Problems of elastic wave scattering by surface-breaking and near-surface cracks are of considerable current interest for ultrasonic nondestructive evaluation. Ultrasonic scattering by planar cracks near or at the free surface of a semi-infinite elastic homogeneous medium has been studied theoretically by many authors. References to recent papers on this subejct can be found in [1], [2] and [3]....

Drying aqueous suspensions of monodisperse silica nanoparticles can fracture in remarkable patterns. As the material solidifies, evenly spaced cracks invade from the drying surface, with individual cracks undergoing intermittent motion. We show that the growth of cracks is limited by the advancement of the compaction front, which is governed by a balance of evaporation and flow of fluid at the ...

It is of great interest to describe and quantify the evolution microstructure for a better understanding rock deformation processes. In this study, 2D images salt are analyzed at several stages consolidation tests cyclic compression magnitude orientation solidity, coordination, local solid volume fraction, crack volume. both tests, aggregates achieved by grain rearrangement greater than that an...

The cracking elements method (CEM) is a novel numerical approach for simulating fracture of quasi-brittle materials. This method is built in the framework of conventional finite element method (FEM) based on standard Galerkin approximation, which models the cracks with disconnected cracking segments. The orientation of propagating cracks is determined by local criteria and no explicit or implic...

Microtubules (MTs) are cytoplasmic protein polymers that are essential for fundamental cellular processes including the maintenance of cell shape, organelle transport and formation of the mitotic spindle. Microtubule dynamic instability is critical for these processes, but it remains poorly understood, in part because the relationship between the structure of the MT tip and the growth/depolymer...

In polycrystalline metals, local deformation heterogeneities induced by the microstructure influence fatigue crack initiation and micro-crack propagation. The localization in plastic strains associated with heterogeneous deformation has been described as a necessary condition and a precursor for the nucleation of fatigue cracks. However, a clear and quantitative assessment of the correlation be...

AIMS Biodegradable coatings on drug-eluting stents (DES) may help to avoid adverse long-term effects of DES such as late/very late stent thrombosis which is partly attributed to durable polymers. As the post-expansion morphology of biodegradable coatings is greatly unknown, we investigated the polylactic acid coating on biolimus-eluting BioMatrix stents. METHODS AND RESULTS Scanning electron ...

Although concrete is one of the most widely used construction materials, it is characterized by substantially low tensile strength in comparison to its compression strength, and the occurrence of cracks is unavoidable. In addition, cracks progress due to environmental conditions including damage by freezing, neutralization, and salt, etc. Moreover, detrimental damage can occur in concrete struc...

Tensile strength is an important parameter in many engineering applications. In loess slopes, for instance, it governs the development and propagation of tension cracks that usually ultimately lead to crack–sliding toppling failures, which are among most common modes slope failure Loess Plateau China. Reliable measurement tensile geomaterial therefore a necessity. Commonly used methods have lim...