Smart Multifunctional Composite Materials for Improvement of Structural and Non-Structural Properties

Abstract

The principal aim of this thesis is to analyse the effectiveness of multifunctional smartmaterials as intelligent structures to improve mechanical properties and activateadditional non-structural features. In order to investigate these multiple aspects, acomprehensive literature review has been presented focusing on the state of the art inmultifunctional and smart materials. From this analysis, five different systems basedon different designing solutions and manufacturing techniques were developed andexperimentally validated.Multiscaled composites are a typical example of multifunctional materials and arebased on the addition of engineered nanoscaled reinforcement to traditionalmesoscopic systems. To test the effectiveness of nanomodification, an experimentalcampaign has been carried out, aimed to the characterisation of a nanocompositeobtained embedding Graphene Nanoplatelets (GNPs) in the polymeric structure ofLow Density Polyethylene films at difference concentrations. Nanoscaled fillers weresubsequently used to manufacture a threephasic multi-scaled composite based on theinclusion of nanometric SiO2 particles in a traditional carbon fabric/epoxy system.Following a different approach, hybrid structures with embedded Non-Newtonianfluids have been manufactured and tested and the results showed that nonlinearviscosity can be exploited to dynamically enhance material properties during animpact event.The possibility to intervene both on structural and non-structural properties has beeninvestigated with another hybrid system, based on the embodiment of Shape memoryAlloys (SMA) wires within a traditional unidirectional CFRP. The study of the impactproperties pointed out that the superelasticity effect and the hysteretic stress/strainbehaviour of the embedded wires reduce the extent of the internal delamination forsamples subjected to low velocity impacts. Moreover, by exploiting the SMAs thermoelectricalproperties it is possible to use the embedded metallic network as a strainsensor by measuring the electrical resistance variation and as an embedded heatsource to be used for rapid thermographic damage location and evaluation.

Date of Award	31 Dec 2013
Original language	English
Awarding Institution	University of Bath
Supervisor	Michele Meo (Supervisor)