292 research outputs found
Fluid-plasticity of thin cylindrical shells
Dynamic plastic response of a thin cylindrical shell, immersed in a potential fluid initially at rest and subjected to internal pressure pulse of arbitrary shape and duration, is examined. The shell is assumed to respond as a rigid-perfectly plastic material while the fluid is taken as inviscid and incompressible. The fluid back pressure is incorporated into the equation of motion of the shell as an added mass term. Since arbitrary pulses can be reduced to equivalent rectangular pulses, the equation of motion is solved only for a rectangular pulse. The influence of the fluid in reducing the final plastic deformation is demonstrated by a numerical example
Statistical mechanics of damage phenomena
This paper applies the formalism of classical, Gibbs-Boltzmann statistical
mechanics to the phenomenon of non-thermal damage. As an example, a non-thermal
fiber-bundle model with the global uniform (meanfield) load sharing is
considered. Stochastic topological behavior in the system is described in terms
of an effective temperature parameter thermalizing the system. An equation of
state and a topological analog of the energy-balance equation are obtained. The
formalism of the free energy potential is developed, and the nature of the
first order phase transition and spinodal is demonstrated.Comment: Critical point appeared to be a spinodal poin
Acoustic Emission Monitoring of the Syracuse Athena Temple: Scale Invariance in the Timing of Ruptures
We perform a comparative statistical analysis between the acoustic-emission time series from the ancient Greek Athena temple in Syracuse and the sequence of nearby earthquakes. We find an apparent association between acoustic-emission bursts and the earthquake occurrence. The waiting-time distributions for acoustic-emission and earthquake time series are described by a unique scaling law indicating self-similarity over a wide range of magnitude scales. This evidence suggests a correlation between the aging process of the temple and the local seismic activit
Applicability and non-applicability of equilibrium statistical mechanics to non-thermal damage phenomena: II. Spinodal behavior
This paper investigates the spinodal behavior of non-thermal damage
phenomena. As an example, a non-thermal fiber-bundle model with the global
uniform (meanfield) load sharing is considered. In the vicinity of the spinodal
point the power-law scaling behavior is found. For the meanfield fiber-bundle
model the spinodal exponents are found to have typical meanfield values.Comment: Version related: More careful explanation for the critical
slowing-down. General: The topological properties of non-thermal damage are
described by the formalism of statistical mechanics. This is the continuation
of arXiv:0805.0346. Comments, especially negative, are very welcom
Universality behind Basquin's law of fatigue
One of the most important scaling laws of time dependent fracture is
Basquin's law of fatigue, namely, that the lifetime of the system increases as
a power law with decreasing external load amplitude, , where the exponent has a strong material
dependence. We show that in spite of the broad scatter of the Basquin exponent
, the fatigue fracture of heterogeneous materials exhibits intriguing
universal features. Based on stochastic fracture models we propose a generic
scaling form for the macroscopic deformation and show that at the fatigue limit
the system undergoes a continuous phase transition when changing the external
load. On the microlevel, the fatigue fracture proceeds in bursts characterized
by universal power law distributions. We demonstrate that in a range of
systems, including deformation of asphalt, a realistic model of deformation,
and a fiber bundle model, the system dependent details are contained in
Basquin's exponent for time to failure, and once this is taken into account,
remaining features of failure are universal.Comment: 4 pages in Revtex, 4 figures, accepted by PR
On the Occurrence of Finite-Time-Singularities in Epidemic Models of Rupture, Earthquakes and Starquakes
We present a new kind of critical stochastic finite-time-singularity, relying
on the interplay between long-memory and extreme fluctuations. We illustrate it
on the well-established epidemic-type aftershock (ETAS) model for aftershocks,
based solely on the most solidly documented stylized facts of seismicity
(clustering in space and in time and power law Gutenberg-Richter distribution
of earthquake energies). This theory accounts for the main observations (power
law acceleration and discrete scale invariant structure) of critical rupture of
heterogeneous materials, of the largest sequence of starquakes ever attributed
to a neutron star as well as of earthquake sequences.Comment: Revtex document of 4 pages including 1 eps figur
Bursts in a fiber bundle model with continuous damage
We study the constitutive behaviour, the damage process, and the properties
of bursts in the continuous damage fiber bundle model introduced recently.
Depending on its two parameters, the model provides various types of
constitutive behaviours including also macroscopic plasticity. Analytic results
are obtained to characterize the damage process along the plastic plateau under
strain controlled loading, furthermore, for stress controlled experiments we
develop a simulation technique and explore numerically the distribution of
bursts of fiber breaks assuming infinite range of interaction. Simulations
revealed that under certain conditions power law distribution of bursts arises
with an exponent significantly different from the mean field exponent 5/2. A
phase diagram of the model characterizing the possible burst distributions is
constructed.Comment: 9 pages, 11 figures, APS style, submitted for publicatio
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