Interlaminar toughening approaches for additively manufactured liquid crystal polymers

Master thesis (2023)

Authors

B.C. Ulyanov Aerospace Engineering

Contributors

K. Masania Aerospace Manufacturing Technologies - Aerospace Engineering (supervisor 1)
C.C.M.C.A.G. Houriet Aerospace Manufacturing Technologies - Aerospace Engineering (supervisor 2)
Faculty
Aerospace Engineering
Copyright: © 2023 Boris Ulyanov
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Published Date

10-11-2023

Language

English

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Faculty

Aerospace Engineering

Abstract

Liquid crystalline polymers have recently attracted attention for their great tensile properties. However, their interlaminar fracture toughness is low. To solve this, toughening approaches inspired by Nature are applied, exploiting the shaping freedom of fused deposition modelling. Three approaches are studied: the matchstick approach, z-pinning and sawtooth layers. Their effectiveness in increasing the Mode I interlaminar toughness of the material is evaluated through compact tension tests.

These tests reveal that z-pinning fails to increase toughness, while the matchstick approach and especially the sawtooth layers have a beneficial effect. The matchstick approach increases the interlaminar toughness of Vectra A950 by strengthening fiber bridging, a toughening phenomenon natural to the material. The sawtooth layers stall crack growth through geometry, but also trigger fiber bridging more reliably and postpone fibre tearing. This synergy quadruples the toughness. These two methods prove that bio-inspired structures are an excellent way to provide toughness in additive manufacturing.