Synthesis of Accelerated and More Realistic Vibration Endurance Tests Using Kurtosis 2016-01-0275
Ground vehicle components are designed to withstand the real operational conditions they will experience during their service life. Vibration tests are performed to qualify their endurance. In order to replicate the same failure mechanism as in real conditions, the test specification must be representative of the service loads.
The accelerated testing method, based on fatigue damage spectra (FDS), is a process for deriving a synthesized power spectral density (PSD) representing a random stationary Gaussian excitation and applied over a reduced duration.
In real life, however, it is common that service loading includes non-Gaussian excitations. The consequences of not using a representative test signal during product validation testing are a higher field failure rate and added warranty costs.
The objective of this paper is to describe a method for synthesizing a PSD test specification with a given kurtosis value, which represents a nonstationary non-Gaussian signal. Since a high kurtosis value will invariably increase the fatigue damage, kurtosis can be used to reduce the test duration, possibly in addition to the load amplification method. The relationship between kurtosis, fatigue damage, and test duration is also addressed in this paper.
Test profiles can be used in both physical tests and Finite Element Analysis (FEA)-based simulations. Durability simulations based on FEA help to optimize the design of a component and can significantly reduce the number of prototypes required.
An example excitation signal measured at an automotive manufacturer is used throughout the paper to illustrate the application of the method.