Thin-ply thermoplastic composites: from weak to robust transverse performance through microstructural and morphological tuning

TL;DR

This paper enhances the transverse strength of thin thermoplastic carbon fiber composites by microstructural tuning and controlled crystallization, enabling more robust and reliable thin-shell structures for advanced engineering applications.

Contribution

It introduces a novel manufacturing approach for ultra-thin thermoplastic composites and demonstrates significant improvements in transverse performance through microstructural and morphological optimization.

Findings

158% increase in transverse strength compared to thermoset counterparts

Microstructure tuning and isothermal crystallization are key to performance enhancement

Processing sensitivity highlights the importance of precise manufacturing control

Abstract

Thin shell carbon fiber composites have great potential for structures that require large recoverable deformations, high stiffness and low weight, as in deployable space structures, biomedical devices and robotics. Despite being astonishingly flexible in fiber direction, thin shells are highly sensitive to off-axis loading. High sensitivity to imperfections, manufacturing limitations and a missing in-depth mechanical understanding hinders the creation of transversely robust shells. This paper provides crucial insights into the factors influencing the transverse strength of ultra-thin composites using a highly accurate manufacturing technique to produce novel thermoplastic thin-ply (35 {\mu}m) carbon fiber-PEEK plies. The effects of fiber type, microstructure and polymer morphology are addressed. It was found that a combination of microstructure tuning and isothermal crystallization can achieve thin shell composites with a 158% improved transverse performance compared to state-of-the-art thermosets. Moreover, this work outlines the sensitivity to all related processing conditions, highlighting the need for accurate control of all named parameters.