MODELS FOR THE ELASTIC-DEFORMATION OF HONEYCOMBS

A theoretical model has been developed for predicting the elastic cons tants of honeycombs based on the deformation of the honeycomb cells by flexure, stretching and hinging. This is an extension of earlier work based on flexure alone. The model has been used to derive expressions for the tensile moduli, shear moduli and Poisson's ratios. Examples a re given of structures with a negative Poisson's ratio. It is shown ho w the properties can be tailored by varying the relative magnitudes of the force constants for the different deformation mechanisms. Off-axi s elastic constants are also calculated and it is shown how the moduli and Poisson's ratios vary with applied loading direction. Depending o n the geometry of the honeycomb the properties may be isotropic (for r egular hexagons) or extremely anisotropic. Again, the degree of anisot ropy is also affected by the relative magnitude of the force constants for the three deformation mechanisms. (C) 1997 Elsevier Science Ltd.