Fatigue and fracture of engineering materials and structures, and electronics
01 May 2007-Fatigue & Fracture of Engineering Materials & Structures (Blackwell Publishing Ltd)-Vol. 30, Iss: 5, pp 375-375
About: This article is published in Fatigue & Fracture of Engineering Materials & Structures.The article was published on 2007-05-01 and is currently open access. It has received 52 citations till now. The article focuses on the topics: Fracture (geology).
Citations
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15 Feb 2007-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, a microstructurally-based assessment of the mechanisms of fatigue failure is presented, where an as-cast microstructure generated by heat treatment has been investigated in detail.
Abstract: Austempered ductile iron (ADI) is a candidate material for camshafts, where however, the early stages of fatigue damage are of major concern during service. A fundamental microstructurally based assessment of the mechanisms of fatigue failure is important. An ADI microstructure austenitised at 900 °C and austempered at 390 °C has been investigated in detail. Crack initiation and growth behaviour was assessed under three-point bend testing conditions. Primary initiation events occurred exclusively at pores with further micro-crack initiation occurring at decohered graphite nodules in the monotonic plastic zone ahead of the advancing dominant macro-crack tip. Lifetime was however determined by propagation behaviour rather than coalescence events. The changes in the as-cast microstructure generated by this heat treatment have resulted in improved fatigue crack propagation performance due to the reduction in eutectic carbides and the relatively high quantity of retained austenite compared with previous studies, giving rise to greater crack path tortuousity and shielding.
67 citations
29 Apr 2016-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, room temperature tensile properties and micro-hardness of a laser welded Ti-6Al-2Sn-4Zr-2Mo (Ti6242) alloy sheet were examined and correlated to the microstructure evolution across the weld.
Abstract: Room temperature tensile properties and microhardness of a laser welded Ti–6Al–2Sn–4Zr–2Mo (Ti6242) titanium alloy sheet were examined and correlated to the microstructure evolution across the weld. Tensile testing integrated with the optical image correlation Instron® system indicated that the average yield strength (YS), ultimate tensile strength (UTS), and total elongation of the weldment were respectively 88%, 87%, and 69% of the corresponding base material (BM) values. Electron probe microanalysis (EPMA) demonstrated a uniform distribution of the main alloying elements across the weld. The hardness raised increasingly from the BM toward the heat affected zone (HAZ) and the fusion zone (FZ) due to mainly a higher α volume fraction in HAZ and acicular α′ martensite formation in the FZ. Because of the higher hardness of the HAZ and FZ, a higher YS for the weldment relative to the BM would be expected. However, the lower YS as well as the lower UTS of the weldment can be explained by presence of some porosity and underfill in the FZ. The lower total elongation of the weldment compared to the BM can be related to the higher hardness of the HAZ and FZ.
47 citations
Cites background from "Fatigue and fracture of engineering..."
..., at 955 °C for 1 h) to attain a considerable volume fraction of equiaxed primary grains [18]....
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..., at 930 °C) followed by air cooling [18]....
[...]
TL;DR: In this paper, the brittle fracture criterion, namely the strain energy density (SED) over a control volume, which embraces the notch edge, is utilized to assess the experimentally obtained fracture loads of several U-notched Brazilian disk (UNBD) specimens made of a type of commercial graphite under pure mode II loading.
Abstract: The brittle fracture criterion, namely the strain energy density (SED) over a control volume, which embraces the notch edge, is utilized in the present research to assess the experimentally obtained fracture loads of several U-notched Brazilian disk (UNBD) specimens made of a type of commercial graphite under pure mode II loading. The results show that the SED criterion could successfully predict the fracture loads of graphite specimens for different notch tip radii with an average discrepancy of about � 10%. It is proved in this investigation that not only the SED criterion works well on brittle fracture of notched graphite components under pure mode I, mixed mode I/II and pure mode III loading conditions, but also under pure mode II loading.
45 citations
TL;DR: In this article, the maximum tangential strain energy density criterion presented in the past for damage analysis of brittle materials under mixed mode I/II loading is extended to general mixed mode II/III loading.
Abstract: The maximum tangential strain energy density criterion presented in the past for damage analysis of brittle materials under mixed mode I/II loading is extended to general mixed mode I/II/III in ord...
44 citations
Cites background from "Fatigue and fracture of engineering..."
...(2001) have tried to extend their two-dimensional CTOD-based fracture criterion (Ma et al., 1999; Sutton et al., 2000) and simulation tools into the three-dimensional applications....
[...]
...On the other hand, in order to provide a fracture criterion for general mixed mode I/II/III loading, Deng et al. (2001) have tried to extend their two-dimensional CTOD-based fracture criterion (Ma et al., 1999; Sutton et al., 2000) and simulation tools into the three-dimensional applications....
[...]
...Sutton et al. (2000) introduced the crack-tip opening displacement (CTOD) criterion based on a detailed analysis of crack kinking in arbitrary directions and assumed that the crack growth takes place when the current CTOD reaches a critical value....
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TL;DR: In this paper, an original mathematical algorithm for experimental data treatment was developed to obtain a power of heat source caused by plastic deformation at the crack tip, which includes spatial-time filtration and relative motion compensation procedures.
