Synthesis of Shaker Input Signals with High Kurtosis for Vibration Qualification Testing

In many industrial, automotive, and aerospace applications, electro-mechanical systems are subjected to random vibration excitations, and the most critical components are required to undergo qualification tests to verify their suitability. Measured field data are commonly considered as reference for the synthesis of random stationary signals used as shaker input excitations in laboratory tests. For the most popular procedures of random-control testing, the user sets the input profiles in terms of power spectral density (PSD) associated with randomized phases generated by the shaker controller to finally provide the physical motion. As a result, the overall probability distribution of the test signal tends toward Gaussian, whereas many real-life random excitations prove non-Gaussian due to distinctive bursts and peaks. The quantitative estimate of the number and amplitudes of peaks present in a certain signal is usually made through the statistical parameter known as kurtosis. The so-called kurtosis control methods presented in the literature are conceived to perform qualification tests with random and non-Gaussian vibration excitations. In this paper, two novel algorithms able to synthesize shaker input signals for random-control testing with prescribed PSD and kurtosis value are proposed, and the results of their application are comparatively discussed to assess their effectiveness and potentialities in different kinds of qualification testing, including accelerated fatigue-life tests.