diff --git a/lrftubes.bib b/lrftubes.bib
index 9669a45..946a177 100644
--- a/lrftubes.bib
+++ b/lrftubes.bib
@@ -381,4 +381,21 @@ The full solution of the problem has been obtained by Kirchhoff (1868) in the fo
 	date = {2009-04},
 	langid = {english},
 	file = {Kino et al. - 2009 - Investigation of non-acoustical parameters of comp.pdf:/home/anne/.literature/storage/I9P5SZAE/Kino et al. - 2009 - Investigation of non-acoustical parameters of comp.pdf:application/pdf}
-}
\ No newline at end of file
+}
+
+@article{leniowska_plate_resonance_1999,
+    title = {Vibrations of circular plate interacting with an ideal compressible fluid},
+    volume = {24},
+    url = {https://acoustics.ippt.pan.pl/index.php/aa/article/viewFile/1117/952},
+    pages = {427--441},
+    number = {4},
+    journaltitle = {Archives of acoustics},
+    author = {Leniowska, L.},
+    date = {1999}
+}
+
+@misc{calcdevice,
+	title = {Natural frequency calculators (web page)},
+	url = {https://calcdevice.com/natural-frequency-of-circular-plate-id224.html},	
+	urldate = {2022-05-25}
+}
diff --git a/lrftubes.lyx b/lrftubes.lyx
index e80c2dc..f20fccc 100644
--- a/lrftubes.lyx
+++ b/lrftubes.lyx
@@ -7113,6 +7113,405 @@ Membrane
 A membrane is a mechanical 
 \end_layout
 
+\begin_layout Section
+Circular plate membrane
+\end_layout
+
+\begin_layout Standard
+series_impedance/class CircPlateMembrane(SeriesImpedance)
+\end_layout
+
+\begin_layout Standard
+A thin circular plate can be modeled using CircPlateMembrane.
+ It behaves like an acoustic compliance.
+ A typical use is the attenuation of acoustic pressure by combining it with
+ an enclosed volume.
+\end_layout
+
+\begin_layout Standard
+Two boundary condition cases can be applied: fixed/clamped edges and simply
+ supported edges.
+ The general equation for the static displacement of the plate is given
+ by 
+\begin_inset CommandInset citation
+LatexCommand cite
+after "p. 487"
+key "young_roarks_2002"
+literal "false"
+
+\end_inset
+
+:
+\end_layout
+
+\begin_layout Standard
+\begin_inset Formula 
+\begin{equation}
+y\left(r\right)=y_{c}+\frac{M_{c}r^{2}}{2D\left(1+\nu\right)}+LT_{y}
+\end{equation}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+in which 
+\begin_inset Formula $y_{c}$
+\end_inset
+
+ and 
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\strikeout off
+\xout off
+\uuline off
+\uwave off
+\noun off
+\color none
+
+\begin_inset Formula $M_{c}$
+\end_inset
+
+ are
+\family default
+\series default
+\shape default
+\size default
+\emph default
+\bar default
+\strikeout default
+\xout default
+\uuline default
+\uwave default
+\noun default
+\color inherit
+ the displacement and moment at the center of the plate, 
+\begin_inset Formula $LT_{y}$
+\end_inset
+
+ is the load term in the y-direction, 
+\begin_inset Formula $\nu$
+\end_inset
+
+ is the Poisson's ratio of the plate material and 
+\begin_inset Formula $D$
+\end_inset
+
+ is the flexural stiffness of the plate, which is given by the equation:
+\end_layout
+
+\begin_layout Standard
+\begin_inset Formula 
+\begin{equation}
+D=\frac{Et^{3}}{12\left(1-\nu^{2}\right)}
+\end{equation}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+in which 
+\begin_inset Formula $E$
+\end_inset
+
+ is the Young's modulus of the plate material and 
+\begin_inset Formula $t$
+\end_inset
+
+ is the plate thickness.
+ Substituting 
+\begin_inset Formula $D$
+\end_inset
+
+, 
+\begin_inset Formula $y_{c}$
+\end_inset
+
+, 
+\begin_inset Formula $M_{c}$
+\end_inset
+
+ and 
+\begin_inset Formula $LT_{y}$
+\end_inset
+
+ for this specific load case (uniform load/pressure) and boundary conditions
+ 
+\begin_inset CommandInset citation
+LatexCommand cite
+after "p. 458 & p. 488"
+key "young_roarks_2002"
+literal "false"
+
+\end_inset
+
+ and simplifying yields the following equations for the static plate deflection:
+\begin_inset Note Note
+status collapsed
+
+\begin_layout Plain Layout
+In these equations the distributed load 
+\begin_inset Formula $q$
+\end_inset
+
+ is replaced by 
+\begin_inset Formula $-p$
+\end_inset
+
+.
