The compression of anisotropic fibre monofilaments. II

Abstract

A synthetic fibre monofilament was compressed between transparent flats mounted on a microscope stage. The change in the monofilament diameter parallel to the plane of the flats was determined as a function of load for polyethylene terephthalate and nylon monofilaments. These monofilaments can be regarded as transversely isotropic elastic cylinders. A theoretical solution was therefore derived for the change in diameter of a transversely isotropic elastic cylinder compressed between two rigid parallel planes. The solution for the change in diameter in terms of the elastic constants and the applied load was verified experimentally. Measurements of the change in diameter as a function of load were combined with measurements of the width of the contact zone between the cylinder and the upper transparent flat. The results together with subsidiary measurements of extensional compliance and extensional Poisson’s ratio were then used to derive the transverse compliance and the transverse Poisson’s ratio of the monofilaments. This compression problem provides the first reported determination of the transverse Poisson’s ratio for synthetic fibre monofilaments. It is therefore now possible to obtain all five independent elastic constants, four of which are related to the measurements described in this paper. For the sake of completeness, results for the torsional compliance of these monofilaments have been undertaken thus giving complete specification of the elastic properties.