On the Use of Kurtosis Control Methods in Shaker Testing for Fatigue Damage

Random vibration testing with increased kurtosis introduces high peaks into shaker drive signals to simulate land vehicle vibration more accurately and also to shorten the required test time. Two methods of controlling kurtosis by phase manipulation in the inverse fast Fourier transform were implemented, tested, and compared. The first method generates high-kurtosis excitations with a gradual, smooth pattern of peak heights from low to high, and the second method produces isolated high peaks with intervals of stable background vibration between them. When applying a kurtosis increase for accelerated fatigue damage testing, the kurtosis control method must be able to pass high-kurtosis values from the generated shaker table vibration into the stress response of the unit under test. However, this is not always the case, and only one of the considered methods was capable of doing so. In the article, the fatigue damage spectrum model was used for an evaluation of the time to failure. An experimental study was carried out using operational vibration measured in a car. Shaker testing of cantilever specimens was performed for Gaussian, non-Gaussian, and accelerated non-Gaussian excitations.