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 proceedingChapterpeer-review


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 Integrity and Durability of Advanced Composites
Subtitle of host publicationInnovative Modelling Methods and Intelligent Design
EditorsPeter W.R. Beaumont, Constantinos Soutis, Alma Hodzic
Place of PublicationCambridge, UK
Number of pages34
ISBN (Electronic)9780081001387
Publication statusPublished - 20 May 2015

Publication series

NameWoodhead Publishing Series in Composites Science and Engineering
PublisherWoodhead Publishing


  • composite laminate
  • delamination
  • fracture
  • micromechanical modelling
  • stiffness degradation


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