Application of Sonic Wave Theory to the Measurement of the Dynamic Elastic Moduli of Woven and Knitted Fabrics

Abstract

The dynamic elastic modulus is one of the fundamental properties of textile materials and also one of the most difficult to quantify. The development of sonic methods to measure this property results in a test that is simple and nondestructive as well as being independent of sample cross-sectional characteristics. A brief survey of the literature based on this technique reveals both the limited application of theory and also the limited range of test samples and conditions that have been treated, especially in the fabric area. The fundamental theory of dynamic modulus measurement and the theory of sonic wave propagation is developed in this paper and is applied to series of laboratory- produced and commercially-produced fabrics. Three separate series of experiments are undertaken to quantify the effects of fabric parameters (i.e. yarn crimp, degree of set, and fiber diameter) and yarn on the principal dynamic elastic moduli and the dynamic shear modulus for both woven and knitted fabrics. These experimental results show that the method predicts the configuration of fibers in fabrics and yarns. The indications are that this work can be expanded by the use of microprocessors and computers to predict fabric specifications from fiber and yarn properties. The application of this technique to quality and process control is also discussed.