University of Minnesota
Aerospace Engineering and Mechanics
Winter 1998 Seminar Series
Constitutive Equations and Length Scales in Solids
The application of micromechanics principles has led to valuable new
understanding of the relation of the configuration of material microstructure or
mesostructure to effective properties such as stiffness and thermal
conductivity. Contributions have been most well-developed in the area of
effective properties of damaged or reinforced materials, including effects of
voids, microcracks and multiple phases with different elastic properties. In
contrast, our understanding of the evolution of internal structure of the
material and its influence on change of properties is in more nascent state.
Specifically, principles for homogenization of evolving structure and its effect
on properties must be developed that respect the role of extremal
characteristics and their influence on driving forces for dissipative
rearrangement of internal structure. Tacit application of volume averaging
principles for a dissipation potential, for example, has perhaps subtle but very
demanding limitations. This lecture deals with some of these issues of evolving
structure, using the context of internal state variable (ISV) formalism as a
means to convey some hierarchical principles of material evolution at multiple
length and time scales. Applications include thermally activated flow and
hardening of metals, textural anisotropy and intergranular interactions, and
evolution of distributed damage in brittle microcracked solids.
Friday, February 20, 1998
209 Akerman Hall
Refreshments served after the seminar in
227 Akerman Hall.
Disability accomodations provided upon request.
Audrey Stark-Evers, Senior Secretary,