The mechanical behavior of porous metal fiber sintered sheets

Porous metal fiber sintered sheets (MFSSs) are a type of low density cellular materials promising for functional and structural applications. A micromechanics random beam model is proposed to investigate the elasto-plastic behavior of MFSSs. The relative density dependence of the elastic constants and yield strength of MFSSs is predicted and found to agree well with available experimental results. Fiber stretching is identified as the dominant deformation mechanism under uniaxial and multiaxial loading. When compared with two-dimensional Voronoi foams and honeycombs, the stretching deformation dominated MFSSs exhibit higher stiffness and tensile strength, but lower compressive strength due to long fiber buckling. With the developed micromechanics model, the multiaxial elasto-plastic responses of MFSSs are simulated. A macroscopic phenomenological constitutive model with a segmented yield function is proposed to describe the predicted multiaxial responses. The yield function and its evolution can be fully calibrated in terms of the uniaxial tension and compression responses rather than complex multiaxial loading responses, which can greatly facilitate practical applications of the model. This constitutive model is also expected to be applicable to other fiber sintered materials with hydrostatic pressure sensitive and asymmetric tension-compression yielding behaviors. (C) 2012 Elsevier Ltd. All rights reserved.