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Title: Multifunctional elastomers with tailored anisotropic response
Author: Stanier, David Charles
ISNI:       0000 0004 6058 2911
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2016
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Traditional engineering design focusses on the load-bearing capabilities of materials, and develops functionality by adding the structure. However, hybridising with functional materials allows non-load bearing capabilities to be integrated, that simplify the design. Material anisotropy can effect this multi-functionality in complimentary ways, however its effects need to be understood. The aims of this study were to produce tailored anisotropy in elastomers, and to investigate the resulting mechanical and magnetic performance. Hence, a combination of experimental testing, and numerical & constitutive modelling were used to analyse the mechanical behaviour. The placement of fibres with a homogeneous magnetic field is demonstrated and described by a simple model. The resulting transversely isotropic elastomers, reinforced by short nickel-coated carbon fibres, are compared to a number of numerical and constitutive mechanical models. Current methods for describing the behaviour of aligned reinforcements assume an inherent anisotropy, analogous to continuous fibre reinforcement, rather than discontinuous reinforcements. However, it is demonstrated that a simple constitutive model can adequately describe the behaviour up to moderate strains (<30%). In addition, a simplified numerical model is shown to represent the behaviour, and could be adapted to investigate complex effects, such as failure and interfacial properties. In addition, the specimens actuate in a magnetic field, due to the nickel-functionalised fibres. The actuation is dependent on the reinforcement angle and is described by a simple model; furthermore, the combination of the magnetic and mechanical models allows the complimentary behaviour of these properties to be described. The multi-functional material could be envisaged in a number of high performance applications, such as the active surface of micro-swimmers & -controllers. However, there are a number of challenges in experimental testing of anisotropic materials that require further investigation. Never-the-less, the orientation of reinforcements could be used to produce bespoke fibre alignments or for through-thickness composite repair.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available