Mechanical modelling of the creep behaviour of Hollow-Sphere Structures

Hollow-Sphere Structures could represent an alternative to classical cellular materials (like metal foams or honeycombs) for numerous structural applications, for instance in which mechanical energy absorption in case of impact is important. The present work explores the main mechanisms that govern the viscous behaviour of Hollow-Sphere Structures in view of their potential high-temperature applications, and more specifically under creep loading. It aims at understanding how elastic, plastic and viscous properties of the constitutive material contribute to the effective behaviour of the structure. In the computational framework mechanical properties can be deliberately varied in order to make their effects stand out clearly. The results show a strong strain rates heterogeneity in the structure because of stress concentration phenomena. Hence the architecture causes an additional non-linearity in the overall mechanical response that has to be taken into account in order to correctly capture overall creep mechanisms.