On the Crushing Response of Foam Core Sandwich Specimens Subjected to Edgewise Compression with Varied Size Circular Face/Core Debond: Experimental

Foam core sandwich structure and used extensively in the primary structures of aircraft and launch vehicles. The study presents the result of an experimental investigation on failure analysis of foam core sandwich panels with varied size circular debonds. Edgewise compression test is conducted to characterize peak load carrying capacity in a variety of sandwich specimens (60mm×60mm) which contain circular debonds of 0.5-inch, 1-inch, 1.5-inch and the 2.0-inch diameter between the Glass/Epoxy Face sheet and Foam Core. Launch industry criteria were used in selecting the Debond sizes. PTFE inserts of required size are used to obtain the desired debonded area between the face sheets and the core. Specimens containing 0.5-inch, 1.0-inch, 1.5-inch, and 2.0 inch debonds were tested according to ASTM C 364-99. Testing demonstrated that reduction in strength is less for 0.5inch to 1.5inch debonds and 2.0-inch debond exhibits significant strength reductions. The study showed that a multiple failures occurs with face sheet buckling motivating delamination in the specimen, eventually leading to face sheet compression failure for debonds larger than 1.5 inches. The circular debonds of 1.5 inches set the thrush hold for the debonding failure of the panels considered.