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.

A Finite Element Study of Stable Crack Growth Under Plane Stress Conditions: Part II—Influence of Hardening

1987 ◽  
Vol 54 (4) ◽  
pp. 846-853 ◽  
Author(s):  
R. Narasimhan ◽  
A. J. Rosakis ◽  
J. F. Hall
Keyword(s):  
Finite Element ◽  
Crack Growth ◽  
Plane Stress ◽  
Crack Opening ◽  
Stable Crack Growth ◽  
Small Scale ◽  
Opening Displacement ◽  
Element Analysis ◽  
Critical Crack ◽  
Perfectly Plastic

A detailed finite element analysis is performed to model quasi-static crack growth under plane stress, small-scale yielding conditions in elastic-plastic materials characterized by isotropic power law hardening and the Huber-Von Mises yield surface. A nodal release procedure is used to simulate crack extension. Results pertaining to the influence of hardening on the extent of active yielding and the near-tip stress and deformation fields are presented. Clear evidence of an elastic unloading wake following the active plastic zone is found, but no secondary (plastic) reloading along the crack flank is numerically observed for any level of hardening. A ductile crack growth criterion based on the attainment of a critical crack opening displacement at a small microstructural distance behind the tip, is employed to investigate the nature of the J resistance curves under plane stress. In addition, the same criterion is employed to investigate the influence of hardening on the potential for stable crack growth under plane stress. It is found that predictions based on a perfectly plastic model may be unconservative in this respect, which is qualitatively similar to the conclusions reached in antiplane shear and Mode I plane strain.

STRESS FUNCTION OF SIMPLY SUPPORTED CONCRETE BEAM WITH A FRACTURE PROCESS ZONE UNDER UNIFORM LOAD

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Shujin Duan ◽  
Quanmin Guo
Keyword(s):  
Boundary Conditions ◽  
Stress Function ◽  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Crack Opening ◽  
Crack Problem ◽  
Cohesive Crack ◽  
Opening Displacement ◽  
Simply Supported

Based on the weight integration to obtain the closed solution of cohesive crack problem, a method is proposed to obtain the stress function of a simply supported beam under uniform distributed forces in this paper. The key technique is to determine the weight of several solutions of elastic mechanics problems to satisfy the given crack traction within the cohesive crack surfaces and the boundary conditions. The error degree of the function to satisfy the boundary conditions mainly depends on the number and the location of the selected points. In the formed fracture process zone, there is both the finite magnitude of stress concentration and the smooth closed-crack opening displacement. The FE numerical simulation is also carried out; its results are in good agreement with the present theoretical calculation results.

A Comparison of Cohesive Crack Model and Crack Band Model in Concrete Fracture

2012 ◽  
Vol 170-173 ◽  
pp. 3375-3380
Author(s):  
Liang Wu ◽  
Ze Li ◽  
Shang Huang
Keyword(s):  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Crack Opening ◽  
Cohesive Crack ◽  
Band Model ◽  
Crack Model ◽  
Concrete Fracture ◽  
Cohesive Crack Model ◽  
Crack Band

The cohesive crack model and the crack band model are two convenient approaches in concrete fracture analysis. They can describe in full the fracture process by the different manner: The entire fracture process zone is lumped into the crack line and is characterized in the form of a stress-displacement law which exhibits softening; or the inelastic deformations in the fracture process zone are smeared over a band of a certain width, imagined to exist in front of the main crack. The correlation of the two models is developed based on a characteristic width of crack band. The analysis shows that they can yield about the same results if the crack opening displacement in the cohesive crack model is taken as the fracturing strain that is accumulated over the width of the crack band model. Some basic problems are also discussed in finite element analysis.

The Influence of the Chosen Type of Form Lubricator in the Form for Cement Paste with Fly Ash on the Fracture Process Zone

2017 ◽  
Vol 731 ◽  
pp. 92-97
Author(s):  
Barbora Mužíková ◽  
Pavel Padevět
Keyword(s):  
Fly Ash ◽  
Crack Growth ◽  
Cement Paste ◽  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
The Other ◽  
Mode Ii ◽  
Air Bubbles ◽  
The Real

This paper is focused on the cracks growth in mode II of specimens made of cement paste with fly ash. Three prescriptions were made for testing in mode II, during the making air bubbles arose at the bottom of the specimen that were lubricated with oil. These little caverns can have an influence on the growth of the cracks in the fracture process zone. On the other side, specimens that were lubricated with a wax, no caverns were observed. There are complex mechanisms of crack growth in the fracture process zone, cavern or inertial elements have a fundamental effect on the success of the real tests in mode II. Specimens lubricated with wax have a 50 % higher successful running of the test than those, whose forms were lubricated with the oil.

Does the Process Zone Control Crack Growth?

1992 ◽  
Vol 45 (8) ◽  
pp. 367-376 ◽  
Author(s):  
H. Abe´ ◽  
M. Saka ◽  
S. Ohba ◽  
T. Hashida
Keyword(s):  
Crack Growth ◽  
Main Crack ◽  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Crack Tip ◽  
Compact Tension ◽  
Initial Crack ◽  
Zone Control ◽  
Notch Length

Fracture toughness tests were carried out by using small compact tension specimens of Westerly granite. Relation between the load-line displacement and the initial crack-tip separation changed from linear to nonlinear and then to linear again with increasing loading. The onset of the main crack growth was found to occur in a loading level at which the relation was nonlinear. This result disclosed that the onset of main crack growth in granite occurred without experience of the complete area under the tension-softening curve. The critical value of the initial crack-tip separation for onset of the main crack growth was obtained independently of the initial notch length. Also monitoring of the growth of the fracture process zone by ultrasonic technique showed that its length related with the crack-tip separation independently of the initial notch length. By combining the results just mentioned, it was concluded that the fracture process zone controlled the onset of the main crack growth.

scholarly journals A theory of viscoelastic crack growth-Revisited

2021 ◽  
Author(s):  
Richard A Schapery
Keyword(s):  
Crack Growth ◽  
Creep Compliance ◽  
Process Zone ◽  
Crack Opening ◽  
Shift Factor ◽  
Analytical Relationship ◽  
Failure Zone ◽  
Opening Displacement ◽  
Linear Elastic ◽  
Linear Elastic Body

Abstract A theory of viscoelastic crack growth developed nearly five decades ago is generalized to express traction in the so-called fracture process zone or failure zone as a function of the crack opening displacement (COD). In earlier work, except for minor exceptions, traction was specified as a function of location. The new model leads to a nonlinear double integral that has to be solved for the COD before crack growth can be predicted. First, a closed-form, accurate approximation is found for a linear elastic body. We then show that this COD may be easily and accurately extended to linear viscoelasticity using a realistic, broad spectrum creep compliance. An analytical relationship connecting the stress intensity factor to crack speed then follows. Consistent with earlier work, it is defined almost entirely by the creep compliance. Five different failure zone tractions are employed; their differences are shown to have little effect on crack growth other than through a speed shift factor. The Appendix discusses initiation of growth.

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