Abstract
The paper investigates small-scale effects on the Rayleigh-type surface wave propagation in an isotopic elastic half-space upon laser irradiation. Based on Eringen’s theory of nonlocal continuum mechanics, the basic equations of wave motion and laser-induced atomic defect dynamics are derived. Dispersion equation that governs the Rayleigh surface waves in the considered medium is derived and analyzed. Explicit expressions for phase velocity and attenuation (amplification) coefficients which characterize surface waves are obtained. It is shown that if the generation rate is above the critical value, due to concentration-elastic instability, nanometer sized ordered concentration-strain structures on the surface or volume of solids arise. The spatial scale of these structures is proportional to the characteristic length of defect-atom interaction and increases with the increase of the temperature of the medium. The critical value of the pump parameter is directly proportional to recombination rate and inversely proportional to deformational potentials of defects.
Highlights
During the last decades elastic wave propagation in solids with nonequilibrium atomic defects has received a lot of attention [1,2,3,4]
We summarise the theory formulated in [8] to analyze the effects of nonlocal atom-atom and atom-defect interactions on the surface wave propagation in solids with defect generation
Where ω is the frequency of wave propagation, q is the wave number, and l = √Dτ; the phase velocity is given by c = ωr/q and attenuation constant by Γ = −ωi, where ωr = Re(ω) and ωi = Im(ω) mean, respectively, the real and imaginary parts of ω. λ = λ(q) = λ0(1 − g2q2) and μ = μ(q) = μ0(1 − g2q2) are the nonlocal elastic moduli; β = β(q) = β0(1 − h2q2) is the nonlocal constant characterizing lattice deformation due to atomic defects; ũ(q, z), ̃V(q, z), and ñ(q, z) are unknown functions
Summary
The paper investigates small-scale effects on the Rayleigh-type surface wave propagation in an isotopic elastic half-space upon laser irradiation. Based on Eringen’s theory of nonlocal continuum mechanics, the basic equations of wave motion and laser-induced atomic defect dynamics are derived. Dispersion equation that governs the Rayleigh surface waves in the considered medium is derived and analyzed. It is shown that if the generation rate is above the critical value, due to concentration-elastic instability, nanometer sized ordered concentration-strain structures on the surface or volume of solids arise. The spatial scale of these structures is proportional to the characteristic length of defect-atom interaction and increases with the increase of the temperature of the medium. The critical value of the pump parameter is directly proportional to recombination rate and inversely proportional to deformational potentials of defects
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