Copyright: © Falk Koenemann

A new approach to solid mechanics based on thermodynamics

The previous solid mechanics is based on concepts of the 18th century. In the period of 1840-1870 there were tremendous developments in both physics and mathematics that are not possible without a modern, energetic understanding of deformation as a three-dimensional physical process. They are part of every engineering course. These concepts are still missing in continuum mechanics. It will be shown that the core concepts of the previous theory, stress and strain, are meaningless from a modern point of view, and that the previous continuum mechanics has no valid working term. Elastic deformation is inherently a change of state in the sense of the first law of thermodynamics. Conventional thermodynamics is written in scalars (P, V, T) and is therefore implicitly isotropic. The new approach builds on potential theory; it is thermodynamic theory in vector field form (f, r, T). This allows anisotropic boundary conditions to be modeled. A new thermodynamic state variable was discovered that occurs only under anisotropic loading. In addition, a kinematic bifurcation was discovered in the transition from elastic-reversible to irreversible material behavior. Together they explain a large number of previously puzzling observations in all types of material behavior (elastic, plastic, viscous, fracture). The calculated eigendirections especially for "simple shear" are fully confirmed by observations. The new approach explains a large number of observations such as conjugate fracture shears in gneisses, S-C microstructure and tongue folds in plastic shear zones, and turbulence in viscous flow.

• Referent: Dr. Falk Koenemann
• Date: Thursday, 12.10.2023, 18:30
• Place: LIH 504, Lochnerstraße 4-20
• Language: german