Description: In applications involving polymers or elastomeric foam materials, it is often important to obtain the steady-state dynamic response of a structure (frequency domain analysis) at the end of a general nonlinear static response (time domain analysis). In frequency domain applications, dynamic material properties such as the storage and loss moduli play an important role. ABAQUS/Standard has long supported capabilities to obtain the steady-state dynamic response (about nonlinear base states) of structures made out of polymers and/or elastomeric foams. However, the user interface in Version 6.5 requires the specification of normalized (with respect to long-term elastic properties) shear and bulk storage/loss moduli. In addition, it assumes that the normalized storage and loss moduli are independent of the level of preload incurred in attaining the nonlinear base state.

The Version 6.6 user interface is improved significantly by allowing the direct specification of storage and loss moduli obtained from uniaxial and volumetric tests for viscoelastic materials using a tabular frequency definition, without requiring normalization. As a consequence, the assumption of the independence of the normalized ratios with respect to preload is no longer necessary. Figure 7–2 shows the new Type and Preload options in the ABAQUS/CAE material editor. The Traction type is intended for use with gaskets and does not allow entry of volumetric storage and loss moduli. The Isotropic type can be used for any element with continuum material properties and allows you to enter uniaxial and/or volumetric moduli.

Property module:
   Edit Material: MechanicalElasticityViscoelastic: Domain: Frequency: Select
   Tabular frequency data: Type: Isotropic and select the desired Preload for the material.