Antiplane shear crack in a prestressed elastic medium based on the couple stress theory

A prestressed elastic medium containing a mode-Ⅲcrack is studied by means of the couple stress theory(CST).Based on the CST under initial stresses,a governing differential equation along with a mixed boundary value problem is established.The singularities of the couple stress and force stress near the crack tips are analyzed through the asymptotic crack-tip fields resulting from the characteristic expansion method.To determine their intensity,a hypersingular integral equation is derived and numerically solved with the help of the Chebyshev polynomial.The obtained results show a strong size-dependence of the out-of-plane displacement on the crack and the couple stress intensity factor(CSIF)and the force stress intensity factor(FSIF)around the crack tips.The symmetric part of the shear stress has no singularity,and the skew-symmetric part related to the couple stress exhibits an r^(-3/2)singularity,in which r is the distance from the crack tip.The initial stresses also affect the crack tearing displacement and the CSIF and FSIF.

Application of caustic method to determining stress intensity factor of compressive shear crack

The caustic method is applied to compressive shear experiment and used to detect the stress intensity factors of cracks prefabricated on plexiglass sample. Loading, friction of crack planes and influence among cracks are not needed to know as they are combined and transformed into the caustic shadow used in detecting the stress intensity factor. Even boundary condition is not necessary. Therefore it is effective to determine the stress intensity factor of compressive shear crack.

CRACK PROBLEM UNDER SHEAR LOADING IN CUBIC QUASICRYSTAL

The axisymmetric elasticity problem of cubic quasicrystal is reduced to a single higher_order partial differential equation by introducing a displacement function. Based on the work, the analytic solutions of elastic field of cubic quasicrystal with a penny_shaped crack under the shear loading are found, and the stress intensity factor and strain energy release rate are determined.

Shear-resistant behavior of light composite shear wall

Shear test results for a composite wall panel in a light composite structure system are compared with test results for shear walls in Japan.The analysis results show that this kind of composite wall panel works very well,and can be regarded as a solid panel.The composite wall panel with a hidden frame is essential for bringing its effect on shear resistance into full play.Comprehensive analysis of the shear-resistant behavior of the composite wall panel suggests that the shear of the composite shear wall panel can be controlled by the cracking strength of the web shearing diagonal crack.

Fracture characteristics of bulk metallic glass under high speed impact

High speed impact experiments of rectangular plate-shaped Zr 41 Ti 14 Cu 12.5 Ni 10 Be 22.5 bulk metallic glass（BMG） were performed using a two-stage light gas gun.Under spherical shock waves with impact velocities ranging from 0.503 km/s to 4.917 km/s,obvious traces of laminated spallation at the back（free） surface and melting（liquid droplets） at the impact point were observed.The angles about 0掳,17掳,36掳,and 90掳to the shocking direction were shown in the internal samples because of the interaction between the compressive shock waves and the rarefaction waves.The compressive normal stress was found to induce the consequent temperature rise in the core of the shear band.

Analysis of mode Ⅲ crack perpendicular to the interface between two dissimilar strips

The present work is concerned with the problem of mode Ⅲ crack perpendicular to the interface of a bi-strip composite. One of these strips is made of a functionally graded material and the other of an isotropic material, which contains an edge crack perpendicular to and terminating at the interface. Fourier transforms and asymptotic analysis are employed to reduce the problem to a singular integral equation which is numerically solved using Gauss-Chebyshev quadrature formulae. Furthermore, a parametric study is carried out to investigate the effects of elastic and geometric characteristics of the composite on the values of stress intensity factor.

Testing the intraplate origin of mega-earthquakes at subduction margins

The disastrous Mw 9.3 （seismic moment 1.0 × 10^30 dyn/cm） earthquake that struck northwest Sumatra on 26 December 2004 and triggered -30 m high tsunami has rejuvenated the quest for identi- fying the forcing behind subduction related earthquakes around the world. Studies reveal that the stron- gest part （elastic core） of the oceanic lithosphere lie between 20 and 60 km depth beneath the upper （- 7 km thick） crustal layer, and compressive stress of GPa order is required to fail the rock-layers within the core zone. Here we present evidences in favor of an intraplate origin of mega-earthquakes right within the strong core part （at the interface of semi-brittle and brittle zone）, and propose an alternate model exploring the flexing zone of the descending lithosphere as the nodal area for major stress accumulation. We believe that at high confining pressure and elevated temperature, unidirectional cyclic compressive stress loading in the flexing zone results in an increase of material yield strength through strain hardening, which transforms the rheology of the layer from semi-brittle to near-brittle state. The increased compres- sive stress field coupled with upward migration of the neutral surface （of zero stress fields） under non- coaxial deformation triggers shear crack. The growth of the shear crack is initially confined in the near-brittle domain, and propagates later through the more brittle crustal part of the descending oceanic lithosphere in the form of cataclastic failure,

Shear-Resistant Behavior Analysis of Light Composite Shear Walls

Shear test results for a composite wall panel in a light composite structure system are compared with test results for shear walls in Japan in this paper. The analysis results show that this kind of composite wall panel works very well, and can be regarded as a solid panel. The composite wall panel with a hidden frame is essential for bringing its effect on shear resistance into full play. Comprehensive analysis of the shear-resistant behavior of the composite wall panel suggests that the shear of the composite shear wall panel can be controlled by the cracking strength of the web shearing diagonal crack.