Compressive creep buckling of single cell metamaterial at elevated temperatures

Abstract

The benefits of tailored lattice topologies are limited in elevated temperature conditions without a clear understanding about the interplay between the metamaterial structure and the creep response of the base material. This study showed that the metamaterial structure causes the lattice compressive creep behavior to differ largely from that of bulk structures of the same base material. Inconel 625 FCCZ lattices and solid round bar specimens were crept in compression at two elevated temperatures and at three stress levels. The solid round bar specimens experienced only small increases in the steady state creep rate with a steady state exponent of 0.35 and 0.63 at 550 C and 650 C. The solid round bar specimens did not exhibit a deformation mechanism change over the temperatures and stress levels tested. The FCCZ lattices exhibited much larger changes in creep rates with changing stress and temperature with a steady state exponent of 18.3 and 20.2 at 550 C and 650 C, respectively.Additionally, the lattice specimens experienced three different failure behaviors with increasing temperature and stress from stable creep, to progressive buckling, and finally rapid collapse.