Initial densification strain point’s determination of honeycomb structure subjected to out-of-plane compression

Compression ratio is significant for cellular structures on energy absorption. In the present work, theoretical formulas to determine the initial densification strain of honeycomb structure were put forward by means of minimum energy principle. Detailed densification strain points were identified, with full fold model for kinds of specimens. To validate, corresponding numerical simulations were carried out with explicit finite element method. Excellent agreement in terms of initial densification stain point has been observed between the theoretical calculation and numerical simulation. The results show that: ① different honeycomb structure has different initial densification strain point, and its geometric configuration of cells plays an evident role on densification; ② half-wave length of the wrinkle of honeycomb in folding process significantly influences on the densification strain point; ③ the initial densification point is an decreasing power function of the ratio of foil thickness to cell length, with the exponent 2/3. These achievements provide important references for design in cellular energy absorption devices.