The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Lizhong Liu - One of the best experts on this subject based on the ideXlab platform.
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a Tensile Specimen of tailor rolled blanks with equal probability in yield and its mechanical behavior analysis
Materials, 2018Co-Authors: Sijia Zhang, Xianghua Liu, Lizhong LiuAbstract:In this paper, the microstructure and mechanical properties that distribute regulation along the rolling direction of tailor rolled blanks (TRB) were investigated. A Tensile Specimen with equal probability in yield (EYS) was first designed considering variation both in thickness and in material strength. The uniaxial tension test was carried out with a digital image correlation method to analyze the mechanical behaviors. The results showed that the strain distribution of EYS was homogeneous. From the results, it can be known that a new design philosophy for a TRB Tensile Specimen is reasonable and EYS is suitable to characterize the mechanical behavior of TRB. The true stress-strain curves of metal in different cross sections of TRB were calculated. On the basis of the true stress-strain curves, a material model of TRB was constructed and then implemented into finite element simulations of TRB uniaxial Tensile tests. The strain distribution of numerical and experimental results was similar and the error between the elongation of the Specimen after fracture obtained by experiment and FE ranged from 9.51% to 13.06%. Therefore, the simulation results match well with the experimental results and the material model has high accuracy and as well as practicability.
Dhiraj Kumar Singh - One of the best experts on this subject based on the ideXlab platform.
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cohesive zone based axisymmetric modelling of hydrogen assisted cracking in a circumferentially notched Tensile Specimen
International Journal of Hydrogen Energy, 2018Co-Authors: S K Maiti, Dhiraj Kumar Singh, Tanmay K Bhandakkar, R Singh K RamanAbstract:Abstract The paper presents an axisymmetric finite element model to study hydrogen-assisted cracking (HAC) in a circumferentially notched Tensile (CNT) Specimen of a high-strength steel. The model includes an axisymmetric 2-D stress analysis coupled with an axisymmetric 1-D hydrogen diffusion analysis. Crack initiation is handled through cohesive elements whose strength is adjusted depending on the local hydrogen concentration. The model successfully predicted the critical SIFs of tempered AISI 4340 under different hydrogen charging conditions in rising displacement tests. Furthermore, the model is able to simulate of typical delayed failure of Specimens under HAC conditions in constant load tests. Reported HAC of three different microstructures of AISI 4340 was simulated under rising displacement condition, and the respective model parameters were then also used to simulate crack initiation in the same microstructures under constant load condition. Closeness of critical SIFs from both the simulations indicates that the model parameters calibrated through slow strain rate tests are transferable to constant load situations. Moreover, it is shown that the present 2-D analysis, while being computationally advantageous, is an acceptable alternative of a 3-D model reported earlier.
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efficient approach for cohesive zone based three dimensional analysis of hydrogen assisted cracking of a circumferentially notched round Tensile Specimen
International Journal of Hydrogen Energy, 2017Co-Authors: S K Maiti, Dhiraj Kumar Singh, Tanmay K Bhandakkar, R Singh K RamanAbstract:Abstract An efficient ABAQUS based finite element (FE) analysis for hydrogen-assisted cracking is presented. Analysis of two dimensional (2-D) diffusion of hydrogen is coupled with three dimensional (3-D) stress analysis incorporating cohesive elements. The deleterious effect of hydrogen on crack growth is introduced through the hydrogen enhanced decohesion (HEDE) mechanism where modification to the cohesive energy is related to local hydrogen concentration. The proposed method is applied to hydrogen-assisted cracking of a circumferentially notched Tensile (CNT) Specimen under three different conditions of hydrogen supply and its performance is demonstrated through the close agreement between the corresponding computed critical stress intensity factors (SIFs) and the experimental results reported in the literature. The modelling duly accounts for the off-centre precracked ligament usually resulting from fatigue precracking of CNT Specimens. The results clearly bring out the non-axisymmetric nature of concentration distribution and stress field, and reveal enhanced hydrogen diffusion at a point on the outer edge of the ligament profile where crack depth is the highest and wherefrom the crack extension is likely to initiate.
Yulong Li - One of the best experts on this subject based on the ideXlab platform.
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Progressive Failure Simulation of Notched Tensile Specimen for Triaxially-Braided Composites
Materials, 2019Co-Authors: Zhenqiang Zhao, Haoyuan Dang, Jun Xing, Xi Li, Chao Zhang, Wieslaw K. Binienda, Yulong LiAbstract:The mechanical characterization of textile composites is a challenging task, due to their nonuniform deformation and complicated failure phenomena. This article introduces a three-dimensional mesoscale finite element model to investigate the progressive damage behavior of a notched single-layer triaxially-braided composite subjected to axial tension. The damage initiation and propagation in fiber bundles are simulated using three-dimensional failure criteria and damage evolution law. A traction–separation law has been applied to predict the interfacial damage of fiber bundles. The proposed model is correlated and validated by the experimentally measured full field strain distributions and effective strength of the notched Specimen. The progressive damage behavior of the fiber bundles is studied by examining the damage and stress contours at different loading stages. Parametric numerical studies are conducted to explore the role of modeling parameters and geometric characteristics on the internal damage behavior and global measured properties of the notched Specimen. Moreover, the correlations of damage behavior, global stress–strain response, and the efficiency of the notched Specimen are discussed in detail. The results of this paper deliver a throughout understanding of the damage behavior of braided composites and can help the Specimen design of textile composites.
Guillermo Requena - One of the best experts on this subject based on the ideXlab platform.
