Determination of the fracture toughness of debonded asymmetric sandwich beams with a thin-walled skin considering plastic deformation

This paper analyzes the delamination behavior of thin-walled asymmetric sandwich beams. DCB tests are used for the calculation of fracture toughness values and show a high dependency of the delamination behavior on the damage configuration and geometry. The thickness of the sandwich skin and the position of the delamination relative to the adhesive layer prove to be crucial. The skin's plastic deformation is quantified by estimation using graphical and semi-analytical methods. Plastic strains occur over most of the cross section of the delaminated bending aluminum skin and have significant effects on the resulting fracture toughness. All results underlie significant variances due to several influences as shown.