Experimental and Numeral Investigation on X-cor Sandwich Structure under Low-velocity Impact

Abstract

X-cor sandwich is a new kind of foam sandwich reinforced by Z-pin techniques. Under low velocity impact damage, failure mechanism of X-cor sandwich structure is complex. Failure behavior of X-cor sandwich structure at different energy stages was analyzed, and the effects of the volume fraction of Z-pin implant and the density of the foam core on the failure behavior were also discussed. Z-pin diameter of specimens in low speed impact test was 0.5 mm, and the implantation angle was 22°, and the type of foam and Z-pin implant volume fraction in the experiment was variable .The results show that under 6 J impact energy, the impact energy is mainly absorbed by the panel’s delamination. The sandwich contained Z-pin is beneficial to reduce the delamination area, while the delamination area of blank sample increases by 45.1%. The foam density has little effect on the delamination area. The Z-pin fails under 12 J impact energy. The residual compressive strength ratio increases first and then decreases with the increase of volume fraction of Z-pin. The sample has the highest residual compressive strength ratio when the volume fraction reaches 0.42%. As the foam density increases, the residual compressive strength ratio increases. When the energy reaches 18 J, shear crack appears in the foam core, and the crack absorbs most of the energy. The weaker the foam core, the larger the residual compressive strength ratio is, and the more the volume fraction of Z-pin implanted, the lower the residual compressive strength ratio is. The low velocity impact model is also established by numerical simulation, and the result of impact damage is directly transferred and applied to study the residual strength model; the result obtained is 25%~29% higher than the experimental value.

Keywords

• low-velocity impact
• delamination area
• sandwich
• residual strength
• numerical simulation