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Updated: Feb 1, 2026

The Frequency Domain Thermoreflectance Technique for Thermal Property Measurements
Published on: December 5, 2025
An anisotropic linear thermo-viscoelastic constitutive law: Elastic relaxation and thermal expansion creep in the
Heinz E Pettermann1, Antonio DeSimone2
11Institute of Lightweight Design and Structural Biomechanics, Vienna University of Technology, Vienna, Austria.
Abstract:
A constitutive material law for linear thermo-viscoelasticity in the time domain is presented. The time-dependent relaxation formulation is given for full anisotropy, i.e., both the elastic and the viscous properties are anisotropic. Thereby, each element of the relaxation tensor is described by its own and independent Prony series expansion. Exceeding common viscoelasticity, time-dependent thermal expansion relaxation/creep is treated as inherent material behavior. The pertinent equations are derived and an incremental, implicit time integration scheme is presented. The developments are implemented into an implicit FEM software for orthotropic material symmetry under plane stress assumption. Even if this is a reduced problem, all essential features are present and allow for the entire verification and validation of the approach. Various simulations on isotropic and orthotropic problems are carried out to demonstrate the material behavior under investigation.
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