The effect of hole size upon the strength of metallic and polymeric foams

Tensile and compressive tests have been performed on centre-hole panels, ma de from three types of metallic foams and two polymeric foams. In compressi on., the foams fail in a ductile, notch-insensitive manner, in support of a "net section strength" criterion. In tension, a ductile-brittle transition is observed for some of the foams at sufficiently large specimen sizes: fo r a small hole diameter the net section strength criterion is obeyed, where as for a large hole a local stress criterion applies and the net section st rength is reduced. For a number of the foams, the panel size was not suffic iently large to observe this ductile-brittle switch in behaviour. The predi ctions of a cohesive zone model are compared with the measured strengths an d are found to be in good agreement. (C) 2001 Elsevier Science Ltd. All rig hts reserved.