Modelling crack-induced delamination in composite laminates subjected to fatigue loadings.

  • Maragoni, Lucio (University of Padova)
  • Carraro, Paolo Andrea (University of Padova)
  • Simonetto, Mirko (University of Padova)
  • Quaresimin, Marino (University of Padova)

In session: - Fatigue

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At a macroscopic level, fatigue damage in composite laminates consists of matrix cracks, delamination, and fibre failure. By causing local stress concentrations, matrix cracks and delamination induce premature fibre failures. At the same time, their presence is associated to an overall stiffness loss of the laminate. Therefore, for an advanced design of primary composite structures, it is essential to develop predictive models that include account for both matrix cracks and delamination, including their mutual interaction. In the present work, first some recent experimental findings by the authors [1] are presented concerning the initiation and propagation of crack-induced delamination in glass/epoxy composite laminates subjected to tensile-tensile loadings. Based on experimental evidence, an innovative methodology was developed to include delamination in a damage predictive procedure based on discrete damage modelling [2], such as that developed by the authors in Ref. [3]. Delamination initiation takes place along with crack initiation, and delamination propagation is treated using fracture mechanics tools, considering the effect of the local damage scenario on the Energy Release Rate along the delamination front. The proposed procedure is able to consider the mutual interaction between matrix cracks and delamination during the fatigue life of the laminate, and it reduces the amount of computationally intensive analyses compared to alternative approaches. The damage predictions were compared to previous and new experimental results, showing a satisfactory agreement. [1] – Carraro PA, Maragoni L, Quaresimin M. Characterisation and analysis of transverse crack-induced delamination in cross-ply composite laminates under fatigue loadings. Int J Fatigue 2019; 129:105217 [2] – Maragoni L, Carraro PA, Quaresimin M. A novel method to include crack-induced delamination in a fatigue damage predictive procedure for composite laminates. Under review. [3] – Carraro PA, Maragoni L, Quaresimin M. Prediction of the crack density evolution in multidirectional laminates under fatigue loadings. Compos Sci Technol 2017; 145:24-39.