Transformation Toughening of a Two-Phase, Transversely Isotropic Solid

10.30009/CJM.200303.0006

H. H. Pan；G. J. Weng

Fracture toughness ； Phase transformation ； Transverse isotropy

The Chinese Journal of Mechanics

19卷1期（2003 / 03 / 01）

133 - 141

英文

Based on an energy criterion and the weight function approach, a micromechanics theory is developed to determine the effect of inclusion shape and concentration, and the elastic heterogeneity of the constituents, on the transformation height H of the process zone and the fracture toughness increment –△K of a two-phase, transversely isotropic composite. The composite is taken to consist of a brittle matrix and metastable ellipsoidal inclusions that are randomly oriented in the 2-3 plane to form overall transverse isotropy. It is found that both H and -△K of the transversely isotropic solid depend strongly on the inclusion shape and concentration. It is further found that, when both constituent phases have the same elastic moduli, this 2-D, transversely isotropic solid provides exactly the same toughness increment as a 3-D randomly oriented isotropic one, but that when both phase have different moduli, the results are distinctly different. The developed theory is applied to examine the effect of these microstructural features on both the partially stabilized zirconia and the zirconia-toughened alumina, and a parametric study is also conducted to disclose how the inclusion shape, volume concentration, shear modulus and Poisson's ratio of the constituents affect the toughness increment of the material through phase transformation.