Abstract: Overlap-add method is always used to realize randomization in random vibration control system. Spectral leakage and poor control dynamic introduced by overlap-add method exist in many vibration control systems. On the study of the overlap-add method and doing many random vibration tests applying various windows, the reason of the problems is found out. By comparing the spectral characters of various windows, hanning window is suitable for randomization in random vibration test, but it introduces intensity fluctuations to the time signals. Therefore, a new method is brought out. Based on applying hanning window on original random signals, the amplitude is overlap-added and compensated in time domain. This method eliminates spectral leakage and fluctuations, improves control dynamic greatly, and is in good agreement with the experimental test.

Key words: Overlap-add, Random vibration test, Randomization