Models of interface separation accompanied by plastic dissipation at multiple scales

Citation
Yg. Wei et Jw. Hutchinson, Models of interface separation accompanied by plastic dissipation at multiple scales, INT J FRACT, 95(1-4), 1999, pp. 1-17
Citations number
23
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Mechanical Engineering
Journal title
INTERNATIONAL JOURNAL OF FRACTURE
ISSN journal
0376-9429 → ACNP
Volume
95
Issue
1-4
Year of publication
1999
Pages
1 - 17
Database
ISI
SICI code
0376-9429(1999)95:1-4<1:MOISAB>2.0.ZU;2-H
Abstract
Two continuum mechanical models of interface fracture for interfaces joinin g materials where at least one undergoes plastic deformation are reviewed a nd examined critically. The embedded process zone model (EPZ model) has an adhesive zone, characterized by a work of separation and an interface stren gth, embedded within a continuum model of the adjoining materials. The SSV model imposes an elastic, plasticity-free layer of prescribed thickness bet ween the interface and the surrounding elastic-plastic continuum. Crack adv ance requires the work of separation to be supplied by the local elastic cr ack tip field. The objective of each model is to provide the relation betwe en the macroscopic interface toughness (the total work of fracture) and the work of separation. Under steady-state crack growth, the total work of fra cture is the work of separation plus the work of plastic dissipation, the l atter often far exceeding the former. It will be argued that each model has its own domain of validity, subject to the accuracy of conventional contin uum plasticity at small scales, but neither is able to capture the dramatic trends which have been observed in macroscopic toughness measurements stem ming from alterations in interface bonding conditions. A unified model is p roposed which coincides with the two models in their respective domains of validity and provides a transition between them. Interface separation energ y and interface strength (the peak separation stress) each play a central r ole in the unified model. Strain gradient plasticity is used to illustrate the effect of plastic deformation at the micron scale on the link between i nterface and macroscopic properties.