Elasticity data might be frequency dependent

[ClemensLinnhoff]

Describe the bug Currently, the elasticity data contains Young's modulus and Poisson's ratio as single values for one material, see here. However, the elasticity properties depend on the frequency, which is especially important for ultrasonic simulation. Here are some sources:

• https://faculty.kfupm.edu.sa/are/djamel/Publications/frequency_dependence_moe_wood.pdf
• https://www.researchgate.net/profile/Doufnoune-Rachida/post/how_does_damping_factor_is_related_to_frequency_in_DMA_measurement_of_rubber_material/attachment/5d72293acfe4a7968dc86805/AS%3A800069099986944%401567762746063/download/Evaluation+of+the+frequency-dependent+and+damping+factor+of+rubber.pdf

Expected behavior Me might need to turn this data into look-up tables similar to electromagnetic properties.

[ClemensLinnhoff]

@ipg-jsc what do you think?

[lyndyRott]

As far as I understand it, the descriptions in the attachments/links discuss material properties such as Young's Modulus, Poisson's ration,... in the frequency domain (after transforming it from time domain via a chosen method, e.g. Fourier-, Laplace- or Z-transform). In the frequency domain the values become frequency dependent, since it is the independent variable.

The supported (density) frequency modes in a geometric body made from a certain material, however, depend on its geometry, its dimensions/extensions(length, height, depth) and the mechanical material properties (based on the microscopic structure), which are dimension/extension independent.

A nice description of the measurement process to determine mechanical constants based on dynamic frequency analysis can be found here Barboni_2018_IOP_Conf._Ser.__Mater._Sci._Eng._416_012063.pdf The vibration frequency modes supported depend on the elastic constant, not the other way around.

The elastic, viscoelastic or plastic property of a material are stress-strain relations that vary across the range of applied force. In particular YM, etc. vary with temperature, which might be of interest to us in the standard.

I agree that the complex values could be of interest to us in terms of damping/absorption properties, as you mentioned, e.g., for ultrasonic sensor properties. https://en.wikipedia.org/wiki/Dynamic_modulus

[ClemensLinnhoff]

Clemens will talk to an ultrasonic expert to get an opinion on this.