Evaluation of interfacial fracture toughness using cohesive zone model

2002 ◽  
Vol 33 (10) ◽  
pp. 1433-1447 ◽  
Author(s):  
Namas Chandra
Keyword(s):  
Fracture Toughness ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Interfacial Fracture ◽  
Zone Model ◽  
Interfacial Fracture Toughness

Quantitative Characterization of Hydride Spacing for Cohesive-Zone Modelling of Fracture Toughness in Zr-2.5Nb Pressure Tubes

2016 ◽  
Author(s):  
Cheng Liu ◽  
Leonid Gutkin ◽  
Douglas Scarth
Keyword(s):  
Fracture Toughness ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Model Development ◽  
Threshold Value ◽  
Pressure Tube ◽  
Zone Model ◽  
Empirical Distributions ◽  
Hydride Formation ◽  
Pressure Tubes

Zr-2.5Nb pressure tubes in CANDU 1 reactors are susceptible to hydride formation when the solubility of hydrogen in the pressure tube material is exceeded. As temperature decreases, the propensity to hydride formation increases due to the decreasing solubility of hydrogen in the Zr-2.5Nb matrix. Experiments have shown that the presence of hydrides is associated with reduction in the fracture toughness of Zr-2.5Nb pressure tubes below normal operating temperatures. Cohesive-zone approach has recently been used to address this effect. Using this approach, the reduction in fracture toughness due to hydrides was modeled by a decrease in the cohesive-zone restraining stress caused by the hydride fracture and subsequent failure of matrix ligaments between the fractured hydrides. As part of the cohesive-zone model development, the ligament thickness, as represented by the radial spacing between adjacent fractured circumferential hydrides, was characterized quantitatively. Optical micrographs were prepared from post-tested fracture toughness specimens, and quantitative metallography was performed to characterize the hydride morphology in the radial-circumferential plane of the pressure tube. In the material with a relatively low fraction of radial hydrides, further analysis was performed to characterize the radial spacing between adjacent fractured circumferential hydrides. The discrete empirical distributions were established and parameterized using continuous probability density functions. The resultant parametric distributions of radial hydride spacing were then used to infer the proportion of matrix ligaments, whose thickness would not exceed the threshold value for low-energy failure. This paper describes the methodology used in this assessment and discusses its results.

Investigation of Cohesive Zone Model Parameters for Steel Used in Shipbuilding Structure

2017 ◽  
Author(s):  
Vikas Chaudhari ◽  
D. M. Kulkarni ◽  
Shivam Rathi ◽  
Akshay Sancheti ◽  
Swadesh Dixit
Keyword(s):  
Fracture Toughness ◽  
Plane Strain ◽  
Plane Stress ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
High Strength ◽  
Model Parameters ◽  
Zone Model ◽  
Low Carbon ◽  
Two Parameters

Present work deals with the investigation of fracture toughness and modeling parameters need in FEA application for steel use in shipbuilding structure. The investigated steel was 12.5mm thick low carbon high strength steel. Two types of tests were performed, tensile test and fracture test to evaluate mechanical properties and fracture toughness respectively. Cohesive zone model (CZM) was used because it is very computer effective and requires only two parameters, which can be determined in experiments with relative ease. Cohesive zone model with trapezoidal traction law found suitable for the investigated steel. To simulate CZM, bulk section with plane stress elements and bulk section with plane stress with plane strain core scheme are found suitable however bulk section with plane stress with plane strain core scheme gives accurate numerical results.

