EVALUATION OF CONSTRAINT FACTOR AND J-INTEGRAL FOR SINGLE-EDGE NOTCHED SPECIMEN

1980 ◽  
pp. 425-434 ◽  
Author(s):  
M. Shiratori ◽  
T. Miyoshi
Keyword(s):  
J Integral ◽  
Single Edge ◽  
Constraint Factor ◽  
Notched Specimen

Fracture Mechanism and Fracture Toughness at the Interface Between Cortical and Cancellous Bone

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Pankaj Shitole ◽  
Arpan Gupta ◽  
Rajesh Ghosh
Keyword(s):  
Fracture Toughness ◽  
Cortical Bone ◽  
Cancellous Bone ◽  
Fracture Mechanism ◽  
Fracture Mechanisms ◽  
J Integral ◽  
Single Edge ◽  
Plastic Part ◽  
Edge Notch ◽  
Sample Width

The microstructure at the interface of cortical and cancellous bone is quite complicated. The fracture mechanisms at this location are necessary for understanding the comprehensive fracture of the whole bone. The goal of this study is to identify fracture toughness in terms of J integral and fracture mechanism at the interface between cortical and cancellous bone. For this purpose, single edge notch bend (SENB) specimens were prepared from bovine proximal femur according to ASTM-E399 standard. Bone samples were prepared such that half of the sample width consists of cortical bone and other half of the width was cancellous bone; this interfacial bone is referred as a corticellous bone. Elastic–plastic fracture mechanics was used to measure fracture toughness. The J integral (both elastic and plastic) was used to quantify the fracture toughness. The plastic part of J integral value (Jpl) of corticellous specimen was 9310 J m−2, and shown to be 27 times of the J integral of the elastic part (Jel), 341 J m−2. The total J integral of the corticellous bone was found to be 9651 J m−2, which is close to two times of the cortical bone, 4731 J m−2. This study observed that J integral of corticellous bone is higher than the cortical bone since more energy is required for plastic deformation of corticellous bone due to crack branches and slowdown at the interface between cortical and cancellous bone.

Assessment of Fracture Toughness Using Small Punch Tests of Prenotched Specimens

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Yangyan Zheng ◽  
Xiao Chen ◽  
Zheng Yang ◽  
Xiang Ling
Keyword(s):  
Fracture Toughness ◽  
Numerical Simulations ◽  
Stress Gradient ◽  
Element Model ◽  
Bending Test ◽  
J Integral ◽  
Notched Specimen ◽  
Small Punch ◽  
Three Point Bending ◽  
The Difference

In this paper, line- and ring-notched small punch test (SPT) specimens were studied; a three-dimensional (3D) model of a ring-notched SPT specimen was established using the contour integral method, and the validity of the model was verified using ring-notched specimens. The stress and strain fields were analyzed using numerical simulations of a ring-notched SPT specimen, and the change in the stress gradient during deformation was considered. To verify the finite element model, the results of the numerical simulations were compared with those of three-point bending tests and a Gurson–Tvergaard–Needleman (GTN) model. Compared with the line-notched specimen, the ring-notched specimen was more suitable for notch propagation analysis and fracture toughness evaluation. The results of the numerical simulations were in good agreement with those of the experiments, which showed that the numerical model used in this study was correct. For a notch that initiated when the load reached its maximum value, the value of the J integral was 335 × 10−6 kJ/mm2, and at time 0.85Pmax, the value of the J integral was 201 × 10−6 kJ/mm2, and the difference from the result of the three-point bending test was 14.4%. For a notch that initiated during the stretching deformation stage, the relevant fracture toughness was 225 × 10−6 kJ/mm2, and the difference from the result of the three-point bending test was 3%.

Fracture-mechanics Parameters of the Composite-Enamel Bond

1990 ◽  
Vol 69 (1) ◽  
pp. 31-35 ◽  
Author(s):  
R. De Groot ◽  
H.C. Van Elst ◽  
M.C.R.B. Peters
Keyword(s):  
Fracture Mechanics ◽  
Strain Energy ◽  
Strain Energy Release Rate ◽  
Resin Composite ◽  
Strain Energy Release ◽  
Critical Values ◽  
J Integral ◽  
Single Edge ◽  
Opening Mode ◽  
Mode Stress

