Analysis of delamination in laminates with angle-ply matrix cracks: Onset of damage and residual stiffness properties

Maria Kashtalyan, C. Soutis

Research output: Chapter in Book/Report/Conference proceedingChapter

4 Citations (Scopus)


The failure process of composite laminate under quasi-static or fatigue loading involves sequential accumulation of intra- and interlaminar cracking. Matrix cracking parallel to the fibres in the off-axis plies is the first damage mode observed. It triggers development of other harmful resin-dominated modes such as delaminations. In this chapter, analytical modelling of crack-induced delaminations in composite laminates subjected to general in-plane loading is presented and discussed. A two-dimensional shear lag analysis is used to determine ply stresses in a representative segment and the equivalent laminate concept is applied to derive expressions for mode I and mode II and the total strain energy release rate associated with uniform local delaminations. These expressions could be used with appropriate fracture criteria to estimate the onset of local delamination in an already cracked off-axis laminate. Dependence of strain energy release rate on crack density, delamination area and ply orientation angle in unbalanced symmetric laminates is examined and discussed, and the effect of crack-induced delamination on the laminate stiffness is predicted.
Original languageEnglish
Title of host publicationStructural Durability and Durability of Advanced Composites
Subtitle of host publicationInnovative Modelling Methods and Intelligent Design
EditorsP.W.R. Beaumont, C. Soutis, A. Hodzic
Number of pages34
ISBN (Electronic)9780081001387
ISBN (Print)9780081001370
Publication statusPublished - 2015

Bibliographical note

Acknowledgements: Financial support of this research by the Engineering and Physical Sciences Research Council (EPSRC/GR/L51348) and the British Ministry of Defence is gratefully acknowledged.


  • Composite laminate
  • Delamination
  • Fracture
  • Micromechanical modelling
  • Stiffness degradation


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