A new feature for the computation of the dynamical behavior for viscoelastic structures

by N. Merlette et B. Delmache, Tangent’delta ; N. Brie, EDF / R&D / AMA

Tangent’delta is an engineering office specialized in acoustics, vibrations and heat transfer. Expert of the materials and the finite elements analysis, Tangent’delta developed, for its needs, a new feature in Code_Aster for the dynamic computation of viscoelastic materials. Two papers dealing with these developments have been published [1, 2] before being proposed in Code_Aster. Because of its generic nature and the benefit for EDF, the industrialization and the implementation was carried out jointly with EDF.

A new operator, DYNA_VISCO, has been introduced for the eigenmodes of vibration and frequency response computation of structures comprising viscoelastic materials. Previously, harmonic computation of a viscoelastic structure was carried out by considering a viscoelastic material as an elastic material with constant mechanical properties whatever the frequency. Now, eigenmodes of vibration (real or complex) and frequency response are computed by taking into account the frequency dependence of the mechanical properties (Young’s modulus and loss factor) of the viscoelastic materials. Frequency responses are obtained by the modal synthesis method. This new command leads to more accurate predictions of the viscoelastic behaviors.

Available starting from version 12.3.3

Figure 1: Natural mode of an automobile windshield laminated glass with a viscoelastic layer (Polyvinyl butyral), calculated with DYNA_VISCO.

[1] Merlette N., Pagnacco E., Structural dynamics of solid propellants with frequency dependent properties, 12th European Conference on Spacecraft Structures, Materials and Environmental Testing, Noordwijk, Netherlands, 2012.

[2] Merlette N., Pagnacco E., Ladier A., Recent developments in Code_Aster to compute FRF and modes of VEM with frequency dependent properties, Proceedings of Acoustics 2012, Nantes, France, 2012.