Numerical Investigation of the Damage Behavior of S355 EBW by Cohesive Zone Modeling

2015 ◽  
Vol 1102 ◽  
pp. 149-153 ◽  
Author(s):  
H.Y. Tu ◽  
Ulrich Weber ◽  
Siegfried Schmauder
Keyword(s):  
Tensile Test ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Crack Opening ◽  
Compact Tension ◽  
Initial Crack ◽  
Cohesive Zone Modeling ◽  
Zone Model ◽  
Opening Displacement ◽  
Zone Modeling

In this paper, the cohesive zone model is used to study the fracture behavior of an electron beam welded (EBW) steel joint. Mechanical properties of different weld regions are derived from the tensile test results of flat specimens, which are obtained from the respective weld regions. Based on the tensile test of notched round specimens, the cohesive strength T0can be fixed. With the fixed T0value, the cohesive model is applied to compact tension (C(T)) specimens with the initial crack located at different positions of weldment with different cohesive energy values Γ0. Numerical simulations are compared with the experimental results in the form of force vs. Crack Opening Displacement (COD) curves as well as fracture resistance (JR) curves.

Comparison of Through-Wall and Complex Crack Behaviors in Dissimilar Metal Weld Pipe Using Cohesive Zone Modeling

2013 ◽  
Author(s):  
Do-Jun Shim ◽  
David Rudland ◽  
Frederick Brust
Keyword(s):  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Cohesive Zone Modeling ◽  
Zone Model ◽  
Ductile Crack ◽  
Dissimilar Metal ◽  
Ductile Crack Growth ◽  
Zone Modeling ◽  
Dissimilar Metal Weld ◽  
Metal Weld

Cohesive zone modeling has been shown to be a convenient and effective method to simulate and analyze the ductile crack growth behavior in fracture specimens and structures. Recently, authors have applied the cohesive zone model to simulate the ductile fracture behavior of a through-wall cracked pipe test consisting of a single material. In this paper, cohesive zone modeling has been applied to simulate the ductile crack growth in dissimilar metal weld pipe tests that was recently conducted by the U.S. NRC. Two crack types, i.e. through-wall and complex cracks, were simulated in the work. This paper describes how the cohesive parameters were determined and discusses in detail about the finite element modeling of the cohesive zone model. Various fracture parameters were compared between the finite element analyses and the experiments to validate the model. The results of the cohesive zone models showed good agreement with the pipe test results. Furthermore, the results of the cohesive zone model demonstrate that the fracture toughness (J at crack initiation, Jinit.) of the complex cracked pipe can be significantly lower (factor of 0.41) than that of the through-wall cracked pipe.

Physics Based Formulation of a Cohesive Zone Model for Ductile Fracture

2015 ◽  
Vol 651-653 ◽  
pp. 993-999 ◽  
Author(s):  
Tuncay Yalcinkaya ◽  
Alan Cocks
Keyword(s):  
Ductile Fracture ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Volume Element ◽  
Cohesive Zone Modeling ◽  
Mode I ◽  
Zone Model ◽  
Metallic Materials ◽  
Bound Solution ◽  
Zone Modeling

This paper addresses a physics based derivation of mode-I and mode-II traction separation relations in the context of cohesive zone modeling of ductile fracture of metallic materials. The formulation is based on the growth of an array of pores idealized as cylinders which are considered as therepresentative volume elements. An upper bound solution is applied for the deformation of the representative volume element and different traction-separation relations are obtained through different assumptions.

Cohesive Zone Modeling for 3D Ductile Crack Propagation

2016 ◽  
Vol 853 ◽  
pp. 132-136 ◽  
Author(s):  
Xiao Li ◽  
Huang Yuan
Keyword(s):  
Crack Propagation ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Three Dimensional ◽  
Stress Triaxiality ◽  
Cohesive Zone Modeling ◽  
Zone Model ◽  
Ductile Materials ◽  
Zone Modeling ◽  
Good Agreement

Computational modeling of three-dimensional crack propagation in very ductile materials is still a challenge in fracture mechanics analysis. In the present work a new stress-triaxiality-dependent cohesive zone model (TCZM) is proposed to describe elastic-plastic fracture process in full three-dimensional specimens. The cohesive parameters are identified as a function of the stress triaxiality from ductile fracture experiments. The predictions of TCZM show good agreement with the experimental results for both side-grooved C(T) specimen and rod bar specimen.

