Creep-rupturing of cellular materials: Regular hexagonal honeycombs with dual imperfections

The creep-rupturing of regular hexagonal honeycombs with dual imperfections of variable-thickness and non-straight cell edges is theoretically analyzed. The variable-thickness of cell edges is taken to be a Plateau border and the profile of non-straight cell edges is circular. At the same time, the solid making up the cell edges in hexagonal honeycombs is assumed to obey power law creep while its creep rupturing is to follow the Monkman-Grant relationship. Theoretical results indicate that the creep-rupturing of hexagonal honeycombs with dual imperfections is affected by the solid distribution in cell edges, the curvature of cell edges and the Monkman-Grant parameters of solid cell edges. In addition, the effects of dual imperfections on the creep strain rates and creep-rupturing times of hexagonal honeycombs are more drastic than those of any single imperfection. Furthermore, it is verified that the normalized Monkman-Grant parameters of hexagonal honeycombs with dual imperfections are approximately equal to the products of those with each single imperfection.