The Experts below are selected from a list of 14160 Experts worldwide ranked by ideXlab platform
J Segurado - One of the best experts on this subject based on the ideXlab platform.
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On the accuracy of spectral solvers for micromechanics based Fatigue Modeling
Computational Mechanics, 2019Co-Authors: S Lucarini, J SeguradoAbstract:A framework based on FFT is proposed for micromechanical Fatigue Modeling of polycrystals as alternative to the Finite Element method (FEM). The variational FFT approach (de Geus et al. in Comput Methods Appl Mech Eng 318:412–430, 2017 ; Zeman et al. in Int J Numer Methods Eng 110:903–926, 2017 ) is used with a crystal plasticity model for the cyclic behavior of the grains that is introduced through a FEM material subroutine, in particular an Abaqus umat . The framework also includes an alternative projection operator based on discrete differentiation to improve the microfield fidelity allowing to include second phases. The accuracy and efficiency of the FFT framework for microstructure sensitive Fatigue prediction are assessed by comparing with FEM. The macroscopic cyclic response of a polycrystal obtained with both methods were indistinguishable, irrespective of the number of cycles. The microscopic fields presented small differences that decrease when using the discrete projection operator, which indeed allowed simulating accurately microstructures containing very stiff particles. Finally, the maximum differences in the Fatigue life estimation from the microfields respect FEM were around 15%. In summary, this framework allows predicting Fatigue life with a similar accuracy than using FEM but strongly reducing the computational cost.
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on the accuracy of spectral solvers for micromechanics based Fatigue Modeling
arXiv: Computational Physics, 2018Co-Authors: S Lucarini, J SeguradoAbstract:A framework based on FFT is proposed for micromechanical Fatigue Modeling of polycrystals as alternative to the Finite Element method (FEM). The variational FFT approach is used with a crystal plasticity model for the cyclic behavior of the grains introduced through a FEM material subroutine, in particular an Abaqus umat. The framework also includes an alternative projection operator based on discrete differentiation to improve the microfield fidelity allowing to include second phases. The accuracy and efficiency of the FFT framework for microstructure sensitive Fatigue prediction are assessed by comparing with FEM. The macroscopic cyclic response of a polycrystal obtained with both methods were indistinguishable, irrespective of the number of cycles. The microscopic fields presented small differences that decrease when using the discrete projection operator, which indeed allowed simulating accurately microstructures containing very stiff particles. Finally, the maximum differences in the Fatigue life estimation from the microfields respect FEM were around 15% . In summary, this framework allows predicting Fatigue life with a similar accuracy than using FEM but strongly reducing the computational cost.
David L. Mcdowell - One of the best experts on this subject based on the ideXlab platform.
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simulation based strategies for microstructure sensitive Fatigue Modeling
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: David L. McdowellAbstract:Abstract Further efforts to provide more direct dependence of Fatigue life estimation methods on microstructure of alloy systems must consider various factors that are not explicitly addressed by conventional Fatigue design tools such as the strain-life curve, the stress-life curve, the modified Goodman diagram, or Fatigue limit concepts, or by traditional linear elastic fracture mechanics approaches. In this work, we offer insight from micromechanical perspectives on tradeoffs of Fatigue crack formation and growth regimes in low cycle and high cycle Fatigue, including considerations of effects of notches of various scales. Relations between remote loading conditions and microstructure-scale cyclic plasticity/crack behavior are considered as a function of stress amplitude and microstructure to support assessment of intrinsic microstructure Fatigue resistance (percolation limits for connected microplasticity) as well as effects of extrinsic features such as non-metallic inclusions. Algorithms are summarized for computing nonlocal cyclic plastic shear strain and inferring Fatigue resistance, both in terms of mean behavior and variability with microstructure. Several applications are presented, including intrinsic and extrinsic Fatigue resistance of Ni-base superalloys, Fatigue of polycrystals, cast A356-T6 Al alloy, and fretting Fatigue of Ti–6Al–4V.
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microstructure based multistage Fatigue Modeling of aluminum alloy 7075 t651
Engineering Fracture Mechanics, 2007Co-Authors: Yibin Xue, David L. Mcdowell, Mark F. Horstemeyer, M H Dale, J. B. JordonAbstract:Abstract The multistage Fatigue model for high cycle Fatigue of a cast aluminum alloy developed by McDowell et al. is modified to consider the structure–property relations for cyclic damage and Fatigue life of a high strength aluminum alloy 7075-T651 for aircraft structural applications. The multistage model was developed as a physically-based framework to evaluate sensitivity of Fatigue response to various microstructural features to support materials process design and component-specific tailoring of Fatigue resistant materials. In this work, the model is first generalized to evaluate both the high cycle Fatigue (HCF) and low cycle Fatigue (LCF) regimes for multiaxial loading conditions, with appropriate modifications introduced for wrought materials. The particular microstructural features of relevance to Fatigue in aluminum alloy 7075-T651 include micron-scale Fe-rich intermetallic particles and rolling textures. The model specifically addresses the role of local constrained cyclic microplasticity at fractured inclusions in Fatigue crack incubation and microstructurally small crack growth, including the effect of crystallographic orientation on crack tip displacement as the driving force. The model is able to predict lower and upper bounds of the Fatigue life based on measured inclusion sizes.
