I would like to know if about any formal standards or specifications regarding the frequency difference between a structure's operating and resonant frequencies. I understand that this would change for different applications (i.e. the vibration requirements for a microscope sensors application will be different to that of an office building or car chassis), and I would like to know if there is a formalized list of acceptable levels.

I ask this question in relation to a specific sensor application where I need to know if the current operating frequency is interacting with calculated resonant frequencies (as obtained from an FEA modal analysis.)