Beneficial pre-stress in laser fabricated, metallic, square cellular sandwich panels

Abstract

The fabrication of flat, lightweight, stiff, strong, metallic, square cellular sandwich panels, LASCELLTM (Patent Pending), employing laser cutting and stake welding has been applied to the fabrication of large, watertight door panels and frames in a collaborative program with the Naval Surface Weapons Center Carderock Division – Ship Systems Engineering Station, Philadelphia and Northrop Grumman Corporation, Newport News. Using a restraining fixture, remarkably flat panels and frames have been fabricated with beneficial pre-stress that increases their resistance to failure from the observed failure mode, which is localized, face sheet buckling on the compression side. This paper reports measurement of thermally induced strains at various stages of the welding process with resistance strain gages fastened to panel face sheets. Although further work is needed, measurements so far confirm the development of the beneficial pre-stress.The fabrication of flat, lightweight, stiff, strong, metallic, square cellular sandwich panels, LASCELLTM (Patent Pending), employing laser cutting and stake welding has been applied to the fabrication of large, watertight door panels and frames in a collaborative program with the Naval Surface Weapons Center Carderock Division – Ship Systems Engineering Station, Philadelphia and Northrop Grumman Corporation, Newport News. Using a restraining fixture, remarkably flat panels and frames have been fabricated with beneficial pre-stress that increases their resistance to failure from the observed failure mode, which is localized, face sheet buckling on the compression side. This paper reports measurement of thermally induced strains at various stages of the welding process with resistance strain gages fastened to panel face sheets. Although further work is needed, measurements so far confirm the development of the beneficial pre-stress.