Critical tensile stresses for cohesive failure and critical compressiv
e stresses for delaminations (thick layers), respectively, and shear c
racking (thin layers) could be determined by means of tensile and comp
ressive four-point bending experiments combined with X-ray measurement
s of the elastic strains. In addition, the influence of macroscopic st
resses on hardness and critical load L-Cl were investigated with the s
ame devices. The hardness and the L-Cl differences amount to 1000 HV a
nd 25 N; respectively. (C) 1997 Elsevier Science S.A.