes and crack closure values were, in general, in agreement with those found in the experimental observations. Full article

(This article belongs to the Special Issue Fracture Mechanics and Fatigue Design in Metallic Materials)

► Show Figures

Figure 1

15 pages, 10127 KiB

Open AccessArticle

Hydrogen Assisted Fracture of 30MnB5 High Strength Steel: A Case Study

by Garikoitz Artola and Javier Aldazabal

Metals 2020, 10(12), 1613; https://doi.org/10.3390/met10121613 - 30 Nov 2020

Cited by 4 | Viewed by 2217

Abstract

When steel components fail in service due to the intervention of hydrogen assisted cracking, discussion of the root cause arises. The failure is frequently blamed on component design, working conditions, the manufacturing process, or the raw material. This work studies the influence of [...] Read more.

When steel components fail in service due to the intervention of hydrogen assisted cracking, discussion of the root cause arises. The failure is frequently blamed on component design, working conditions, the manufacturing process, or the raw material. This work studies the influence of quench and tempering and hot-dip galvanizing on the hydrogen embrittlement behavior of a high strength steel. Slow strain rate tensile testing has been employed to assess this influence. Two sets of specimens have been tested, both in air and immersed in synthetic seawater, at three process steps: in the delivery condition of the raw material, after heat treatment and after heat treatment plus hot-dip galvanizing. One of the specimen sets has been tested without further manipulation and the other set has been tested after applying a hydrogen effusion treatment. The outcome, for this case study, is that fracture risk issues only arise due to hydrogen re-embrittlement in wet service. Full article

(This article belongs to the Special Issue Fracture Mechanics and Fatigue Design in Metallic Materials)

► Show Figures

Figure 1

16 pages, 3924 KiB

Open AccessArticle

An Ultra-High Frequency Vibration-Based Fatigue Test and Its Comparative Study of a Titanium Alloy in the VHCF Regime

by Wei Xu, Yanguang Zhao, Xin Chen, Bin Zhong, Huichen Yu, Yuhuai He and Chunhu Tao

Metals 2020, 10(11), 1415; https://doi.org/10.3390/met10111415 - 24 Oct 2020

Cited by 18 | Viewed by 2949

Abstract

This paper proposes an ultra-high frequency (UHF) fatigue test of a titanium alloy TA11 based on electrodynamic shaker in order to develop a feasible testing method in the VHCF regime. Firstly, a type of UHF fatigue specimen is designed to make its actual [...] Read more.

This paper proposes an ultra-high frequency (UHF) fatigue test of a titanium alloy TA11 based on electrodynamic shaker in order to develop a feasible testing method in the VHCF regime. Firstly, a type of UHF fatigue specimen is designed to make its actual testing frequency reach as high as 1756 Hz. Then the influences of the loading frequency and loading types on the testing results are considered separately, and a series of comparative fatigue tests are hence conducted. The results show the testing data from the present UHF fatigue specimen agree well with those from the conventional vibration fatigue specimen with the loading frequency of 240 Hz. Furthermore, the present UHF testing data show good consistency with those from the axial-loading fatigue and rotating bending fatigue tests. But the obtained fatigue life from ultrasonic fatigue test with the loading frequency of 20 kHz is significantly higher than all other fatigue test results. Thus the proposed ultra-high frequency vibration-based fatigue test shows a balance of high efficiency and similarity with the conventional testing results. Full article

(This article belongs to the Special Issue Fracture Mechanics and Fatigue Design in Metallic Materials)

► Show Figures

Figure 1

13 pages, 3336 KiB

Open AccessArticle

Capturing and Micromechanical Analysis of the Crack-Branching Behavior in Welded Joints

by Wenjie Wang, Jie Yang, Haofeng Chen and Qianyu Yang

Metals 2020, 10(10), 1308; https://doi.org/10.3390/met10101308 - 29 Sep 2020

Cited by 2 | Viewed by 1702

Abstract

During the crack propagation process, the crack-branching behavior makes fracture more unpredictable. However, compared with the crack-branching behavior that occurs in brittle materials or ductile materials under dynamic loading, the branching behavior has been rarely reported in welded joints under quasi-static loading. Understanding [...] Read more.

During the crack propagation process, the crack-branching behavior makes fracture more unpredictable. However, compared with the crack-branching behavior that occurs in brittle materials or ductile materials under dynamic loading, the branching behavior has been rarely reported in welded joints under quasi-static loading. Understanding the branching criterion or the mechanism governing the bifurcation of a crack in welded joints is still a challenge. In this work, three kinds of crack-branching models that reflect simplified welded joints were designed, and the aim of the present paper is to find and capture the crack-branching behavior in welded joints and to shed light on its branching mechanism. The results show that as long as there is another large enough propagation trend that is different from the original crack propagation direction, then crack-branching behavior occurs. A high strength mismatch that is induced by both the mechanical properties and dimensions of different regions is the key of crack branching in welded joints. Each crack branching is accompanied by three local high stress concentrations at the crack tip. Three pulling forces that are created by the three local high stress concentrations pull the crack, which propagates along with the directions of stress concentrations. Under the combined action of the three pulling forces, crack branching occurs, and two new cracks initiate from the middle of the pulling forces. Full article

(This article belongs to the Special Issue Fracture Mechanics and Fatigue Design in Metallic Materials)

► Show Figures

Figure 1

Review

Jump to: Editorial, Research

23 pages, 4945 KiB

Open AccessReview

Recent Advances in Very High Cycle Fatigue Behavior of Metals and Alloys—A Review

by Ashutosh Sharma, Min Chul Oh and Byungmin Ahn

Metals 2020, 10(9), 1200; https://doi.org/10.3390/met10091200 - 08 Sep 2020

Cited by 37 | Viewed by 11712

Abstract

We reviewed the research and developments in the field of fatigue failure, focusing on very-high cycle fatigue (VHCF) of metals, alloys, and steels. We also discussed ultrasonic fatigue testing, historical relevance, major testing principles, and equipment. The VHCF behavior of Al, Mg, Ni, [...] Read more.

We reviewed the research and developments in the field of fatigue failure, focusing on very-high cycle fatigue (VHCF) of metals, alloys, and steels. We also discussed ultrasonic fatigue testing, historical relevance, major testing principles, and equipment. The VHCF behavior of Al, Mg, Ni, Ti, and various types of steels were analyzed. Furthermore, we highlighted the major defects, crack initiation sites, fatigue models, and simulation studies to understand the crack development in VHCF regimes. Finally, we reviewed the details regarding various issues and challenges in the field of VHCF for engineering metals and identified future directions in this area. Full article

(This article belongs to the Special Issue Fracture Mechanics and Fatigue Design in Metallic Materials)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Fracture Mechanics and Fatigue Design in Metallic Materials

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Published Papers (12 papers)

Editorial

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI