Computer Simulation of Fracture in Brittle Polycrystalline Solids: Effect of Modulus Amisotropy

1992 ◽  
Vol 291 ◽  
Author(s):  
Shiun Ling ◽  
Michael P. Anderson
Keyword(s):  
Fracture Behavior ◽  
Careful Analysis ◽  
Fracture Morphology ◽  
Constitutive Relationship ◽  
Stress Distributions ◽  
Compliance Matrix ◽  
Spring Network Model ◽  
Polycrystalline Solids ◽  
D Model ◽  
Crystalline Symmetry

ABSTRACTA simulation procedure based on the spring network model has been developed for studying the fracture behavior in brittle, polycrystalline solids. In this 2-D model, the effect of crystalline symmetry is accounted for by imparting to individual bonds a constitutive relationship using the material compliance matrix. Using this model, it was found that the fracture morphology becomes more intragranular in nature with increasing modulus anisotropy. Careful analysis suggests that this is due to the wider stress distributions, and the resulting larger number of cracks generated in the interior of anisotropic grains.

Mechanical Properties and Fracture Behavior of Indirect Squeeze-Cast A354 Alloy Using Local Pressurization

2016 ◽  
Vol 850 ◽  
pp. 502-510
Author(s):  
Hai Jun Liu ◽  
Lie Jun Li ◽  
Jian Wei Niu ◽  
Ji Xiang Gao ◽  
Xue Wen Chen
Keyword(s):  
Mechanical Properties ◽  
Tensile Properties ◽  
Fracture Behavior ◽  
Eutectic Silicon ◽  
Solidification Rate ◽  
Fracture Morphology ◽  
Shrinkage Cavity ◽  
Squeeze Cast ◽  
Ductile Mode ◽  
Eutectic Si

The effect of local pressurization on mechanical properties and fracture behavior of indirect squeeze-cast A354 alloy has been investigated. As compared to conventional process, the porosity and shrinkage cavity for heavy sectioned squeeze castings were improved by the indirect squeeze casting, while its tensile properties were inferior to other parts of the casting. That is mainly due to that inhomogeneous eutectic Si particles within strip, angular and fragment shapes distribute in bulky α-Al cells, which is caused by slower solidification rate. After T6 treatment, the fragmentation and spheroidization of the eutectic silicon happened. Under this situation, the effect of fragmentation on α-Al matrix reduced. Tensile properties of the casting (both local pressurization part and non-local pressurization part) were enhanced greatly, by 36.8% and 25.4%, respectively. Fracture analysis results show that the type of fracture morphology is changed from mixed mode of brittle cleavage and ductile to ductile mode after T6-treatment.

Influence of Heat Treatment Process on Tensile Fracture Behavior of Cu-Based Metallic Glass

2013 ◽  
Vol 742 ◽  
pp. 170-174
Author(s):  
Ling Zhang ◽  
De Chun Luo ◽  
Xiang Bin Yi
Keyword(s):  
Tensile Strength ◽  
Fracture Behavior ◽  
Isothermal Annealing ◽  
Flow Behavior ◽  
Performance Testing ◽  
Fracture Morphology ◽  
Test Sample ◽  
Fracture Pattern ◽  
Tensile Fracture ◽  
Venation Pattern

The Cu50Zr42Al8dumbbell-shaped alloy with original scale distance of 25 mm and diameters of 4.5 mm was prepared by the suspend melting-copper mould suction casting. The structure tensile performance testing and the fracture morphology observation of Cu50Zr42Al8BMG as-quenched and 400k/1h isothermal annealing were investigated, respectively. The deformation and fracture behavior of samples had been studied. The results showed that the structure of all samples were composed of amorphous phase and possess good glass formation abilitysample as-quenched is always in the elastic deformation stage during elongation and the tensile strength is 629MPa; however ,for specimen after 400k/1h isothermal annealing ,the yield phenomenon occurs before breaking and the maximum tensile strength is 755Mpa, and the same time, the maximum failure extensibility increases from 0.56% for sample as-quenched to 0.80% for 400k/1h isothermal annealing. The fracture pattern of test sample at annealing assumes venation pattern, which is similar to fractography of Cu50Zr42Al8BMG as-quenched, in addition, which appeared apparent viscous flow behavior and melting characteristics.

