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Title: Numerical simulation of elastic wave propagation in textile composite structures
Author: Thierry, Victor
ISNI:       0000 0004 9355 0502
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2020
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This manuscript presents a novel approach allowing damped ultrasonic wave propagation analysis of textile composite structures modelled at a mesoscopic level (i.e. modelling the yarns and matrix distinctively). Current modelling approaches rely on material homogenisation for analysis at a macroscopic scale and thus overlook the effect of textile architecture on wave propagation. This work aims at predicting wave propagation characteristics in damped textile composite structures and the induced complex phenomena for applications in structural health monitoring. The developed methodology involves mesoscale modelling of a textile composite structure period using a specialised textile modeller for pre-processing as well as conventional finite element methods. This is combined with the periodic structure theory as well as a mode-based reduction method named Craig-Bampton allowing for solving a reduced eigenproblem deriving from the equation of motion. A multiscale approach is used throughout the thesis to enable the comparison of standard wave propagation analysis of composite structures, using homogenised properties, with the more complex analysis proposed in this thesis. The need for this methodology is demonstrated as well as its validity. The first axis of this thesis describes the methodology for undamped wave propagation analysis in textile composites. Its advantages, such as the prediction of complex phenomena and the possible applications, are thoroughly described and issues discussed. Its increased accuracy over macroscale prediction methods is exposed. A second axis of the thesis is experimental validation of the methodology by means of linear scans of waves measured by a laser vibrometer and generated by a piezoelectric transducer in 3D woven composite samples. It is shown that the numerical mesoscale methodology provides accurate predictions. The third axis is the prediction of dispersion characteristics in large layered assemblies of textile composites. An attempt toward homogenisation of textile composites using a dispersion curves inversion technique based on genetic algorithms is proposed for this purpose. It is concluded that complex textile composites cannot be approximated by simple macroscale models. The last axis of the thesis introduces a damping model to predict the frequency dependent loss factor of waves propagating in these textile composite structures. The strong influence of mesoscale architecture over loss factor is demonstrated.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: TA 365 Acoustics in engineering. Acoustical engineering