Application of a continuum constitutive model to metallic foam DEN-specimens in compression

The behavior of double-edge notched specimens of metallic foams in compression is studied numerically. To model the constitutive behavior of the metallic foam, a recently developed phenomenological, pressure-sensitive yield surface is used. Compressive yielding in response to hydrostatic stress is incorporated through a dependence on the plastic Poisson ratio νp. Results are presented in terms of limit load Flim, as a function of notch depth, a/W , and the plastic Poisson ratio νp. For incompressible plastic behavior, νp=0.5, the results show notch-strengthening due to constrained plastic deformation near the crack/notch-tip. For fully compressible plastic behavior (no lateral expansion on uniaxial compression, νp=0), no notch-effect is observed. The validity of using a continuum model for the analysis of metallic foam notched specimens is discussed.