The influence of imperfections on the nucleation and propagation of buckling driven delaminations

The influence of prototypical imperfections on the nucleation and propagati on stages of delamination of compressed thin films has been analyzed. Energ y release rates for separations that develop from imperfections have been c alculated, These demonstrate two characteristic quantities: a peak that gov erns nucleation and a minimum that controls propagation and failure. These quantities lead to two separate criteria that both need to be satisfied to cause failure. They involve a critical film thickness for nucleation and a critical imperfection wavelength for buckling. Implications for the avoidan ce of failure are discussed. (C) 2000 Elsevier Science Ltd. All rights rese rved.