Fracture Behavior and Its Shear Lag – Monte Carlo Simulation of SiC/SiC Composite Exposed in Air at High Temperatures

2005 ◽  
Vol 475-479 ◽  
pp. 1101-1104
Author(s):  
Kohei Morishita ◽  
H. Tanaka ◽  
Shigeru Kimura ◽  
Hiroshi Okuda ◽  
Shojiro Ochiai ◽  
...  
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
High Temperatures ◽  
Fracture Behavior ◽  
High Strength ◽  
Simulation Method ◽  
Fracture Morphology ◽  
Sio2 Layer ◽  
Monte Carlo Simulation Method ◽  
Shear Lag

It has been reported that SiC/SiC composite has high strength and toughness, but is degraded when exposed in air at high temperatures due to the propagation of the crack made by the premature fracture of the SiO2 layer. The present work aimed to describe such a behavior with a computer simulation. For this aim, the shear lag - Monte Carlo simulation method was applied. The variation of strength of the composite as a function of thickness of the SiO2 layer and change of fracture morphology with progressing oxidation could be reproduced satisfactorily by this method.

Effect of Si Content on the Fatigue Fracture Behavior of Wrought Al-xSi-0.7Mg Alloy

2018 ◽  
Vol 941 ◽  
pp. 1143-1148 ◽  
Author(s):  
Guang Dong Wang ◽  
Ni Tian ◽  
Chong Li ◽  
Gang Zhao ◽  
Liang Zuo
Keyword(s):  
Structural Material ◽  
Fatigue Fracture ◽  
Fracture Behavior ◽  
Low Cost ◽  
Fracture Morphology ◽  
Alloy Sheet ◽  
Fatigue Properties ◽  
Low Thermal Expansion ◽  
Si Content ◽  
Fatigue Fracture Behavior

The wrought Mg-containing high-silicon aluminum alloy has become more attractive as an ideal structural material, because it has moderate strength and the ductility, high wear and corrosion resistance, low thermal expansion coefficient and low cost. However, as structural material, the fatigue properties and the fatigue fracture behavior of it should be paid much more attention to, especially the effect of Si content on the fatigue properties of wrought Mg-containing Al-Si alloy. In this paper, the wrought Al-(1.44%, 4.92%, 6.61%, 8.81% and 12.4%)Si-0.7%Mg alloy were prepared through DCC and homogenization treatment, and then hot-rolled and cold-rolled into 1.3mm sheets. The microstructure and fatigue fracture morphology of Al-(1.44~12.4)Si-0.7Mg-T4 alloy sheet after fatigue test were investigated by LSCM and SEM. The results showed that the size of Si particles in Al-(1.44~12.4)Si-0.7Mg alloy sheets was approximately the same, but the number of Si particles increased as the Si content increased. The size of recrystallization grain in Al-(1.44~12.4)Si-0.7Mg alloy sheets decreased from 47μm to 10μm when Si content increased from 1.44% to 12.4%, which indicates that increasing of Si content can refine the grain of Al-(1.44~12.4)Si-0.7Mg alloy sheets. With the increasing of Si content the propagation area of fatigue fracture surface of Al-(1.44~12.4)Si-0.7Mg alloy sheets in T4 temper became rougher, and crack propagation became more difficult. Moreover, dimples in the fast fracture area became larger in amount, smaller in size and more uniform in distribution.

Fracture Behavior and Microstructure of 60Si2MnA Spring Steels Modified by V-Nb Inoculants

2011 ◽  
Vol 415-417 ◽  
pp. 1085-1089
Author(s):  
Tie Bao Wang ◽  
Chun Xiang Cui ◽  
Lin Fang ◽  
Shao Jing Bu
Keyword(s):  
Melt Spinning ◽  
Fracture Behavior ◽  
Prior Austenite ◽  
Fracture Morphology ◽  
Tensile Fracture ◽  
Grain Sizes ◽  
Austenite Grain ◽  
Spring Steels ◽  
Nb Microalloyed Steel ◽  
Prior Austenite Grain

