Composite materials play an ever increasing role in the design of modern day
aeronautical and automotive structures due to their weight saving potential. Generally
progress in constituent material production and composite manufacturing have
resulted in lower costs for composite structures, which has made them more
attractive for a number of industries, including the aeronautical and automotive
However, while sufficiently accurate numerical models exist to model damage
initiation and progression in metal structures similar models are not yet available for
composite structures. Yet the ability to model damage accurately is an integral part of
the design process in both the aeronautical as well as the automotive industry.
Due to the more complex microstructure of textile composites compared to metals a
numerical model to predict the behaviour of a macrostructure needs to take
microstructural effects into account. Multi-scale modelling approaches are uniquely
suited to efficiently incorporate not only micro-scale affects but also higher scale
affects like tow buckling.
Therefore a multi-scale approach to model damage initiation and progression in
textile composites based on the finite element method is presented in this thesis. A
number of mechanical tests of a benchmark composite are conducted to measure
input parameters for the multi-scale approach as well as mechanical behaviour for
comparison with model predictions.
The multi-scale approach is used to predict the mechanical behaviour of the
benchmark composite for two different load cases, pure tension and pure shear.
Results for the pure shear load case show significant deviations between predicted
and experimentally measured stress-strain curve. For the pure tension load case
transverse strain predictions also deviate significantly from the experimental data,
stress-strain data in the loading direction however show good agreement between
predicted values and experimentally measured data.
Whilst further improvements are still required, the approach presented in this thesis
provides a solid foundation for designers to predict damage initiation behaviour and
progression in textile composites.
Submitted in partial fulfilment of the requirements for the award of Doctor of
Philosophy (Ph.D.) of Loughborough University.