SPP 1713: Strong Coupling of Thermo-Chemical and Thermo-Mechanical States in Applied Materials

Basic data for this project

Description

Many applied materials like metals and solid-state polymers consist of multiple phases. Their properties depend crucially on the internal phase-structure, i.e., the fraction and local distribution of the phases, their composition and their molecular configuration. Chemical aspects influence the mechanical properties as well as mechanical load couples back to chemistry. This strong interrelation is expressed in the thermodynamic functional of the material, which is composed of a thermo-chemical or thermo-solutal part, on the one hand, and a temperature-dependent mechanical part, on the other hand. The mutual interaction between chemistry and mechanics in applied materials is the central goal of the Priority Programme. Human hair, as a common example for a shape memory polymer, changes its shape by the intake of water, or it keeps its curly state after drying. Also metals, commonly viewed as dead bodies, show strong mechanical response on changes of their constitution. They expand or contract by the formation of new crystallographic phases, or show a macroscopic response by the sheering of crystal lattices. In return, external load or external fields can prevent or enhance phase separation both in metals and polymers. Most applied materials are stabilised far out of equilibrium by an internal balance of chemical and mechanical forces. The separate focus on either the chemical aspect or the mechanical aspect respectively in different scientific communities corresponds to good scientific tradition: theoretical models are developed for cases in which individual phenomena can well be separated. In these cases a clear identification of cause and effect is possible, which can be unambiguously formulated in constitutive equations including a consistent parameterisation. In the Priority Programme we aim to surmount this separation, we aim to combine established approaches of computational thermodynamics, continuum mechanics and theory of materials, as well as polymer sciences and metallurgy for materials with strong thermo-chemo-mechanical coupling. The collaborative research shall establish a new paradigm of physically bases material modelling integrating the influence of process history and external chemo-mechanical load to be applicable to optimise production, properties and life-time of applied materials for a sustainable economy.