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synchrotron based holotomography and x ray fluorescence study on the stress corrosion cracking behavior of the peak aged 7075 aluminum alloy
Journal of Alloys and Compounds, 2020Co-Authors: Christoph Altenbach, Christian Schnatterer, Ulises Alfaro Mercado, Jussipetteri Suuronen, Daniela Zander, Guillermo RequenaAbstract:Abstract The demand to reduce weight in the automobile industry necessitates an enhanced understanding of the stress corrosion cracking (SCC) mechanism of 7xxx series aluminum wrought alloys. Thus, the SCC susceptibility of 7075 aluminum wrought alloy wires, with respect to the heat treatment condition, solution annealed, peak-aged and overaged, was investigated via slow strain rate testing in 3.5 wt % sodium chloride solution. The SCC crack, initiated in a notched Tensile Specimen of the peak-aged condition, was investigated in detail by means of synchrotron-based high resolution holotomography and X-ray fluorescence as well as STEM in order to understand the correlation of microstructural features and cracking behavior. The local crack initiation and macroscopic crack propagation was found to be dependent on the stress fields, which were simulated by the finite element method. In the peak-aged condition, the SCC crack propagated microscopically along the grain boundaries leading to a brittle intergranular fracture. The SCC mechanism in the peak-aged condition was related to a combination of hydrogen embrittlement and an anodic-dissolution-induced notch effect that was attributed to a continuous seam of grain boundary (GB) precipitates.
Todd J Turner - One of the best experts on this subject based on the ideXlab platform.
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fiducial marker application method for position alignment of in situ multimodal x ray experiments and reconstructions
Journal of Applied Crystallography, 2016Co-Authors: Paul A Shade, Joel V Bernier, Jay C Schuren, Peter Kenesei, R M Suter, David B Menasche, Junsang Park, Todd J TurnerAbstract:An evolving suite of X-ray characterization methods are presently available to the materials community, providing a great opportunity to gain new insight into material behavior and provide critical validation data for materials models. Two critical and related issues are sample repositioning during an in situ experiment and registration of multiple data sets after the experiment. To address these issues, a method is described which utilizes a focused ion-beam scanning electron microscope equipped with a micromanipulator to apply gold fiducial markers to samples for X-ray measurements. The method is demonstrated with a synchrotron X-ray experiment involving in situ loading of a titanium alloy Tensile Specimen.
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combined near and far field high energy diffraction microscopy dataset for ti 7al Tensile Specimen elastically loaded in situ
Integrating Materials and Manufacturing Innovation, 2016Co-Authors: Todd J Turner, Paul A Shade, Joel V Bernier, Jay C Schuren, Jonathan Lind, U Lienert, Peter Kenesei, R M Suter, Basil BlankAbstract:High-energy diffraction microscopy (HEDM) constitutes a suite of combined X-ray characterization methods, which hold the unique advantage of illuminating the microstructure and micromechanical state of a material during concurrent in situ mechanical deformation. The data generated from HEDM experiments provides a heretofore unrealized opportunity to validate meso-scale modeling techniques, such as crystal plasticity finite element modeling (CPFEM), by explicitly testing the accuracy of these models at the length scales where the models predict their response. Combining HEDM methods with in situ loading under known and controlled boundary conditions represents a significant challenge, inspiring the recent development of a new high-precision rotation and axial motion system for simultaneously rotating and axially loading a sample. In this paper, we describe the initial HEDM dataset collected using this hardware on an alpha-titanium alloy (Ti-7Al) under in situ Tensile deformation at the Advanced Photon Source, Argonne National Laboratory. We present both near-field HEDM data that maps out the grain morphology and intragranular crystallographic orientations and far-field HEDM data that provides the grain centroid, grain average crystallographic orientation, and grain average elastic strain tensor for each grain. Finally, we provide a finite element mesh that can be utilized to simulate deformation in the volume of this Ti-7Al Specimen. The dataset supporting this article is available in the National Institute of Standards and Technology (NIST) repository ( https://doi.org/hdl.handle.net/11256/599 ).
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the influence of crystallographic texture and slip system strength on deformation induced shape changes in aa 7050 thick plate
Mechanics of Materials, 2002Co-Authors: Todd J Turner, Matthew P Miller, Nathan R BartonAbstract:The development of a multiscale modeling formulation to predict the mechanical response of AA 7050 thick plate is presented. Due to the heterogeneous processing conditions of this material, a significant gradient in both texture and macroscale hardness is observed through the thickness of the plate. These gradients create substantial variations in material state and properties, and have limited the widespread employment of AA 7050 thick plate in flight-critical airframe components. An elasto-viscoplastic finite element formulation was employed in modeling the mechanical response of a Tensile Specimen machined through the thickness of the plate material. The Tensile Specimen displayed measurable differences in the mechanical response along its gage length, where the cross-sectional shape of the Specimen became non-circular at the quarter planes of the plate while it remained circular along the centerplane. In addition, the centerplane strained more than any other location along the gage length. The modeling framework employed in this work was able to capture various trends observed in the small strain aspects of this mechanical response, by combining descriptions of the texture and slip system strength distributions with a polycrystal based finite element formulation. With this multiscale modeling framework, the influence of crystallographic texture and slip system strength on the mechanical performance of the thick plate material was explored. It was found that a description of both the gradients in texture and slip system strength were ultimately necessary to predict the experimentally observed mechanical response. If these two aspects of material structure were varied independently, the mechanical performance was not well captured.
