This paper describes a series of experiments and analyses that were used to examine crack growth near sapphire/epoxy interfaces. Adhesion of the epoxy to the sapphire was enhanced by coating the sapphire with mixtures of two silane coupling agents that form self-assembled monolayers. A new biaxial loading device was used to conduct a series of mixed-mode fracture experiments. Crack opening interferometry, atomic force microscopy, and angle-resolved X-ray photoelectron spectroscopy allowed cohesive zone sizes, fracture surface topographies, and loci of fracture to be established. The experiments were complemented by finite element analyses that accounted for the rate- and pressure-dependent yielding of the epoxy. The analyses also made use of traction-separation laws to represent the various interphases that were produced by the mixed monolayers. The intrinsic toughness (defined as the area underneath the traction-separation curve) of the bare sapphire interfaces was independent of mode-mix and lower than values from previous experiments with glass/epoxy and quartz/epoxy specimens. The increase in overall toughness with mode-mix was completely accounted for by viscoplastic dissipation in the epoxy outside the cohesive zone. The minimum toughness of the coated sapphire interfaces was about five times higher than the mode-mix independent intrinsic toughness of the uncoated specimens. The increase in overall toughness with mode-mix was almost completely accounted for by increases in the intrinsic toughness as the traction-separation law varied with mode-mix. As a result, viscoplastic dissipation outside the cohesive zone was minimal. Atomic force fractography and X-ray photoelectron spectroscopy indicated that the crack growth mechanisms and the loci of fracture in the coated and uncoated specimens were quite different.
Skip Nav Destination
Article navigation
September 2006
Additional Technical Papers
The Effect of Self-Assembled Monolayers on Interfacial Fracture
Alberto W. Mello,
Alberto W. Mello
Research Center for the Mechanics of Solids, Structures and Materials, Department of Aerospace Engineering and Engineering Mechanics,
The University of Texas at Austin
, Austin, TX 78712
Search for other works by this author on:
Kenneth M. Liechti
Kenneth M. Liechti
Research Center for the Mechanics of Solids, Structures and Materials, Department of Aerospace Engineering and Engineering Mechanics,
The University of Texas at Austin
, Austin, TX 78712
Search for other works by this author on:
Alberto W. Mello
Research Center for the Mechanics of Solids, Structures and Materials, Department of Aerospace Engineering and Engineering Mechanics,
The University of Texas at Austin
, Austin, TX 78712
Kenneth M. Liechti
Research Center for the Mechanics of Solids, Structures and Materials, Department of Aerospace Engineering and Engineering Mechanics,
The University of Texas at Austin
, Austin, TX 78712J. Appl. Mech. Sep 2006, 73(5): 860-870 (11 pages)
Published Online: October 8, 2004
Article history
Received:
January 13, 2004
Revised:
October 8, 2004
Citation
Mello, A. W., and Liechti, K. M. (October 8, 2004). "The Effect of Self-Assembled Monolayers on Interfacial Fracture." ASME. J. Appl. Mech. September 2006; 73(5): 860–870. https://doi.org/10.1115/1.1940662
Download citation file:
Get Email Alerts
Complex Flow Patterns in Compressible Viscoelastic Liquids: Blood Flow Through a Compliant Aorta
J. Appl. Mech (February 2025)
Extraction of Mechanical Properties of Shape Memory Alloys From Instrumented Spherical Indentation
J. Appl. Mech (February 2025)
Sound Mitigation by Metamaterials With Low-Transmission Flat Band
J. Appl. Mech (January 2025)
Related Articles
A Review of In Situ Mechanical Characterization of Polymer Nanocomposites: Prospect and Challenges
Appl. Mech. Rev (September,2017)
Double Cantilever Beam Measurement and Finite Element Analysis of Cryogenic Mode I Interlaminar Fracture Toughness of Glass-Cloth/Epoxy Laminates
J. Eng. Mater. Technol (April,2001)
A Hybrid Continuum-Molecular Analysis of Interfacial Force Microscope Experiments on a Self-Assembled Monolayer
J. Appl. Mech (September,2006)
Probe-Tip Induced Damage in Compliant Substrates
J. Manuf. Sci. Eng (June,2010)
Related Proceedings Papers
Related Chapters
DEVELOPMENTS IN STRAIN-BASED FRACTURE ASSESSMENTS - A PERSPECTIVE
Pipeline Integrity Management Under Geohazard Conditions (PIMG)
Introduction
Bacteriophage T4 Tail Fibers as a Basis for Structured Assemblies
In Situ Self-Assembly of Mild Chemical Reduction Graphene for Three-Dimensional Architectures
International Conference on Computer and Electrical Engineering 4th (ICCEE 2011)