Fatigue Damage Assessment of Vibration Test Exaggeration Methods

Exaggerated vibration durability tests are often used to evaluate ground vehicle components. The development of these vibration tests is often based on the guidance of MIL-STD-810D. The technique involved proposes that a significant reduction of test time compared to field exposure time can be accomplished by intensifying the vibration input to a specimen. The exposure time of the specimen to the intensified spectrum represents a nonlinear reduction of time when compared with the amount the spectrum is intensified.

This report examines the equivalence of the test exaggeration by intensification method from a strain life [1] fatigue damage assessment perspective. In the interest of appropriate application of the technique, some of the underlying assumptions are examined and illustrated.

Two procedures are implemented. In the first one, only the exaggeration equation is used and the results are assessed with a strain life fatigue damage calculation technique. In the second one, the transmissibility of a single degree of freedom dynamic model is invoked in order to improve the test to field correlation.