Urheberrecht: © Falk Koenemann

An approach to deformation theory based on thermodynamic principles

The mechanics of solids theory is based on concepts from the 18^th C. However, vast advances in the understanding both of physics and mathematics were made in the period 1840-1870, without which a modern energetic understanding of deformation as a three-dimensional physical process is not possible. They are part of any regular engineering curriculum. These concepts are missing continuum mechanics to this day. It will be shown that the core terms in the traditional theory, stress and strain, are meaningless in the modern context, and that continuum mechanics does not have a valid work term.

By nature, elastic deformation is a change of state in the sense of the First Law of thermodynamics. Conventional thermodynamics is written in scalars (P, V, T), therefore it is implicitly isotropic. The new approach uses potential theory to transform the thermodynamic theory into vector field form (f, r, T). It is now possible to model anisotropic boundary conditions. A new thermodynamic state function has been discovered which can occur only in anisotropic loading. In addition, at the transition from elastic-reversible to irreversible material behavior an energetic-kinematic bifurcation has been discovered. Together they explain a large number of so far enigmatic observations in all regimes of material behavior (elastic, plastic, viscous, brittle). The predicted eigendirections especially for simple shear are fully supported by observations. The new approach explains the properties of conjugate joint sets in gneisses, S-C fabric and sheath folds in plastic shear zones, and turbulence in fluid flow, to name just a few.

• Referent: Dr. Falk Koenemann
  
• Datum: Donnerstag, 12.10.2023, 18:30Uhr
  
• Ort: LIH 504, Lochnerstraße 4-20
  
• Sprache des Vortrags: Englisch