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Microstructure-based multistage Fatigue Modeling of a cast AE44 magnesium alloy
International Journal of Fatigue, 2007Co-Authors: Mark F. Horstemeyer, David L. Mcdowell, H. El KadiriAbstract:The multistage Fatigue model developed by McDowell et al. was modified to study the Fatigue life of a magnesium alloy AE44 for automobile applications. The fractographic examination indicated three distinct stages of Fatigue damage in the high cycle Fatigue loading regime: crack incubation, microstructurally small crack growth, and long crack growth. Cracks incubated almost exclusively at the cast pores that were near the free surface, located near sharp geometry changes of the test specimen, or at extremely large pores inside the specimens. Microstructurally small cracks grew in the eutectic region along the weak boundaries of the grains and dendrites or at very closely packed microstructural discontinuities. Long cracks were observed to grow in a transgranular fashion. Specimens fabricated from as-cast bars and extracted from a cast engine cradle were tested at room temperature and an elevated temperature typically required for automotive powertrain applications. A large variation of Fatigue life in the high cycle Fatigue region was observed in specimens from both conditions due to the sensitivity from microstructural discontinuities. The microstructure-based multistage Fatigue model was generalized for the AE44 magnesium alloy to capture the network of porosity and temperature dependence. The modified multistage Fatigue model was also used to estimate the upper and lower bounds of the strain-life curves based on the extreme microstructural discontinuities.
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microstructure based Fatigue Modeling of cast a356 t6 alloy
Engineering Fracture Mechanics, 2003Co-Authors: David L. Mcdowell, Mark F. Horstemeyer, Ken Gall, Jinghong FanAbstract:Abstract High cycle Fatigue (HCF) life in cast Al–Mg–Si alloys is particularly sensitive to the combination of microstructural inclusions and stress concentrations. Inclusions can range from large-scale shrinkage porosity with a tortuous surface profile to entrapped oxides introduced during the pour. When shrinkage porosity is controlled, the relevant microstructural initiation sites are often the larger Si particles within eutectic regions. In this paper, a HCF model is introduced which recognizes multiple inclusion severity scales for crack formation. The model addresses the role of constrained microplasticity around debonded particles or shrinkage pores in forming and growing microstructurally small Fatigue cracks and is based on the cyclic crack tip displacement rather than linear elastic fracture mechanics stress intensity factor. Conditions for transitioning to long crack Fatigue crack growth behavior are introduced. The model is applied to a cast A356-T6 Al alloy over a range of inclusion severities.
S Lucarini - One of the best experts on this subject based on the ideXlab platform.
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On the accuracy of spectral solvers for micromechanics based Fatigue Modeling
Computational Mechanics, 2019Co-Authors: S Lucarini, J SeguradoAbstract:A framework based on FFT is proposed for micromechanical Fatigue Modeling of polycrystals as alternative to the Finite Element method (FEM). The variational FFT approach (de Geus et al. in Comput Methods Appl Mech Eng 318:412–430, 2017 ; Zeman et al. in Int J Numer Methods Eng 110:903–926, 2017 ) is used with a crystal plasticity model for the cyclic behavior of the grains that is introduced through a FEM material subroutine, in particular an Abaqus umat . The framework also includes an alternative projection operator based on discrete differentiation to improve the microfield fidelity allowing to include second phases. The accuracy and efficiency of the FFT framework for microstructure sensitive Fatigue prediction are assessed by comparing with FEM. The macroscopic cyclic response of a polycrystal obtained with both methods were indistinguishable, irrespective of the number of cycles. The microscopic fields presented small differences that decrease when using the discrete projection operator, which indeed allowed simulating accurately microstructures containing very stiff particles. Finally, the maximum differences in the Fatigue life estimation from the microfields respect FEM were around 15%. In summary, this framework allows predicting Fatigue life with a similar accuracy than using FEM but strongly reducing the computational cost.
