Case Study
Composite
Wingsail Design
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Linear static
analysis of leading section, spar and connecting strip
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Viewing of
stresses in individual laminae
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Cowin failure
criteria showed where design could be improved
Designed using aerospace technology, the 13.65m high wingsail is made
from layers of glass and carbon fibre surrounding a Nomex-type core. The trailing section
or 'wing' is separated from the leading section or 'flap' by an air directing slat. Upper
and lower booms connect both of these sections to the tail. The whole assembly is mounted
on a large diameter ring bearing allowing a precise and constant angle of attack to the
wind to be obtained.
To
analyse the new wing design a 3D FE model was created in LUSAS Composite using 8
noded quadrilateral thin shell elements from DXF and additional coordinate data. To match
the method of fabrication the model was divided into 3 main parts: a leading section, a
spar section and a strip section that bonds the leading and spar sections together. To
achieve the specified composite structure, 17 different geometry and composite data sets
were created for each of the 3 main parts of the model with each composite dataset
containing detailed information about layup sequence, material orientation and relative
thickness of the layers. By using LUSAS Composite, lay-ups can be defined
independent of the component to be analysed and the lay-up orientation and sequence can be
viewed visually, giving a fast and accurate model definition.
Four loadcases, consisting of a UDL acting on the upper 12.8m of the trailing
section; inertia forces in the trailing section itself; and upper and lower boom forces
applied as concentrated loads 8.2 and 0.75 m from the bottom of the trailing section were
used to arrive at a resultant load combination for the analysis. The linear static stress
analysis gave excellent results. By using the extensive LUSAS results processing
facilities principal stresses in each composite layer could be viewed. Stresses
perpendicular to the material orientation were generally low with the exception of the
transition area near the base of the wing where, as could be expected, some areas of high
stress were found where rapid changes in geometry took place. By applying Cowin failure
criteria to the composite structure, areas where the design could be further
optimised
were highlighted.
"By using
LUSAS Composite for this analysis Walker Wingsail Systems were able to go into the prototype build
stage with enhanced confidence in a very satisfactory lighter
design."
Other LUSAS Composite case
studies:
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Software Information
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