Statistical damage model for quasi-brittle materials under uniaxial tension

Abstract

Based on the parallel bar system, combining with the synergetic method, the catastrophe theory and the acoustic emission test, a new motivated statistical damage model for quasi-brittle solid was developed. Taking concrete for instances, the rationality and the flexibility of this model and its parameters-determining method were identified by the comparative analyses between theoretical and experimental curves. The results show that the model can simulate the whole damage and fracture process in the fracture process zone of material when the materials are exposed to quasi-static uniaxial tensile traction. The influence of the mesoscopic damage mechanism on the macroscopic mechanical properties of quasi-brittle materials is summarized into two aspects, rupture damage and yield damage. The whole damage course is divided into the statistical even damage phase and the local breach phase, corresponding to the two stages described by the catastrophe theory. The two characteristic states, the peak nominal stress state and the critical state are distinguished, and the critical state plays a key role during the whole damage evolution course.

Damage Quantification in Concrete under Fatigue Loading Using Acoustic Emission

“…The types of cracks are generally distinguished as follows: the irreversible opening of mode-I crack due to locking mechanisms of crack faces [31], the irreversible sliding-like of mode-II crack (not mode-II microcracks) due to toughness of crack faces [32,33], the irreversible-frictional sliding over crack surface [34,35], the irreversible cracking of fracture process zone [27,36], the irreversible mode-II microcracks [37,38], and other cracking mechanisms [39,40]. It is verified that the irreversible deformation element is able to effectively model the development of the irreversible/residual strains in the materials [24][25][26][27][28][29][30]. Precisely, the fibers and irreversible deformation elements with random thresholds are introduced in FBMs for modelling the events of microcracking in the materials, which were detected by AE sensors.…”

“…The development of irreversible/residual strain is a significant property for describing the fatigue behaviors in the sense of material behavior. Therefore, in order to characterize such property, the irreversible deformation element was introduced into the classical FBMs [24][25][26][27][28][29][30]. Specifically, the irreversible deformation element is able to simulate the development of irreversible strains represented by the progressive fracture of elements.…”

“…Specifically, the irreversible deformation element is able to simulate the development of irreversible strains represented by the progressive fracture of elements. These models [24][25][26][27][28][29][30] were developed to characterize both the progressive elastic deformation damage resulted from the micro mode-I crack process and the irreversible/residual deformation damage produced by serials of types of cracks. The types of cracks are generally distinguished as follows: the irreversible opening of mode-I crack due to locking mechanisms of crack faces [31], the irreversible sliding-like of mode-II crack (not mode-II microcracks) due to toughness of crack faces [32,33], the irreversible-frictional sliding over crack surface [34,35], the irreversible cracking of fracture process zone [27,36], the irreversible mode-II microcracks [37,38], and other cracking mechanisms [39,40].…”

“…Note that this work only focuses on the damage and AE responses of the concrete materials (i.e., the representative volume elements (RVEs)) due to the sophisticated behaviors under fatigue loading, although a number of works have been contributed by researchers concerning that of reinforced concrete structures. Considering that the materials' behaviors are essential for further analysis of the mechanical behaviors of structures, a great number of studies have been already conducted in the literature [14,15,17,19,28,29,31,42,43]. In addition, the damages of concrete structures subjected to mode-I, mode-II, and mixing mode loading were classified by using AE [3].…”

Micromechanical and microstructural aspects affecting rock damage, ‎fracture and cutting mechanisms

“…The maximum CMOD was measured as 1.23 and 2.42 mm for monzonite and tuff, respectively. As discussed earlier, Several interpretations of the size and the quartz content effect have been proposed, but most of the proposed models are phenomenological and do not attempt to describe the physical and mechanical causes for rock fracturing under cyclic loading [10,37,41,42]. As shown in this study, various rock types or anisotropy features could influence fracturing energy reduction by applying SCL and CCL, although the general phenomenon of the energy dissipation trend was similar for different rock types.…”