Semi-solid materials undergo strain localization and shear band formation as a result of granular nature of semi-solid deformation. In the present study, to analyze the shear localization, a unified viscoplastic constitutive model was developed for the homogeneous flow. Then, a linearized analysis of the stability performed by examining the necessary condition for the perturbation growth. For t...

The determination of shear wave speed is an important subject in the field of elastography, since elevated shear wave speeds can be directly linked to increased stiffness of tissues. MRI and ultrasound scanners are frequently used to detect shear waves and a variety of estimators are applied to calculate the underlying shear wave speed. The estimators can be relatively simple if plane wave beha...

In this work, we explored the potential of measuring shear wave propagation using optical coherence elastography (OCE) based on a swept-source optical coherence tomography (OCT) system. Shear waves were generated using a 20 MHz piezoelectric transducer (circular element 8.5 mm diameter) transmitting sine-wave bursts of 400 μs, synchronized with the OCT swept source wavelength sweep. The acousti...

The occurrence of SH wave propagation under the effect of a point source in an orthotropic substratum lying over a heterogeneous orthotropic half space is deliberated in the prospect of a devastating earthquake. The quadratic alteration is acknowledged for density and shear modulus which is hypothesized to be a function of depth. The method of Green's function and transformation technique contr...

Wave propagation is used as an advanced tool of determining elastic properties of rocks. In spite of being cheap and non destructive tests of rock mechanics, due to its modernity method is not yet replacing the traditional dear and destructive tests. In order to pave ways of replacing this test and making best use of it all effective factors of such method are to be assessed. One fundamental fa...

This paper studies the propagation of disturbances in an initially stress-free elastic circular rod. Starting from the Mindlin-Hermann equations, we derive a fourth-order partial differential equation as the governing equation for small axial-radial deformations in a rod composed of an incompressible material. Then, we consider an initial-value problem with an initial singularity in the shear s...

Conventional imaging of diagnostic ultrasound is widely used. Although it makes the differences in the soft tissues echogenicities’ apparent and clear, it fails in describing and estimating the soft tissue mechanical properties. It cannot portray their mechanical properties, such as the elasticity and stiffness. Estimating the mechanical properties increases chances of the identification of les...

Introduction: Magnetic resonance elastography (MRE) allows the measurement of the mechanical properties of living tissue by combining shear waves and motion sensitive MRI [1]. In classical MRE, shear wave images are evaluated using an appropriate wave inversion technique for calculating an estimate of the spatial distribution of the shear modulus within the region of interest [2]. Problem: Wave...

impedance (AI) and a parameter related to shear-wave velocity from seismic data, our ability to discriminate between different lithologies and fluid phases will increase. Prestack inversion on individual CDP gathers and inverting directly for VP, VS, and density have been tested in several ways, but the estimated parameters are often poorly determined. A more robust approach is to apply poststa...

[1] Shear wave splitting observed in microearthquake data at the axis of the Mid-Atlantic Ridge near 35 N has a fast polarization direction that is parallel to the trend of the axial valley. The time delays between fast and slow S wave arrivals range from 35 to 180 ms, with an average of 90 ms, and show no relationship with ray path length, source-toreceiver azimuth, or receiver location. The a...