The Ductile Damage and Fracture Mechanisms Analysis with Random Dispersion Multivoids

2006 ◽  
Vol 324-325 ◽  
pp. 763-766
Author(s):  
Hai Dong Yu ◽  
Zhong Qin Lin ◽  
Ke Shi Zhang ◽  
Yong Jin Guo
Keyword(s):  
Cell Model ◽  
Early Stage ◽  
Tensile Load ◽  
Nodular Cast Iron ◽  
Uniaxial Tensile ◽  
Fracture Mechanisms ◽  
Stress Parameter ◽  
Damage And Fracture ◽  
The Matrix ◽  
Random Dispersion

The cell model with twenty-five random dispersion voids was employed to analyze the damage and fracture mechanism of the nodular cast iron. The results show that the growth velocity of the voids has obvious difference with each other due to the random dispersion of voids. In the early stage of the deformation, the growth of the voids is mainly determined by the distance of the voids since the triaxiality stress parameter of the matrix around the voids is approximately equal. With the increase of the triaxiality stress parameter of the matrix materials around the void, the evolution velocity of the voids increases quickly. At the same time, this will influence the neighboring voids to grow quickly. The chain reaction of the rapidly increase of voids lead to the final material failure. The results can explain the fracture appearance of the smooth bar specimens under uniaxial tensile load really.

Determination of the relationship between microstructure and constitutive behaviour of nodular cast iron with a unit cell model

2005 ◽  
Vol 40 (2) ◽  
pp. 107-116 ◽  
Author(s):  
L Collini ◽  
G Nicoletto
Keyword(s):  
Cast Iron ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
Cell Model ◽  
Nodular Cast Iron ◽  
Unit Cell ◽  
Constitutive Law ◽  
Cast Irons ◽  
Present Contribution ◽  
The Matrix

Unit cell models have been proposed to predict the constitutive law and failure of ductile materials with complex microstructures, such as ferritic nodular cast iron and particulate metal matrix composites (PMMCs). The present contribution aims to extend this modelling approach to the prediction of the constitutive response of nodular cast iron with a mixed ferritic/pearlitic matrix. The finite element method is used within the framework of continuum mechanics to carry out the calculations. The effect of some microstructural features, such as graphite volume fraction and ferrite-pearlite ratio of the matrix, on the mechanical performance is determined. The computational results are compared to results obtained in a previous experimental activity on nodular cast irons.

scholarly journals Elevated Temperature Tensile Creep Behavior of Aluminum Borate Whisker-Reinforced Aluminum Alloy Composites (ABOw/Al–12Si)

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1217
Author(s):  
Yameng Ji ◽  
Yanpeng Yuan ◽  
Weizheng Zhang ◽  
Yunqing Xu ◽  
Yuwei Liu
Keyword(s):  
Elevated Temperature ◽  
Creep Test ◽  
Load Transfer ◽  
Elevated Temperatures ◽  
Tensile Creep ◽  
Uniaxial Tensile ◽  
Fracture Mechanisms ◽  
Transfer Model ◽  
Unreinforced Alloy ◽  
The Matrix

In order to evaluate the elevated temperature creep performance of the ABOw/Al–12Si composite as a prospective piston crown material, the tensile creep behaviors and creep fracture mechanisms have been investigated in the temperatures range from 250 to 400 °C and the stress range from 50 to 230 MPa using a uniaxial tensile creep test. The creep experimental data can be explained by the creep constitutive equation with stress exponents of 4.03–6.02 and an apparent activation energy of 148.75 kJ/mol. The creep resistance of the ABOw/Al–12Si composite is immensely improved by three orders of magnitude, compared with the unreinforced alloy. The analysis of the ABOw/Al–12Si composite creep data revealed that dislocation climb is the main creep deformation mechanism. The values of the threshold stresses are 37.41, 25.85, and 17.36 at elevated temperatures of 300, 350 and 400 °C, respectively. A load transfer model was introduced to interpret the effect of whiskers on the creep rate of this composite. The creep test data are very close to the predicted values of the model. Finally, the fractographs of the specimens were analyzed by Scanning Electron Microscope (SEM), the fracture mechanisms of the composites at different temperatures were investigated. The results showed that the fracture characteristic of the ABOw/Al–12Si composite exhibited a macroscale brittle feature range from 300 to 400 °C, but a microscopically ductile fracture was observed at 400 °C. Additionally, at a low tensile creep temperature (300 °C), the plastic flow capacity of the matrix was poor, and the whisker was easy to crack and fracture. However, during tensile creep at a higher temperature (400 °C), the matrix was so softened that the whiskers were easily pulled out and interfacial debonding appeared.

