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Title:Thin film adhesion measurement by laser induced stress waves
Author(s):Wang, Junlan; Sottos, Nancy R.; Weaver, Richard L.
Stress waves
Abstract:Laser induced stress waves are used to characterize intrinsic interfacial strength of thin films under both tensile and mixed-mode conditions. A short-duration compressive pulse induced by pulsed-laser ablation of a sacrificial layer on one side of a substrate is allowed to impinge upon a thin test film on the opposite surface. Laser-interferometric measurements of test film displacement enable calculation of the stresses generated at the interface. The tensile stress at the onset of failure is taken to be the intrinsic tensile strength of the interface. Fused-silica substrates, with their negative nonlinear elasticity, cause the compressive stress wave generated by the pulse laser to evolve a decompression shock, critical for generation of the fast fall times needed for significant loading of surface film interfaces. By allowing the stress pulse to mode convert as it reflects from an oblique surface, a high amplitude shear wave with rapid fall time is generated and used to realize mixed-mode loading of thin film interfaces. We report intrinsic strengths of an aluminum/fused silica interface under both tensile and mixed mode conditions. The failure mechanism under mixed-mode loading differs significantly from that observed under pure tensile loading, resulting in a higher interfacial strength for the mixed-mode case. Inferred strengths are found to be independent, as they should be, of experimental parameters.
Issue Date:2003-04
Publisher:Department of Theoretical and Applied Mechanics (UIUC)
Series/Report:TAM Reports 1019
Genre:Technical Report
Publication Status:published or submitted for publication
Peer Reviewed:is peer reviewed
Date Available in IDEALS:2007-03-08
Is Version Of:Published as: Junlan Wang, Nancy R. Sottos and Richard L. Weaver. Tensile and mixed-mode strength of a thin film-substrate interface under laser induced pulse loading. Journal of the Mechanics and Physics of Solids, Vol. 52, No. 5, 2004, pp. 999-1022. DOI: 10.1016/j.jmps.2003.09.029. Copyright 2004 Elsevier.

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  • Technical Reports - Theoretical and Applied Mechanics (TAM)
    TAM technical reports include manuscripts intended for publication, theses judged to have general interest, notes prepared for short courses, symposia compiled from outstanding undergraduate projects, and reports prepared for research-sponsoring agencies.

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