INDENTATION OF SANDWICHES USING A PLATE MODEL WITH VARIABLE KINEMATICS AND FIXED DEGREES OF FREEDOM

A recent 3-D, 5 degrees of freedom, variable kinematics zig-zag homogenized model is used for studying sandwich indentation. This model cannot describe in a point-wise sense cells collapse, buckling, debonding failure, plastic yielding, or brittle fracture. Therefore, the progressive folding followed by densification of the core is described through mechanical properties variable with loading, which are computed apart once at a time through a 3D FEA discretization of the core structure. Onset of damage is determined using stress-based criteria; degraded properties of failed regions are obtained from a mesoscale damage model. The results show efficient and accurate this approach.