Development and evaluation of the sandwich edgewise compression after impact test

A compression after impact test method has been developed to assess the damage tolerance of sandwich structures under edgewise compressive loading. This test method, recently standardized as ASTM D8287, was designed to test specimens that have been impact damaged per ASTM D7766. The fixture design utilizes end loading with top and bottom edge supports to prevent end-brooming and out-of-plane rotation. Additionally, knife edge side supports provide out-of-plane restraint to buckling, similar to the existing laminate edgewise compression after impact test fixture. The sandwich configurations investigated were constructed from glass/epoxy and carbon/epoxy facesheets with a Nomex honeycomb core. Mechanical testing was conducted to evaluate the proposed specimen design, fixturing, and test procedure. Finite element analysis was used to verify the strain gage placement and damage size limits.