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Acta Materialia 50 (2002) 11971209 www.actamat-journals.com

Summary: Acta Materialia 50 (2002) 1197­1209
On the interface debond at the edge of a thin film on a thick
B. Erdem Alaca, M.T.A. Saif, Huseyin Sehitoglu *
Mechanical and Industrial Engineering, University of Illinois, 1206 West Green Street, Urbana, IL 61801, USA
Received 16 August 2001; received in revised form 6 November 2001; accepted 6 November 2001
The failure by debonding of 400 nm Al thin films on 152 µm-thick polyimide substrates has been studied in uniaxial
tension experiments. To explain the edge debond of the Al film, the shear stress field along the film­substrate interface
is determined. An analytical solution for the stress field exhibits a square root singularity near the free edges. The
associated stress intensity factor is calculated in closed form by an asymptotic analysis. For a given loading, the stress
intensity factor decreases with increasing length-to-thickness ratio of the film, and with decreasing film-to-substrate
stiffness ratio. Governed by a single, dimensionless parameter, these trends are reported quantitatively in the form of
a plot. Close correspondence is found for the interfacial shear stresses predicted by the presented method and by a
finite element analysis. 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.
Keywords: Thin films; Multilayers; Surfaces & interfaces; Nanofilms; Interface failure; Theory & modeling; Structural behavior
1. Introduction
One of the common modes of failure of thin
film­substrate structures is the `edge debond', the


Source: Alaca, B. Erdem - Department of Mechanical Engineering, Koc University


Collections: Engineering