Dynamic mechanical test. (Instruments).

Dynamic mechanical analysis (DMA) applies a dynamic stress and, by measuring the resulting strain, calculates the intrinsic viscoelastic properties of a rubber specimen. The main use of DMA is said to be to analyze the material's mechanical properties' dependence on both temperature and frequency. Servohydraulic machines allow customized tests combining various transient or periodical conditions on either final products or material specimens. The Viscoanalyzer Series (VA-2000-VA30000 and VA40000) includes Multidyn testware that allows the analysis potential of the Viscoanalyzer series to be used fully. In contrast to the classical DMA mode where the excitation signal is sinusoidal, but the strain signal applied to the specimen is often not purely sinusoidal due to the non-linear rubber behavior, Multidyn is said to make it possible to control in real time the shape of the true excitation applied to the specimen. Shear modulus, Young's modulus, tan delta, glass transition determination, Payne effect, Mullins effect, thermal expansion coefficients, fatigue tests, creep and stress relaxation may be analyzed with one Viscoanalyzer. (Metravib R.D.S., 200, Chemin des Ormeaux, F-69578, Limonest cedex, France)

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