This work examines the history of industrial fabrics
and investigates how certain of these fabrics have
developed to meet the changing demands of their end-uses.
It also examines how woven textile fabrics are increasingly
competing with the traditional engineering materials as new
fibres and filaments allow an ever increasing range of
properties; improved fabric engineering techniques are also
ensuring that industrial fabrics are more suited to their
end-uses.
To aid fabric engineering a greater knowledge is
required of fabric structure and mechanics, so developments
in this field are examined.
To help improve fabric research of this type,
realistic physical testing methods are required both to
test the usefulness of mathematical models, and to simulate
conditions experienced in use. Due to certain restrictions
of this type of testing, a suitable selective fabric
extension measuring device is required so that problem
areas such as clamping effects can be avoided. The. lack ofa
suitable device to help overcome problems such as this
has been a long standing difficulty, so the development of
a new fabric extension gauge was one of the main objects of
this work.
Before such a device could be developed research first
involved a survey of many of the previous extension
measuring devices, however, as expected nothing suitable
emerged. After considering many ideas for possible new
devices, it was decided to try and develop a gauge using
the relatively new material PVDF piezo polymer film. This
is a thin, low modulus film which develops an electrical
charge proportional to a CHANGE in mechanical stress, and
which can be easily cut to any desired dimensions. Initial
attempts to develop a suitable extension measuring device
were not completely successful, but when suitable following
circuitry was found, and a proper mounting procedure
determined, the new gauge appeared very promising.
When it was considered that a suitable extension
measuring device was available, the next task involved the
design of a biaxial tensile and shear testing machine for
the new Clothworkers' Textile Hechanics and Structures
Laboratory. It was considered that the availability of a
suitable selective extension measuring device was of
paramount importance before the design of the new tester
could be considered. This apparatus was based essentially
on, the proven principles of Yendell's and Bassett's
testers, but a number of unique features were to be added,
such as independently controlled clamps, and the ability to
cycle in shear. The principles involved in the design of
the mechanical hardware are described, as also are certain
original recommendations which have been suggested for the
second stage of the project in which the sophisticated
control, measurement and analysis techniques will be
developed.