scholarly journals Damage Evolution and Fracture Behavior of C/SiC Minicomposites with Different Interphases under Uniaxial Tensile Load

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1525
Author(s):  
Zhongwei Zhang ◽  
Longbiao Li ◽  
Zhaoke Chen
Keyword(s):  
Damage Evolution ◽  
Fracture Behavior ◽  
Crack Opening ◽  
Tensile Load ◽  
Image Correlation ◽  
Matrix Cracking ◽  
Elastic Response ◽  
Uniaxial Tensile ◽  
Damage And Fracture ◽  
Tensile Damage

In this paper, the tensile damage and fracture behavior of carbon fiber reinforced silicon carbide (C/SiC) minicomposites with single- and multiple-layer interphases are investigated. The effect of the interphase on the tensile damage and fracture behavior of C/SiC minicomposites is analyzed. The evolution of matrix cracking under the tensile load of the C/SiC minicomposite with a notch is observed using the digital image correlation (DIC) method. The damage evolution process of the C/SiC minicomposite can be divided into four main stages, namely, (1) an elastic response coupled with partial re-opening of thermal microcracking; (2) multiple matrix microcracking perpendicular to the applied loading; (3) crack opening and related fiber/matrix, bundle/matrix, and inter-bundle debonding; and (4) progressive transfer of the load to the fibers and gradual fiber failure until composite failure/fracture. On the fracture surface, a large number of fibers pulling out of the samples with both single-layer and multi-layer interphases can be clearly observed.

Fracture Behavior of Cu/Cu–WCP Layered Composites

2014 ◽  
Vol 609-610 ◽  
pp. 500-503
Author(s):  
Feng Yan ◽  
Rong Xin Guo ◽  
Hai Ting Xia ◽  
Hai Yu ◽  
Yu Bo Zhang
Keyword(s):  
Failure Modes ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Fracture Mechanisms ◽  
Layered Composites ◽  
In Situ Experiments ◽  
Microcrack Initiation ◽  
The Matrix ◽  
Visible Defect

In order to understand the fracture mechanisms of Cu/CuWCP layered composites. An in-situ experimental study was carried out to investigate the behavior of the composites under uniaxial tensile loading. The specimens were manufactured by vacuum hot-pressed sintering technique, microscopic observations displayed that the microstructure of Cu/CuWCP layered composites distribute uniformly, and have no visible defect at interface. In situ tensile tests were performed in a scanning electron microscope (SEM) and the tensile strengths, failure modes of composites were measured. From the in situ experiments, the stages of nucleation, growth and coalescence of cracks in the vicinity of particles are well observed and understood. The results indicated that microcrack initiation happens at particle agglomeration and the matrix-particle interface because bond strength is weak,. With the density of microcracks increaseing, macrocrack formed, and finally cause failure of CuWCP layer, however, the Cu layer is not fracture during the whole testing.

scholarly journals Numerical Analysis of the Perforated Steel Sheets Under Uni-Axial Tensile Force

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 632 ◽  
Author(s):  
Ahmed M. Sayed
Keyword(s):  
Load Capacity ◽  
Tensile Force ◽  
Three Dimensional ◽  
Tensile Load ◽  
Experimental Tests ◽  
Strain Engineering ◽  
Uniaxial Tensile ◽  
Fe Model ◽  
Stress Strain ◽  
Steel Sheets

The perforated steel sheets have many uses, so they should be studied under the influence of the uniaxial tensile load. The presence of these holes in the steel sheets certainly affects the mechanical properties. This paper aims at studying the behavior of the stress-strain engineering relationships of the perforated steel sheets. To achieve this, the three-dimensional finite element (FE) model is mainly designed to investigate the effect of this condition. Experimental tests were carried out on solid specimens to be used in the test of model accuracy of the FE simulation. Simulation testing shows that the FE modeling revealed the ability to calculate the stress-strain engineering relationships of perforated steel sheets. It can be concluded that the effect of a perforated rhombus shape is greater than the others, and perforated square shape has no effect on the stress-strain engineering relationships. The efficiency of the perforated staggered or linearly distribution shapes with the actual net area on the applied loads has the opposite effect, as it reduces the load capacity for all types of perforated shapes. Despite the decrease in load capacity, it improves the properties of the steel sheets.

