Particle debonding using different yield criteria

Effects of plastic anisotropy in relation to debonding of rigid inclusions embedded in an elastic-viscoplastic metal are studied. Full finite strain analyses are carried out for plane cells assuming plane stress or plane strain. The overall stress strain response is calculated, when the cell is subjected to a fixed biaxial stress state.

Four phenomenological anisotropic yield criteria are considered, namely Hill [Hill, R., 1948. Proc. Roy. Soc. London Ser. A 193, 281-297], Barlat and Lian [Barlat, F., Lian, J., 1989. Int. J. Plasticity 5, 51-66], Barlat et al. [Barlat, F., Lege, D.J., Brem, J.C., 1991. Int. J. Plasticity 7, 693-712; Barlat, F., et al., 2003.

Int. J. Plasticity 19, 1297-1319], or the von Mises isotropic yield surface. Also a non-normality flow rule is adopted in some of the studies. Significant effects of plastic anisotropy are seen on the plane stress cell, due to the initial extent and shape of the particular yield function considered.

The required overall straining of the cell for debonding initiation is related to the extent of the yield surfaces, since a high yield stress promotes debonding. Additionally, the maximum overall stress level for the cell is lower for the Hill [Hill, R., 1948. Proc. Roy. Soc. London Ser. A 193, 281-297] and Barlat et al. [Barlat, F., Lege, D.J., Brem, J.C., 1991.

Int. J. Plasticity 7, 693-712] materials than that predicted by the other three yield functions. In all cases analyzed the non-normality flow rule hastens the particle-matrix debonding. Keeping all material parameters fixed, the material response of the plane strain cell is considerably affected, due to debonding at a much reduced overall plastic strain compared to the corresponding plane stress cell. (C) 2004 Elsevier SAS.

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