Facesheet Wrinkling of Damaged Honeycomb Sandwich Structures

Critical facesheet wrinkling stresses are determined for thin gauge sandwich structure constructed from thick, highly orthotropic, honeycomb-cored materials containing sub-surface damage due to soft-body impact. A closed-form, analytical expression is extended to account for regions of crushed core extending a uniform depth into the core material. The results show that sub-surface core damage can significantly decrease facesheet support, further reducing the critical wrinkling stress computed from classical formulae. The model accounts for shear traction at the core/facesheet interface and provides a means of assessing the fundamental parameters governing the initiation of facesheet wrinkling in initially flat panels constructed from thick orthotropic cores containing sub-surface damage. The results are discussed in terms of the damage tolerance of panels used in aerospace applications.