Title:
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Impact modelling of composites
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In this thesis, the damage mechanisms and failure behaviour of four scaled laminated
carbon fibre composite plates under transverse loading '(low-velocity impact and static
indentation) and subsequent compression after impact/indentation loading were investigated
by highly-detailed experiments, high-fidelity finite element modelling and simple analytical
methods. Interrupted static indentation tests with the use of X-ray CT-scans at different
damage stages helped to study the damage evolution and interaction between inter- and intra-laminar
damages during impact and indentation. Finite element models with interface
elements and user defined constitutive model were embedded into regions inside and between
plies to model matrix cracks and delaminations. The predictive capabilities were validated by
the detailed experimental results both qualitatively and quantitatively. The models were able
to accurately predict the individual damage modes as well as the damage mode interaction.
The scaling effects and geometric nonlinear response associated with delamination
propagation during impact/indentation were observed and modelled by nonlinear analytical
solutions. The damage sequence and failure behaviour of laminates under compression after
impact were also studied via experiments and finite element modelling including the key
driving damage mechanisms. Possible solutions for reducing the computational cost of
deploying the developed high-fidelity finite element models were provided. These solutions
were validated and shown to be advantageous for capturing the overall response and damage
prediction for large and complex composite structures.
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