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The employment of lightweight structures is one of the most important goals in various industries.The lightweight sandwich panel is an excellent energy absorber and also a perfect way for decreasing the risk of impact. In this paper, a numerical study of high-velocity impact on honeycomb sandwich panels reinforced with polymer foam was performed. The results of the numerical simulation are compared with experimental findings. The numerical modelling of high velocity penetration process was carried out using nonlinear explicit finite element code, LS-DYNA. The aluminum honeycomb structure, unfilled honeycomb sandwich panel, and the sandwich panels filled with three types of polyurethane foam (foam1: 56.94, foam2: 108.65 and foam3: 137.13 kg/m 3 ) were investigated to demonstrate damage modes, ballistic limit velocity, absorbed energy, and specific energy absorption (SEA) capacity. The numerical ballistic limit velocity of sandwich panels filled with three types of foam were more than the bare honeycomb core and unfilled sandwich panel. In addition, the numerical results show that the sandwich panel filled with the highest density foam could increase the strength of sandwich panel and the numerical specific energy absorption of this structure is 23% more than unfilled. Finally, the numerical results were in good agreement with experimental findings.

In this paper, the quasi-static penetration tests were investigated on unfilled and polyurethane foam filled honeycomb sandwich panels. Failure mechanisms, specific energy absorption, interaction mechanisms and some structural responses were studied. Comparing the three types of the foam filled sandwich panels with unfilled type, indicates that the absorbed energy of the first, second and third type of the panels are 23%, 33% and 58% more than unfilled ones, respectively. In addition, the results showed the enhancement in the dynamic strength and 2 remarkably decrease in the damage area of the sandwich structure when its honeycomb core was filled with polymer foam.

Soil adhesion is a physical phenomenon which results in undesirable effects including increment in drag force and energy consumption of cutting or tillage tools. One method to reduce the soil adhesion is biomimetics, i.e., focusing on the technique soil-burrowing animals’ benefit. In this study, three types of blade were designed and built: flat blade, corrugated blade and a combination of flat and corrugated blades. The corrugated blade was simulated from Armadillidium vulgare body surface geometrical shape. Experimental results showed that in dry soil, flat and corrugated blades required similar drag force while the combined blade showed higher drag force requirements. In wet soil, the corrugated blade resulted in the lowest drag force, which was due to faster movement of soil layer on the blade surface. Drag force of the corrugated blade was lower than the half of the drag force of two other blades at travel speed of 0.04 m/s. Besides, the drag force of corrugated blade decreased by increasing the blade travel speed. Furthermore, in wet soil, the energy consumption of the corrugated blade at the travel speeds of 0.02 and 0.04 m/s was 66% and 83% lower than the flat blade, respectively.