use of ETFE foil is becoming more common as a component
of cladding systems. ETFE cushions provide a lightweight,
cost effective and geometrically flexible solution with
good thermal performance and high transparency. They
are typically installed within special aluminium boundary
profiles, which are in turn supported by steel, timber
or bi-directional cable nets.
thickness between 50 and 250 microns are usually employed
in 2 or 3-layer cushion construction with a constantly
maintained air pressure between 200 and 750 Pa. This
pressure may be automatically increased to support higher
of the high strain characteristics of ETFE foil it is
possible to install a flat unstressed membrane into
a planar boundary frame and develop the rise of the
cushion to approximately 10% of its span solely through
elastic strain of the material under inflation. This
no longer works satisfactorily when a higher cushion
rise is required to reduce stresses under load, or when
the boundary frame is curved or warped.
have developed unique software for the patterning of
ETFE foil cushions. This permits the development of
wrinkle free surfaces, even when inflated within highly
non-planar boundary frames.
load analysis the variation of pressure within the cushion
must also be considered, especially for load cases with
a combination of wind pressures and suctions. The inTENS
software has options to specify constant pressure, constant
volume or constant mass of air within a closed cell
during its 3D finite element analysis.