Abstract: In order to explore the protection ability and damage mechanism of glassfiber sandwich bulkhead under explosion and fragment loadings，the deformation and failure tests of glassfiber sandwich structure were performed using cast TNT and prefabricated fragments. The damage characteristics of glassfiber composite sandwich structure，of which protection ability is quantitatively compared with those of aramid and high-strength polyethylene composite sandwich structures，are studied，and the failure mode of each layer composite sandwich structure and its corresponding failure mechanism are analyzed. The results show that E-glass core is required to be 1.37 times and 2.50 times heavier than aramid core and high-strength polyethylene core，respectively，when sandwich structure is applied to resist explosion and fragment loadings. The failure mode of front panel is co-determined by three factors，including shock wave，fragment load,and core constraint. Fragment load plays a major role on core failure mode，the failure mode of rear panel is related to core impact and fragment load. The shock wave and core impact are surface loads，which lead to the bending deformation of front and rear panels，the fragment load is point load，which leads to the local piercing holes on panel and core，and the core constraint limits the deformation space of the front panel. Key

Key words: ordnancescienceandtechnology, experimentalinvestigation, failuremode, protectionability, compositesandwichstructure