This research attempted to describe the geometry of HexWeb CR-III-1/8-5052-8.1N commercial aluminum honeycomb core and give some statistical information about its deviation from the average. The finite element model of hexagonal honeycomb aluminum core was developed and validated using uniaxial tension-compression experimental data. The model was used for studying the effect of the geometrical irregularities, residual stresses, and strains on in-plane mechanical behavior of material. The homogenized yielding envelope was obtained based on developed model. The node bond failure was observed to occur in a stable manner and contributed significantly to the overall yielding of the core when the loads were dominated by transverse tension.