Cohesive zone modeling of coupled buckling – Debond growth in metallic honeycomb sandwich structure

2012 ◽  
Vol 14 (6) ◽  
pp. 679-693 ◽  
Author(s):  
KC Gopalakrishnan ◽  
R Ramesh Kumar ◽  
S Anil Lal
Keyword(s):  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Cohesive Zone Modeling ◽  
Zone Model ◽  
Interfacial Bond Strength ◽  
Tension Tests ◽  
Honeycomb Sandwich ◽  
Zone Modeling ◽  
Buckling Failure ◽  
Peel Tests

Buckling-induced skin–core debond growth in honeycomb sandwich cantilever beam is demonstrated using a cohesive zone model. The input parameters for the analysis are interfacial bond strength, mode I and mode II interfacial fracture toughness values, obtained from flatwise tension tests, drum-peel tests and three-point end notch flexure tests, respectively. Debonded honeycomb specimens are tested and the acoustic emission technique was used to observe the initiation of the debond growth. The load-displacement response from the cohesive zone model model shows a good agreement with the experimental results. The conventional analysis without cohesive zone model overestimates failure load by 56%. Cohesive zone model is able to predict the coupled debond growth and buckling failure in honeycomb sandwich structures.

Thermo-Mechanical Analysis of Mixed-Mode Damage: Cohesive Zone Modeling

2015 ◽  
Author(s):  
Hussain Altammar ◽  
Sudhir Kaul ◽  
Anoop Dhingra
Keyword(s):  
Cohesive Zone ◽  
Composite Beam ◽  
Mixed Mode ◽  
Cohesive Zone Model ◽  
Mechanical Load ◽  
Element Model ◽  
Mechanical Analysis ◽  
Cohesive Zone Modeling ◽  
Zone Model ◽  
Damage Initiation

Damage detection and diagnostics is a key area of research in structural analysis. This paper presents results from the analysis of mixed-mode damage initiation in a composite beam under thermal and mechanical loads. A finite element model in conjunction with a cohesive zone model (CZM) is used in order to determine the location of joint separation as well as the contribution of each mode in damage (debonding) initiation. The composite beam is modeled by using two layers of aluminum that are bonded together through a layer of adhesive. Simulation results show that the model can successfully detect the location of damage under a thermo-mechanical load. The model can also be used to determine the severity of damage due to a thermal load, a mechanical load and a thermo-mechanical load. It is observed that integrating thermal analysis has a significant influence on the fracture energy.

Multiscale cohesive zone modeling and simulation of high-speed impact, penetration, and fragmentation

2018 ◽  
Vol 03 (01n02) ◽  
pp. 1850003
Author(s):  
Chao Wang ◽  
Dandan Lyu
Keyword(s):  
Cohesive Zone ◽  
High Speed ◽  
Cohesive Zone Model ◽  
Bulk Material ◽  
Cohesive Zone Modeling ◽  
Zone Model ◽  
Spall Fracture ◽  
Weak Formulation ◽  
High Speed Impact ◽  
Different Characteristics

In this work, a multiscale cohesive zone model (MCZM) is developed to simulate the high-speed penetration induced dynamic fracture process such as fragmentation in crystalline solids. This model describes bulk material as a local quasi-continuum medium which follows the Cauchy–Born rule while cohesive zone element is governed by an interface depletion potential, such that the cohesive zone constitutive descriptions are genetically consistent with that of bulk element. This multiscale method proved to be effective in describing material inhomogeneities and it is constructed and implemented in a cohesive finite element Galerkin weak formulation. Numerical simulations of high-speed penetration with different shape of penetrators, i.e., square, circle and parabola nose penetrators are performed. Results show that the proposed MCZM can successfully capture spall fracture, the penetration process and different characteristics of fragmentation under different shape of penetrators.

