Repair and qualification of sandwich materials.

A reliable characterisation of repair techniques of sandwich materials is restricted by the failure behaviour of the sandwich specimen. Depending on the structure of the sandwich predominately either a shear failure of the core or a compressive failure under the load cylinders during the bending tests can be observed. For this reason the inset of a waist into the four point bending specimen can help to force the failure into a defined area where repair techniques can be qualified. For this reason waisted undamaged, damaged and repaired sandwich specimens were mechanically tested. The stress distributions were calculated analytically and via numerical simulations.