Mixed-mode cohesive zone parameters from integrated digital image correlation on micrographs only

A.P. Ruybalid, J.P.M. Hoefnagels (Corresponding author), O. van der Sluis, M.P.F.H.L. van Maris, M.G.D. Geers

Research output: Contribution to journalArticleAcademicpeer-review

5 Citations (Scopus)
12 Downloads (Pure)

Abstract

Mixed-mode loading conditions strongly affect the failure mechanisms of interfaces between different material layers as typically encountered in microelectronic systems, exhibiting complex material stacking and 3D microstructures. The integrated digital image correlation (IDIC) method is here extended to enable identification of mixed-mode cohesive zone model parameters under arbitrary levels of mode-mixity. Micrographs of a mechanical experiment with a restricted field of view and without any visual data of the applied far-field boundary conditions are correlated to extract the cohesive zone model parameters used in a corresponding finite element simulation. Reliable or accurate force measurement data is thereby not available, which constitutes a complicating factor. For proof-of-concept, a model system comprising a bilayer double cantilever beam specimen loaded under mixed-mode bending conditions is explored. Virtual experiments are conducted to assess the sensitivities of the technique with respect to mixed-mode loading conditions at the interface. The virtual experiments reveal the necessity of (1) optimizing the applied local boundary conditions in the finite element model and (2) optimizing the region of interest by analyzing the model's kinematic sensitivity relative to the cohesive zone parameters. From a single test-case, exhibiting a range of mode-mixity values, the mixed-mode cohesive zone model parameters are accurately identified with errors below 1%. The IDIC-procedure is shown to be robust against large variations in the initial guess values for the parameters. Real mixed-mode bending experiments are conducted on bilayer specimens comprising two spring steel beams and an epoxy adhesive interface, under different levels of mode-mixity. The mixed-mode cohesive zone model parameters are identified, demonstrating that IDIC is a powerful technique for characterizing interface properties of interfaces, imaged with a limited field of view, as is typically the case in microelectronic applications.

Original languageEnglish
Pages (from-to)179-193
Number of pages15
JournalInternational Journal of Solids and Structures
Volume156-157
DOIs
Publication statusPublished - 1 Jan 2019

Keywords

  • Cohesive zone model
  • Digital Image Correlation
  • Finite element model
  • Full-field identification
  • Integrated Digital Image Correlation
  • Interface characterization
  • Inverse methods
  • Microelectronics
  • Mixed-mode adhesion properties

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