I just wanted to clarify my understanding of RMS results when running random vibration analysis. From what I have read, I understand the RMS results to be a statistical value that means the displacement values for a given input PSD represent one sigma of certainty within the normal distribution. Is this the correct breakdown of the meaning of these values? Can I also then say that if I multiply by 3x I would capture 6 sigma and thus know with roughly 99.7% confidence that the actual displacement values would be those computed or less?
Any help getting a good lame-man's explanation or technical resource to read through would be great. I have read through Vibartion Analsys with SolidWorks Simulation 2015 by Kurowski and I have skimmed the COSMOS Companion but never really felt like either provided great explanations.