Analysis of stable crack growth in brittle materials Part I: A process zone model

1996 ◽  
Vol 75 (2) ◽  
pp. 95-114 ◽  
Author(s):  
David K. M. Shum
Keyword(s):  
Crack Growth ◽  
Process Zone ◽  
Brittle Materials ◽  
Stable Crack Growth ◽  
Zone Model

Automated Control of Stable Crack Growth for R-Curve Measurements in Brittle Materials

2012 ◽  
Vol 53 (2) ◽  
pp. 163-170 ◽  
Author(s):  
H. Jelitto ◽  
F. Hackbarth ◽  
H. Özcoban ◽  
G. A. Schneider
Keyword(s):  
Crack Growth ◽  
Brittle Materials ◽  
Stable Crack Growth ◽  
Automated Control

Role of Crack Wake Toughening on Elevated Temperature Crack Growth in a Fiber Reinforced Ceramic Composite

1993 ◽  
Vol 115 (3) ◽  
pp. 273-280 ◽  
Author(s):  
Shantikumar V. Nair ◽  
Tsung-Ju Gwo
Keyword(s):  
Elevated Temperature ◽  
Crack Growth ◽  
Crack Front ◽  
Volume Fraction ◽  
Process Zone ◽  
Stable Crack Growth ◽  
Creep Process ◽  
Failure Behavior ◽  
Matrix Cracks ◽  
Presence And Absence

Theoretical models were developed to predict the nature of the elevated temperature failure behavior in composites containing bridged cracks both for the case where crack front creep is absent (brittle regime) and for the case where a frontal creep process zone is present (ductile regime). The nature of the thermally activated time-dependent bridging of matrix cracks was first briefly reviewed from an earlier study and then applied to the case where crack front creep was present. Stable crack growth was predicted both in the presence and absence of crack front creep after an initial delay period, or initiation, which depends on crack size and wake parameters, such as, fiber diameter, volume fraction and interface properties. The dependence of the initiation time and crack growth rates on flaw size and wake parameters as well as on composite microstructure was derived both for the presence and absence of crack front creep. The implications of the results for elevated temperature composite component design are discussed.

Existence and Convergence Questions in Computational Modelling of Crack Growth in Brittle and Quasi-Brittle Materials

2016 ◽  
Vol 258 ◽  
pp. 157-160 ◽  
Author(s):  
Jiří Vala
Keyword(s):  
Crack Growth ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Computational Modelling ◽  
Brittle Materials ◽  
Zone Model ◽  
Static Tests ◽  
Materials Used ◽  
Proper Analysis

Computational modelling of the crack growth in brittle and quasi-brittle materials used in mechanical, civil, etc. engineering applies the cohesive zone model with various traction separation laws; determination of micro-mechanical parameters comes then from static tests, microscopic observation and numerical calibration. Although most authors refer to ill-possedness and need of artificial regularization in inverse problems (identification of material parameters), some difficulties originate even in nonlinear formulations of direct and sensitivity problems. This paper demonstrates the possibility of proper analysis of the existence of a weak solution and of the convergence of a corresponding numerical algorithm for such model problem, avoiding non-physical assumptions.

Verification of a Cohesive Zone Model for Ductile Fracture

1996 ◽  
Vol 118 (2) ◽  
pp. 192-200 ◽  
Author(s):  
Huang Yuan ◽  
Guoyu Lin ◽  
Alfred Cornec
Keyword(s):  
Ductile Fracture ◽  
Crack Growth ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Normal Modes ◽  
Stable Crack Growth ◽  
Small Region ◽  
Zone Model ◽  
Cohesive Law ◽  
Ductile Crack Growth

In the present paper, ductile crack growth in an aluminium alloy is numerically simulated using a cohesive zone model under both plane stress and plane strain conditions for two different fracture types, shear and normal modes. The cohesive law for ductile fracture consists of two parts—a specific material’s separation traction and energy. Both are assumed to be constant during ductile fracture (stable crack growth). In order to verify the assumed cohesive law to be suitable for ductile fracture processes, experimental records are used as control curves for the numerical simulations. For a constant separation traction, determined experimentally from tension test data, the corresponding cohesive energy was determined by finite element calculations. It is confirmed that the cohesive zone model can be used to characterize a single ductile fracture mode and is roughly independent of stable crack extention. Both the cohesive traction and the cohesive fracture energy should be material specific parameters. The extension of the cohesive zone is restricted to a very small region near the crack tip and is in the order of the physical fracture process. Based on the present observations, the cohesive zone model is a promising criterion to characterize ductile fracture.

Modeling Stable and Unstable Crack Growth Observed in Quasi-Static Adhesively Bonded Beam Tests

2004 ◽  
Author(s):  
Rakesh K. Kapania ◽  
Dhaval P. Makhecha ◽  
Eric R. Johnson ◽  
Josh Simon ◽  
David A. Dillard
Keyword(s):  
Crack Growth ◽  
Cohesive Zone Model ◽  
Computational Study ◽  
Stable Crack Growth ◽  
Epoxy Adhesive ◽  
Zone Model ◽  
Adhesively Bonded ◽  
Unstable Crack ◽  
Interface Elements ◽  
Unstable Crack Growth

An experimental and computational study of an adhesively bonded, double cantilevered beam (DCB) under quasi-static loading is presented. The polymeric adhesives are either an acrylic or an epoxy, and the adherends are 6061 aluminum alloy. DCB tests bonded with the acrylic exhibited stable crack growth, while the DCB tests bonded with the epoxy exhibited unstable crack growth. The responses of the DCB test speciments were modeled in the ABAQUS/Standard® software package. Interface finite elements were located between bulk elements to model crack initiation and crack growth in the adhesive. These interface elements are implemented as user-defined elements in ABAQUS®, and the material law relating the interfacial tractions to the separation displacements is based on a cohesive zone model (CZM). Using interface elements only to model the acrylic adhesive, the simulation correlates very well to the test. Good correlation between the simulation and the test for the epoxy adhesive is achieved if both bulk modeling of the adhesive and inertia of the specimen are included.

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.

Crack Growth Resistance of Ceramic Composite

1992 ◽  
Vol 287 ◽  
Author(s):  
Seijiro Hayashi ◽  
H. Baba ◽  
A. Suzuki
Keyword(s):  
Crack Growth ◽  
Fracture Process ◽  
Ceramic Composite ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Crack Opening ◽  
Stable Crack Growth ◽  
Beam Specimen ◽  
Opening Displacement ◽  
Element Analysis

ABSTRACTFracture process zone in SiCw/Si3N4 ceramic composite was studied by a hybrid experimental-numerical analysis employing moire interferometry and finite element analysis. A chevron-notched, wedge-loaded double cantilever beam specimen was used to obtain a stable crack growth. The relation between crack closure stress and crack opening displacement which govern fracture process zone was obtained.

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