About Built-in Frequency Domain Simulation Models

Built-in frequency domain simulation models are easy-to-use models for performing material calibrations using test data from dynamic mechanical analysis (DMA). They can provide an accurately replication the most common material testing scenarios. You can use them in the analytical and numerical execution modes only.

This page discusses:

Frequency Domain Simulation Models

Two deformation modes are available in the frequency domain: uniaxial, E, and shear, G. The deformation mode you choose determines the built-in simulation model you use for calibration. It also specifies whether the app specifies storage and loss modulus data in terms of Young's modulus or the shear modulus.

The simulations for all the deformation modes are based on a homogenous deformation. However, some DMA tests, such as torsion or bending, result in nonuniform deformation states. Typically, test machines determine the complex modulus from these tests, which are based on the measured force-displacement behavior, by using structural mechanics equations that assume a linear elastic response. This response can be comparable to homogeneous deformation for calibrating linear viscoelasticity to tests with small loading magnitudes. However, the homogeneous deformation assumption might not be appropriate for calibrating the nonlinear viscoelastic behavior of the parallel rheological framework material model to tests of specimens with heterogeneous deformation states.

Execution Modes and Supported Material Models

In the analytical execution mode, you can use frequency domain data with Hyperelastic+Viscoelastic material behavior. The app calculates the response using equational relationships that involve the viscoelastic Prony series and the initial moduli of the hyperelastic potential.

In the numerical execution mode, you can use frequency domain data with any material model. The app calculates the response by creating a time history of strain internally and evaluating the stress-time response, then processing this time-domain response data to obtain the frequency response. You can control some aspects of this frequency-time conversion.

Uniaxial Deformation Mode

The uniaxial deformation mode simulates a specimen under uniform uniaxial tension. In the analytical execution mode, selecting this deformation mode prompts the app to use the instantaneous Young's modulus of the hyperelastic potential in the analytical evaluations of storage and loss modulus. In the numerical execution mode, the app uses the same constraints in the converted time history simulation that it imposes for the uniaxial deformation mode for the built-in time-domain simulation model.

Shear Deformation Mode

The shear deformation mode simulates a specimen under uniform simple shear. In the analytical execution mode, selecting this deformation mode prompts the app to use the instantaneous shear modulus of the hyperelastic potential in the analytical evaluations of storage and loss modulus. In the numerical execution mode, the app uses the same constraints in the converted time history simulation as are imposed for the simple shear deformation mode for the built-in time-domain simulation model.

Conversion Parameters for the Numerical Execution Mode

In the numerical execution mode, the app evaluates frequency domain test data by converting the data to a time domain strain history, evaluating the time domain stress history, and determining the frequency domain response from the time domain stress and strain. You can control several aspects of the generation of this time-domain data. The app assigns default values that provide a balance between performance and obtaining an accurate steady-state response for most situations.