scholarly journals A parametric study of crack propagation in paintings caused by temperature and relative humidity cycles based on irreversible cohesive zone model

2020 ◽  
Author(s):  
Mohammad Yaghoub Abdollahzadeh Jamalabadi
Keyword(s):  
Relative Humidity ◽  
Crack Initiation ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Initial Crack ◽  
Zone Model ◽  
Initiation Time ◽  
One Dimensional ◽  
Linear Elastic ◽  
Effects Of Temperature

Abstract The current paper aims to use an irreversible cohesive zone model to investigate the effects of temperature and relative humidity cycles on multilayer thin-film paintings crack pattern. The homogenous one-dimensional paint layers composed of alkyd and acrylic gesso over a canvas foundation (support) with known constant thicknesses are considered as the mechanical model of painting. Experimental data used for mathematical modeling of canvas as a linear elastic material and paint as a viscoelastic material with the Prony series. Fatigue damage parameters such as crack initiation time and maximum loads are calculated by an irreversible cohesive zone model used to control the interface separation. With the increase of the painting thickness and/or the initial crack length, the value of the maximum force increases. Moreover, by increasing the relative humidity (RH) and the temperature difference at loading by one cycle per day, the values of initiation time of delamination decrease. It is shown that the thickness of painting layers is the most important parameter in crack initiation times and crack growth rate in historical paintings in museums and conservation settings.

Cohesive Zone Modeling of Stable Crack Propagation in Highly Ductile Steel

2018 ◽  
Vol 774 ◽  
pp. 167-172 ◽  
Author(s):  
Andreas Burgold ◽  
Stephan Roth ◽  
Meinhard Kuna
Keyword(s):  
Cohesive Zone ◽  
Large Scale ◽  
Cohesive Zone Model ◽  
Cohesive Zone Modeling ◽  
Zone Model ◽  
Minor Effect ◽  
Stable Crack Propagation ◽  
Wide Range ◽  
Separation Relation ◽  
A Minor

A recent cohesive zone model is applied to the simulation of crack extension in austenitic stainless steel under large scale yielding conditions. The shape of the corresponding exponential traction-separation-relation can be modified in a wide range. In order to investigate the sensitivity regarding the cohesive zone parameters, a systematic parametric study is performed. The shape of the traction-separation envelope has a minor effect on the results compared to the cohesive strength and the work of separation. The aim is to fit experimental data by an appropriate choice of these parameters. Therefore, not only force-displacement curves should be used, but also crack growth resistance curves should be employed. A promising strategy for parameter identification is derived.

scholarly journals MODELLING OF CRACK PROPAGATION: COMPARISON OF DISCRETE LATTICE SYSTEM AND COHESIVE ZONE MODEL

2020 ◽  
Vol 26 ◽  
pp. 39-44 ◽  
Author(s):  
Karel Mikeš ◽  
Franz Bormann ◽  
Ondřej Rokoš ◽  
Ron H.J. Peerlings
Keyword(s):  
Crack Propagation ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Process Zone ◽  
Crack Opening ◽  
Lattice Models ◽  
Bending Test ◽  
Zone Model ◽  
Realistic Problem ◽  
Micro Structures

Lattice models are often used to analyze materials with discrete micro-structures mainly due to their ability to accurately reflect behaviour of individual fibres or struts and capture macroscopic phenomena such as crack initiation, propagation, or branching. Due to the excessive number of discrete interactions, however, such models are often computationally expensive or even intractable for realistic problem dimensions. Simplifications therefore need to be adopted, which allow for efficient yet accurate modelling of engineering applications. For crack propagation modelling, the underlying discrete microstructure is typically replaced with an effective continuum, whereas the crack is inserted as an infinitely thin cohesive zone with a specific traction-separation law. In this work, the accuracy and efficiency of such an effective cohesive zone model is evaluated against the full lattice representation for an example of crack propagation in a three-point bending test. The variational formulation of both models is provided, and obtained results are compared for brittle and ductile behaviour of the underlying lattice in terms of force-displacement curves, crack opening diagrams, and crack length evolutions. The influence of the thickness of the process zone, which is present in the full lattice model but neglected in the effective cohesive zone model, is studied in detail.

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