||The fourth volume of Continuum Physics is devoted to the exposition of field theories for bodies which possess inner structure that can interact with mechanical and electromagnetic fields. The purpose here is a thorough and precise presentation of exact continuum theories on materially nonuniform or nonsimple bodies (bodies composed of single, dipolar, and deformable elements) that can respond to short- and long-range interparticle loads and fields. Most of these theories have acquired their present definitive forms during the last decade or so, even though basic ideas and certain limited or approximate developments on some of these theories can be traced back to the turn of the century. With the explosive developments that have taken place during the last decade, continuum physics is now very rich, and the impossible dream of bridging the gap between classical phenomenological physics and atomic and molecular physics is in sight.
Presently, there exists no published treatise on the subjects covered in this volume except some partial exposition and limited reviews that are scattered in the literature. We believe that the present unified approach, which includes improvements, additions, and/or completions of various aspects of these theories, will make this book valuable for graduate study and research.
Part I is devoted to the study of continuum field theories for bodies having inner structure. All materials, to some extent, are composed of particles that behave like small rigid bodies (micropolar media) or deformable particles (micromorphic media), unlike the geometrical points of the classical continuum theory. Granular solids, rocks, bone, animal blood, liquid crystals, composite materials, and many other large classes of amorphous materials fall into this category. Kinematics, dynamics, thermodynamics, and constitutive equations of such materials must be developed afresh, modifying and extending the basic principles of continuum physics developed in Volume II. These are the subject of Part I, which contains expositions for both solids and fluids. These topics are also relevant to continuum dislocation theory, on which a part was originally planned. However, in spite of its importance, because of the present status of this field, this project was abandoned.