Comparative study on prediction of fracture toughness of CFRP laminates from size effect law of open hole specimen using cohesive zone model

2018 ◽  
Vol 191 ◽  
pp. 277-285 ◽  
Author(s):  
Mohammed Y. Abdellah
Keyword(s):  
Fracture Toughness ◽  
Size Effect ◽  
Comparative Study ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Zone Model ◽  
Cfrp Laminates ◽  
Open Hole

Effects of Stacking Sequence on Notched Strengths of Cross-Ply CFRP Laminates and Analysis Using a Cohesive Zone Model

2007 ◽  
Vol 340-341 ◽  
pp. 155-160 ◽  
Author(s):  
Masamichi Kawai ◽  
Akihiro Tanaka
Keyword(s):  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Notch Sensitivity ◽  
Tensile Fracture ◽  
Zone Model ◽  
Additional Energy ◽  
Cfrp Laminates ◽  
Double Edge ◽  
Open Hole ◽  
Notched Strength

Effects of the thickness of plies of the same orientation on the notched strength of symmetric cross-ply CFRP laminates are examined. Three kinds of symmetric cross-ply CFRP laminates with the same total number of plies and the different number and sequence of adjacent laminae of the same orientation are used. Notch sensitivity of those laminates is evaluated for different shapes of notches: double-edge notches (DEN) and a center open hole (CH). Validity of an analytical cohesive zone model (CZM) is evaluated by comparing with experimental results on the three kinds of cross-ply laminates with a center hole. It is clearly observed that the tensile fracture strengths of the DEN and CH specimens significantly reduce as the notch size increases. The sensitivity to notches is highest in the case of alternating cross-ply configuration. The results of this study suggest that additional energy dissipation due to damage around notches should appropriately be considered to estimate the effective fracture toughness used in CZM calculations, especially for a class of cross-ply laminates with lower notch sensitivity.

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.

A comparative study of cohesive zone models for predicting delamination fracture behaviors of arterial wall

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 467-477
Author(s):  
Ting Miao ◽  
Liqiong Tian ◽  
Xiaochang Leng ◽  
Zhangmu Miao ◽  
Jingjing Wang ◽  
...  
Keyword(s):  
Comparative Study ◽  
Cohesive Zone ◽  
Arterial Wall ◽  
Cohesive Zone Model ◽  
Bulk Material ◽  
Zone Model ◽  
Fracture Failure ◽  
Delamination Fracture ◽  
Cohesive Models ◽  
Arterial Tissue

AbstractArterial tissue delamination, manifested as the fracture failure between arterial layers, is an important process of the atherosclerotic plaque rupture, leading to potential life-threatening clinical consequences. Numerous models have been used to characterize the arterial tissue delamination fracture failure. However, only a few have investigated the effect of cohesive zone model (CZM) shapes on predicting the delamination behavior of the arterial wall. In this study, four types of CZMs (triangular, trapezoidal, linear–exponential, and exponential–linear) were investigated to compare their prediction of the arterial wall fracture failure. The Holzapfel–Gasser–Ogden (HGO) model was adopted for modeling the mechanical behavior of the aortic bulk material. The CZMs optimized during the comparison of the aortic media delamination simulations were also used to perform the comparative study of the mouse plaque delamination and human fibrous cap delamination. The results show that: (1) the numerical predicted the relationships of force–displacement in the delamination behaviors based on the triangular, trapezoidal, linear–exponential, and exponential–linear CZMs match well with the experimental measurements. (2) The traction–separation relationship results simulated by the four types of CZMs could react well as the corresponding CZM shapes. (3) The predicted load–load point displacement curves using the triangular and exponential–linear CZMs are in good agreement with the experimental data, relative to the other two shapes of CZMs. All these provide a new method combined with the factor of shape in the cohesive models to simulate the crack propagation behaviors and can capture the arterial tissue failure response well.

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.

Sign in / Sign up

Export Citation Format

Share Document