Fault dip variations related to elastic layering

2019 ◽  
Author(s):  
M Nespoli ◽  
M E Belardinelli ◽  
M Bonafede
Keyword(s):  
Boundary Element Method ◽  
Crack Growth ◽  
Stress Drop ◽  
Maximum Energy ◽  
Gravitational Energy ◽  
Surface Fracture ◽  
Complex Fault ◽  
Dip Angle ◽  
Maximum Energy Release ◽  
Surface Fracture Energy

Summary In this paper we model the crack growth in an elastic medium constituted by two welded half-spaces with different rigidities. We implement a 2D Boundary Element Method (BEM) computing shear and normal tractions acting on the crack and the slip accommodating stress drop from an arbitrary initial configuration to a final frictional configuration. The direction of crack growth follows the criterion of maximum energy release (strain and gravitational energy) provided that it overcomes the surface fracture energy and the work dissipated by friction. The energetic criterion leads to estimates of the dip angle of seismic faults depending on the amplitude of the initial stress and it includes the classical Anderson's results as a particular case. Moreover, in presence of a sharp rigidity contrast, the direction of crack growth is strongly deflected. The model simulates non-planar, complex, fault geometries, as in the case of detachment and listric faults and it explains the increase of dip angles for both normal and reverse faults, when they enter soft sedimentary layers.

A Phenomenological Model for the Effect of R Ratio on Fatigue of Strain Crystallizing Rubbers

2003 ◽  
Vol 76 (5) ◽  
pp. 1241-1258 ◽  
Author(s):  
W. V. Mars ◽  
A. Fatemi
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Phenomenological Model ◽  
Maximum Energy ◽  
Loading Cycle ◽  
R Ratio ◽  
Maximum Energy Release

Abstract The fatigue crack growth rate in strain crystallizing rubbers depends not only on the maximum energy release rate experienced during a loading cycle, but also on the minimum, or equivalently, the R ratio. The R ratio is the quotient of the minimum and maximum energy release rates occurring during a loading cycle. This article proposes a simple phenomenological model for the effect of R ratio on fatigue crack growth rate in strain crystallizing rubbers. The model may also be applied for Wohler-style (S-N style) fatigue life curves. The model is compared against experimental results reported by Lindley, by Cadwell, Merrill, Sloman, and Yost, and by the authors. The ability of the model to represent the experimental data is found to be reasonable. The model provides a simple approach to estimating fatigue performance when limited data are available, and may find application in the analysis of load histories from actual service. Such variable amplitude load histories typically contain cycles covering a wide range of R ratios.

scholarly journals Энерговыделение при бомбардировке атомами дейтерия поверхности вольфрама

2019 ◽  
Vol 45 (11) ◽  
pp. 51
Author(s):  
Д.С. Мелузова ◽  
П.Ю. Бабенко ◽  
М.И. Миронов ◽  
В.С. Михайлов ◽  
А.П. Шергин ◽  
...  
Keyword(s):  
Energy Loss ◽  
Energy Range ◽  
Energy Release ◽  
Maximum Energy ◽  
Wide Energy Range ◽  
Tokamak Reactor ◽  
Tungsten Target ◽  
Wide Energy ◽  
Bragg Maximum ◽  
Maximum Energy Release

The distribution of energy release (linear energy loss) over depth was calculated when bombarded with deuterium atoms of a tungsten target in a wide energy range of incident particles of 100 eV - 10 MeV. It is shown that in the energy range up to 100 keV, the maximum energy release, contrary to the prevailing ideas, is near the surface of a solid. At energies above 100 keV, the nature of the distribution changes and the Bragg maximum appears near the point where the particle stops. The distribution of the energy release over depth in tungsten is obtained for conditions typical of the ITER tokamak reactor, which makes it possible to estimate the wall heating during bombardment by plasma atoms.

Fault parameters determined by near- and far-field data: The Wakasa Bay earthquake of March 26, 1963

1974 ◽  
Vol 64 (5) ◽  
pp. 1369-1382 ◽  
Author(s):  
Katsuyuki Abe
Keyword(s):  
Effective Stress ◽  
Stress Drop ◽  
P Wave ◽  
Slip Angle ◽  
Polarization Angle ◽  
S Wave ◽  
Seismological Data ◽  
Fault Parameters ◽  
Wakasa Bay ◽  
Dip Angle

