Complex Modulus and Damping Measurements Using Resonant and Non-Resonant Methods 951333

The stress-strain relationship of visco-elastic materials, generally used in the damping treatment of structures, can be described by two properties, such as the perfectly elastic (in-phase) stress-strain modulus and the loss factor. The values of these properties need to be determined in tension or compression for materials used as unconstrained damping layers and as anti-vibration mountings under machinery and under foundation blocks.
Using a dual channel FFT analyzer, the specimen can be excited using wide band random excitation, and the properties determined from the frequency response spectra, as a continuous function of frequency, as shown in the following.
Another possibility is to preload the specimen by a well-known mass, such that the preloaded damping material becomes a part of a resonant mass-spring-damper system. Damping, e.g. loss factor, is then determined from the 3 dB bandwidth of the resonance. The procedure is then repeated at different frequencies of the specimen using different mass-loadings.
The two methods are demonstrated and compared in this article.


Subscribers can view annotate, and download all of SAE's content. Learn More »


Members save up to 40% off list price.
Login to see discount.
Special Offer: With TechSelect, you decide what SAE Technical Papers you need, when you need them, and how much you want to pay.