This thesis first reviews, and then evaluates, the importance of fibre/matrix interfacial bonding in determining composite properties with particular reference to unidirectional E-glass reinforced vinyl ester systems. The potential of various non-destructive evaluation (NDE) techniques for determining the correlation between fibre treatment and bulk composite properties (such as interlaminar shear strength and tensile strength etc.) are described in detail. Acoustic Emission (AE) in particular is demonstrated to be useful in studying the process of damage during the mechanical tests. Some samples are also examined by optical and scanning electron microscopy, dynamic mechanical analysis, and by a new and novel technique known as Sound Image Analysis (SIA) which allows the total spectrum of crack sound output to be analysed. Overall it has been established that the NDE techniques used can distinguish between different levels of interfacial bond strength and that AE can follow the progressive changes in fracture mode that follow from fibre surface treatment variations.

Polymeric composites are used widely in modern industry. The prediction of mechanical behaviour of these material under different loadings is therefore of vital importance in many applications. Mathematical modelling offers a robust and cost effective method to satisfy this objective. In this project a comprehensive finite element model for particulate and fibre reinforced composites is developed. The most significant features of this model are: The inclusion of slip boundary conditions: The inclusion of flux terms across the inter-phase boundaries to take the discontinuity of the material properties into account in the model: The use of penalty method in conjunction with Stokes flow equations which allow the application of the developed model to solid elasticity analysis as well as creeping viscous flows. The predictions of this model are compared with available theoretical models and experimental data. These comparisons show that the developed model yields accurate and reliable data for composite deformation.

This study comprised five clinical trials in children and young adults, and a series of supporting laboratory investigations. The first trial compared a second generation glass polyalkenoate cement with amalgam as a restorative material in the deciduous dentition. The glass polyalkenoate material underwent a more rapid loss of anatomical form and marginal integrity, and also had a higher failure rate than amalgam. The second trial compared a minimal composite restoration/ fissure sealant technique with a conventional amalgam restoration as treatment for occlusal caries in permanent molars. Although there has been some loss of anatomical form and marginal integrity of the amalgam restorations, and loss of the fissure sealant component of the composite restorations, only 11 amalgam and 8 composites have failed. There was no statistical difference in terms of failure between the two techniques. The third trial involved a study of glass polyalkenoatecomposite resin class II sandwich restorations in premolar and molar teeth. Results showed that a layer of glass polyalkenoate cement brought out to the approximal tooth surface in the box areas was not a reliable method of restoration and certainly not a solution to cervical gap formation found with composite resins alone in the class II cavity. The fourth trial involved a study of a microfilled composite resin veneer technique for improving the aesthetics of anterior teeth. Results showed a low failure rate and high patient satisfaction over a 30 month period. The fifth trial involved the use of a hydrochloric acid—pumice abrasion technique for removal of superficial enamel stains. The technique was quick and easy to perform, and results were impressive. Patient satisfaction and appreciation was very high. Laboratory investigations were largely centred around the use of glass polyalkenoate cements in the sandwich technique. Results showed that etching of glass polyalkenoate cement with acid gave no advantages over a simple wash with water, prior to bonding to composite resin. Also that etching before the manufacturers recommended time, and failure to use an unfilled intermediate resin resulted in a poorer bond between glass polyalkenoate cement and composite resin.

Carbon fibre composites are increasingly being used in aircraft structures due to their superior physical and mechanical properties. The process of drilling of carbon fibre composites in aircraft manufacture is economically important since the extremely abrasive nature of the fibres limits drill life. The hole quality produced by drilling in terms of fibre pullout and matrix cracking affects the notch sensitivity of the hole. The present thesis describes an experimental and analytical study of drilling of the carbon fibre composites carried out with the support of British Aerospace (Military Aircraft Division). Full drill life testing was carried out using four low cost commercial cemented carbide drills, three of which had brazed inserts, and drill life was determined by measuring the outer drill corner wear. Hole quality was measured in terms of diametrical tolerance using accurate plug gauges. Drill forces were measured using a two component Kistler dynamometer and attempts were made to measure residual stress in the workpiece using the birefringent photoelastic technique. The hole quality was related to drill wear, cutting forces and heat generated during drilling. Independent tasks were carried out to relate cemented carbide physical and mechanical properties to wear using several standard sliding wear experiments. Three different cemented carbide tool materials were investigated in terms of cobalt layer thickness, carbide distribution and physical properties including hardness and fracture toughness. Independent sliding wear tests were performed using a Pin-on-Disc machine, lathe and machining centre. These tests allowed the materials to be ranked in terms of wear resistance when rubbing against carbon fibre composite. The fracture toughness was measured using the techniques developed by Palmqvist. The wear resistance was correlated to the physical and mechanical properties of the tool materials. Hole quality was studied experimentally using scanning electron microscopy and fibre pullout shown to be primarily dependent on the fibre-matrix interface bond strength and the intrinsic strength of the fibres. The surface morphology of the fractured fibres in areas of fibre pullout showed inultimode damage due to anisotropy of the carbon fibre composite and the dynamics of drilling. The degree and pattern of damage developed in the drilled holes was found to be highly directionally dependent. The experimental results and theoretical analysis showed that the degree of hole damage depends not only on drilling parameters but also on the material composition and the manufacturing process of the carbon fibre composite.

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Thesis (M.S.)--University of Alabama at Birmingham, 2007. / Description based on contents viewed Feb. 4, 2008; title from title screen. Includes bibliographical references (p. 77-81).

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (p. 95-99).

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 72-75). Also available via the Internet.