Abstract
The fiber-to-fiber contact has been considered to be fundamental problem of micromechanics, since the mechanical properties of fibrous assemblies are largely related to the number of fiber-to-fiber contacts. Also, other important properties of fiber assemblies, such as heat conduction, filtration, electrical conduction, and evaporation, are strongly related to bulk fiber arrangement and pore distribution. However, experimental estimation of the number fiber-to-fiber contacts, which is essential in checking the findings of each theory, is a difficult task. Fiber-to-fiber contact in fiber assemblies plays a crucial role in their electrical resistance. Measurement of compression dependence of electrical resistance of a fiber assembly is an effective method for estimating spatial distribution of fiber-to-fiber contact. We have proposed a method and equation to estimate the number of fiber-to-fiber contacts starting from the compressional properties of the electrical resistance of a fiber assembly. Tests carried with samples of different fiber assemblies, both loose staple fibers and woven or knitted fabrics, clearly showed that compressional properties can be accurately approximated by a power function, as predicted by all actual theoretical approaches. However, experimental power index data of the power function vary in a range from 1.5 up to 3.23, which shows that the problem of fiber-to-fiber contact in fiber assemblies remains complex, and more accurate theoretical approaches are needed to describe the phenomenon.
The electrometrical method that we propose is a valuable tool for estimating fiber-to-fiber contact and experimentally testing theoretical approaches that tend to describe compressional properties of fiber assemblies. However, more detailed and properly designed tests are needed to verify the method.