scholarly journals Specimen thickness effect on elastic-plastic constraint parameter A

2015 ◽  
Vol 9 (33) ◽  
pp. 73-79 ◽  
Author(s):  
G.P. Nikishkov ◽  
Yu.G. Matvienko
Keyword(s):  
Thickness Effect ◽  
Specimen Thickness ◽  
Elastic Plastic ◽  
Plastic Constraint

The Effect of Specimen Thickness on the Tearing Energy of a Gum Vulcanizate

1989 ◽  
Vol 62 (5) ◽  
pp. 850-862 ◽  
Author(s):  
Kenneth A. Mazich ◽  
K. N. Morman ◽  
F. G. Oblinger ◽  
T. Y. Fan ◽  
P. C. Killgoar
Keyword(s):  
Finite Element ◽  
Laboratory Experiments ◽  
Pure Shear ◽  
Thickness Effect ◽  
Specimen Thickness ◽  
J Integral ◽  
Shear Specimen ◽  
Standard Specimens ◽  
Finite Element Calculations ◽  
Tearing Energy

Abstract We have examined the effect of thickness on the critical tearing energy of a simple gum vulcanizate of SBR in pure shear. Laboratory experiments and finite-element calculations agree that the tearing energy that is measured with a pure-shear specimen increases with the thickness of the specimen. Laboratory measurements indicate that the deformation for crack growth in a pure-shear specimen increases with the thickness of the specimen. Finite-element calculations show that the energy available for release at a given deformation also increases with thickness in the range from t=1.4 mm to t=14 mm. Experiments show that the crtical tearing energy varies linearly with thickness in the range t=0.7 mm to t=2.7 mm. The effect of thickness on the tearing energy was also studied by calculating the J-integral at various points of the crack through the thickness of the pure-shear specimen. In general, the J-integral calculated at the surface of the specimen can be higher than the J-integral calculated at the center of the specimen for specimens that are sufficiently thick. The thickness effect measured in this work suggests that the “critical tearing energy” obtained from standard laboratory specimens may not be a true material property. For this reason, critical tearing energy that is measured on standard specimens may not be generally applied to predict failure in arbitrary elastomeric components.

Reliability Assessment on Thickness Effect in Fatigue Crack Growth

2005 ◽  
Vol 297-300 ◽  
pp. 1913-1918
Author(s):  
Seon Jin Kim ◽  
Yu Sik Kong ◽  
Sang Woo Kwon
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Random Fields ◽  
Crack Surface ◽  
Simulation Method ◽  
Thickness Effect ◽  
Specimen Thickness ◽  
Fatigue Crack Growth Life ◽  
Non Gaussian

The evaluation of specimen thickness effect of fatigue crack growth life by the simulation of probabilistic fatigue crack growth is presented. In this paper, the material resistance to fatigue crack growth is treated as a spatial stochastic process, which varies randomly on the crack surface. Using the previous experimental data, the non-Gaussian (eventually Weibull, in this report) random fields simulation method is applied. This method is useful to estimate the probability distribution of fatigue crack growth life and the variability due to specimen thickness by simulating material resistance to fatigue crack growth along a crack path.

Validation on the Relationship Between J Integral and CTOD for Offshore Structural Steel Weldments by Experimental and Numerical Analyses

2014 ◽  
Author(s):  
Dong Hyun Moon ◽  
Jeong Soo Lee ◽  
Jae Myung Lee ◽  
Myung Hyun Kim
Keyword(s):  
Plastic Deformation ◽  
Crack Tip ◽  
J Integral ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Constraint Factor ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Plastic Constraint ◽  
The Relationship

Elastic plastic fracture mechanics (EPFM) is the domain of fracture analysis which considers extensive plastic deformation at crack tip prior to fracture. J integral and crack tip opening displacement (CTOD) have been commonly used as parameters for EPFM analysis. The relationship between these parameters has been extensively studied by industry and academia. The plastic constraint factor can serve as a parameter to characterize constraint effects in fracture involving plastic deformation. Therefore, the characteristics of plastic constraint factor are important in EPFM analysis. In this study, the relationship between J Integral and CTOD was investigated by conducting fracture toughness tests using single edge notched bend (SENB) specimens. Also, plastic constraint factor was investigated by using finite element analysis. Numerical analysis was carried out using ABAQUS elastic-plastic analysis mode.

