Experimental research of sandwich specimens’ failure mechanisms with facing layers from unidirectional fiber reinforced plastic with [0°] lay-up under axial compression

Abstract

An experimental technique for compression tests of the sandwich specimens with thin outer layers made of fiber reinforced composite is proposed. The proposed method is focused on testing thin layers of composite material, specimens of which, even with a very short gage length, lose their stability, thereby distorting the determined value of the ultimate stress. Experimental studies of the failure mechanism of sandwich specimens with outer layers with [0°] lay-up under axial compression have been carried out. The possibility of realizing the shear buckling mode for specimens with different geometric parameters was revealed, which allows the determined ultimate stress formed in the outer layers to be taken as a mechanical characteristic when calculating the strength of structures made of composite materials. It is shown that for specimens with a honeycomb core in the outer layers under compression, an in-phase flexural buckling mode occurs. The implementation of a non-classical shear buckling mode is possible only for specimens with a rigid core, which was used as balsa wood.