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.

scholarly journals CHARACTERIZATIONS ON FRACTURE PROCESS ZONE OF PLAIN CONCRETE

2019 ◽  
Vol 25 (8) ◽  
pp. 819-830
Author(s):  
Yuxiang Tang ◽  
Hongniao Chen
Keyword(s):  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Speckle Pattern ◽  
Plain Concrete ◽  
Cohesive Crack ◽  
Electronic Speckle Pattern Interferometry ◽  
Crack Model ◽  
Fe Model ◽  
Durability Analysis

The fracture property of concrete is essential for the safety and durability analysis of concrete structures. Investigating the characteristics of the fracture process zone (FPZ) is of great significance to clarify the nonlinear fracture behaviour of concrete. Experimental and numerical investigations on the FPZ of plain concrete in pre-notched beams subjected to three-point bending were carried out. Electronic speckle pattern interferometry (ESPI) technique was used to observe crack evolution and measure the full-field deformation of the beams. The development of the FPZ were evaluated qualitatively and quantitatively based on the in-plane strain contours and displacement field measured by ESPI, respectively. By integrating the cohesive crack model and finite element (FE) model, various tension softening curves (TSCs) were employed to simulate the fracture response of concrete beams. By comparing the deformation obtained by FE simulation and experiments, the TSCs of plain concrete were evaluated and most suitable TSCs of concrete were recommended.

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.

scholarly journals A Particle-Based Cohesive Crack Model for Brittle Fracture Problems

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3573
Author(s):  
Hu Chen ◽  
Y. X. Zhang ◽  
Linpei Zhu ◽  
Fei Xiong ◽  
Jing Liu ◽  
...  
Keyword(s):  
Fracture Process ◽  
Cohesive Crack ◽  
Contact Model ◽  
Experimental Result ◽  
Crack Model ◽  
Mixed Mode Fracture ◽  
Cohesive Crack Model ◽  
Zone Method ◽  
The Impact ◽  
Linear Softening

Numerical simulations of the fracture process are challenging, and the discrete element (DE) method is an effective means to model fracture problems. The DE model comprises the DE connective model and DE contact model, where the former is used for the representation of isotropic solids before cracks initiate, while the latter is employed to represent particulate materials after cracks propagate. In this paper, a DE particle-based cohesive crack model is developed to model the mixed-mode fracture process of brittle materials, aiming to simulate the material transition from a solid phase to a particulate phase. Because of the particle characteristics of the DE connective model, the cohesive crack model is constructed at inter-particle bonds in the connective stage of the model at a microscale. A potential formulation is adopted by the cohesive zone method, and a linear softening relation is employed by the traction–separation law upon fracture initiation. This particle-based cohesive crack model bridges the microscopic gap between the connective model and the contact model and, thus, is suitable to describe the material separation process from solids to particulates. The proposed model is validated by a number of standard fracture tests, and numerical results are found to be in good agreement with the analytical solutions. A notched concrete beam subjected to an impact loading is modeled, and the impact force obtained from the numerical modeling agrees better with the experimental result than that obtained from the finite element method.

Fracture Parameters of Alkali-Activated Aluminosilicate Composites with Ceramic Precursor

2020 ◽  
Vol 309 ◽  
pp. 73-79
Author(s):  
Hana Šimonová ◽  
Ivana Kumpová ◽  
Iva Rozsypalová ◽  
Patrik Bayer ◽  
Petr Frantik ◽  
...  
Keyword(s):  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Mouth Opening ◽  
Crack Mouth Opening Displacement ◽  
Crack Model ◽  
Mechanical Fracture ◽  
Ceramic Precursor ◽  
Fracture Parameters ◽  
Alkali Activated

This paper deals with selected alkali-activated aluminosilicate composites with a ceramic precursor in terms of their characterization using mechanical fracture parameters. Three composites were studied. They were manufactured using brick powder as a precursor and an alkaline activator with a dimensionless silicate modulus of Ms = 1.0, 1.2 and 1.4. The test specimens were nominally 40 × 40 × 160 mm in size and had a central edge notch with a depth of 1/3 of the specimen’s height. At least 6 specimens made of each composite were tested at the age of 28 days. The specimens were subjected to three-point bending tests, during which diagrams showing force vs. deflection at midspan (F–d diagrams) and force vs. crack mouth opening displacement (F–CMOD diagrams) were recorded. After the processing of these diagrams, values were determined for the static modulus of elasticity, effective fracture toughness (including its initiation component from the analysis of the first part of the F–CMOD diagrams), effective toughness and specific fracture energy using the effective crack model, Work-of-Fracture method, and Double-K fracture model. After the fracture experiments had been performed, compressive strength values were determined for informational purposes from one part of each specimen that remained after testing. In order to obtain visual information about the internal structure of the composites before and after the mechanical testing, the selected specimen was examined via X-ray microtomography. Tomographic measurements and image processing were performed for the qualitative and quantitative evaluation of internal structural changes with an emphasis on the calculation of porosimetry parameters as well as the visualization of the fracture process zone. The fractal dimension of the fracture surface and fracture process zone was determined. The porosity and microstructure images of selected samples taken from specimens were assessed.

Concrete Fracture Process Zone Characterization with Fiber Optics

2001 ◽  
Vol 127 (5) ◽  
pp. 494-502 ◽  
Author(s):  
E. Denarié ◽  
V. E. Saouma ◽  
A. Iocco ◽  
D. Varelas
Keyword(s):  
Fiber Optics ◽  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Concrete Fracture
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