The role of cellular structure in creep of two-dimensional cellular solids

The creep response of cellular solids is sensitive to the details of the mi crostructure. Here. finite element simulations were used to model the stead y state, secondary creep rate of several two-dimensional cellular solids: a Voronoi honeycomb, representing a structure with a random variation in cel l shape; a plane section of a micrograph of a commercially available closed -cell aluminum foam; and the same plane section of the foam, but with the c urvature of the cell walls suppressed. The solid was assumed to follow powe r-law creep. Both periodic boundary conditions and boundary conditions corr esponding to a finite size sample were analyzed. The results of the models are compared with the analytical results for a regular hexagonal honeycomb of the same relative density. The creep rates of all of the other structure s are higher than that of the regular hexagonal honeycomb. The results indi cate that the details of the microstructure can have a significant effect o n the creep rate, and thus the lifetime, of the cellular solid. Cell wall c urvature plays the most significant role, but the distribution of cell shap e and size also influences the creep rate. (C) 2001 Elsevier Science B.V. A ll rights reserved.