compatible on the debonded layers. This case is called “with contact”
condition in contrast to “without contact” condition in which
the layers separate each other and the normal stress is null on
them. The real contact condition in a debonded region is a combination
of the “with contact” and “without contact” conditions
which causes nonlinearity in the structure's behavior. To overcome
this nonlinearity, the free vibration response of the debonded beam
can be studied using the linear “with contact” and “without contact”
models (Schwarts-Givli and Rabinovitch, 2007; Frostig et al.,
2004