Modelling delaminations using adaptive cohesive segments with rotations in dynamic explicit analysis

Jagan Selvaraj*, Supratik Mukhopadhyay, Luiz F Kawashita , Stephen R Hallett

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

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Abstract

Multiple delamination planes can form when a composite structure is subjected to out-of-plane stresses during static over-loading or impact loading. Numerical modelling of such events is often prohibitively expensive because large numbers of cracks can co-exist and interact, and fracture models usually affect the time step size in explicit solutions. Here a new method called Adaptive Mesh Segmentation is proposed, which introduces segmentation ‘on-the-fly’ in meshes of quadratic finite elements with six degrees of freedom per node, without any intervention from the user and without any reductions in time step size for solution stability. A novel cohesive formulation with rotational degrees of freedom is introduced which increases the resolution of the numerical cohesive zone and allows the use of relatively coarse meshes. Once a critical stress criterion is met, new degrees of freedom are added at element boundaries to model strong discontinuities. A new moment–damage relationship is proposed to link the discontinuity in rotational degrees of freedom with the cohesive zone law which is translational by definition. A method for initiating cohesive tractions and moments with minimal disturbances to the surrounding stress field is also presented. Finally, the model is applied in the analysis of composite delamination benchmarks using relatively coarse meshes and modest model sizes. Considerable improvements in accuracy are observed when compared to conventional methods.

Original languageEnglish
Article number107571
Number of pages22
JournalEngineering Fracture Mechanics
Volume245
Early online date27 Jan 2021
DOIs
Publication statusPublished - 9 Feb 2021

Bibliographical note

Funding Information:
This work was supported by the Engineering and Physical Sciences Research Council (EPSRC), United Kingdom through the Centre for Doctoral Training in Advanced Composites at the University of Bristol (Grant no. EP/L016028/1 ). The authors would also like to acknowledge Rolls-Royce plc for their support of this research through the Composites University Technology Centre (UTC) at the University of Bristol, United Kingdom .

Publisher Copyright:
© 2021 Elsevier Ltd

Keywords

  • Adaptive Mesh Segmentation
  • Delamination
  • Explicit analysis

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