Abstract: The work is devoted to the experimental study of heat dissipation process caused by fatigue crack propagation. To investigate a spatial and time temperature evolution at the crack tip set of experiments was carried out using specimens with pre-grown centered fatigue crack. An original mathematical algorithm for experimental data treatment was developed to obtain a power of heat source caused by plastic deformation at crack tip. The algorithm includes spatial-time filtration and relative motion compensation procedures. Based on the results of mathematical data treatment, we proposed a way to estimate the values of J-integral and stress intensity factor for cracks with pronounced the plastic zone.
39 citations
Cites methods from "Fatigue and fracture of engineering..."
...The infrared thermography can be also applied during mechanical tests in order to obtain detailed information about the process of structure evolution, damage accumulation and damage-fracture transition in solids [6-8]....
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References
More filters
15 Feb 2007-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, a microstructurally-based assessment of the mechanisms of fatigue failure is presented, where an as-cast microstructure generated by heat treatment has been investigated in detail.
Abstract: Austempered ductile iron (ADI) is a candidate material for camshafts, where however, the early stages of fatigue damage are of major concern during service. A fundamental microstructurally based assessment of the mechanisms of fatigue failure is important. An ADI microstructure austenitised at 900 °C and austempered at 390 °C has been investigated in detail. Crack initiation and growth behaviour was assessed under three-point bend testing conditions. Primary initiation events occurred exclusively at pores with further micro-crack initiation occurring at decohered graphite nodules in the monotonic plastic zone ahead of the advancing dominant macro-crack tip. Lifetime was however determined by propagation behaviour rather than coalescence events. The changes in the as-cast microstructure generated by this heat treatment have resulted in improved fatigue crack propagation performance due to the reduction in eutectic carbides and the relatively high quantity of retained austenite compared with previous studies, giving rise to greater crack path tortuousity and shielding.
67 citations
29 Apr 2016-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, room temperature tensile properties and micro-hardness of a laser welded Ti-6Al-2Sn-4Zr-2Mo (Ti6242) alloy sheet were examined and correlated to the microstructure evolution across the weld.
Abstract: Room temperature tensile properties and microhardness of a laser welded Ti–6Al–2Sn–4Zr–2Mo (Ti6242) titanium alloy sheet were examined and correlated to the microstructure evolution across the weld. Tensile testing integrated with the optical image correlation Instron® system indicated that the average yield strength (YS), ultimate tensile strength (UTS), and total elongation of the weldment were respectively 88%, 87%, and 69% of the corresponding base material (BM) values. Electron probe microanalysis (EPMA) demonstrated a uniform distribution of the main alloying elements across the weld. The hardness raised increasingly from the BM toward the heat affected zone (HAZ) and the fusion zone (FZ) due to mainly a higher α volume fraction in HAZ and acicular α′ martensite formation in the FZ. Because of the higher hardness of the HAZ and FZ, a higher YS for the weldment relative to the BM would be expected. However, the lower YS as well as the lower UTS of the weldment can be explained by presence of some porosity and underfill in the FZ. The lower total elongation of the weldment compared to the BM can be related to the higher hardness of the HAZ and FZ.
47 citations
TL;DR: In this paper, the brittle fracture criterion, namely the strain energy density (SED) over a control volume, which embraces the notch edge, is utilized to assess the experimentally obtained fracture loads of several U-notched Brazilian disk (UNBD) specimens made of a type of commercial graphite under pure mode II loading.
Abstract: The brittle fracture criterion, namely the strain energy density (SED) over a control volume, which embraces the notch edge, is utilized in the present research to assess the experimentally obtained fracture loads of several U-notched Brazilian disk (UNBD) specimens made of a type of commercial graphite under pure mode II loading. The results show that the SED criterion could successfully predict the fracture loads of graphite specimens for different notch tip radii with an average discrepancy of about � 10%. It is proved in this investigation that not only the SED criterion works well on brittle fracture of notched graphite components under pure mode I, mixed mode I/II and pure mode III loading conditions, but also under pure mode II loading.
45 citations
TL;DR: In this article, the maximum tangential strain energy density criterion presented in the past for damage analysis of brittle materials under mixed mode I/II loading is extended to general mixed mode II/III loading.
Abstract: The maximum tangential strain energy density criterion presented in the past for damage analysis of brittle materials under mixed mode I/II loading is extended to general mixed mode I/II/III in ord...
44 citations
TL;DR: In this paper, an original mathematical algorithm for experimental data treatment was developed to obtain a power of heat source caused by plastic deformation at the crack tip, which includes spatial-time filtration and relative motion compensation procedures.
Abstract: The work is devoted to the experimental study of heat dissipation process caused by fatigue crack propagation. To investigate a spatial and time temperature evolution at the crack tip set of experiments was carried out using specimens with pre-grown centered fatigue crack. An original mathematical algorithm for experimental data treatment was developed to obtain a power of heat source caused by plastic deformation at crack tip. The algorithm includes spatial-time filtration and relative motion compensation procedures. Based on the results of mathematical data treatment, we proposed a way to estimate the values of J-integral and stress intensity factor for cracks with pronounced the plastic zone.
39 citations