The microstructure of V-Nb inoculants after melt spinning was investigated by performing TEM examination and to the sample steels, the prior austenite grain sizes and fracture morphology were investigated by SEM observation. The results show that the V-Nb inoculants obtained is amorphous and the sample steel modified by V-Nb inoculants which make it possible to be a large amount of nucleation centers existing in the form of (V, Nb)C and achieve the effect of grain refinement in the solidification stages of liquid steel has been found to have the finest prior austenite grain sizes and the average prior austenite grain sizes of steel without addition of V and Nb(Steel A), steel microalloyed with V and Nb(Steel B) and steel modified by V-Nb inoculants(Steel C) are respectively 30μm, 20μm and 10μm. Tensile behavior of samples was studied under tempering at 400°C for 30 min after quenching, tensile results show that the fracture of steel modified by V-Nb inoculants appears dimples which represent ductile fracture. However the tensile fracture of V-Nb microalloyed steel is mixture of quasi-cleavages and dimples. Under tempering at 550°C for 30 min, Steel B and Steel C both show a fractograph with cleavage fracture.

Numerical Simulation of Stress Corrosion Cracking in a Pipe Using S-Version FEM

2010 ◽  
Vol 452-453 ◽  
pp. 577-580
Author(s):  
Masanori Kikuchi ◽  
Yoshitaka Wada ◽  
Yuto Shimizu ◽  
Yu Long Li
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Crack Growth ◽  
Fracture Behavior ◽  
Three Dimensional ◽  
Stress Fields ◽  
Crack Growth Behavior ◽  
Stress Distributions ◽  
Residual Stress Field ◽  
Energy Agency

Fracture in heat affected zone (HAZ) in welding has been a serious problem for the integrity of machines. Prediction of fracture behavior due to the residual stress field in HAZ is important. In this paper, S-Version FEM(S-FEM) is applied to simulate the crack growth under thermal and residual stress fields. For evaluation of stress intensity factor, virtual crack closure integral method (VCCM) is employed. The residual stress data was provided by JAEA, Japan Atomic Energy Agency, based on their numerical simulation. SCC crack growth of a surface crack at inner suface of a pipe under thermal residual stress is simulated in three-dimensional filed. Distributions of residual stress is not axi-symmetric along pipe wall, and it affects the crack growth behavior. Ttwo cases, for axi-symmetric and non-symmetric thermal stress distributions, are assumed and crack growth behaviors are obtaiend and discussed.

scholarly journals Fracture Behavior of Single-Crystal Sapphire in Different Crystal Orientations

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 930
Author(s):  
Shizhan Huang ◽  
Jiaming Lin ◽  
Ningchang Wang ◽  
Bicheng Guo ◽  
Feng Jiang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Surface Roughness ◽  
Single Crystal ◽  
Fracture Behavior ◽  
Three Dimensional ◽  
Fracture Morphology ◽  
High Tech ◽  
Bending Tests ◽  
Three Point Bending ◽  
Single Crystal Sapphire

In order to study the anisotropy of fracture toughness and fracture mechanism of single-crystal sapphire, the three-point bending tests and the single-edge V-notch beam (SEVNB) were used to test the fracture toughness of A-plane, C-plane, and M-plane sapphire, which are widely used in the semiconductor, aerospace, and other high-tech fields. Fracture morphology was investigated by a scanning electron microscope and three-dimensional video microscopy. The fracture toughness and fracture morphology of different crystal planes of sapphire showed obvious anisotropy and were related to the loading surfaces. C-plane sapphire showed the maximal fracture toughness of 4.24 MPa·m1/2, and fracture toughness decreases in the order of C-plane, M-plane, and A-plane. The surface roughness is related to the dissipation of fracture energy. The surface roughness of the fracture surface is in the same order as C-plane > M-plane > A-plane. The fracture behavior and morphology of experiments were consistent with the theoretical analysis. C-plane sapphire cleavages along the R-plane with an angle of 57.6 degrees and the rhombohedral twin were activated. M-plane and A-plane sapphire cleavages along their cross-section.

