The Experts below are selected from a list of 18648 Experts worldwide ranked by ideXlab platform
Xi Chen - One of the best experts on this subject based on the ideXlab platform.
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characteristics of windshield Cracking upon low speed impact numerical simulation based on the extended finite element method
Computational Materials Science, 2010Co-Authors: Xi Chen, Mengyi Zhu, Yuan Yan, Bohan LiuAbstract:Abstract Windshield glass Crack characteristics are of great interest to vehicle manufacturers, safety engineers, and accident investigators, because they contain important information on energy mitigation, pedestrian protection, and accident reconstruction. We use the extended finite element method (XFEM) to analyze the model problem of low-speed head impact on a windshield plate. Both the radial Crack and circumferential Crack propagations are characterized. A parametric study is carried out to investigate the effects of impact speed, head mass, initial material flaw, material fracture criterion, etc., and correlate them with the Crack Direction and length. It is found that the critical accident information, such as the impact speed or damage stress, can be deduced from the Crack pattern characteristics. A qualitative bridge can be established between numerical simulation result and real-world accident via the Crack growth mechanism. Our study shows that XFEM is a useful tool for simulating several types of Cracks that appear during quasi-static indentation or low-speed impact of foreign objects on windshield materials.
Masao Sakane - One of the best experts on this subject based on the ideXlab platform.
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equi biaxial tension compression low cycle fatigue for type 304 and cr mo v cruciform specimen
ASME 2003 Pressure Vessels and Piping Conference, 2003Co-Authors: Masao SakaneAbstract:This paper describes high temperature multiaxial low cycle fatigue lives of type 304 stainless steel and 1Cr-1Mo-1/4V steel cruciform specimens at 823K and 923K in air. Strain controlled multiaxial low cycle fatigue tests were carried out using cruciform specimens at the principal strain ratios between −1 and 1. The principal strain ratio had a significant effect on low cycle fatigue lives. Fatigue lives drastically decreased as the principal strain ratio increased. Multiaxial low cycle fatigue strain parameters were applied to the experimental data and the applicability of the parameters was discussed. The equivalent strain based on Crack opening displacement (COD strain) developed in the paper and Γ*-plane parameter successfully predicted multiaxial low cycle fatigue lives. The Crack morphology was also extensively discussed from not only the surface Crack Direction but also the Crack inclination into the specimen.Copyright © 2003 by ASME
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High Temperature Multiaxial Low Cycle Fatigue of Cruciform Specimen
Journal of Engineering Materials and Technology-transactions of The Asme, 1994Co-Authors: Masao SakaneAbstract:This paper describes high temperature multiaxial low cycle fatigue lives of type SUS304 stainless steel and 1Cr-1Mo-1/4V steel cruciform specimens at 923 K and 823 K in air. Strain controlled multiaxial low cycle fatigue tests were carried out using cruciform specimens at the principal strain ratios between [minus]1 and 1. The principal strain ratio had a significant effect on low cycle fatigue lives. Fatigue lives drastically decreased as the principal strain ratio increased. Multiaxial low cycle fatigue strain parameters were applied to the experimental data and the applicability of the parameter was discussed. The equivalent strain based on Crack opening displacement (COD strain) developed in the paper and [Gamma][sup *] -- plane parameter successfully predicted multiaxial low cycle fatigue lives. The Crack morphology was also extensively discussed from not only the surface Crack Direction but also the Crack inclination into the specimen.
A. Navarro - One of the best experts on this subject based on the ideXlab platform.
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Fatigue life and Crack growth Direction in 7075-T6 aluminium alloy specimens with a circular hole under biaxial loading
International Journal of Fatigue, 2019Co-Authors: V. Chaves, G. Beretta, J.a. Balbín, A. NavarroAbstract:Abstract This work shows the results of a set of tests in 7075-T6 aluminium alloy specimens. The tests were under load control at R = - 1 . From the tests, the corresponding S-N curves were built, and the endurance limits were calculated for 1 million cycles. The ratio between the pure torsion and tension endurance limits was 0.58, i.e., the behaviour of this material in fatigue is of the von Mises type. Specimens with circular holes of various diameters under tension, torsion and in-phase biaxial loading were tested. The Directions of the Cracks that grew from the holes were studied with an optical microscope, a scanning electron microscope (SEM) and a non-contact 3D optical profiler. In particular, the points where the Cracks began and the Direction in which the Cracks propagated along the first 150 μm were analysed. In general, the initiation point was close to the maximum principal stress point, and the Crack Direction was close to the maximum principal stress Direction. The endurance limit predictions were close to the experimental results.
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stage i Crack Directions under in phase axial torsion fatigue loading for aisi 304l stainless steel
International Journal of Fatigue, 2015Co-Authors: V. Chaves, A. Navarro, C MadrigalAbstract:Abstract Smooth AISI 304L stainless steel specimens were tested in fatigue. The tests were axial, torsional and in-phase axial–torsional, all of them under load control with R = −1. S–N curves were constructed following the ASTM E739 standard and the fatigue limits were obtained following the method of maximum likelihood proposed by Betinelli. The ratio between the pure torsion and tension fatigue limits, τ FL / σ FL , was 0.91, close to 1, which is a typical value for fragile materials. The fatigue limits determined by the biaxial tests were represented on σ - τ axes. These experimental values were well fitted with an elliptical quadrant, although this fitting is considered appropriate for ductile materials. The Crack Direction along the surface was analysed using a microscope, with special attention dedicated to the Crack initiation zones. The Crack Direction along the first grains, or Stage I, was much closer to the Mode I Direction than to the Mode II Direction.
