Characterizing the fast evolution of microstructural defects is key to understanding "crackling" phenomena during the deformation of solid materials. For example, it has been proposed using atomistic simulations of crack propagation in elastic materials that the formation of a nonlinear hyperelastic or plastic zone around moving crack tips controls crack velocity. To date, progress in understan...

OBJECTIVES This research was designed to analyse the frequency spectra of joint crack sounds produced during spinal manipulative therapy applied to the upper cervical spine of 50 volunteers and to determine if the spectra differed between the sexes and or for those with a history of previous neck trauma compared with those without a history of trauma. DESIGN Randomised experimental study. S...

We investigate the velocity dependence of the friction between two rigid blocks limited by a self-affine surface such as the one generated by a crack. The upper solid is subjected either to gravity or to an extemal elastic stiffness, and is driven horizontally at constant velocity, V, while the lower solid is fixed. For low velocities, the apparent friction coefficient is constant. For high vel...

High-speed digital photography was used to study rupture propagation on the interface between transparent damaged and undamaged photoelastic plates. Bilateral ruptures were nucleated on pre-machined faults at an angle α to the uniaxial loading axis. Stress concentration at the crack tips produced fringes in polarized laser light that allowed their positions to be measured in successive photos. ...

We discuss the stick-slip motion of an elastic block sliding along a rigid substrate. We argue that for a given external shear stress this system shows a discontinuous nonequilibrium transition from a uniform stick state to uniform sliding at some critical stress which is nothing but the Griffith threshold for crack propagation. An inhomogeneous mode of sliding occurs when the driving velocity ...

Railway concrete sleepers have been developed and utilized in railway industry for over 50 years. Cyclic loading because of vibration on sleepers due to the train loading and the velocity of train itself and also a small percentage of bad wheels, can eventually lead to a crack network and failure of component. The objective of this study is to investigate the load carrying capacity of the selec...

Anisotropy in physical properties of rocks can arise from preferred mineral orientation, mineral layering, nonhydrostatic stress, and anisotropic crack distribution. For instance, all of the following cause acoustic double refraction: preferential orientation of olivine grains in dunites, alternating layers in laboratory-sizedsamples of such mineral pairs as olivine-feldspar, wollastonite-diops...