scholarly journals Numerical-Experimental Correlation of Interlaminar Damage Growth in Composite Structures: Setting Cohesive Zone Model Parameters

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
F. Di Caprio ◽  
S. Saputo ◽  
A. Sellitto
Keyword(s):  
Cohesive Zone ◽  
Composite Laminates ◽  
Composite Structures ◽  
Cohesive Zone Model ◽  
Numerical Models ◽  
Experimental Tests ◽  
Model Parameters ◽  
Zone Model ◽  
Growth Phenomenon ◽  
Interlaminar Damage

Composite laminates are characterized by high mechanical in-plane properties while experiencing, on the contrary, a poor out-of-plane response. The composite laminates, indeed, are often highly vulnerable to interlaminar damages, also called “delaminations.” One of the main techniques used for the numerical prediction of interlaminar damage onset and growth is the cohesive zone model (CZM). However, this approach is characterised by uncertainties in the definition of the parameters needed for the implementation of the cohesive behaviour in the numerical software. To overcome this issue, in the present paper, a numerical-experimental procedure for the calibration of material parameters governing the mechanical behaviour of CZM based on cohesive surface and cohesive element approaches is presented. Indeed, by comparing the results obtained from the double cantilever beam (DCB) and end-notched flexure (ENF) experimental tests with the corresponding numerical results, it has been possible to accurately calibrate the parameters of the numerical models needed to simulate the delamination growth phenomenon at coupon level.

Effects of asphalt concrete characteristics on cohesive zone model parameters of hot mix asphalt mixtures

2016 ◽  
Vol 43 (3) ◽  
pp. 226-232 ◽  
Author(s):  
S. Pirmohammad ◽  
H. Khoramishad ◽  
M.R. Ayatollahi
Keyword(s):  
Asphalt Concrete ◽  
Cohesive Energy ◽  
Cohesive Zone ◽  
Hot Mix Asphalt ◽  
Cohesive Zone Model ◽  
Experimental Tests ◽  
Model Parameters ◽  
Zone Model ◽  
Binder Type ◽  
Air Void

In this paper, the effects of the main asphalt concrete characteristics including the binder type and the air void percentage on the cohesive zone model (CZM) parameters were studied. Experimental tests were conducted on semi-circular bend (SCB) specimens made of asphalt concrete and the fracture behavior was simulated using a proper CZM. The CZM parameters of various hot mix asphalt (HMA) mixtures were determined using the SCB experimental results. Five types of HMA mixtures were tested and modeled to consider the effects of binder type and air void percentage on the CZM parameters. The results showed that as the binder in HMA mixture softened, the cohesive energy strength increased, whereas enhancing the air void percentage led to reduction of the cohesive energy and strength values. Among the studied HMA mixtures, the highest values of CZM parameters were found for the HMA mixture containing a copolymer called styrene-butadiene-styrene.

scholarly journals Simulation numérique de la propagation de fissure dans les superalliages monocristallins

2007 ◽  
pp. 845-863
Author(s):  
Jean-Luc Bouvard ◽  
Jean-Louis Chaboche ◽  
Frédéric Feyel ◽  
Franck Gallerneau
Keyword(s):  
Crack Growth ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Mesh Size ◽  
Experimental Tests ◽  
Coupled Analysis ◽  
Model Parameters ◽  
Zone Model ◽  
Cohesive Zone Modelling ◽  
Convergence Study

In this study, a numerical method is developped to simulate fatigue crack growth. This method is based on a numerical coupled analysis using a cohesive zone modelling under cyclic loading in order to develop a coupled predictive approach of the crack growth. First, we present this damage law, then its validation by a convergence study of the solution with mesh size. We apply this model to the crack growth calculations in the case of a smooth specimen with a precracking made with a single crystal superalloy. Finally, we define the method to calibrate the cohesive zone model parameters on the base of experimental tests performed in pur fatigue regime.

Effects of adhesive thickness on the mode I cohesive zone model parameters of a high toughness structural adhesive

2018 ◽  
Author(s):  
M. H. R. de Oliveira ◽  
A. F. Ávila ◽  
R. R. Chaves ◽  
H. Nascimento Júnior ◽  
F. D. Passos
Keyword(s):  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Model Parameters ◽  
Mode I ◽  
Zone Model ◽  
High Toughness ◽  
Adhesive Thickness ◽  
Structural Adhesive

Multiscale Model to Study the Effect of Interfaces in Carbon Nanotube-Based Composites

2005 ◽  
Vol 127 (2) ◽  
pp. 222-232 ◽  
Author(s):  
S. Namilae ◽  
N. Chandra
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Finite Element ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Interfacial Region ◽  
Model Parameters ◽  
Zone Model ◽  
Pullout Tests ◽  
Nanoscale Interfaces

