Damage mechanics : basic variables in continuum theories

It is shown that any type of material damage that causes sti}ness degradation in general requires description by an eighth order damage tensor but that the principle of strain equivalence permits a reduction to a tensor of order four[ The actual number of independent damage parameters in such a tensor is related to the material and damage symmetry[ For the isotropic case\ there must be two independent damage parameters which can be expressed in terms of damage parameter with physical meaning[ 0887 Elsevier Science Ltd[ All rights reserved[