In a previous study, the critical values of the opening mode stress intensity factor (K1 ), its equivalent, the strain energy-release rate (G1 ), and the J integral (J1 ) (in the elastic case being equal to that of G1 ) were determined for resin composite. In this study, the strength of the composite-tooth interface was investigated. The critical values of K1 and J1 were measured with single-edge notched-bend (SENB) specimens of resin composite bonded to enamel, with the notch at midspan at the bonded interface. Due to enamel's anisotropy, the values of K1c and J1c to be used in a fracture-mechanics application for failure prediction of a structure depend on the enamel prism orientation relative to the adhesive interface. Where interfacial failure is to be expected, the following values for J 1c and K1c can be used: Silux, J1c = 145 ± 35 Jm-2 and K1c = 0.84 ± 0.16 MNm-3/2; P-30, J1c = 163 ± 13 Jm-2 and K1c = 1.02 ± 0.07 MNm-3/2. Where enamel failure is expected or where the failure mode cannot be predicted, the following values can be applied: Silux, J 1c = 89 ± 15 Jm-2 and K1c = 0.84 ± 0.16 MNm-3/2; P-30, J1c = 89 ± 15 Jm-2 and K 1c = 0.75 ± 0.10 MNm-3/2.

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.

Comparison of J-Integral Measurement Methods on Clamped Single-Edge Notched Tension Specimens

2016 ◽  
Author(s):  
Timothy S. Weeks ◽  
Jeffrey W. Sowards ◽  
Ross A. Rentz ◽  
David T. Read ◽  
Enrico Lucon
Keyword(s):  
Mouth Opening ◽  
Surface Strain ◽  
Image Correlation ◽  
Crack Mouth Opening Displacement ◽  
J Integral ◽  
Crack Mouth ◽  
Single Edge ◽  
Opening Displacement ◽  
Strain Gradients

This paper reports an extension of a previous study that compared methods of evaluating J by the crack mouth opening displacement and by surface strain gradients. Here, the surface strain gradients are measured by three-dimensional digital image correlation. The results herein represent a small test matrix that involved evaluation of the J-integral for clamped single-edge notched tensile specimens from API 5L X65 base-metal, weld metal and the adjacent heat affected zone; the J-integral was evaluated by a standardized procedure utilizing the crack mouth opening displacement (CMOD) and by the contour integral method on an external surface strain contour. Digital image correlation provides sufficient full-field strain data for use by this method and is considerably more robust than surface-mounted strain gage instrumentation. A series of validity checks are presented that demonstrate that the data are useful and valuable. Experimental determination of the J-integral is not limited to thoroughly analyzed test geometries and may be achieved with limited instrumentation. Furthermore, the method described does not require a determination of crack size nor any instrumentation that requires access to the crack mouth.

Finite Element Analyses for Thickness Effects on J-Integral Testing using Non-Standard Testing Specimens

2004 ◽  
Vol 261-263 ◽  
pp. 693-698
Author(s):  
J.S. Kim ◽  
Young Jin Kim ◽  
S.M. Cho
Keyword(s):  
Fracture Toughness ◽  
Finite Element ◽  
Three Dimensional ◽  
Specimen Thickness ◽  
J Integral ◽  
Finite Element Analyses ◽  
Single Edge ◽  
Fracture Toughness Testing ◽  
Standard Testing ◽  
Toughness Testing

This paper compiles solutions of plastic η factors for standard and non-standard fracture toughness testing specimens, via detailed three-dimensional (3-D) finite element (FE) analyses. Fracture toughness testing specimens include a middle cracked tension (M(T)) specimen, SE(B), single-edge cracked bar in tension (SE(T)) and C(T) specimen. The ligament-to-thickness ratio of the specimen is systematically varied. It is found that the use of the CMOD overall provides more robust experimental estimation than that of the LLD, for all cases considered in the present work. Moreover, the estimation based on the load- CMOD record is shown to be insensitive to the specimen thickness, and thus can be used for testing a specimen with any thickness.

The J-Integral for a Single-Edge Cracked Panel Subjected to Combined Remote Tension and Bending

2009 ◽  
Author(s):  
Masaaki Matsubara
Keyword(s):  
Crack Initiation ◽  
Ductile Fracture ◽  
Strain Hardening ◽  
Structural Integrity ◽  
Crack Size ◽  
Strain Hardening Exponent ◽  
J Integral ◽  
Single Edge ◽  
Energy Concept

On structural integrity evaluation, a single-edge cracked panel subjected to combined remote tension and bending is the typical one. The J-integral is a valid way for handling the ductile fracture problem immediately after stable crack initiation. The complimentary energy concept combined with fully plastic solutions to make it to estimate the J-integral of the panel. The proposed method is able to give us the J-integral as a function of the crack size/panel width and the strain hardening exponent.

J-Integral Evaluation of Single-Edge Notched Specimens under Mixed-Mode I/II Loading

2001 ◽  
Vol 29 (3) ◽  
pp. 239 ◽  
Author(s):  
DR Petersen ◽  
RE Link ◽  
CD Donne ◽  
A Pirondi
Keyword(s):  
Mixed Mode ◽  
Mode I ◽  
J Integral ◽  
Single Edge ◽  
Integral Evaluation ◽  
Notched Specimens
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