Crystal Plasticity Finite-Element Simulation of Single Phase Titanium Alloy with 3D Polycrystalline Models

2014 ◽  
Vol 789 ◽  
pp. 608-615
Author(s):  
Shao Xie ◽  
Bin Tang ◽  
Yi Liu ◽  
Feng Bo Han ◽  
Hong Chao Kou ◽  
...  
Keyword(s):  
Finite Element ◽  
Crystal Plasticity ◽  
Voronoi Tessellation ◽  
Three Dimensional ◽  
Local Stress ◽  
Strain Response ◽  
Stress Strain ◽  
Β Phase ◽  
Crystallographic Slip ◽  
Mesh Density

Based on the rate-dependent crystal plasticity theory, a finite element code which considers crystallographic slip as deformation mechanism of material was developed to investigate the stress–strain response of the β phase of Ti-5553 during uniaxial tension. Three dimensional models with random grain shapes generated by Voronoi tessellation were used for simulations, and two discretization methods were used to disperse the models. Firstly, the parameters of material were identified by fitting simulation stress-strain curves with experimental data. Then the global stress-strain curves were calculated, and effects of mesh type and mesh density were discussed. Results show that mesh type has a relatively significant influence on overall responses, whereas the influence of mesh density is slight. Investigate of local stress-strain response in each grain was also conducted, and obvious inter-granular heterogeneities were observed. Quantitative analysis indicates that the range of stress and strain variations is affected by mesh type.

Crystal Plasticity Finite Element Simulations of Polycrystalline Aluminium Alloy under Cyclic Loading

2014 ◽  
Vol 891-892 ◽  
pp. 1609-1614 ◽  
Author(s):  
Ling Li ◽  
Lu Ming Shen ◽  
Gwénaëlle Proust
Keyword(s):  
Finite Element ◽  
Cyclic Loading ◽  
Aluminium Alloy ◽  
Crystal Plasticity ◽  
Three Dimensional ◽  
Grain Morphology ◽  
Element Model ◽  
Electron Back Scatter Diffraction ◽  
Plastic Deformation Zone ◽  
Mesh Density

A three-dimensional crystal plasticity (CP) finite element model is developed to reproduce the grain level stress concentration and deformation of polycrystalline aluminium alloy 7075 (AA7075) during fatigue experiments. The grains contained in the model possess the same size and crystallographic orientations obtained from electron back-scatter diffraction experiments. A modified CP constitutive model, which considers the backstress evolution, is employed to describe the mechanical behaviour of AA7075 under cyclic loading. A round-notched specimen from a fatigue test is simulated using the proposed CP model. Convergence studies in terms of mesh density and plastic deformation zone size are carried out to determine the appropriate conditions for the simulation. The simulation results are compared with those obtained using the elasto-plastic model and the CP model without grain morphology. The comparison indicates that with the embedded grain morphology, the proposed model can capture very well the local response induced by the microstructure features, which is vital to the accurate fatigue life prediction of aluminium alloys.

Local Stress-Strain Method for the Effects of Scratch on Fatigue Performances of Cabin Glass

2011 ◽  
Vol 299-300 ◽  
pp. 51-56
Author(s):  
Hua Ding ◽  
Yu Ting He ◽  
Jin Qiang Du ◽  
Li Ming Wu ◽  
Hai Wei Zhang ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Three Dimensional ◽  
Local Stress ◽  
Element Model ◽  
Fatigue Tests ◽  
Three Dimensional Model ◽  
Stress Strain ◽  
Finite Element Software ◽  
Strain Method

The three-dimensional finite element model of cabin glass with surface scratch is built using the finite element software ANSYS, which is aimed to analyze the detailed stress around the scratch route tip. Then the fatigue notch factor can be gained through utilizing of results from three-dimensional model, which is followed by the estimation of fatigue life based on local stress-strain method. It is found that the stress around scratch route tip is nearly linearly increased with the increasing of tip depth (0.2mm<h<0.8mm) and the fatigue performances of cabin glass with surface scratch are sensitive to scratch depth. Finally, fatigue tests are carried out with the specimens of different scratch route tip depths, and validation against fatigue life by local stress-strain method and experimental data shows a good agreement, which indicates that the scratch model and the local stress-strain method for the effects of scratch on cabin glass fatigue performances are valid.