Thickness Influence on the Creep Response of DD6 Ni-Based Single-Crystal Superalloy

2016 ◽  
Vol 35 (9) ◽  
pp. 871-880 ◽  
Author(s):  
Zhixun Wen ◽  
Haiqing Pei ◽  
Dongfan Li ◽  
Zhufeng Yue ◽  
Jingyun Gao
Keyword(s):  
Single Crystal ◽  
Oxide Thickness ◽  
Single Crystal Superalloy ◽  
Thickness Effect ◽  
Specimen Thickness ◽  
Thin Wall ◽  
Creep Life ◽  
Creep Response ◽  
Standard Specimens ◽  
Lower Temperature

AbstractThe effect of specimen thickness on the creep response of Ni-based single-crystal superalloy DD6 was investigated. With the thickness of 0.3 mm, 0.6 mm and 1.2 mm, a series of thin-wall specimens were tested in this paper respectively at 760℃, 980℃ and 1,100℃. Under the conditions of lower temperatures and higher stresses, the creep life of thin-wall specimens increases with the increase of δ, but it is almost equal under higher temperatures and lower stresses conditions. Compared with the standard specimens, an obvious reduction (about 60%) of creep life of the thin-wall specimens was found at 760℃, whereas it is almost the same at 980℃ and 1,100℃. Therefore, obvious thickness effect is prone to lower temperature and higher stress. The thickness effect is a comprehensive effect, which is caused by fracture mode, the degree of necking, the shape and quantity of creep cavities, oxide thickness, etc. Under each condition, an increased thickness resulted in increased creep strain to rupture.

Three-Dimensional Finite Element Analysis of Elastic-Plastic Crack Problems

1981 ◽  
Vol 103 (3) ◽  
pp. 214-218 ◽  
Author(s):  
B. V. Kiefer ◽  
P. D. Hilton
Keyword(s):  
Finite Element ◽  
Normal Stress ◽  
Crack Front ◽  
Stress Component ◽  
Three Dimensional ◽  
Specimen Thickness ◽  
Element Analysis ◽  
Finite Element Program ◽  
Elastic Plastic ◽  
Crack Problems

A three-dimensional, elastic-plastic finite element program is developed and applied to analyze the stress field in a plate containing a through crack. The center cracked plate is subjected to uniform tensile loading which results in mode I opening of the crack surfaces. Transverse variations of the opening tensile stress component and of the effective stress (von Mises) in the vicinity of the crack front are presented. They clearly demonstrate the three-dimensional nature of this problem with distributions that depend on specimen thickness. For thinner plates, the plastic deformation concentrates near the plate surfaces while the normal stress is largest in the plate interior. In thicker plates the deformation and normal stress fields are more uniform in the plate interior near the crack front, but they develop a rapid boundary layer-type variation in the vicinity of the plate surfaces.

scholarly journals Thickness Effect Analysis on Fatigue Crack Propagation of 7475 Plate Material under Variable Amplitude Loading

2018 ◽  
Vol 188 ◽  
pp. 02015
Author(s):  
Jakub Šedek ◽  
Roman Růžek
Keyword(s):  
Plastic Zone ◽  
Crack Growth ◽  
Prediction Models ◽  
Model Simulation ◽  
Thickness Effect ◽  
Original Form ◽  
Specimen Thickness ◽  
Constraint Factor ◽  
Variable Amplitude Loading ◽  
Variable Amplitude

