Static Behaviour of Wrinkled Fabrics
Abstract
There is an increasing focus on research for automating the textile industry, particularly for labor-intensive tasks such as fabric manipulation and assembly. The highly flexible nature of these materials makes the automation of such tasks very challenging. Not only are the fabrics difficult to manipulate,but their geometric characteristics are difficult to measure using conventional instrument technology. Accurate ways of measuring the state of the workpiece are needed to provide feedback for system control. This thesis proposes a system for measuring the shape and range of locations for a wrinkle along the length of a fabric strip, based on a measurement of the difference between the total unwrinkled length and the total wrinkled length of the fabric,
A relationship can be established between D Ltotal and the forces
necessary to sustain the wrinkle that corresponds to this
shortened length using Clapp's model for the fabric elastica
and a model of the flat fabric lying on the table. Force
balances which include the frictional force required to support the
wrinkle provide the basis to locate the wrinkle along a spatial
length. 
A non-dimensional variation of Clapp's model shows that
there are many possible solutions, or modes, for a
wrinkle shapethat correspond to one value of D Ltotal,
although the boundary forces will be different for each of these
modes. Each wrinkle shape is unique in the number of
"humps'' it contains. This variation of the model also
shows that as the wrinkle gets taller, an effect similar to
an invertedpendulum is observed as the simulated wrinkle will tend
to lean to one side or the other. These results can be
observed experimentally with actual fabrics. 
This system will
provide a useful measuring tool for industry. The general
solution provided by the non-dimensional model defines the
important relationships between the wrinkle's boundary forces and
the shortened length. Finding the material parameters of a
fabric, which costs only a small initial time investment, provides
the information the general model needs to predict a shapeand range
of locations for a wrinkle in a high speed industrial
environment.
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