Localized Shear Deformation of Amorphous Metals

1981 ◽  
Vol 8 ◽  
Author(s):  
J.C.M. Li
Keyword(s):  
Stress Concentration ◽  
Shear Deformation ◽  
Narrow Band ◽  
Shear Localization ◽  
Amorphous Metals ◽  
Localized Deformation ◽  
Crystalline Materials ◽  
Localized Shear Deformation

ABSTRACTThe characteristics of localized deformation in amorphous metals are reviewed. All the available evidences seem to suggest that dislocations are responsible for shear localization. These dislocations seem to require a stress concentration for their nucleation. Once nucleated, they are capable of producing both forward and reverse shear in a narrow band, much like the dislocations in crystalline materials.

Localized Shear Deformation and Fracture in a Zr-Based Bulk Metallic Glass

2007 ◽  
Vol 539-543 ◽  
pp. 2094-2099
Author(s):  
Tatsuya Morikawa ◽  
Tetsuro Kawada ◽  
Kenji Higashida
Keyword(s):  
Metallic Glass ◽  
Shear Deformation ◽  
Bulk Metallic Glass ◽  
Shear Bands ◽  
Step Height ◽  
Bending Test ◽  
Crystalline Materials ◽  
Apparent Fracture Toughness ◽  
Surface Steps ◽  
Localized Shear Deformation

Behaviors of fracture and deformation in a Zr-Al-Ni-Cu bulk metallic glass(BMG) was investigated by using three-point bending tests. Apparent fracture toughness obtained by bending test was 40MPam1/2 which is comparable to the value of ductile crystalline metals. This high toughness of the BMG should be understood by the crack-tip plasticity as well as crystalline metals. It is well known that plastic deformation occurs very inhomogeneously when BMGs are deformed at room temperature. Such inhomogeneity is manifested by the appearance of surface steps caused by localized shear deformation. In the present study, the surface steps due to the localized shear bands near a fracture surface have been examined in detail by using SEM and AFM, where much attention has been paid on the variation of the surface step height measured along the localized shear band. The variation of the step height indicates the gradient of plastic shear deformation, and it can be understood, in principle, as the introduction of elastic singularities corresponding dislocations in the case of crystalline materials.

Effect of Stress Concentration on Laminated Plates

2012 ◽  
Vol 29 (2) ◽  
pp. 241-252 ◽  
Author(s):  
A. S. Sayyad ◽  
Y. M. Ghugal
Keyword(s):  
Stress Concentration ◽  
Shear Deformation ◽  
Transverse Shear ◽  
Deformation Theory ◽  
Shear Deformation Theory ◽  
Laminated Plates ◽  
Shear Stresses ◽  
Normal Strain ◽  
Concentrated Load ◽  
Transverse Shear Stresses

AbstractThis paper deals with the problem of stress distribution in orthotropic and laminated plates subjected to central concentrated load. An equivalent single layer trigonometric shear deformation theory taking into account transverse shear deformation effect as well as transverse normal strain effect is used to obtain in-plane normal and transverse shear stresses through the thickness of plate. Governing equations and boundary conditions of the theory are obtained using the principle of virtual work. A simply supported plate with central concentrated load is considered for the numerical analysis. Anomalous behavior of inplane normal and transverse shear stresses is observed due to effect of stress concentration compared to classical plate theory and first order shear deformation theory.

Highly localized shear deformation in a Mg–Al–Mn alloy subjected to ballistic impact

Vacuum ◽  
2019 ◽  
Vol 169 ◽  
pp. 108868 ◽  
Author(s):  
Bo Zhang ◽  
Jian-Tang Jiang ◽  
Li Liu ◽  
Guo-Ai Li ◽  
Wen-Zhu Shao ◽  
...  
Keyword(s):  
Shear Deformation ◽  
Ballistic Impact ◽  
Localized Shear Deformation

Inelastic strain rate and stress fields in and around an aseismic zone of Kyushu Island, Japan, inferred from seismic and GNSS data

2020 ◽  
Vol 221 (1) ◽  
pp. 289-304
Author(s):  
Y Yuasa ◽  
S Matsumoto ◽  
S Nakao ◽  
T Matsushima ◽  
T Ohkura
Keyword(s):  
Stress Concentration ◽  
Strain Rate ◽  
Crustal Deformation ◽  
Lower Crust ◽  
Seismic Activity ◽  
Deformation Zone ◽  
Inelastic Deformation ◽  
Upper Crust ◽  
Localized Deformation ◽  
Concentration Process

SUMMARY Understanding earthquake processes and crustal deformation requires knowledge of the stress concentration process in the crust. With the enhancement of observation networks, it has become possible to consider in detail the relationships between localized deformation and seismic activity in island arcs and the process of stress concentration. According to previous studies, inelastic deformation in localized weak zones in the crust is considered to play an important role in the stress concentration process. Kyushu, located in southwest Japan, has a 20–30 km band-like active seismic activity and an enclosed aseismic zone. In particular, a part of the seismic active region called the Beppu-Simahara Graben, which is dominated by north–south extensional deformation, is characterized by high seismic activity and a remarkable aseismic zone. We identified the relationship between inelastic deformation and stress concentration processes in this area by using analyses of geodetic and seismic data. The results inverted from both the strain rate field obtained by the geodetic observations and the deviatoric stress field estimated from focal mechanism data reveal a large inelastic deformation zone ($\sim {10^{ - 7}} \,\mathrm{ yr}^{-1}$) beneath the area of active seismicity. From comparison with previous works, the inelastic deformation zone in the lower crust may correspond to an area with high temperature and/or fluid. This may suggest that inelastic deformation is in progress in the area where the strength of lower crustal rocks has reduced due to the presence of geothermics and/or fluids. Furthermore, we confirmed that this inelastic deformation causes stress concentrations of up to $10\,\,{\rm{kPa}}\,\,{\rm{yr}}^{-1}$ in the upper crust. These results show that stress concentration occurs locally in the upper crust, above the inelastic deformation zone in the weakened lower crust, owing to the presence of geothermal and/or fluid; this stress concentration induces seismic activity and crustal deformation.

Groove Bottom Contours of Minimum Stress Concentration for Antiplane Shear Deformation

1985 ◽  
Vol 52 (2) ◽  
pp. 379-384 ◽  
Author(s):  
B. H. Eldiwany ◽  
L. T. Wheeler
Keyword(s):  
Stress Concentration ◽  
Numerical Methods ◽  
Shear Deformation ◽  
Half Space ◽  
Optimization Problems ◽  
Integral Form ◽  
Antiplane Shear ◽  
Space Boundary ◽  
Minimum Stress ◽  
Special Case

Results from free streamline hydrodynamics are exploited in order to solve optimization problems for antiplane shear deformation, in which the stress concentration is to be minimized. These problems pertain to the optimum shapes for grooves cut into a half-space. We obtain results, which from the standpoint of the hydrodynamics problem, complement those presently in the literature. The solution is given in an integral form which in general must be evaluated by numerical methods, but that reduces to elliptic integrals for the special case of a notch whose faces meet the half-space boundary at right angles.

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