Investigation of Force-Limited Vibration for Reduction of Overtesting

The force-limited vibration approach was developed in the 1990s to reduce overtesting associated with conventional vibration tests of aerospace hardware. Because of its numerous advantages, the semiempirical method is presently the most widely used method to derive the force limits. The configuration-dependent constant parameter C is one of the key parameters of the method. The main results and findings of a research and development project investigating the semiempirical method are presented. More specifically, the project investigated the range of values taken by C (or C2) and the parameters on which it depends. The details and the results of an in-depth analytical sensitivity study with 134 different cases and the results of the experimental validation of the analytical procedures are included. The analytical sensitivity study shows that the C2 value depends mainly on 1) the effective mass ratio between the test item and the mounting structure, at the fundamental frequency of the test item, 2) the number and position of the interface attachment points between the test item and the mounting structure, and 3) the direction of excitation. It also shows that the C2 value is basically independent of the damping value for most configurations.