JEC COMPOSITES MAGAZINE - Issue #144 - January/February 2022 - 52

TECHNOLOGY AFP
lnstrumented and shape-adaptive propellers
using advanced carbon composites with AFP
GanGadHara pruSty,
PhD MIEAust FRINA
Professor, UNSW Mechanical &
Manufacturing Engineering
Director, ARC Training Centre for Automated
Manufacture of Advanced Composites
UNSW Sydney
A
n exceptional benefit of FRP composites for propeller applications
is their bend-twist coupling characteristics - the ability of
a composite structure to twist under a pure transverse bending
load. This bend-twist coupling is very beneficial to marine propellers
as it allows passive pitch adaptation under varying flow speeds, leading
to efficiency and performance improvements. Propellers with such
bend-twist ability are known as shape-adaptive propellers.
Full-scale hydrofoil design with
embedded optical fibre sensors
With the aim to develop such high-performance propellers for
future marine vessels, the ARC Training Centre for Automated
Manufacturing of Advanced Composites AMAC, in collaboration with
Defence Science and Technology Group's (DSTG) Maritime Division,
designed and manufactured a 1.35 m-long composite hydrofoil using
automated fibre placement (AFP) at the Automated Composite
Laboratory of the University of New South Wales (UNSW). This firstin-the-world
hydrofoil AFP manufacture received the JEC Asia 2019
Innovation Award in the Marine category (Figure 1). The hydrofoil
design comprises two main components: the " core " and the " skin " . The
core is made of glass-fibre/epoxy to minimise manufacturing costs,
whereas the skin is a 96-layer carbon/epoxy prepreg laminate wrapped
around the core using AFP. The precise control offered by AFP in
laying the prepreg at specific fibre orientations accurately allowed
for the introduction of tailored stiffness distribution into the passive
shape-adaptive structure. Another innovative feature of this composite
hydrofoil is the integration of distributed optical fibre sensors, which
were embedded inside the hydrofoil during the manufacture. These
fibre sensors provide valuable information while monitoring strains
and evaluating the operational performance of the structure. The information
gathered from distributed sensors while the component is
in-service is indeed vital to validate the design and complete certification
processes.
Fig. 1: 2019 international composites event,
JEC Asia: Innovation Award Ceremony in Seoul, Korea
52 jec composites magazine / N°
Innovative design and manufacture
offer cost and performance advantages
This hydrofoil design offers to reduce cost, increase productivity and
flexibility, improve quality and increase customers' confidence towards
composite products. The use of a fibre-reinforced plastic (FRP)
composite allows for a significantly lighter weight (75%) hydrofoil
compared to a similar metallic structure. This lightweight improvement,
combined with the shape-adaptive design, increases propulsion
efficiency and reduces fuel consumption significantly for maritime
vessels. Due to the use of FRP composites, a high resistance to fatigue
and to the harsh marine environment can be achieved, and thus longer
component life can be expected. In addition to the improved quality
offered by the hydrofoil design, the use of AFP technology also ensures
cost-effective (less labour) and efficient (less waste and production
time) manufacturing processes. In-situ monitoring via integrated
sensors during manufacture and operation will help to detect faults or
damages in the early stages of manufacture, prompting cheaper repairs
and more reliable products (Figure 2).
144 January - February 2022
A growing interest in the application of fibre-reinforced polymer
(FRP) composites in marine structures has led to high-performance
composite propeller designs, which are usually made of nickel aluminium
bronze (NAB). This interest is mainly driven by the favourable
properties of FRP composites such as lightweight, high strength and
better fatigue and corrosion resistance.
JEC COMPOSITES MAGAZINE - Issue #144 - January/February 2022

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