The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
S.r. Daniewicz - One of the best experts on this subject based on the ideXlab platform.
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The influence of T-stress on plasticity induced Crack Closure under plane strain conditions
International Journal of Fatigue, 2011Co-Authors: Marcos Lugo, S.r. DaniewiczAbstract:Abstract A small scale yielding two-parameter modified boundary layer analysis is performed to study the occurrence of plasticity induced fatigue Crack Closure under constant amplitude plane strain conditions. A wide range of T-stress and KI levels are considered in the finite element analysis with the purpose of exploring the behavior of the Crack opening stress. The influence of the T-stress on Crack Closure is shown. Crack Closure was observed for some values of T-stress, while other values of T-stress resulted in an absence of Closure under steady-state conditions.
Marcos Lugo - One of the best experts on this subject based on the ideXlab platform.
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The influence of T-stress on plasticity induced Crack Closure under plane strain conditions
International Journal of Fatigue, 2011Co-Authors: Marcos Lugo, S.r. DaniewiczAbstract:Abstract A small scale yielding two-parameter modified boundary layer analysis is performed to study the occurrence of plasticity induced fatigue Crack Closure under constant amplitude plane strain conditions. A wide range of T-stress and KI levels are considered in the finite element analysis with the purpose of exploring the behavior of the Crack opening stress. The influence of the T-stress on Crack Closure is shown. Crack Closure was observed for some values of T-stress, while other values of T-stress resulted in an absence of Closure under steady-state conditions.
Pizhong Qiao - One of the best experts on this subject based on the ideXlab platform.
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Virtual Crack Closure technique in peridynamic theory
Computer Methods in Applied Mechanics and Engineering, 2020Co-Authors: Heng Zhang, Pizhong QiaoAbstract:Abstract In this paper, the virtual Crack Closure technique (VCCT), commonly used in the numerical finite element method (FEM), is for the first time reformulated in nonlocal peridynamic theory, and a new peridynamics-based virtual Crack Closure technique (PD_VCCT) is proposed for the energy release rate calculation in the framework of peridynamics. The mode I, mode II, and their mixed mode fracture cases are considered. Two typical tests using the single edge-notched tension (SENT) and asymmetric double cantilever beams (ADCB) specimens are considered for implementation and verification, and the numerical energy release rates calculated by the present PD_VCCT are compared with those by the FEM-based VCCT. The close comparisons demonstrate that the proposed PD_VCCT can successfully predict the energy release rates for the cases of mode I, mode II and their mixed mode fracture and it can be used as a viable and effective tool for fracture analysis.
W Grosinger - One of the best experts on this subject based on the ideXlab platform.
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fatigue Crack Closure from lcf to small scale yielding
International Journal of Fatigue, 2013Co-Authors: Reinhard Pippan, W GrosingerAbstract:Abstract Most of the research on Crack Closure has been devoted to Crack propagation under small scale yielding. In this paper, the effect of different length scale from micro-Crack to long Cracks and different loading conditions from low cycle fatigue, LCF, to small scale yielding on Crack Closure are considered. The main focus is on LCF Crack Closure behaviour which is studied by in situ fatigue experiments in a scanning electron microscope. The results demonstrate the importance of Crack Closure for the explanation of the LCF behaviour. The change of Crack Closure from LCF to high cycle fatigue and their consequences for lifetime prediction will be discussed.
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Fatigue Crack Closure: from LCF to small scale yielding
2011Co-Authors: Reinhard Pippan, W GrosingerAbstract:Crack Closure has been one of the research topics in the 1980ies and 1990ies. A vast number of papers have been published in this area. However, most of the research work has been devoted to Crack propagation under small scale yielding. In this presentation, the different length scale from micro-Crack to long Cracks and different loading conditions (from low cycle fatigue, LCF, to small scale yielding) affecting Crack Closure and as a consequence, the near Crack tip stress and strain fields are considered. The main focus is on LCF Crack Closure behaviour which is studied by in-situ scanning electron microscopy. The results demonstrate the importance of Crack Closure for the explanation of the LCF behaviour. The change of Crack Closure from LCF to high cycle fatigue and their consequences for lifetime prediction will be discussed.
Michael Andersson - One of the best experts on this subject based on the ideXlab platform.
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Experimental and numerical investigation of Crack Closure measurements with electrical potential drop technique
International Journal of Fatigue, 2006Co-Authors: Michael Andersson, Christer Persson, Solveig MelinAbstract:Crack Closure measurements during fatigue Crack propagation using the electrical potential drop (PD) technique is evaluated using a combination of experiments and simulations. From finite element simulations it is shown that variations in the potential drop value over a fatigue cycle can be explained by Crack Closure and strain induced conductivity changes. It is also demonstrated that Closure measurements made with PD are consistent with Closure observations made from in situ SEM observations of Crack Closure. Finally, it was observed that Closure measurements made by a compliance-based measuring technique gave a somewhat lower opening load as compared to the PD-measurement.
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High Strain Fatigue Crack Growth and Crack Closure
2005Co-Authors: Michael AnderssonAbstract:Understanding of the growth of fatigue Cracks is of utmost importance since such growth often has a profound influence on the life of components subjected to cyclic loading. Thus, reliable fatigue life models enable a more efficient use of materials and improve the performance and efficiency in many applications. This thesis deals with the growth of fatigue Cracks subjected to high load amplitudes. One mechanism that is known to have a strong influence on fatigue Crack growth is Crack Closure, i.e. premature contact between the Crack surfaces, caused by for instance residual plastic deformation, Crack surface asperities or oxidation of the Crack surfaces. Closure can reduce the effective load driving the Crack, thus influencing the Crack growth rate. In this thesis the use of the electrical potential drop (PD) technique for Crack Closure measurements has been investigated by a combination of numerical simulations and experiments. It has been shown that Crack Closure has a strong influence on the variations of the PD-value during a load cycle. Also, Crack opening measured with the PDtechnique is consistent with Closure measurements made from in situ fatigue Crack growth observations using a scanning electron microscope. Furthermore, the growth of fatigue Cracks subjected to high load amplitudes in Ti-6Al-4V at room temperature and Inconel 718 at 650°C has also been studied. It has been shown that Crack growth under high strain amplitudes can be analysed using a strain intensity approach or by using the cyclic J-integral. In both cases Crack Closure plays an important role and must be accounted for by using an effective strain intensity range or an effective cyclic J-integral. For Inconel 718 at 650°C, Crack growth occurs by a combination of cyclic and time dependent growth, and thus the load frequency is of importance for the Crack growth rate. A Crack growth law based on the product between the effective cyclic J-integral and a function compensating for the frequency was proposed. Finally an in situ SEM study of Crack growth in an aluminium alloy was performed. It was shown that on a micro scale Crack growth is a highly irregular process that is strongly influenced by the local microstructure at the Crack tip. Also, there is no correlation between the local Crack opening and the Crack growth rate. Thus, it is difficult to predict the Crack growth during an individual load cycle, but for Crack growth rate on a macro scale the stress intensity range, compensated for Crack Closure, is a proper measure.