Abstract The source process of the Wakasa Bay earthquake (M = 6.9, 35.80°N, 135.76°E, depth 4 km) which occurred near the west coast of Honshu Island, Japan, on March 26, 1963, is studied on the basis of the seismological data. Dynamic and static parameters of the faulting are determined by directly comparing synthetic seismograms with observed seismograms recorded at seismic near and far distances. The De Hoop-Haskell method is used for the synthesis. The average dislocation is determined to be 60 cm. The overall dislocation velocity is estimated to be 30 cm/sec, the rise time of the slip dislocation being determined as 2 sec. The other fault parameters determined, with supplementary data on the P-wave first motion, the S-wave polarization angle, and the aftershocks, are: source geometry, dip direction N 144°E, dip angle 68°, slip angle 22° (right-lateral strike-slip motion with some dip-slip component); fault dimension, 20 km length by 8 km width; rupture velocity, 2.3 km/sec (bilateral); seismic moment, 3.3 × 1025 dyne-cm; stress drop, 32 bars. The effective stress available to accelerate the fault motion is estimated to be about 40 bars. The approximate agreement between the effective stress and the stress drop suggests that most of the effective stress was released at the time of the earthquake.

scholarly journals An Experimental and Numerical Investigation on the Initiation and Interaction of Double Cracks in Rocks under Hydromechanical Coupling

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Jie Mei ◽  
Wanzhi Zhang
Keyword(s):  
Water Pressure ◽  
Critical Length ◽  
Maximum Energy ◽  
Enhancement Effect ◽  
Hydromechanical Coupling ◽  
Underground Engineering ◽  
Side Rock ◽  
Crack Tips ◽  
Dip Angle ◽  
Interaction Behaviors

The growth of double cracks is the main factor leading to progressive rock failure under hydromechanical coupling. The initiation modes and interaction behaviors of double cracks were investigated by using laboratory tests, and the influences of water pressure were analyzed. The maximum energy release rate criterion was modified to determine the crack growth characteristics. A numerical model was established and then verified by the test results. Based on the simulation, the distribution of stress fields and key fracture parameters of double cracks was investigated. Then, initiation characteristics and interaction behaviors of parallel and nonparallel cracks were quantitatively analyzed. The results indicate that the increase in water pressure leads to the crack initiation being inclined to the original surfaces and the growth length along the crack fronts tending to be uniform; the small tensile stress zones are formed close to the crack tips, and significant compressive stress zones are formed at both sides of the crack surfaces; stress superposition and interaction occur when crack spacing is less than 2.5a; the interactive weakening effect is mainly present in the inner side (rock bridge zone) of cracks, while a certain degree of interactive enhancement effect exhibits in the outer sides; the cracks are much easier to initiate at the outer wing cracks when the spacing is less than the critical length (0.5a); and cracks with a dip angle of 45° are much easier to initiate at the endpoints of long axis. The research results provide certain theoretical guidance for the safety assessment of underground engineering.

Analysis of Branched Interface Cracks

1990 ◽  
Vol 57 (4) ◽  
pp. 887-893 ◽  
Author(s):  
D. J. Mukai ◽  
R. Ballarini ◽  
G. R. Miller
Keyword(s):  
Energy Release Rate ◽  
Energy Release ◽  
Interface Crack ◽  
Finite Length ◽  
Release Rate ◽  
Rate Ratio ◽  
Maximum Energy ◽  
Crack Branching ◽  
Maximum Energy Release ◽  
Branch Crack

A solution is presented for the problem of a finite length crack branching off the interface between two bonded dissimilar isotropic materials. Results are presented in terms of the ratio of the energy release rate of a branched interface crack to the energy release rate of a straight interface crack with the same total length. It is found that this ratio reaches a maximum when the interface crack branches into the softer material. Longer branches tend to have smaller maximum energy release rate ratio angles indicating that all else being equal, a branch crack will tend to turn back parallel to the interface as it grows.

Fracture Under Combined Loads by Maximum-Energy-Release-Rate Criterion

1978 ◽  
Vol 45 (3) ◽  
pp. 553-558 ◽  
Author(s):  
C.-H. Wu
Keyword(s):  
Maximum Stress ◽  
Maximum Energy ◽  
Antiplane Shear ◽  
Combined Loads ◽  
Biaxial Load ◽  
Title Problem ◽  
Minimum Strain Energy ◽  
Energy Release Rate Criterion ◽  
Rate Criterion ◽  
Maximum Energy Release

The title problem is studied for the cases: (1) crack-perpendicular tension and crack-parallel shear, (2) plane biaxial load, (3) crack-parallel shear and antiplane shear, and (4) unidirectional load and antiplane shear. All the results are based on a fundamental investigation reported in references [1, 2], the results of which are partly exact, and partly asymptotic and numerical. Neither the maximum-stress nor the minimum-strain-energy-density criterion indicates a coupling between plane and antiplane loads.

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