The transverse compression of anisotropic fibre monofilaments

Abstract

A synthetic fibre monofilament was compressed between transparent fiats mounted on a microscope stage, and an image of the contact area thrown onto a screen. The contact area was determined as a function of load for polyethylene terephthalate, polypropylene and nylon monofilaments. These monofilaments can be regarded as transversely isotropic elastic cylinders and show considerable anisotropy, the extensional modulus being at least six times the transverse modulus. A theoretical solution was therefore derived for the contact area of a cylinder compressed between two rigid planes when the cylinder is a transversely isotropic elastic body. The solution is given in terms of the elastic constants, the radius of the cylinder and the applied load and was found to hold experimentally. The theory was used together with measurements of Poisson’s ratio and extensional modulus to derive the transverse modulus of the filaments from the compression experiments. In polyethylene terephthalate and polypropylene the calculated moduli are in reasonable agreement with those obtained directly from uniaxially oriented films.