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Pol Grasland-Mongrain edited Simu disp maps.tex
almost 8 years ago
Commit id: 98b7c075b98681fad428c79fdff04505a178fbca
deletions | additions
diff --git a/Simu disp maps.tex b/Simu disp maps.tex
index 1e9e28a..6fa9e1c 100644
--- a/Simu disp maps.tex
+++ b/Simu disp maps.tex
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\label{eq:stressAbla}
\end{equation} where $L$ is the latent heat required to vaporize the solid, and $T_V$ and $T_0$ are the vaporization and initial temperatures, respectively.
By assuming $\mu \ll \lambda$ and a zero stress state at the medium surface, equation \ref{eq:stressAbla} leads to a
displacement, $u_z$, of:
\begin{equation}
u_z displacement $u_z =
\frac{\zeta}{\rho \lambda}\frac{I^2}{(L+C(T_V-T_0))^2}
\label{eq:deplAblaApprox}
\end{equation} (\zeta I^2) / (\rho \lambda(L+C(T_V-T_0))^2)$. Using high-energy experimental parameters, $\zeta \approx \gamma^{-1}$ = 40 $\mu$m (average depth of absorption), $\lambda$ = 2 GPa (first Lamé's coefficient of water), $L$ = 2.2 MJ.kg$^{-1}$ (vaporization latent heat of water), and $T_V-T_0$ = 373-298 = 75 K, we obtain a displacement $u_z$ of 2.9 $\mu$m. Again, this value is in agreement with the experimentally obtained displacement (2.5 $\mu$m). Both theoretical and experimental displacements are directed towards the inside of the medium (see arrow in the white circle in Figures \ref{figElastoPVA}-(B) and \ref{figGreen}-(B)).
To calculate the propagation of the displacement as a function of space and time, we modeled the ablative regime as a point force directed along the Z axis with a depth of 40 $\mu$m and a constant value from -2.5 to 2.5 mm. The magnitude of the force was stored in a matrix, $H_z^{abla}(y,z,t)$. Displacements along the Z axis are again equal to the convolution between $H_z^{abla}$ and $G_{zz}$ \cite{aki1980quantitative}:
\begin{equation}