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on the accuracy of spectral solvers for micromechanics based Fatigue Modeling
arXiv: Computational Physics, 2018Co-Authors: S Lucarini, J SeguradoAbstract:A framework based on FFT is proposed for micromechanical Fatigue Modeling of polycrystals as alternative to the Finite Element method (FEM). The variational FFT approach is used with a crystal plasticity model for the cyclic behavior of the grains introduced through a FEM material subroutine, in particular an Abaqus umat. The framework also includes an alternative projection operator based on discrete differentiation to improve the microfield fidelity allowing to include second phases. The accuracy and efficiency of the FFT framework for microstructure sensitive Fatigue prediction are assessed by comparing with FEM. The macroscopic cyclic response of a polycrystal obtained with both methods were indistinguishable, irrespective of the number of cycles. The microscopic fields presented small differences that decrease when using the discrete projection operator, which indeed allowed simulating accurately microstructures containing very stiff particles. Finally, the maximum differences in the Fatigue life estimation from the microfields respect FEM were around 15% . In summary, this framework allows predicting Fatigue life with a similar accuracy than using FEM but strongly reducing the computational cost.
Bodaghi Mahdi - One of the best experts on this subject based on the ideXlab platform.
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Fatigue Modeling and numerical analysis of re-filling probe hole of friction stir spot welded joints in aluminum alloys
'MDPI AG', 2021Co-Authors: Yousefi Armin, Serjouei Ahmad, Hedayati R., Bodaghi MahdiAbstract:In the present study, the Fatigue behavior and tensile strength of A6061-T4 aluminum al-loy, joined by friction stir spot welding (FSSW), are numerically investigated. The 3D finite element model (FEM) is used to analyze the FSSW joint by means of Abaqus software. The tensile strength is determined for FSSW joints with both a probe hole and a refilled probe hole. In order to calculate the Fatigue life of FSSW joints, the hysteresis loop is first determined, and then the plastic strain amplitude is calculated. Finally, by using the Coffin-Manson equation, Fatigue life is predicted. The results were verified against available experimental data from other literature, and a good agree-ment was observed between the FEM results and experimental data. The results showed that the joint’s tensile strength without a probe hole (refilled hole) is higher than the joint with a probe hole. Therefore, re-filling the probe hole is an effective method for structures jointed by FSSW subjected to a static load. The Fatigue strength of the joint with a re-filled probe hole was nearly the same as the structure with a probe hole at low applied loads. Additionally, at a high applied load, the Fatigue strength of joints with a refilled probe hole was slightly lower than the joint with a probe hole.
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Fatigue Modeling and numerical analysis of re-filling probe hole of friction stir spot welded joints in aluminum alloys
'MDPI AG', 2021Co-Authors: Yousefi Armin, Serjouei Ahmad, Hedayati R., Bodaghi MahdiAbstract:In the present study, the Fatigue behavior and tensile strength of A6061-T4 aluminum al-loy, joined by friction stir spot welding (FSSW), are numerically investigated. The 3D finite element model (FEM) is used to analyze the FSSW joint by means of Abaqus software. The tensile strength is determined for FSSW joints with both a probe hole and a refilled probe hole. In order to calculate the Fatigue life of FSSW joints, the hysteresis loop is first determined, and then the plastic strain amplitude is calculated. Finally, by using the Coffin-Manson equation, Fatigue life is predicted. The results were verified against available experimental data from other literature, and a good agree-ment was observed between the FEM results and experimental data. The results showed that the joint’s tensile strength without a probe hole (refilled hole) is higher than the joint with a probe hole. Therefore, re-filling the probe hole is an effective method for structures jointed by FSSW subjected to a static load. The Fatigue strength of the joint with a re-filled probe hole was nearly the same as the structure with a probe hole at low applied loads. Additionally, at a high applied load, the Fatigue strength of joints with a refilled probe hole was slightly lower than the joint with a probe hole.Novel Aerospace Material
H. El Kadiri - One of the best experts on this subject based on the ideXlab platform.
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Microstructure-based multistage Fatigue Modeling of a cast AE44 magnesium alloy
International Journal of Fatigue, 2007Co-Authors: Mark F. Horstemeyer, David L. Mcdowell, H. El KadiriAbstract:The multistage Fatigue model developed by McDowell et al. was modified to study the Fatigue life of a magnesium alloy AE44 for automobile applications. The fractographic examination indicated three distinct stages of Fatigue damage in the high cycle Fatigue loading regime: crack incubation, microstructurally small crack growth, and long crack growth. Cracks incubated almost exclusively at the cast pores that were near the free surface, located near sharp geometry changes of the test specimen, or at extremely large pores inside the specimens. Microstructurally small cracks grew in the eutectic region along the weak boundaries of the grains and dendrites or at very closely packed microstructural discontinuities. Long cracks were observed to grow in a transgranular fashion. Specimens fabricated from as-cast bars and extracted from a cast engine cradle were tested at room temperature and an elevated temperature typically required for automotive powertrain applications. A large variation of Fatigue life in the high cycle Fatigue region was observed in specimens from both conditions due to the sensitivity from microstructural discontinuities. The microstructure-based multistage Fatigue model was generalized for the AE44 magnesium alloy to capture the network of porosity and temperature dependence. The modified multistage Fatigue model was also used to estimate the upper and lower bounds of the strain-life curves based on the extreme microstructural discontinuities.
