Prediction of Creep Properties of Fiber-Reinforced Closed-Cell Metallic Foams

Abstract

The anti-creep capability of metallic foams is important to structural applications at elevated temperatures. Currently, available creep models for opened-cell foam materials are usually derived by rather simplified meso-structural models. Here, we try to predict the creep properties of new fiber-reinforced closed-cell foams with more realistic 3D meso-structures. In the study, three-dimensional Voronoi structures are constructed to describe the inner structure of closed-cell foams, and reinforcing fibers are modeled by line segments penetrating through cell walls. Based on the recommended model, not only the steady creep strain rates of both the unreinforced and the reinforced foam materials are well predicted with considering the effects of temperature, stress, and relative density, but also the creep evolution features of metal foam are revealed from the meso-deformation behaviors. It is found that, at moderate temperature and stress, the creep rate of the fiber-reinforced metallic foam can also be well described by a power law with respect to the foam relative density. The influence of addition of fibers on the creep properties is parametrically studied and it is shown that addition of fibers has a positive effect on restricting the creep rate. It is observed that during creep, the stresses of cell walls are redistributed and become more homogeneous with time. When the creep rate of metallic foam reaches steady state depends on when the stresses of cell walls become homogeneous.