Cohesive zone modeling of the autoclave pressure effect on the delamination behavior of composite laminates

2018 ◽  
Vol 37 (24) ◽  
pp. 1468-1480
Author(s):  
Tengfei Chang ◽  
Lihua Zhan ◽  
Wei Tan ◽  
Xintong Wu
Keyword(s):  
Fracture Toughness ◽  
Cohesive Zone ◽  
Composite Laminates ◽  
Cohesive Zone Model ◽  
Cohesive Strength ◽  
Mode Ii ◽  
Zone Model ◽  
Mode Ii Fracture ◽  
Mode Ii Fracture Toughness ◽  
Delamination Behavior

Current manufacturing processes using resin transfer molding or low-pressure prepreg curing may result in different defects and interfacial properties. The effect of autoclave pressure on the delamination behavior of T800/X850 composite laminates is explored. Cohesive zone model was used to model the delamination of unidirectional composite laminates under short-beam bending. Composites with various interlaminar properties were manufactured using autoclave under cure pressure from 0 MPa to 0.6 MPa. Cohesive zone model was validated using the material parameters of the composite cured under 0.6 MPa. The effect of cohesive zone model parameters including cohesive strength, mode I fracture toughness ([Formula: see text]), and mode II fracture toughness ([Formula: see text]) on the delamination behavior and load–displacement response was investigated. Parametric study shows that interlaminar cohesive strength and mode II fracture toughness dominated the initiation of yield and post-yield region, respectively. The correlation between autoclave pressure and mode II fracture toughness was predicted, which is mainly affected by void content.

scholarly journals A cohesive zone model and scaling analysis for mixed-mode interfacial fracture

2017 ◽  
Vol 129 ◽  
pp. 167-176 ◽  
Author(s):  
Shruti Jain ◽  
Seung Ryul Na ◽  
Kenneth M. Liechti ◽  
Roger T. Bonnecaze
Keyword(s):  
Cohesive Zone ◽  
Mixed Mode ◽  
Cohesive Zone Model ◽  
Interfacial Fracture ◽  
Scaling Analysis ◽  
Zone Model

Stable Crack Growth in Rate-Dependent Materials With Damage

1993 ◽  
Vol 115 (3) ◽  
pp. 252-261 ◽  
Author(s):  
Leif-Olof Fager ◽  
J. L. Bassani
Keyword(s):  
Fracture Toughness ◽  
Crack Growth ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Creep Damage ◽  
Stable Crack Growth ◽  
Damage Function ◽  
Small Scale ◽  
Zone Model ◽  
Rate Dependent

A cohesive zone model of the Dugdale-Barenblatt type is used to investigate crack growth under small-scale-creep/damage conditions. The material inside the cohesive zone is described by a power-law viscous overstress relation modified by a one-parameter damage function of the Kachanov type. The stress and displacement profiles in the cohesive zone and the velocity dependence of the fracture toughness are investigated. It is seen that the fracture toughness increases rapidly with the velocity and asymptotically approaches the case that neglects damage.

Experimental and Numerical Study of Interfacial Fracture Parameters of a Brazed Joints

2015 ◽  
Vol 1099 ◽  
pp. 9-16
Author(s):  
A. Baazaoui ◽  
T. Fourcade ◽  
Olivier Dalverny ◽  
Joël Alexis ◽  
Moussa Karama
Keyword(s):  
Experimental Data ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Numerical Study ◽  
Fem Simulation ◽  
Interfacial Fracture ◽  
Constitutive Law ◽  
Zone Model ◽  
Fracture Parameters ◽  
Brazed Joints

This paper deals with an identification methodology of the interfacial fracture parameters to predict the lifetime of a metallic brazed joint. The methodology is based on an experimental-numerical study whereby the optimal parameters are obtained. The experimental data, using the scanning electron microscope analysis, allowed approving that failure of the assembly based AuGe solder seems first to appear near the interfaces. These results were confirmed by micrographs analysis of the solder/insert and solder/substrate interfaces. Then, using shear test results and parametric identification coupled with a finite elements model (FEM) simulation, the damage constitutive law of the interfacial fracture based on a bilinear cohesive zone model are identified. The agreement between the numerical results and the experimental data shows the applicability of the cohesive zone model to fatigue crack growth analysis and life estimation of brazed joints.

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