Nondestructive Photoelastic and Machine Learning Characterization of Surface Cracks and Prediction of Weibull Parameters for Photovoltaic Silicon Wafers

2021 ◽  
pp. 1-40
Author(s):  
Logan Rowe ◽  
Alexander J. Kaczkowski ◽  
Tung-Wei Lin ◽  
Gavin Horn ◽  
Harley Johnson
Keyword(s):  
Machine Learning ◽  
Learning Algorithm ◽  
Tensile Load ◽  
Silicon Wafers ◽  
Uniaxial Tensile ◽  
Support Vector ◽  
Weibull Parameters ◽  
Bulk Stress ◽  
Wire Motion

Abstract A nondestructive photoelastic method is presented for characterizing surface microcracks in monocrystalline silicon wafers, calculating the strength of the wafers, and predicting Weibull parameters under various loading conditions. Defects are first classified from through thickness infrared photoelastic images using a support vector machine learning algorithm. Characteristic wafer strength is shown to vary with the angle of applied uniaxial tensile load, showing greater strength when loaded perpendicular to the direction of wire motion than when loaded along the direction of wire motion. Observed variations in characteristic strength and Weibull shape modulus with applied tensile loading direction stem from the distribution of crack orientations and the bulk stress field acting on the microcracks. Using this method it is possible to improve manufacturing processes for silicon wafers by rapidly, accurately, and nondestructively characterizing large batches in an automated way.

scholarly journals Squamous Cell Carcinoma in a Calyceal Diverticulum Detected by Percutaneous Nephroscopic Biopsy

2018 ◽  
Vol 2018 ◽  
pp. 1-4
Author(s):  
Taku Mitome ◽  
Tadashi Tabei ◽  
Yukio Tsuura ◽  
Kazuki Kobayashi
Keyword(s):  
Computed Tomography ◽  
Squamous Cell Carcinoma ◽  
Cell Carcinoma ◽  
Squamous Cell ◽  
Early Stage ◽  
High Grade ◽  
Curative Intent ◽  
The Matrix ◽  
Calyceal Diverticulum ◽  
Pathological Assessment

A 73-year-old woman was referred to our department with a complaint of asymptomatic gross hematuria. Dynamic computed tomography revealed a complicated (Bosniak type IIF) cyst in the upper pole of her right kidney, which was diagnosed as a calyceal diverticulum. The diagnosis was confirmed by ureteroscopy. The diverticulum was filled with a soft protein matrix that was difficult to completely remove from the inner surface of the calyceal diverticulum. Endoscopy combined with intrarenal surgery (ECIRS) was performed to completely remove the matrix. Percutaneous nephroscopy further revealed papillary lesions on the surface of the diverticulum, confirmed as squamous cell carcinoma on pathological assessment. A laparoscopic right radical nephroureterectomy was performed, with curative intent. Pathological assessment confirmed a high-grade squamous cell carcinoma with renal parenchymal invasion (pT3). Although carcinomas in a calyceal diverticulum are highly uncommon, when present, these tend to be high-grade neoplasms that deeply invade the parenchymal wall. As the effective management of these lesions is difficult, early-stage diagnosis is required for curative treatment. We report the case of squamous cell carcinoma in a calyceal diverticulum that was difficult to diagnose on preoperative computed tomography, urinal cytology examination, and ureteroscopy but was found during ECIRS.

Simulation of Impact Damage in Foam-Based Sandwich Composites

2013 ◽  
Vol 569-570 ◽  
pp. 25-32
Author(s):  
Dian Shi Feng ◽  
Francesco Aymerich
Keyword(s):  
Impact Damage ◽  
Element Model ◽  
Fracture Mechanisms ◽  
Sandwich Composites ◽  
Typically Developing ◽  
Damage Resistance ◽  
Damage And Fracture ◽  
Closed Cell ◽  
Impact Energies ◽  
The Impact

The paper describes the application of a 3D finite element model for prediction of impact induced damage in sandwich composites consisting of laminated skins bonded to a closed cell foam core. The major damage and fracture mechanisms typically developing in transversally loaded sandwich composites were simulated in the model. The model was implemented in the FE package ABAQUS/Explicit and used to predict the impact damage resistance of sandwich panels with different core densities, core thicknesses, and skins layups. Numerical results obtained by FE simulations were compared with experimental data and observations collected through impact tests carried out at various impact energies.

Sign in / Sign up

Export Citation Format

Share Document