In the crack growth prediction models, the effect of variable amplitude loading is taken into account by different ways. One of them the Newman’s model is used very often, but in its original form it is not able to take into account the effect of specimen thickness. The new modification which involves the specimen thickness is presented. The study of variable thickness impact is based on the FE – analysis of M(T) specimen. The variability of constrained factor α was analysed for several load levels and specimen thicknesses. The value of α is governed by the ratio of thickness B versus plastic zone size rp. The effect of overloads on the plastic zone and relevant constraint factor value is analysed as well. During loading, it was found, that the constraint factor value is lower after overloads than when creating monotonic plastic deformation on the same load level in a large part of the cycle. The influence of thickness effect based on different α value after overload was successfully implemented into the strip yield model. Simulation of crack growth taking into account the thickness of the specimen under variable amplitude loading shows similar behaviour like the experimental data.

Modeling of thickness effect on the creep properties of Ni-based superalloys

2017 ◽  
Vol 13 (3) ◽  
pp. 464-470 ◽  
Author(s):  
Xinmei Wang ◽  
Yao Wang ◽  
Xinzhong Wang
Keyword(s):  
Creep Behavior ◽  
Present Model ◽  
Thickness Effect ◽  
Specimen Thickness ◽  
Thin Wall ◽  
Thin Specimen ◽  
Creep Properties ◽  
Content Type ◽  
Oxidation Effect ◽  
Different Thickness

Purpose Specimen thickness has great influences on the creep behavior of single crystal Ni-based superalloys when it is less than 3.0 mm, which is known as thickness debit effect. Experiments have detected that oxidation can influence the microstructure of the Ni-based superalloys. Here, a model is proposed to bring in both the oxidation effect and void caused damage to account for the thickness debit effect. The paper aims to discuss these issues. Design/methodology/approach The model uses the simple Norton type creep relation to describe the creep rate evolution. The damage evolution caused by void is taken to be stress controlled. The load baring area changes are calculated with the consideration of oxidation and void evolutions. Findings Simulations on specimens with different thickness from 3.0 to 0.3 mm are carried out. The results show that the present model can reproduce the decrease of the creep strength with the decreases of the specimen thickness. The damage plays a major role in the creep behavior of the thick specimen. Both the damage and the oxidation are important for the thin specimen which should be paid attention to during the calculation of the creep response of the thin-wall turbine blade. Originality/value A model is proposed to account for the thickness debit effect on the creep behavior of Ni-based superalloys. Both oxidation influence and void caused damage are introduced. The simulation results show the capability of the model to reproduce the thickness debit effect.

scholarly journals Modelling Electron Channeling Contrast Intensity of Stacking Fault and Twin Boundary Using Crystal Thickness Effect

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1696
Author(s):  
Hana Kriaa ◽  
Antoine Guitton ◽  
Nabila Maloufi
Keyword(s):  
Twin Boundary ◽  
Theoretical Approach ◽  
Stacking Fault ◽  
Thickness Effect ◽  
Specimen Thickness ◽  
Crystal Thickness ◽  
Contrast Imaging ◽  
Electron Channeling ◽  
Electron Intensity ◽  
Backscattered Electron

In a scanning electron microscope, the backscattered electron intensity modulations are at the origin of the contrast of like-Kikuchi bands and crystalline defects. The Electron Channeling Contrast Imaging (ECCI) technique is suited for defects characterization at a mesoscale with transmission electron microscopy-like resolution. In order to achieve a better comprehension of ECCI contrasts of twin-boundary and stacking fault, an original theoretical approach based on the dynamical diffraction theory is used. The calculated backscattered electron intensity is explicitly expressed as function of physical and practical parameters controlling the ECCI experiment. Our model allows, first, the study of the specimen thickness effect on the channeling contrast on a perfect crystal, and thus its effect on the formation of like-Kikuchi bands. Then, our theoretical approach is extended to an imperfect crystal containing a planar defect such as twin-boundary and stacking fault, clarifying the intensity oscillations observed in ECC micrographs.

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