Damping Properties Assessment of Very Highly Compliant Sandwich Materials: Are Traditional Methods Really Too Old?

Abstract

Damping and loss factor assessment of high damped materials is a challenging task addressed in the past by several researchers, one of the most important is H. Oberst who defined a standard method to tackle the issue.

In this paper a sandwich beam composed of two aluminium layers separated by the damping material has been studied. First the beam made only of aluminium layer has been tested and then the composite beam has been assembled by using as damping layer a sheet of styrene-butadiene rubber (SBR). The highly damped behaviour of the test sample makes the test very difficult; great care must be taken in the setting up the test itself.

In particular the excitation system has been studied in depth by comparing the results obtained with a traditional non-contact impact test and an electro-dynamic system. Being the impact excitation invasive as well when considering light structures as the object under test, a non-contact electro-magnetic system has been developed in order to limit the influence of the excitation device on the structure behaviour.