plastic deformation modeling of foam-filled tubes with multi-layer foams during compression loading

The purpose of this paper is to investigate the work hardening behavior and energy absorption characteristic of metallic foams and functionally graded foam filled tubes, including single-, double- and triple-layer foams. closed-cell a356 alloy and pure zinc foams are fabricated by casting method. the results illustrate that the metallic foams show partially brittle compressive deformation associated with cell walls’ bending and tearing. a nonlinear asymptotic model, 𝜎𝜎=𝜎𝜎0(1−𝜀𝜀)−𝜌𝜌𝐹𝐹/𝜌𝜌𝑆𝑆, is proposed to represent the hardening behavior of metallic foams and graded foam filled tubes as a function of relative density. the development of a complementary model, 𝜎𝜎=𝜎𝜎0𝜀𝜀sin(𝑛𝑛𝑛𝑛𝑛 )+𝜎𝜎0(1−𝜀𝜀)−𝜌𝜌𝐹𝐹/𝜌𝜌𝑆𝑆, leads to a more accurate estimation of crushing response considering the stress oscillations, particularly for the a356 foam with high degrees of oscillation and multi-layered structures containing distinct plateau regions. therefore, the present model is fairly consistent with the experimental results. greater density and strength of the zinc foam compared to those of the a356 foam cause the highest total energy absorption of 581 j in the zinc foam filled tube and the highest specific energy absorption of 459.2 j/(g/cm3) in the a356 foam filled tube. the presence of zinc foam results in the decrease of specific energy absorption. however, it plays a dominant role in adjusting the crash features of graded structures. the compressive properties of multi-layered structures can be controlled by varying the number and material of the layers at constant geometric features.