229 research outputs found
Detection and localization of debonding damage in composite-masonry strengthening systems with the acoustic emission technique
Different types of strengthening systems, based on fiber reinforced materials, are under investigation for external strengthening of historical masonry structures. A full characterization of the bond behavior and of the short—and long-term failure mechanisms is crucial to ensure effective design, compatibility and durability of the strengthening solution. In this paper, the effectiveness of the Acoustic Emission (AE) technique for debonding characterization and localization on Fiber Reinforced Polymer (FRP)- and Steel Reinforced Grout (SRG)-strengthened clay bricks is investigated. The AE technique proofs to be efficient for damage detection during accelerated ageing tests under thermal cycles and during experimental shear bond tests. AE data demonstrated the thermal incompatibility between brick and epoxy-bonded FRP composites during the accelerated ageing tests and debonding damage was successfully detected, characterized and located during the shear bond tests.- (undefined
Scaling of Crack Surfaces and Implications on Fracture Mechanics
The scaling laws describing the roughness development of crack surfaces are
incorporated into the Griffith criterion. We show that, in the case of a
Family-Vicsek scaling, the energy balance leads to a purely elastic brittle
behavior. On the contrary, it appears that an anomalous scaling reflects a
R-curve behavior associated to a size effect of the critical resistance to
crack growth in agreement with the fracture process of heterogeneous brittle
materials exhibiting a microcracking damage.Comment: Revtex, 4 pages, 3 figures, accepted for publication in Physical
Review Letter
Psi-Series Solution of Fractional Ginzburg-Landau Equation
One-dimensional Ginzburg-Landau equations with derivatives of noninteger
order are considered. Using psi-series with fractional powers, the solution of
the fractional Ginzburg-Landau (FGL) equation is derived. The leading-order
behaviours of solutions about an arbitrary singularity, as well as their
resonance structures, have been obtained. It was proved that fractional
equations of order with polynomial nonlinearity of order have the
noninteger power-like behavior of order near the singularity.Comment: LaTeX, 19 pages, 2 figure
Size Effect in Fracture: Roughening of Crack Surfaces and Asymptotic Analysis
Recently the scaling laws describing the roughness development of fracture
surfaces was proposed to be related to the macroscopic elastic energy released
during crack propagation [Mor00]. On this basis, an energy-based asymptotic
analysis allows to extend the link to the nominal strength of structures. We
show that a Family-Vicsek scaling leads to the classical size effect of linear
elastic fracture mechanics. On the contrary, in the case of an anomalous
scaling, there is a smooth transition from the case of no size effect, for
small structure sizes, to a power law size effect which appears weaker than the
linear elastic fracture mechanics one, in the case of large sizes. This
prediction is confirmed by fracture experiments on wood.Comment: 9 pages, 6 figures, accepted for publication in Physical Review
Fractional Variations for Dynamical Systems: Hamilton and Lagrange Approaches
Fractional generalization of an exterior derivative for calculus of
variations is defined. The Hamilton and Lagrange approaches are considered.
Fractional Hamilton and Euler-Lagrange equations are derived. Fractional
equations of motion are obtained by fractional variation of Lagrangian and
Hamiltonian that have only integer derivatives.Comment: 21 pages, LaTe
Nonholonomic Constraints with Fractional Derivatives
We consider the fractional generalization of nonholonomic constraints defined
by equations with fractional derivatives and provide some examples. The
corresponding equations of motion are derived using variational principle.Comment: 18 page
Fractional Dynamics from Einstein Gravity, General Solutions, and Black Holes
We study the fractional gravity for spacetimes with non-integer dimensions.
Our constructions are based on a geometric formalism with the fractional Caputo
derivative and integral calculus adapted to nonolonomic distributions. This
allows us to define a fractional spacetime geometry with fundamental
geometric/physical objects and a generalized tensor calculus all being similar
to respective integer dimension constructions. Such models of fractional
gravity mimic the Einstein gravity theory and various Lagrange-Finsler and
Hamilton-Cartan generalizations in nonholonomic variables. The approach
suggests a number of new implications for gravity and matter field theories
with singular, stochastic, kinetic, fractal, memory etc processes. We prove
that the fractional gravitational field equations can be integrated in very
general forms following the anholonomic deformation method for constructing
exact solutions. Finally, we study some examples of fractional black hole
solutions, fractional ellipsoid gravitational configurations and imbedding of
such objects in fractional solitonic backgrounds.Comment: latex2e, 11pt, 40 pages with table of conten
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