Simulation of reinforcement-corrosion-induced crack propagation in concrete by acoustic emission technique and boundary element method analysis

2007 ◽  
Vol 34 (10) ◽  
pp. 1197-1207 ◽  
Author(s):  
A K.M Farid Uddin ◽  
M Ohtsu ◽  
K M.A Hossain ◽  
M Lachemi
Keyword(s):  
Acoustic Emission ◽  
Stress Intensity ◽  
Boundary Element Method ◽  
Crack Propagation ◽  
Boundary Element ◽  
Moment Tensor ◽  
Mode I ◽  
Mode Ii ◽  
Dimensionless Stress ◽  
Element Method

Corrosion of reinforcement is one of the major causes of deterioration in reinforced concrete structures. Various crack patterns are nucleated around reinforcement in concrete due to expansion of corrosion products. Crack kinematics of locations, types, and orientations are quantitatively determined by the acoustic emission (AE) – simplified Green’s functions for moment tensor analysis (SiGMA) procedure in association with laboratory tests conducted on concrete specimens simulating corrosion-induced damage. These kinematic outcomes are obtained as three-dimensional (3-D) locations and vectors, and are thus visualized in 3-D by using virtual reality modeling language (VRML). Numerical analysis is conducted by the boundary element method (BEM) based on the concept of linear elastic fracture mechanics (LEFM) to clarify the mechanisms of corrosion-induced crack extension. Relationships between dimensionless stress intensity factors and cracking types are studied by BEM. Contributions of mode I and mode II failures are dependent on the cracking types. It is found that the process of crack propagation due to corrosion of reinforcement in concrete is mostly a mode I fracture with mixed-mode and, in a few cases, mode II fracture.Key words: acoustic emission, moment tensor, corrosion cracking, stress intensity factor.

Fracture mechanisms of quasi-brittle materials based on acoustic emission

1990 ◽  
Vol 5 (1) ◽  
pp. 206-217 ◽  
Author(s):  
A. K. Maji ◽  
C. Ouyang ◽  
S. P. Shah
Keyword(s):  
Acoustic Emission ◽  
Crack Propagation ◽  
Moment Tensor ◽  
Brittle Materials ◽  
Grain Boundary Sliding ◽  
Fracture Mechanisms ◽  
Propagation Mode ◽  
Interface Debonding ◽  
Mode I ◽  
Mode Ii

Recently acoustic emission (AE) techniques have been used to study crack propagation in materials. The application of these techniques to heterogeneous, quasi-brittle materials such as concrete requires a better understanding of how the signal generated from a microfracture is transformed due to wave propagation and due to the transducer response. In this study, piezoelectric transducers were calibrated using displacement transducers. The validity of an elastodynamic Green's function approach was examined for cement-based materials. The acoustic emission source was characterized using moment tensor analysis. Acoustic emission measurements were analyzed for center-cracked-plate specimens of mortar and concrete. It was observed that, as expected, the dominant mode of cracking was mode I (tensile). However, mode II (shear) and mixed mode cracks also occurred, perhaps due to grain boundary sliding and interface debonding. Microfractures appear to localize prior to critical crack propagation. Mode I cracks generally required more energy release than mode II and a smaller inclusion provided a stronger interface bond than the larger ones.

Research on Fracture Behavior of a Cracked Film-Substrate Medium

2006 ◽  
Vol 324-325 ◽  
pp. 903-906
Author(s):  
Bao Liang Liu ◽  
Xian Shun Bi
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Boundary Element Method ◽  
Intensity Factor ◽  
Boundary Element ◽  
Fracture Behavior ◽  
Thickness Ratio ◽  
Film Substrate ◽  
Substrate Medium ◽  
Element Method

This study gives the problem of a crack in the film oriented perpendicular to the film-substrate interface with the crack tip terminating at the interface. Based on Beuth’s theory, three-dimensional model is simplified to plane strain problems, which obtains fracture mechanisms of a cracked film-substrate medium by applying the boundary element method(BEM). The method aptly resolves the problem involving stress concentration and, further, that this study develops the multi-region boundary element method and applies it to evaluate the cracked film-substrate medium. It shows that the stress intensity factor is affected by the different elastic mismatches and the thickness ratio of the film and the substrate. These results indicate: 1) The stress intensity factor has remarkable increased with the decrease of the thickness ratio of the film and the substrate. The effect of the fracture behavior of film is negligible when the thickness ratio of the film and the substrate is above 10, therefore, it is treated as thin film; 2) The stress intensity factor will decrease with the increase of α ( −1 pα p +1) for β = 0 and β =α / 4 , where α and β are called Dundurs parameters. What’s more, this paper studies the special condition of the film-substrate medium, which is the analysis of the fracture of the absence of any elastic mismatch between the film and the substrate, i.e.α=β=0, and revision of the formula of Xia and Hutchinson is put forward for the stress intensity factor of the deep crack problems by comparing to the former conclusions of Y.Murakami.

Sign in / Sign up

Export Citation Format

Share Document