Analysis Of Size Effects In Mechanical Behavior Of Hexagonal Honeycombs

Hexagonal honeycomb is a kind of cellular materials. Its excellent mechanism property with low relative density, high specific strength, light quality, high specific area, good penetration, heat insulation, sound insulation and so on, has been increasingly received concern from the field of engineering and academic. Its applied range is very important sets in military defense, aviation and space, automobile industry, building and packaging.Out-of-plane uniaxial compression tests were experimented with seven kinds of different cell numbers and ten kinds of different height commercial honeycomb specimens in-plane size on the loading rate in6mm/min, in order to determine five important mechanics parameters of the size effect on honeycomb structure (curve modulus Ecurve, elastic modulus Eunload, initial collapse stress σpeak, densification strain εD, plateau stress σp1). The size of the sample mean curve modulus and elastic modulus are compared. Experimental results indicate that curve modulus is higher than elastic modulus. The plastic deformation exists in the process of initial linear loading. Sample size has a significant effect with the initial collapse stress while the other four mechanics parameters are not apparent. Only while in-plane size of honeycomb should be at least more than11×11can be gained the stable mechanics parameters of honeycomb structure. Densification strain and elastic modulus are all influenced by different height of honeycomb specimen. The mechanical properties are stable when the size of honeycomb specimen is N×N=11×11, H/d≥4.16(H=18mm)。Numerical simulation of out-of-plane dynamic uniaxial compression with the mechanical behavior of aluminum honeycomb was carried out by Abaqus. Deformation mode was studied. The influence of plateau stress and densification strain by in-plane size and height are discussed. The result of numerical simulation shows that the deformation of honeycomb was fold on the locality and "V" type deformation on the entirety under the dynamic compression. Because there will be a high-frequency impulse on the process of uniaxial dynamic compression, so the initial collapse stress and elastic modulus are neglected. Only the stress-strain curve of plateau stress and densification strain was output. And size effect was appeared on both. The size effect can be ensured base on two kinds of mechanical parameters. In order to acquire stable mechanical parameters, the in-plane size of aluminum honeycomb specimen must be more than N×N=13×13.The direction of carrying is not just on the out-of-plane in engineering application. Numerical simulation of in-plane dynamic uniaxial compression about the mechanical behavior of aluminum honeycomb was carried out by Abaqus with the loading rate in6mm/min from two directions X1and X2. The simulate result demonstrated that deformation mode of aluminum honeycomb structure divide into two sections which loading direction is X1. One is "V" type, while another is "I" type, then it will be compressing to densification. When the in-plane size of the honeycomb is NxN=11×11, the plateau stress and densification strain all reached equilibrium. The deformation of aluminum honeycomb structure is "I" type. When the in-plane size is NxN=11×11, the mechanical parameter tend to stable.