J-Q Theory to the Fracture of Elastically Mismatched Interfaces. Part II - Structuring the Interfacial Near-Tip Fields in accordance with the J-Q Theory
J-Q Theory the Fracture of Elasticallly Mismatched Interfaces - Part II - Structuring the Interfacial Near Tip Fields in accordance with the J-Q Theory
J. Dollhofer
ABSTRACT The present work has been divided into two parts. Part I appeared in the previous issue of Materials Testing [1] reviewing the fundamentals of the J-Q approach for characterizing constraint in a homogeneous material. The key finding is that for certain classes of power-law hardening specimens, the elastic-plastic near-tip Cauchy stress corresponds, up to a superposed isotropic stress of magnitude Q, to the well-known Mode I solution given by Hutchinson, Rice, and Rosengren (1968). Thus, the set of relevant fracture parameters is (J, Q). In the present Part II, it is shown that the J-Q decomposition is also possible for the elastically mismatched bimaterial specimen when one replaces the HRR reference solution by the deformation plasticity solution presented by Gao and Lou (1990). For contained yielding under Mode 1, the near-tip stress state in the 45°-sector adjacent to the interface may then equally be characterised by (J, Q). These results are discussed in view of experiments obtained by toughness tests applied to a polymer/glass specimen. The work concludes with an evaluation of finite-strain effects.
Publication Source: Materialprüfung, ISSN: 0025-5300
Issue: 2002-6, pp 233-242
Publisher: Carl Hanser Verlag München
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