The Intra-Ply Shear Behaviour of Non-Isothermal Thermoplastic Composite Laminates

Street, George E.; Johnson, Michael S.

Abstract

During the thermoforming of fibre-reinforced thermoplastic (FRTP) organosheets, the desire to minimise tool temperatures leads to non-isothermal temperature profiles through the laminate thickness. The aim of this study was to understand the influence of these non-isothermal conditions on FRTP intra-ply shearing. Novel non-isothermal bias extension tests were conducted, revealing that an average between the isothermal shear curves of both laminate faces approximately represented the respective non-isothermal condition. However, these findings were irrespective of FRTP thickness, and only applied to laminates that wholly remained above the crystallisation onset temperature. Upon the onset of crystallisation in a single ply, the non-isothermal shear resistance skewed heavily towards that (within 5%) of the crystallised ply and inhomogeneous shear angles were observed. Non-isothermal thermoforming validated these findings with the presence of wrinkles on non-isothermal hemispheres in which a single ply had reached crystallisation. This reaffirms the importance of accurate thermal monitoring during FRTP processing.

• Journal Article Type: Article
• Acceptance Date: Sep 28, 2023
• Online Publication Date: Oct 13, 2023
• Publication Date: 2023-10
• Deposit Date: Nov 1, 2023
• Publicly Available Date: Nov 2, 2023
• Journal: Journal of Composites Science
• Electronic ISSN: 2504-477X
• Publisher: MDPI
• Peer Reviewed: Peer Reviewed
• Volume: 7
• Issue: 10
• Article Number: 432
• DOI: https://doi.org/10.3390/jcs7100432
• Keywords: thermoplastic resin; bias extension; mechanical testing; forming; carbon fibre; characterisation
• Public URL: https://nottingham-repository.worktribe.com/output/25956780
• Publisher URL: https://www.mdpi.com/2504-477X/7/10/432
• Additional Information: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).