Effect of variabilities on mechanical properties of textile composites

Matveev, Mikhail Y. (2015) Effect of variabilities on mechanical properties of textile composites. PhD thesis, University of Nottingham.

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Abstract

This work explores effects of selected sources of variability on mechanical properties of textile composites. Current modelling approaches rely on an idealised representation of the geometry and properties of composites while in reality the properties are not uniform and the structure has local variations. Existing approaches to model these variations showed that they can affect manufacturing processes for textile composites and compressive strength of unidirectional composites. This work is an attempt to extend existing methods for modelling of idealised composites and combine them with stochastic approaches in order to predict variability of strength and Young’s modulus of textile composites.

Three sources of variability were selected for this study: single fibre strength variability, yarn path and layer shift variability. All three were analysed experimentally for selected textile reinforced composites. Statistical models were derived for fibre strength and yarn path variabilities using the experimental data. The effect of layer shift was estimated by means of mechanical testing. A multi-scale framework was developed for modelling of composites with single fibre strength variability, closing the gap between micro- and macro-scale variability. An approach based on a Gaussian random field was successfully employed for modelling of yarn path variability and its effect on mechanical properties of textile composites.

It was found that the variability of single fibre strength introduces small variability in the final composite strength, which results in decrease of the strength with increase of macro-scale length. The variability of yarn paths was found to have minimum effect on variability of Young’s modulus but severely reduces the strength of composites. Layer shift was found to be responsible for changes in the shape of the stress-strain curve.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Long, A.C.
Jones, I.A.
Keywords: Composite materials, Mechanical properties, Carbon fibers
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
Faculties/Schools: UK Campuses > Faculty of Engineering
Item ID: 29419
Depositing User: Matveev, Mikhail
Date Deposited: 12 Jan 2016 09:57
Last Modified: 14 Sep 2016 07:13
URI: http://eprints.nottingham.ac.uk/id/eprint/29419

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