Chapter One

The method of science depends upon our attempts to describe the world with simple theories: theories that are complex may become untestable, even if they happen to be true. Science must be described as the act of systematic simplifications. Karl Popper - "The Open Universe"

In order to explain the objective, motivation and the logical structure of this book it is necessary to cast a discriminating eye on the development of the continuum damage mechanics. In a haste to be present at its birth and straighten out some of its adolescent transgressions many authors (this one being no exception), blissfully ignorant of the global picture, embarked on solving an array of specific boundary value problems. The recipe was simple and seemingly efficient. Using guile, a clever ruse, or artifice, a particular mathematical representation was arbitrarily selected to measure the damage which was often implied and rarely defined. The next step was to generalize these continuum models by constructing an irreducible integrity basis for the elastic energy density based on the selected representation of the damage parameter. If this selection happened to be a second rank tensor the rest of the procedure followed the well traveled and familiar path of plasticity theory. Armed with a sufficient number of unidentified "material constants" a particular, experimental data set was fitted with accuracy which was l