Paper number 728

VARIATION IN COMPOSITE TENSILE PROPERTIES DUE TO BIAXIAL DEFORMATION OF KNITTED GLASS FABRICS

K.H. Leong¹ , O.A. Khondker² and I. Herszberg

1Cooperative Research Center for Advanced Composites Structures Ltd
506 Lorimer Street, Fishermens Bend, VIC 3207, Australia.
2Sir Lawrence Wackett Centre for Aerospace Design Technology, Royal Melbourne Institute of Technology, GPO Box 2476V, Melbourne, VIC 3001, Australia.

Summary

In the present study, the effect of simultaneously deforming a weft-knit Milano rib fabric on the overall composite tensile properties has been studied for a number of wale- course stretch ratios. It has been found that the tensile modulus, strength and strain-to-failure are all affected to varying degrees by fabric deformation. It is interesting that, contrary to uniaxial deformation, fabrics undergoing simultaneous deformation in both the wale and course directions do not exhibit significant change in the knit structure. Nevertheless, it is believed that the changes in mechanical properties are related to the re-distribution and re-orientation of the fibres resulting from stretching the fabric, thereby altering the relative contents and/or directionality of the fibres in the composites. Further, failure of the knitted composite are concentrated at the highly stressed crossover points of a knit structure, where stretching could unlock or, alternatively, further increase the induced stresses at these point thereby affecting the overall strength of the composite.

Keywords

knitted preforms, textile composites, tensile properties, biaxial deformation, fractography.