Conclusion
Dynamic tests on composites - Low-frequency characterization

Beam vibration tests can be used to obtain the complex technical moduli of composite materials (Young's modulus, Coulomb modulus) in a frequency range from approximately ten hertz to ten kilohertz, using a variety of equipment and at constant temperature.

The time-temperature superposition technique (WLF principle – Williams, Landel and Ferny – cf. § 4.2) is highly debatable, as the energy dissipation process in composite materials is not only driven by the viscous nature of the resin, but also by the heterogeneous nature of the material: energy dissipation due to interfaces, for example. It is worth highlighting the simplicity of the equipment presented, which can operate in the usual temperature ranges (-40 ˚C, 80 ˚C).

The difficulties encountered in these vibration tests are threefold:

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