Characterising the shear resistance of a unidirectional non-crimp glass fabric using modified picture frame and uniaxial bias extension test methods

Kahavita, K. D. H. N., McCarthy, E. D., Zhang, M., Ó Brádaigh, C. M. and Harrison, P. (2023) Characterising the shear resistance of a unidirectional non-crimp glass fabric using modified picture frame and uniaxial bias extension test methods. International Journal of Material Forming, 16(5), 49. (doi: 10.1007/s12289-023-01765-0)

Abstract

The forming behaviour of a unidirectional non-crimp fabric (UD-NCF) consisting of polyamide stitches with a tricot-chain stitching pattern is explored. Notably, there are no stabilising tows orientated transverse to the main tow direction in this fabric, a common feature in many ‘quasi’ UD-NCFs, this allows extension of the stitch in the transverse direction under certain loading conditions. The lack of stabilising tows introduces a possible low-energy deformation mode to the UD-NCF, which is absent in biaxial fabrics and to a large extent in ‘quasi’ UD-NCFs. The in-plane shear behaviour is initially investigated using both standard ‘tightly-clamped’ picture frame tests and uniaxial bias extension tests. Preliminary results show a dramatic difference in results produced by the two test methods. During the picture frame test, fibres can be subjected to unintended tension due to sample misalignment in the picture frame rig. To mitigate error arising from this effect, the picture frame test procedure is modified in two different ways: by using an intentional pre-displacement of the picture frame rig, and by changing the clamping condition of test specimen. Results show that the modified picture frame test data contain less error than the standard ‘tightly-clamped’ test but also that the shear stiffness of the UD-NCF is notably lower when measured in the bias extension test compared to the picture frame test, mainly due to the difference in loading conditions imposed during the two tests.

• Item Type: Articles
• Additional Information: The authors wish to thank the National Manufacturing Institute Scotland (NMIS) for funding this project and the industrial sponsor Johns Manville (USA) for co-funding, supplying the fabrics used in the study, and sharing a wealth of expert advice and knowledge.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Kahavitage Dona, Himanthi Nimrekha Kahavita and Harrison, Dr Philip
• Authors: Kahavita, K. D. H. N., McCarthy, E. D., Zhang, M., Ó Brádaigh, C. M., and Harrison, P.
• College/School: College of Science and Engineering > School of Engineering > Systems Power and Energy
• Journal Name: International Journal of Material Forming
• Publisher: Springer
• ISSN: 1960-6206
• ISSN (Online): 1960-6214
• Published Online: 19 July 2023
• Copyright Holders: Copyright © 2023 Crown
• First Published: First published in International Journal of Material Forming 16(5): 49
• Publisher Policy: Reproduced under a Creative Commons License