Mixed Modes I and II Concrete Fracture: An Experimental Analysis

1994 ◽  
Vol 61 (4) ◽  
pp. 815-821 ◽  
Author(s):  
Z. K. Guo ◽  
A. S. Kobayashi ◽  
N. M. Hawkins
Keyword(s):  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Crack Opening ◽  
Concrete Specimen ◽  
Element Model ◽  
Dissipated Energy ◽  
Mixed Mode Fracture ◽  
Aggregate Interlocking ◽  
Point Bend

The development of the fracture process zone associated with subcritical crack growth in a three-point bend concrete specimen with an off-centered, single-edged precrack was monitored with moire interferometry. The applied load and the crack opening and sliding displacements together with a finite element model of the concrete specimen were used to determine the crack closing stress due to aggregate bridging. Under this mixed-mode fracture, aggregate interlocking increased the crack closing stresses in the fracture process zone and hence the load carrying capacity of the concrete specimen. The dissipated energy rate in the fracture process zone also increased with aggregate interlocking.

A Continuum Model with an Embedded Fracture Process Zone Modelled as a Cohesive Frictional Interface

2016 ◽  
Vol 846 ◽  
pp. 360-365 ◽  
Author(s):  
Arash Mir ◽  
Giang Dinh Nguyen ◽  
Abdul H. Sheikh
Keyword(s):  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Crack Opening ◽  
Brittle Materials ◽  
Peak Stress ◽  
Dissipated Energy ◽  
Internal Variables ◽  
Frame Work ◽  
Frictional Interface

Failure in quasi-brittle materials, such as concrete and rock, usually develops in a fracture process zone (FPZ), in which dissipative processes takes place. At the onset of bifurcation or upon formation of FPZ the homogeneity of kinematic fields is lost and the stress field is redistributed which gives rise to the so called deterministic size effect problem. The total strain energy stored within a specimen of quasi-brittle materials will scale with its size; however, the amount of dissipated energy does not depend on the specimen size but only on the width of the FPZ. This width is related to the microstructure of the material and is considered a characteristic of the material. In this paper, a cohesive frictional interface is used to model the dissipative behaviour of material inside FPZ. Fundamental micro-mechanisms of energy dissipation such as micro-crack opening in mode I and frictional sliding between micro-crack surfaces are formulated within the frame work of Thermodynamic with internal variables (TIV) to ensure the thermodynamics admissibility of the model. The link between the material behaviour inside and outside FPZ is given through the continuity of tractions along the boundaries of FPZ. It is shown that although the shape of the post-peak stress-strain varies, for specimens of different slenderness, the amount of dissipated energy remains the same in all cases.

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.

Effect Of Aggregate Content On Fracture Behavior Of Concrete

1995 ◽  
Vol 409 ◽  
Author(s):  
Y. Xi ◽  
F.E. Amparano ◽  
Zongjin Li
Keyword(s):  
Fracture Energy ◽  
Fracture Process ◽  
Fracture Behavior ◽  
Fracture Process Zone ◽  
Volume Fraction ◽  
Process Zone ◽  
Aggregate Content ◽  
Grain Structures ◽  
Point Bend ◽  
Two Parameters

AbstractEffect of aggregate content on fracture behaviors of concrete is studied by testing on geometrically similar three-point bend beams. The results are analyzed by using a size effect method in which the fracture behavior of concrete is characterized by two parameters, fracture energy Gf and effective fracture process zone cf. Test results showed that with increasing volume fraction of aggregate in the range 45% - 75%: (1) the modulus of elasticity of concrete decreases slightly, (2) fracture energy Gf increases, but the rate is very small; (3) the size of the fracture process zone, cf, decreases, which may be explained by changes in coarseness of grain structures defined in terms of mosaic patterns.

Simulation of mixed‐mode fracture using SPH particles with an embedded fracture process zone

2020 ◽  
Vol 44 (10) ◽  
pp. 1417-1445 ◽  
Author(s):  
Yingnan Wang ◽  
Hieu T. Tran ◽  
Giang D. Nguyen ◽  
Pathegama G. Ranjith ◽  
Ha H. Bui
Keyword(s):  
Mixed Mode ◽  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Mixed Mode Fracture ◽  
Mode Fracture

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.

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.

Analysis of Energy Balance When Using Cohesive Zone Models to Simulate Fracture Processes

2002 ◽  
Vol 124 (4) ◽  
pp. 440-450 ◽  
Author(s):  
C. Shet ◽  
N. Chandra
Keyword(s):  
Cohesive Energy ◽  
Cohesive Zone ◽  
Strain Energy ◽  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Elastic Strain Energy ◽  
Inelastic Strain ◽  
External Work ◽  
Cohesive Zone Models

Cohesive Zone Models (CZMs) are being increasingly used to simulate fracture and fragmentation processes in metallic, polymeric, and ceramic materials and their composites. Instead of an infinitely sharp crack envisaged in fracture mechanics, CZM presupposes the presence of a fracture process zone where the energy is transferred from external work both in the forward and the wake regions of the propagating crack. In this paper, we examine how the external work flows as recoverable elastic strain energy, inelastic strain energy, and cohesive energy, the latter encompassing the work of fracture and other energy consuming mechanisms within the fracture process zone. It is clearly shown that the plastic energy in the material surrounding the crack is not accounted in the cohesive energy. Thus cohesive zone energy encompasses all the inelastic energy e.g., energy required for grainbridging, cavitation, internal sliding, surface energy but excludes any form of inelastic strain energy in the bounding material.

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