The Liverpool Metropolitan Cathedral is the Roman Catholic Cathedral in Liverpool. It was constructed between 1962 and 1967, to the 1959 competition winning design of Sir Frederick Gibberd. The roof of the building is crowned by a tapering lantern formed from coloured glass adhered by means of an epoxy-based mortar. This construction method was experimental and at the forefront of the technology of the period. Soon after opening, the Cathedral began to exhibit flaws in detailing and construction. Leaks through the glazed lantern, between the epoxy and the glass, were observed. Therefore, the effects of outdoor exposure on the stability and strength of the used epoxy was assessed. Accelerated ageing tests allow the prediction of the effects of weathering and the state of degradation of the mortar used in the LMC in an expedited manner. Since a limited amount of original material from the cathedral is available for testing, a replica mortar was made. After a performed material analysis, the original epoxy/sand/carbon black mortar formulation was replicated. This replica mortar as well as the original mortar core samples were used to undertake accelerated ageing tests (e.g. by moisture, UV exposure and elevated temperature). This was followed by mechanical tests on the replicated specimens, to observe changes in structural integrity and adhesion. The link between the original and the replicated material was made with various chemical analysis, such as FTIR, DSC, DMA and XPS. The generated data showed evidence on that the likelihood of major structural loss is small, within the undertaken testing period. The loss of adhesion is attributed to high relative humidity. Changes in the chemical and physical properties of both materials is difficult to observe. The high filler content in the epoxy may hinder physical changes substantiality. ... Read more

The development and production of carbon fiber reinforced plastic (CFRP) exterior parts with Class-A surface finish in the automotive industry comes with challenges. Next to the structural design of the components, the surface quality as well as the joining technique to the body-in-white and the Mercedes-AMG specific factory integration into the worldwide production lines of the Daimler AG need to be considered.
The aim of the thesis was to experimentally qualify an in-house developed open-mold polyurethane injection bonding technology to produce and bond a subframe structure in one process to the inside of a modular CFRP roof with Class-A surface finish. The qualification was done by means of experimental material and process verification and in close collaboration with the adhesives team at Daimler AG Sindelfingen. ... Read more

The use of fibre reinforced composite polymeric materials for primary helicopter structures has been increasing over the last decades due to their attractive properties; high performance and lightweight inducing more fuel savings than their metallic counterparts. With respect to the joining methods; structural adhesive bonding is preferred when cost and weight are important factors. The qualification of a bonded joint requires the determination of its durability and reliability of the bond strength, but due to the possible degradation of adhesives under certain environments, the lack of a failure criterion and in view of safety consideration, adhesive joints tends to be ‘overdesign’, resulting in an increase of weight and manufacturing costs.
The present project aims to evaluate and investigate the adhesive performance of carbon fibre reinforced PPS; a reinforced high performance thermoplastic qualified in Airbus and already used on certain structural parts of the helicopter. The surface topography and chemistry were evaluated using an optical microscope, XPS and contact angle measurements before and after two surface treatments; hand sanding and grinding. Adhesive joints were manufactured to analyse its single lap shear (SLS) strength and fracture energy, GIC using three different adhesives and two environmental conditions.
Both surface treatments increased the surface energy, but while sanded samples showed an increase of the dispersive component, APP increased to a large extent the polar part. In addition, after hand sanding the morphology of the surface was modified. For most of test configurations, the specimens failed at the interface, however plasma treated samples showed higher values of lap shear strength and fracture toughness energy.
An accelerated ageing condition was simulated by the storage of the samples in a climate chamber at high temperature and humidity. The effect that these environmental conditions had on the adhesion performance depended to a large extent on the adhesive used; in this case all of the adhesive studied showed different trends on the adhesion properties; the epoxy adhesive designed to withstand high temperatures did not present any effect on the adhesive performance but a common epoxy for structural application showed a softening of the adhesive and therefore a decrease on the shear strength but an increase of the fracture toughness and with respect to polyurethane adhesive, the interface was degraded changing the failure from mixed to adhesive mode.
Finally, CF-PEEK samples were tested in single lap shear after these two surface treatments, showing better results than PPS with the same working parameters. However, some configurations still failed at the interface.
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