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+\begin_inset Formula 
+\begin{equation}
+y_{ss}\left(r\right)=\frac{3p\left(1-\nu^{2}\right)}{16Et^{3}\left(1+\nu\right)}\left(a^{2}\left[a^{2}\left\{ 5+\nu\right\} -2r^{2}\left\{ 3+\nu\right\} \right]+r^{4}\left[1+\nu\right]\right)
+\end{equation}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+\begin_inset Formula 
+\begin{equation}
+y_{fix}\left(r\right)=\frac{3p\left(1-\nu^{2}\right)}{16Et^{3}}\left(a^{4}-2a^{2}r^{2}+r^{4}\right)
+\end{equation}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+In which 
+\begin_inset Formula $a$
+\end_inset
+
+ is the radius of the plate and 
+\begin_inset Formula $r$
+\end_inset
+
+ is the radial coordinate.
+ The static acoustic compliance of the plate is given by the equation:
+\end_layout
+
+\begin_layout Standard
+\begin_inset Formula 
+\begin{equation}
+c_{stat}\left(r\right)=\frac{y\left(r\right)}{p}
+\end{equation}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+The static acoustic volume compliance for both cases can be calculated by
+ integrating over the surface of the plate:
+\end_layout
+
+\begin_layout Standard
+\begin_inset Formula 
+\begin{equation}
+C_{stat}=2\pi\int_{0}^{a}c_{stat}\left(r\right)rdr
+\end{equation}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+Performing this integration for both boundary condition cases yields:
+\end_layout
+
+\begin_layout Standard
+\begin_inset Formula 
+\begin{equation}
+C_{stat,ss}=\frac{\pi a^{6}}{16Et^{3}}\left(7-6\nu-\nu^{2}\right)
+\end{equation}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+\begin_inset Formula 
+\begin{equation}
+C_{stat,fix}=\frac{\pi a^{6}}{16Et^{3}}\left(1-\nu^{2}\right)
+\end{equation}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+The dynamic acoustic volume compliance of the plate is given by the equation:
+\end_layout
+
+\begin_layout Standard
+\begin_inset Formula 
+\begin{equation}
+C_{dyn}\left(f\right)=\frac{C_{stat}}{1-\left(\frac{f}{f_{r}}\right)^{2}}
+\end{equation}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+in which 
+\begin_inset Formula $f$
+\end_inset
+
+ is the frequency in Hz and 
+\begin_inset Formula $f_{r}$
+\end_inset
+
+ is the resonance frequency of the plate in Hz.
+ The resonance frequency for the simply supported plate is given by the
+ equation 
+\begin_inset CommandInset citation
+LatexCommand citeyear
+key "calcdevice"
+literal "false"
+
+\end_inset
+
+:
+\begin_inset Note Note
+status collapsed
+
+\begin_layout Plain Layout
+This is an approximation from an online calculator.
+ A more exact equation like the one for the fxed case should be found.
+\end_layout
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+\begin_inset Formula 
+\begin{equation}
+f_{r,ss}=\frac{0.8}{a^{2}}\sqrt{\frac{D}{\rho t}}
+\end{equation}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+in which 
+\begin_inset Formula $\rho$
+\end_inset
+
+ is the density of the plate material.
+ The resonance frequency for the fixed plate is given by the equation 
+\begin_inset CommandInset citation
+LatexCommand cite
+after "p. 430"
+key "leniowska_plate_resonance_1999"
+literal "false"
+
+\end_inset
+
+:
+\end_layout
+
+\begin_layout Standard
+\begin_inset Formula 
+\begin{equation}
+f_{r,fix}=\frac{\gamma_{1}^{2}}{a^{2}}\sqrt{\frac{D}{\rho t}}
+\end{equation}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+in which 
+\begin_inset Formula $\gamma_{1}$
+\end_inset
+
+ is the first solution to the following equation:
+\end_layout
+
+\begin_layout Standard
+\begin_inset Formula 
+\begin{equation}
+J_{0}\left(\gamma_{m}\right)I_{1}\left(\gamma_{m}\right)+J_{1}\left(\gamma_{m}\right)I_{0}\left(\gamma_{m}\right)=0\label{eq:gamma}
+\end{equation}
+
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+in which 
+\begin_inset Formula $J_{n}\left(\gamma_{m}\right)$
+\end_inset
+
+ and 
+\begin_inset Formula $I_{n}\left(\gamma_{m}\right)$
+\end_inset
+
+ are the Bessel function of the first kind and modified Bessel functions
+ of order 
+\begin_inset Formula $n$
+\end_inset
+
+.
+ Solving equation 
+\begin_inset CommandInset ref
+LatexCommand ref
+reference "eq:gamma"
+plural "false"
+caps "false"
+noprefix "false"
+
+\end_inset
+
+ yields 
+\begin_inset Formula $\gamma_{1}=3.196$
+\end_inset
+
+.
+ The impedance is given by the equation:
+\end_layout
+
+\begin_layout Standard
+\begin_inset Formula 
+\begin{equation}
+Z_{cpm}\left(f\right)=\frac{1}{i2\pi fC_{dyn}\left(f\right)}
+\end{equation}
+
+\end_inset
+
+
+\end_layout
+
 \begin_layout Section
 Holes in plate
 \end_layout