An Investigation Into the Robustness of a Crystal Plasticity Finite Element Model

2020 ◽  
Author(s):  
Megan Taylor ◽  
Dylan Agius ◽  
David Knowles ◽  
Mahmoud Mostafavi
Keyword(s):  
Boundary Condition ◽  
Finite Element ◽  
Boundary Conditions ◽  
Crystal Plasticity ◽  
Local Environment ◽  
Strain Response ◽  
Stress Strain ◽  
Crystal Plasticity Finite Element ◽  
Central Volume ◽  
Single Grain

Abstract A crystal plasticity model has been developed for describing the plastic and viscoplastic behaviour of 316H stainless steel. The model has been used successfully to predict the macroscopic response of the material for monotonic and cyclic loading, however the robustness of the model is now being scrutinised to ensure that it captures the underlying mechanisms and local meso-scale deformation characteristics correctly. In order to look at this in more detail, the model has been scripted to allow simulation of diffraction studies on the grains. This is being used to compare the simulation output with neutron and synchrotron experiments. A theoretical study has been completed which adjusts the values of each material parameter within the crystal plasticity finite element (CPFE) framework in isolation to analyse the effect each has upon the shape of the hysteresis loop and how this relates to predictions. A further study had been conducted to investigate the amount of scatter that is produced by altering the initial microstructure of a relatively small volume. The results show that changing the initial microstructure has a negligible effect on the subsequent stress-strain response. This indicates the influence that the grain morphology will have upon the diffraction measurements and that there is no need to consider this further when testing small specimens. To conclude this investigation two further aspects of the model have being scrutinised; the effects of constraining boundary conditions and altering the local environment of a single grain, again to explore the influences which these may have on diffraction studies. The plane boundaries of the volume are currently fixed at zero displacement which will influence the local grains on these boundaries as they are over constrained, but should not alter the overall stress-strain response. To investigate this, grains within the model that have boundary conditions applied have be discarded from the final results to leave the response from the central volume that should be free of the boundary condition effects. The results show that the macroscopic response of the bulk volume and the central volume are very similar but when the individual grain family responses are analysed, it can be seen that the boundary condition do alter the response of the representative volume element (RVE). To analyse how the local environment surrounding a single grain affects its stress-strain response, a centrally located grain will be selected and kept constant while the orientation of the surrounding grains are randomly altered. It has been found that changing the local environment surrounding a single grain will impact the stress-strain response seen by that grain.

scholarly journals Crystal plasticity-based micromechanical finite element modelling of ductile void growth for an aluminium alloy under multiaxial loading conditions

2018 ◽  
Vol 233 (1) ◽  
pp. 52-62
Author(s):  
He-Jie Guo ◽  
Dong-Feng Li
Keyword(s):  
Finite Element ◽  
Single Crystal ◽  
Aluminium Alloy ◽  
Crystal Plasticity ◽  
Void Growth ◽  
Crystallographic Orientation ◽  
Stress Triaxiality ◽  
Void Coalescence ◽  
Stress Strain ◽  
Crystallographic Slip

This work proposes a crystal plasticity-based micromechanical finite element model to account for the inelastic crystallographic slip in an aluminium alloy and its effect on the development of micro-voids. Three-dimensional unit cell with periodic boundary conditions is used to represent the porous single crystal, which is subject to multiaxial external loads with constant stress triaxiality. The effects of stress triaxiality and crystallographic orientation on the ductile failure response for the porous single crystal are then quantified. Through the Taylor–Reuss mean field homogenisation, the stress–strain responses for porous polycrystal under multiaxial stress states are also investigated and compared with the conventional modelling results. The present work indicates that void coalescence strain at single crystal level strongly depends on the crystallographic orientation, particularly when stress triaxiality is low, and the overall stress–strain response of porous polycrystal can be affected by the crystallographic slip-based micro-void growth and polycrystallinity of the material.