Mechanical Properties of LaB6-ZrB2 Composites

2005 ◽  
Vol 297-300 ◽  
pp. 1630-1638 ◽  
Author(s):  
Guang Hui Min ◽  
Ruilan Gao ◽  
Hua Shun Yu ◽  
Jiande Han
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Fracture Behavior ◽  
Fracture Morphology ◽  
Microstructure Observation ◽  
Microstructure And Mechanical Properties ◽  
Different Content ◽  
Peak Value

The polycrystallined LaB6-ZrB2 composites with different content of ZrB2 were fabricated by vacuum hot-pressed sintering technique in this paper. The effects of ZrB2 content on the microstructure and mechanical properties were investigated. For the eutectic LaB6-ZrB2 (21wt%) composite, the hardness, flexural strength and fracture toughness is of 93.0 (HRA), 330.0MPa and 3.70MPa·m1/2, respectively. The results showed the hardness and flexural strength of LaB6-ZrB2 polycrystalline have been enhanced with the increasing of ZrB2 content, but the fracture toughness increases first then arrives at peak value, which is corresponding to the ZrB2 content of 21wt%. The microstructure observation revealed an improved densification due to addition of ZrB2. The fracture morphology showed a tendency of the fracturing from intergranular to transgranular manner with increasing the ZrB2 content. The fracture behavior of the composites was analyzed in the paper

Investigating Morphology Evolution of Damage by a Cellular Automaton Modelling

2007 ◽  
Vol 353-358 ◽  
pp. 1060-1063
Author(s):  
Jing Zhang ◽  
Nai Hui Song ◽  
Xiao Peng Li ◽  
Zhao Hui Ren ◽  
Bang Chun Wen
Keyword(s):  
Cellular Automaton ◽  
Fracture Behavior ◽  
Fracture Morphology ◽  
Morphology Evolution ◽  
Continuum Damage ◽  
Local Rule ◽  
Physical Processes ◽  
Damage Models ◽  
Damage And Fracture ◽  
Ca Model

A two-dimensional cellular automaton (CA) model is developed to simulate damage and fracture morphology evolution on the mesoscale in materials. The plastic convection of damage is mapped onto the CA lattice, and initiation, propagation and coalescence of damage are simulated with a local rule-based scheme of a probability cellular automaton. The model includes known physical distinctions of fracture behavior between microcracks and microvoids, and they are characterized by modifying the probability rule of the cellular automaton. The simulations provide visual insight to understand how those physical processes dynamically progress and they affect the damage evolution in materials. The modeling can be used to link micromechanical models to continuum damage models.

Strength Evaluation of Notch Structure for Semiconductor Encapsulant Resin

2002 ◽  
Vol 124 (4) ◽  
pp. 323-327 ◽  
Author(s):  
Noriyasu Kawamura ◽  
Takashi Kawakami ◽  
Kikuo Kishimoto ◽  
Masaki Omiya ◽  
Toshikazu Shibuya
Keyword(s):  
Stress Distribution ◽  
Critical Stress ◽  
Epoxy Resins ◽  
Fracture Behavior ◽  
Stress Distributions ◽  
Strength Evaluation ◽  
Notched Specimens ◽  
Fracture Tests ◽  
Notch Tip ◽  
Semiconductor Encapsulant

Plastic encapsulated semiconductor packages may crack at the corner regions of die pads or chips if internal delamination occurs at an elevated temperature during the reflow soldering process. Thus, the structural strength design around the notch structures, which will be formed in the encapsulant resin due to the delamination, is considered one of the most important issues. Especially, it becomes a more critical item of the package development in order to realize the reflow process with lead-free solder materials, whose melting points are higher than that of Sn63-Pb37. In this study, the fracture behavior of notched specimens, which were made of silica particulate-filled epoxy resins and modeled as the corner regions in actual packages, were studied with experimental and numerical analyses. First, the fracture tests of the notch structure of semiconductor encapsulant resin were carried out. A notch tip with several different radii was introduced to the specimen. The specimens were fractured by a three-point bending load. Second, the strength evaluation of the notch structure was carried out. The critical stress distribution σCr=max.[KIC/2πr1/2,σB] was used to determine the crack initiation at the notch tip. It is assumed that a fracture occurs when, at any point near the notch tip, the stress distribution exceeds the critical stress distribution determined by fracture toughness and bending strength. Three-dimensional finite element analysis was carried out to obtain the stress distributions around the notch tip in the specimen. The calculated stress distributions around the notch tip were compared with the critical stress distribution to estimate the fracture load of the specimen. Estimated fracture loads at room temperature and at high temperature were compared with the results of the fracture tests. It was confirmed that the predicted results based on the critical stress distribution corresponded very well with the experimental results. The validity of the criterion was confirmed by studying the fracture behavior of the notched specimens of actual silica particulate filled epoxy resins.

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