Nonlinear stress and deformation behaviour of composite sandwich beams

E. E. Gdoutos, I. M. Daniel

Research output: Contribution to journalConference articlepeer-review

8 Scopus citations


The nonlinear load-displacement and normal stress distribution in composite sandwich beams made of unidirectional carbon/epoxy facings and PVC foam cores under bending was studied. The carbon/epoxy after an initial linear response exhibits a stiffening nonlinearity in tension and a softening nonlinearity in compression with the longitudinal strength in tension higher than that in compression. The foam core also presents a nonlinear stress-strain response. It was obtained that the load-displacement behaviour of the beam, after an initial linear part, is not linear. This behavior was modeled by an incremental strength of materials nonlinear analysis. The theoretical predictions were in good agreement with the experimental results. Furthermore, it was obtained that the neutral axis of sandwich beams under bending does not pass through the centroid of the cross section, but is displaced toward the tensile side of the beam. Experimental results by moiré measurements of the in-plane horizontal displacements of the core material corroborated the analytical predictions. These findings imply higher compressive and smaller tensile stresses in the core, than those predicted for facings with identical stress-strain behaviour in tension and compression, and should be taking into consideration in the failure analysis of sandwich beams.

Original languageEnglish (US)
Pages (from-to)91-98
Number of pages8
JournalApplied Mechanics and Materials
StatePublished - 2008
Event6th International Conference on Advances in Experimental Mechanics - London, United Kingdom
Duration: Sep 9 2008Sep 11 2008


  • Deformation
  • Failure
  • Foam cores
  • Nonlinearities
  • Sandwich beams

ASJC Scopus subject areas

  • General Engineering


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