| dc.description.abstract | Composite pressure vessels are becoming widely used for transporting gas, lately also hydrogen.
In order to enable extensive use of the pressure vessels, it is critical to ensure their
societal acceptance, and thus safety under transportation. Being able to judge the damage
of an impacted pressure vessels is one important aspect from a safety and economical point
of view. The lack of knowledge about the behaviour of damaged pressure vessels results
in needlessly discarding damaged vessels with acceptable levels of damage.
This thesis considers impact damage on glass fibre reinforced polymer pipes, produced by
filament winding. Pipe specimens were subjected to well-defined impacts for two energy
levels and the damage was reproduced numerically. Interlaminar damage was modelled
by cohesive elements between composite layers. Intralaminar damage was modelled by
the Hashin failure criterion on continuum shell elements.
Experimental impacts produced unexpected highly asymmetrical delaminations. These delaminations
were reproducible in shape and size for all specimens. The numerical model
predicted the asymmetrical delaminations within the scatter of the experimental results
for both energy levels tested. By studying the interlaminar behaviour of the delamination
in the model, the buckling mode of the pipe was found to determine the direction of delamination.
The intralaminar damage (fibre failure and matrix cracking) was inconsistent
for the experimental impacts. Results ranged from no fibre damage, to large cracks with
total fibre failure. Both the location and extent of fibre damage for the heavily damaged
specimen could be reproduced numerically. Material properties that are critical for the
modelling were identified. | |
