Effect of Lateral Constraint on the Mechanical Properties of a Closed-Cell Al Foam: I. Experiments

An experimental investigation into the effect of lateral constraint on mechanical properties of a closed-cell Al foam, Alporas, was conducted. Results show that while the initial plastic strength of the foam is unaffected, the constraint induces significant strain hardening as plastic deformation progresses. The strain hardening is also sensitive to the relative density of the foam, increasing with density. Further, the constraint is seen to reduce the densification strain and, at the same time, to enhance the energy absorbed per unit volume of the deformed foam. Implications of these changes to the deformation characteristics of foams, in terms of energy absorption efficiency and plastic strain accumulation during fatigue, are demonstrated and discussed. A companion article gives the details of the constitutive modeling undertaken to rationalize the observed strain hardening under constraint.