2,257 research outputs found
Instability of Shear Waves in an Inhomogeneous Strongly Coupled Dusty Plasma
It is demonstrated that low frequency shear modes in a strongly coupled,
inhomogeneous, dusty plasma can grow on account of an instability involving the
dynamical charge fluctuations of the dust grains. The instability is driven by
the gradient of the equilibrium dust charge density and is associated with the
finite charging time of the dust grains. The present calculations, carried out
in the generalized hydrodynamic viscoelastic formalism, also bring out
important modifications in the threshold and growth rate of the instability due
to collective effects associated with coupling to the compressional mode.Comment: 9 pages with 2 figure
Fracture and crack growth in orthotropic laminates
A mathematical model based on the classical shear-lag assumptions is used to study the residual strength and fracture behavior of composite laminates with symmetrically placed buffer strips. The laminate is loaded by a uniform remote longitudinal tensile strain and has initial damage in the form of a transverse crack in the parent laminate between buffer strips. The crack growth behavior as a function of material properties, number of buffer-strip plies, spacing, width of buffer strips, longitudinal matrix splitting, and debonding at the interface is studied. Buffer-strip laminates are shown to arrest fracture and increase the residual strengths significantly over those of one material laminates, with S-glass being a more effective buffer strip material than Kevlar in increasing the damage tolerance of graphite/epoxy panels. For a typical graphite/epoxy laminate with S-glass buffer-strips, the residual strength is about 2.4 times the residual strength of an all graphite/epoxy panel with the same crack length. Approximately 50% of this increase is due to the S-glass/epoxy buffer-strips, 40% due to longitudinal splitting of the buffer strip interface and 10% due to bonding
Fluid simulation studies of the dynamical behaviour of one dimensional relativistic electromagnetic solitons
A numerical fluid simulation investigation of the temporal evolution of a
special class of traveling wave solution of the one dimensional relativistic
cold plasma model is reported.The solutions consist of coupled electromagnetic
and plasma waves in a solitary pulse shape (Phys. Rev. Lett. 68, 3172(1992);
Phys. Plasmas 9, 1820(2002)).Issues pertaining to their stability, mutual
collisional interactions and propagation in an inhomogeneous plasma medium are
addressed. It is found that solitary pulses that consist of a single light peak
trapped in a modulated density structure are long lived whereas structures with
multiple peaks of trapped light develop an instability at the trailing edge.
The interaction properties of two single peak structures show interesting
dependencies on their relative amplitudes and propagation speeds and can be
understood in terms of their propagation characteristics in an inhomogeneous
plasma medium
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