On the analysis of a mixed mode bending sandwich specimen for debond fracture characterization

Amilcar Quispitupa, Christian Berggreen, Leif A. Carlsson

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The mixed mode bending specimen originally developed for mixed mode delamination fracture characterization of unidirectional composites has been extended to the study of debond propagation in foam cored sandwich specimens. The compliance and strain energy release rate expressions for the mixed mode bending sandwich specimen are derived based on a superposition analysis of solutions for the double cantilever beam and cracked sandwich beam specimens by applying a proper kinematic relationship for the specimen deformation combined with the loading provided by the test rig. This analysis provides also expressions for the global mode mixities. An extensive parametric analysis to improve the understanding of the influence of loading conditions, specimen geometry and mechanical properties of the face and core materials has been performed using the derived expressions and finite element analysis. The mixed mode bending compliance and energy release rate predictions were in good agreement with finite element results. Furthermore, the numerical crack surface displacement extrapolation method implemented in finite element analysis was applied to determine the local mode mixity at the tip of the debond.
Original languageEnglish
JournalEngineering Fracture Mechanics
Issue number4
Pages (from-to)594-613
Publication statusPublished - 2009


  • Finite element analysis
  • Experimental mechanics
  • Debond failure mode
  • Mixed mode bending
  • Sandwich structures


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