Periodic Vibration An oscillation whose waveform repeats at equal increments of time. The limiting mean-square acceleration per unit bandwidth. PSD is the industry accepted measurement to describe random vibration amplitude. Random Vibration Vibration whose instantaneous magnitude is not specified for any given instant of time. The instantaneous magnitude of a random vibration is specified only by probability distribution functions giving the probable fraction of the total time that the magnitude lies within a specified frequency range.
Random vibration contains no periodic or quasi-periodic constituents.
Repetitive Shock Impacts of a package on a test platform which occur cyclically from input vibration. Resonance A vibration of large amplitude in a mechanical system caused by a relatively small periodic stimulus of the same or nearly the same period as the natural vibration period of the system. The square root of the mean-square value. In the exclusive case of a sine wave the rms value is 0.707 times peak value. The smallest complete unit that will be subjected to the distribution environment, for example, a shipping container and its contents.