In order to fully harness the outstanding mechanical properties of carbon nanotubes (CNT) as fiber reinforcements, it is essential to understand the nature of load transfer in the fiber matrix interfacial region of CNT-based composites. With controlled experimentation on nanoscale interfaces far off, molecular dynamics (MD) is evolving as the primary method to model these systems and processes. While MD is capable of simulating atomistic behavior in a deterministic manner, the extremely small length and time scales modeled by MD necessitate multiscale approaches. To study the atomic scale interface effects on composite behavior, we herein develop a hierarchical multiscale methodology linking molecular dynamics and the finite element method through atomically informed cohesive zone model parameters to represent interfaces. Motivated by the successful application of pullout tests in conventional composites, we simulate fiber pullout tests of carbon nanotubes in a given matrix using MD. The results of the pullout simulations are then used to evaluate cohesive zone model parameters. These cohesive zone models (CZM) are then used in a finite element setting to study the macroscopic mechanical response of the composites. Thus, the method suggested explicitly accounts for the behavior of nanoscale interfaces existing between the matrix and CNT. The developed methodology is used to study the effect of interface strength on stiffness of the CNT-based composite.

scholarly journals Application of a Cohesive Zone Model for Simulating Fatigue Crack Growth from Moderate to High ΔK Levels of Inconel 718

2018 ◽  
Vol 2018 ◽  
pp. 1-13
Author(s):  
Huan Li ◽  
Jinshan Li ◽  
Huang Yuan
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Rates ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Small Scale ◽  
Model Parameters ◽  
Zone Model ◽  
Crack Growth Rates

A cyclic cohesive zone model is applied to characterize the fatigue crack growth behavior of a IN718 superalloy which is frequently used in aerospace components. In order to improve the limitation of fracture mechanics-based models, besides the predictions of the moderate fatigue crack growth rates at the Paris’ regime and the high fatigue crack growth rates at the high stress intensity factor ΔK levels, the present work is also aimed at simulating the material damage uniformly and examining the influence of the cohesive model parameters on fatigue crack growth systematically. The gradual loss of the stress-bearing ability of the material is considered through the degradation of a novel cohesive envelope. The experimental data of cracked specimens are used to validate the simulation result. Based on the reasonable estimation for the model parameters, the fatigue crack growth from moderate to high ΔK levels can be reproduced under the small-scale yielding condition, which is in fair agreement with the experimental results.

Numerical Modeling and Simulation of Delamination Crack Growth in CF/Epoxy Composite Laminates under Cyclic Loading Using Cohesive Zone Model

2011 ◽  
Vol 326 ◽  
pp. 37-52 ◽  
Author(s):  
Hassan Ijaz ◽  
M Aurangzeb Khan ◽  
Waqas Saleem ◽  
Sajid Raza Chaudry
Keyword(s):  
Crack Growth ◽  
Fatigue Damage ◽  
Composite Laminates ◽  
Damage Evolution ◽  
Composite Structures ◽  
Cohesive Zone Model ◽  
Fatigue Loading ◽  
Zone Model ◽  
Evolution Law ◽  
Delamination Crack

This paper presents the mathematical modelling of fatigue damage able to carry out simulation of evolution of delamination in the laminated composite structures under cyclic loadings. A new elastic fatigue damage evolution law is proposed here. A classical interface damage evolution law, which is commonly used to predict static debonding process, is modified further to incorporate fatigue delamination effects due to high cycle loadings. The proposed fatigue damage model is identified using Fracture Mechanics tests like DCB, ENF and MMB. Simulations of delamination under fatigue loading are performed and results are successfully compared with reported experimental data on HTA/6376C unidirectional material. Delamination crack growth with variable fatigue amplitude is also performed and simulation results show that the proposed fatigue damage law can also accommodate this variable amplitude phenomenon. A study of crack tip behaviour using damage variable evolution is also carried out in this paper. Finally the effect of mesh density on crack growth is also discussed.

Estimating the Cohesive Zone Model Parameters of Carbon Nanotube–Polymer Interface for Machining Simulations

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Lingyun Jiang ◽  
Chandra Nath ◽  
Johnson Samuel ◽  
Shiv G. Kapoor
Keyword(s):  
Carbon Nanotube ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Interfacial Strength ◽  
Weight Fraction ◽  
Model Parameters ◽  
Zone Model ◽  
Fe Model ◽  
Polymer Interface ◽  
Two Parameters

The failure mechanisms encountered during the machining of carbon nanotube (CNT) polymer composites are primarily governed by the strength of the CNT–polymer interface. Therefore, the interface should be explicitly modeled in microstructure-level machining simulations for these composites. One way of effectively capturing the behavior of this interface is by the use of a cohesive zone model (CZM) that is characterized by two parameters, viz., interfacial strength and interfacial fracture energy. The objective of this study is to estimate these two CZM parameters of the interface using an inverse iterative finite element (FE) approach. A microstructure-level 3D FE model for nanoindentation simulation has been developed where the composite microstructure is modeled using three distinct phases, viz., the CNT, the polymer, and the interface. The unknown CZM parameters of the interface are then determined by minimizing the root mean square (RMS) error between the simulated and the experimental nanoindentation load–displacement curves for a 2 wt. % CNT–polyvinyl alcohol (PVA) composite sample at room temperature and quasi-static strain state of up to 0.04 s−1, and then validated using the 1 wt. % and 4 wt. % CNT–PVA composites. The results indicate that for well-dispersed and aligned CNT–PVA composites, the CZM parameters of the interface are independent of the CNT loading in the weight fraction range of 1–4%.

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.

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