First mode of vibration for a glass window How to calculate the first mode of vibration for a glass window?
I have a window of the size 57 cm by 106 cm and 4 mm of width. I hear the loud noise from it on about 166 Hz and want to realize if it is window's self first mode of vibration that intensify this frequency (maybe even with resonance, etc.) or not.
I understand that this could depend on exact glass, fixing, etc., but is there a common idea to calculate it and have at least rough approximation?
If there is some software to calculate it (like shown in the Understanding the Finite Element Method), please advise.
 A: I am a mechanical engineer who does full time work with finite element analysis including modal analysis which involves finding the natural frequencies of structures.
Knowing the exact window dimensions is a good first step, but to calculate the exact first mode with FEM will require the two additional items listed...

*

*You need to know the density and stiffness of the glass.  I don't work with glass and I'm not sure if all forms of glass have the same stiffness or not.


*You need to know the boundary conditions of the edges of the window.  This is very important!  If the window edges are held loosely, then the first mode frequency will be much lower than if the edges are held tightly.
You can likely conduct a test to find the first mode if you have a speaker and computer available.  Place the speaker near the window and play a sine sweep (search for this on Youtube).  Lightly place your finger on the window and you will feel vibrations when the sweep hits your first mode.
Good luck!
