Voron 2.4r2 back panel issue

[SamppaD]

Hi to everyone. I was away for some time from the forum due to some unexpected life issues, but now I back. Starting to build a better enclosure for my printers. So I was printing some parts for project  with my voron and  noticed strange vibration sound during print, like it comes and goes. Couldn't pin point issue during cold run as it was not there but after inspecting during printing with enclosure hot (print as expected failed) notice that  my voron panels are starting to bend /sag, especially back panel. Exhaust fan is mounted on the back and as expected when  exhaust hose is connected to the fan output it start to bend the panel slightly. When enclosure  is hot about 50C panel start to flex in the middle  to the point that gantry belts will start to contact the panel at that Z height.
Any mod or solution to this problem except swapping thicker panels or go glass panels all the way  ? Panel is stock Voron kit black polycarbonate 3mm?

 

Edited 1 hour ago by SamppaD