Abstract:
Adhesively bonded composite structures have been used extensively in both DoD and commercial industries. Despite many attractive features of a bonded composite structure, integrity and durability of adhesively bonded composite structures are the primary concerns due to their known sensitivity to environmental conditions and the presence of bondline defects associated with the fabrication and processing of a bonded composite structure. In order to reduce the testing matrix in characterization of properties of a bondline for the residual strength and life prediction of its bonded composite structure, a multiscale approach is developed based on an automatic generation of a representative unit cell of a heterogeneous bondline interface including voids and inclusions. Equivalent cohesive properties are extracted from a nonlinear finite element analysis for a unit cell with variations in size and geometric distribution of voids and inclusions within the bondline. The impact of a bondline quality on a global structural response is explored using a bonded I-beam with an initial delamination flaw subject to 4-point bending.