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microstructural model for predicting high cycle fatigue strength in the presence of holes under proportional biaxial loading
Theoretical and Applied Fracture Mechanics, 2014Co-Authors: V. Chaves, G. Beretta, A. Navarro, C MadrigalAbstract:Abstract Microstructural fracture mechanics models provide a description of short Crack growth that accounts for the interaction between Cracks and microstructural barriers. In these models the Crack and the plastic zone are represented by a distribution of dislocations. An application to a circular notch under proportional biaxial load is shown. The procedure for calculating the biaxial notched fatigue limit is presented. The Crack initiation point and the Crack Direction are predicted too. The results are compared with experiments from the literature for specimens with a circular hole subjected to pure bending, pure torsion and in-phase biaxial loadings. The need of a biaxial model to account for the Direction of initial Crack growth found in practice is established. An interesting result given by the model is the fact that the smaller the radius of the notch, the wider the region along the notch contour where the likelihood of initiation is equally high.
Marino Arroyo - One of the best experts on this subject based on the ideXlab platform.
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phase field modeling and simulation of fracture in brittle materials with strongly anisotropic surface energy
International Journal for Numerical Methods in Engineering, 2015Co-Authors: Bin Li, Christian Peco, Daniel Millan, Irene Arias, Marino ArroyoAbstract:Crack propagation in brittle materials with anisotropic surface energy is important in applications involving single crystals, extruded polymers, or geological and organic materials. Furthermore, when this anisotropy is strong, the phenomenology of Crack propagation becomes very rich, with forbidden Crack propagation Directions or complex sawtooth Crack patterns. This problem interrogates fundamental issues in fracture mechanics, including the principles behind the selection of Crack Direction. Here, we propose a variational phase-field model for strongly anisotropic fracture, which resorts to the extended Cahn-Hilliard framework proposed in the context of crystal growth. Previous phase-field models for anisotropic fracture were formulated in a framework only allowing for weak anisotropy. We implement numerically our higher-order phase-field model with smooth local maximum entropy approximants in a direct Galerkin method. The numerical results exhibit all the features of strongly anisotropic fracture and reproduce strikingly well recent experimental observations.
V. Chaves - One of the best experts on this subject based on the ideXlab platform.
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Fatigue life and Crack growth Direction in 7075-T6 aluminium alloy specimens with a circular hole under biaxial loading
International Journal of Fatigue, 2019Co-Authors: V. Chaves, G. Beretta, J.a. Balbín, A. NavarroAbstract:Abstract This work shows the results of a set of tests in 7075-T6 aluminium alloy specimens. The tests were under load control at R = - 1 . From the tests, the corresponding S-N curves were built, and the endurance limits were calculated for 1 million cycles. The ratio between the pure torsion and tension endurance limits was 0.58, i.e., the behaviour of this material in fatigue is of the von Mises type. Specimens with circular holes of various diameters under tension, torsion and in-phase biaxial loading were tested. The Directions of the Cracks that grew from the holes were studied with an optical microscope, a scanning electron microscope (SEM) and a non-contact 3D optical profiler. In particular, the points where the Cracks began and the Direction in which the Cracks propagated along the first 150 μm were analysed. In general, the initiation point was close to the maximum principal stress point, and the Crack Direction was close to the maximum principal stress Direction. The endurance limit predictions were close to the experimental results.
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stage i Crack Directions under in phase axial torsion fatigue loading for aisi 304l stainless steel
International Journal of Fatigue, 2015Co-Authors: V. Chaves, A. Navarro, C MadrigalAbstract:Abstract Smooth AISI 304L stainless steel specimens were tested in fatigue. The tests were axial, torsional and in-phase axial–torsional, all of them under load control with R = −1. S–N curves were constructed following the ASTM E739 standard and the fatigue limits were obtained following the method of maximum likelihood proposed by Betinelli. The ratio between the pure torsion and tension fatigue limits, τ FL / σ FL , was 0.91, close to 1, which is a typical value for fragile materials. The fatigue limits determined by the biaxial tests were represented on σ - τ axes. These experimental values were well fitted with an elliptical quadrant, although this fitting is considered appropriate for ductile materials. The Crack Direction along the surface was analysed using a microscope, with special attention dedicated to the Crack initiation zones. The Crack Direction along the first grains, or Stage I, was much closer to the Mode I Direction than to the Mode II Direction.
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microstructural model for predicting high cycle fatigue strength in the presence of holes under proportional biaxial loading
Theoretical and Applied Fracture Mechanics, 2014Co-Authors: V. Chaves, G. Beretta, A. Navarro, C MadrigalAbstract:Abstract Microstructural fracture mechanics models provide a description of short Crack growth that accounts for the interaction between Cracks and microstructural barriers. In these models the Crack and the plastic zone are represented by a distribution of dislocations. An application to a circular notch under proportional biaxial load is shown. The procedure for calculating the biaxial notched fatigue limit is presented. The Crack initiation point and the Crack Direction are predicted too. The results are compared with experiments from the literature for specimens with a circular hole subjected to pure bending, pure torsion and in-phase biaxial loadings. The need of a biaxial model to account for the Direction of initial Crack growth found in practice is established. An interesting result given by the model is the fact that the smaller the radius of the notch, the wider the region along the notch contour where the likelihood of initiation is equally high.
