“…This material has also been identified as a very interesting alternative to traditional materials because of its high bending stiffness and high strength to weight ratios. Composite sandwich structures possess many features that make them applicable in many purposes, among these features are: high relative flexural strength and stiffness [1,2], high impact strength [3][4][5][6], high corrosion resistance [7,8] and the low thermal and acoustics conductivity [9][10][11]. However, the design of composite sandwich structures is a critical issue because it needs a reliable test results of the mechanical response of the skin and the core materials including materials nonlinearity and proper failure criteria under complex loading state [12][13][14][15].…”