[Landau ITP Seminars] Friday 25.03.2022

[Serge Krashakov]

Уважаемые коллеги!

На заседании Ученого совета в пятницу 25 марта в 11:30 будет заслушан 
доклад:

Наиль Иногамов
*Attenuation and inflection of initially planar shock wave generated by 
femtosecond laser pulse*

Evolution of wavefront geometry during propagation and attenuation of 
initially planar shock waves generated by femtosecond laser pulses in 
aluminum is studied. We demonstrate that three stages of shock front 
inflection take place in consistent hydrodynamics and molecular dynamics 
simulations. During the first stage, the distance traveled by a 
near-planar wave DSW ≲ RL is smaller than the radius of heated laser 
spot RL. Wave attenuation is associated with one-dimensional plane (1D) 
rarefaction wave coming from the free surface. Such rarefaction wave 
shapes the shock wave to a 1D triangular pressure profile along 
direction normal to target surface with a shock front followed by an 
unloading tail. The second transitional stage starts after propagation 
of DSW ∼ RL, at which the unloading lateral waves begin to arrive to a 
symmetry axis of flow and initiate inflection of the initially planar 
shock front. Next at the third stage, the wavefront geometry is finally 
rounded and rapid attenuation of shock pressure begins at DSW ≳ RL. It 
is shown that such divergent shock wave cannot generate plastic 
deformations in aluminum shortly after propagation of DSW ∼ RL. Thus, we 
may estimate the maximal peening depth as a radius of focal spot, which 
sets an upper limit for the laser shock peening. The cessation of 
plastic deformation is caused by the fall of the shockwave amplitude 
below the elastic limit. In this case, the elastic-plastic wave 
transitions to a purely elastic mode of propagation. For large-sized 
light spots, this transition ends in the 1D mode of propagation.


ID и пароль онлайн-трансляции в Zoom те же, что и для предыдущих 
трансляций докладов на Ученом совете:
https://zoom.us/j/96899364518?pwd=MzBsR2lYT0lYL2x2b1oyNU9LeWlWUT09
Meeting ID: 968 9936 4518
Пароль: 250319

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