Finite Element Modeling for Steel Cord Analysis in Radial Tires

2013 ◽  
Vol 41 (1) ◽  
pp. 60-79 ◽  
Author(s):  
Wei Yintao ◽  
Luo Yiwen ◽  
Miao Yiming ◽  
Chai Delong ◽  
Feng Xijin
Keyword(s):  
Finite Element ◽  
High Efficiency ◽  
Force Measurement ◽  
Three Dimensional ◽  
Local Stress ◽  
Tension Force ◽  
Center Line ◽  
Element Analysis ◽  
Design Variables ◽  
Steel Cord

ABSTRACT: This article focuses on steel cord deformation and force investigation within heavy-duty radial tires. Typical bending deformation and tension force distributions of steel reinforcement within a truck bus radial (TBR) tire have been obtained, and they provide useful input for the local scale modeling of the steel cord. The three-dimensional carpet plots of the cord force distribution within a TBR tire are presented. The carcass-bending curvature is derived from the deformation of the carcass center line. A high-efficiency modeling approach for layered multistrand cord structures has been developed that uses cord design variables such as lay angle, lay length, and radius of the strand center line as input. Several types of steel cord have been modeled using the developed method as an example. The pure tension for two cords and the combined tension bending under various loading conditions relevant to tire deformation have been simulated by a finite element analysis (FEA). Good agreement has been found between experimental and FEA-determined tension force-displacement curves, and the characteristic structural and plastic deformation phases have been revealed by the FE simulation. Furthermore, some interesting local stress and deformation patterns under combined tension and bending are found that have not been previously reported. In addition, an experimental cord force measurement approach is included in this article.

scholarly journals Finite Element Analysis of Stress-Strain Response at the Tool Pin During Friction Stir Process

2015 ◽  
Vol 76 ◽  
pp. 522-527
Author(s):  
M. Shamil Jaffarullah ◽  
Nur’Amirah Busu ◽  
Cheng Yee Low ◽  
J.B. Saedon ◽  
Armansyah ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Strain Response ◽  
Stress Strain ◽  
Element Analysis ◽  
Friction Stir Process ◽  
Friction Stir ◽  
Tool Pin

Finite Element Analysis of Stress Singularities in Attached Flip Chip Packages

2000 ◽  
Vol 122 (4) ◽  
pp. 301-305 ◽  
Author(s):  
A. Q. Xu ◽  
H. F. Nied
Keyword(s):  
Contact Angle ◽  
Finite Element ◽  
Glass Fiber ◽  
Flip Chip ◽  
Three Dimensional ◽  
Stress Singularity ◽  
Local Stress ◽  
Stress Singularities ◽  
Element Analysis ◽  
Three Dimensional Finite Element

Cracking and delamination at the interfaces of different materials in plastic IC packages is a well-known failure mechanism. The investigation of local stress behavior, including characterization of stress singularities, is an important problem in predicting and preventing crack initiation and propagation. In this study, a three-dimensional finite element procedure is used to compute the strength of stress singularities at various three-dimensional corners in a typical Flip-Chip assembled Chip-on-Board (FCOB) package. It is found that the stress singularities at the three-dimensional corners are always more severe than those at the corresponding two-dimensional edges, which suggests that they are more likely to be the potential delamination sites. Furthermore, it is demonstrated that the stress singularity at the upper silicon die/epoxy fillet edge can be completely eliminated by an appropriate choice in geometry. A weak stress singularity at the FR4 board/epoxy edge is shown to exist, with a stronger singularity located at the internal die/epoxy corner. The influence of the epoxy contact angle and the FR4 glass fiber orientation on stress state is also investigated. A general result is that the strength of the stress singularity increases with increased epoxy contact angle. In addition, it is shown that the stress singularity effect can be minimized by choosing an appropriate orientation between the glass fiber in the FR4 board and the silicon die. Based on these results, several guidelines for minimizing edge stresses in IC packages are presented. [S1043-7398(00)00904-X]

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