Control of the grouting pressure within critical for crack propagation in Ordovician limestone can not only ensure grout penetration length, but also prevent risk creating an artificial water channel. Based on fracture mechanics theory, a formula was proposed to calculate mixed mode I-II cracks limestone. The necessary conditions tilted opening, rationality existing empirical value maximum allo...

In this article, high-speed photographic investigations of the dynamic crack initiation and propagation in several inorganic glasses by the impact of small spherical and conical projectiles are described. These were carried out at speeds of up to approximately 2×10(6) frames s(-1). The glasses were fused silica, 'Pyrex' (a borosilicate glass), soda lime and B(2)O(3). The projectiles were 0.8-2 ...

This paper describes a framework to study the initiation and arrest of an interfacial crack, using a combination of experiment and computation. We consider a test configuration widely used in the microelectronic industry: a sample of two substrates bonded by a stack of thin films, with a pre-crack in one of the substrates, perpendicularly impinging upon the films. When the sample is loaded to a...

In multilayer ferroelectric actuators, electrode edges are the main source of fracture due to the generation of non-uniform electric fields in their vicinity. The electric fields, in turn, induce incompatible strain fields and hence concentrated stresses, which may cause the ceramic to crack. In this paper, the crack initiation from the electrode edges is simulated using a phase-field model. Th...

Corresponding Author: Mirsayar, M.M. Department of Civil Engineeing, Texas A&M University, College Station, TX 77843-3136, USA Email: [email protected] Abstract: Zirconia/veneer bilayered components are extensively used in dental restoration technology to improve resistance of tooth’s surface from decay. The direction of the fracture propagation at the interface of zirconia and veneer is invest...

A three-dimensional failure initiation criterion in brittle materials containing a sharp V-notch is presented and validated by experiments. It is based on simultaneous fulfilment of the stress requirement and a finite fracture mechanics energy release rate (ERR) requirement. Since the ERR cannot determine failure initiation direction for dominant mode III loading, the failure initiation orienta...

The growth of transverse cracks under expanding spherical contact in a model system consisted of soda-lime glass bonded to a polycarbonate substrate is observed in situ from below or from the polished edge of the bilayer. Abrasion or chemical etching is employed on the coating surfaces to control the initial fracture. In the limit case of monoliths, the crack mouth becomes fully engulfed by the...

Understanding the mechanism of fracture is essential for material and process design. While the initiation of fracture in brittle solids is generally associated with the preexistence of material imperfections, the mechanism for initiation of fracture in viscoelastic fluids, e.g., polymer melts and solutions, remains an open question. We use high speed imaging to visualize crack propagation in e...

Relationships between crack initiation and crack growth toughness are reviewed by examining the crack tip fields and microscopic (local) and macroscopic (continuum) fracture criteria for the onset and continued quasi-static extension of cracks in ductile materials. By comparison of the micromechanisms of crack initiation via transgranular cleavage and crack initiation and subsequent growth via ...