EurOCEAN 2000 - Vlaams Instituut voor de Zee

OBJECTIVES:
The aim of the project is to advance European capability in the design and manufacture of
pressure resistant structures using fibre reinforced plastics (FRP), for applications in the oceans
which include unmanned platforms, autonomous underwater vehicles, benthic landers, drifting
floats and instrument housings.
The first objective is to advance capability is design procedures and tools for thick section FRP
materials, to enable the manufacture of reproducible and reliable structures. The second
objective is to demonstrate this capability by manufacturing an all FRP pressure resistant
housing having a 2,000 metre operational depth capability. The chosen focus being a pressure
housing for an autonomous underwater vehicle (AUV). The third objective is to establish the
long-term integrity of FRP structures in the working environment, which is vitally important in
a wide variety of applications. Within the project consideration will be given to extending the
design tools and technology to depths up to 6,000 metres.
Success in meeting these objectives will strongly promote the use of weight- and cost- efficient
FRP structures in future industrial and research applications in the deep oceans.
The project seeks to build on present knowledge and draws on the expertise gained by the
participants in both national and EC funded programmes involving research on FRP materials
in the following areas:
- structural design
- fabrication techniques and quality assurance
- testing and test procedures
- system failure modes
- theoretical modelling and analysis
- operational requirements
Methodology:
As stated the focus of the project is a FRP pressure housing for an AUV, comprising of a
central cylindrical section with dome end closures. Obviously there are a number of promising
fibre reinforced composite materials and some recent developments, such as hollow fibres –
thermoplastic matrices, which may be suitable for high performance AUV hulls and deep
ocean structures. However, the commercial availability, costs and fabrication risks rule out the
use of these materials at the present time. It was therefore decided early on to utilise carbon
fibre reinforced epoxy and a monocoque hull design. The central cylindrical section being
fabricated by the filament winding process with the end-domes fabricated by resin trasnfer
moulding or filament winding. While frame stiffened hulls or sandwich structures may be more
efficient in the longer term, the lack of experimental data, limited design tools and risks
associated with the fabrication processes along with the budgetary and timescale constrains
rule out the use of these construction techniques in this project.
The project involves the design, fabrication and inspection, modelling, testing and analysis of a
number of small-scale (175mm internal diameter) and large-scale (450mm internal diameter)
cylinders and end-domes.
The design of the small-scale cylinders and their end-closures, as well as the design of the
large-scale cylinders will be performed using both analytical and numerical modelling tools.
The numerical tools will allow modelling of the actual material lay-up of both the cylinders
and the domes, not only before buckling, but also in the post-buckling path. Buckling loads,
buckling modes and ultimate failure pressures will be calculated. Strains calculated by these
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