title: Marine applications for structural adhesives
Creators: name: Knox, Esther M.
Publisher: name: University of Glasgow
Year: 1996
Subjects: subject: Naval engineering.

description: Modern structural adhesives are now available that are potentially suitable for the bonding of both metallic components and fibre reinforced polymer materials for structural marine applications. Pultruded grp specimens are increasingly available which together with mass produced grp panels form the building blocks for a wide range of fabricated composite polymer structures. The trends in advanced marine technology are to make greater use of prefabricated components. A major problem in the use of polymer composite materials for large structures is the joining of sub assemblies and laminate panels. This thesis considers the understanding and development of the use of bonded structures and adhesive applications in the offshore and marine industries. The study includes the production, thermal and fatigue performance of bonded grp components and the problem of butt joining of laminates as well as the performance of steel sandwich structures. The results of a small scale experimental study of various detailed design options for panels are supported by finite element analysis. The discussion highlights the advantages and disadvantages of various types of butt joints. Possible failure mechanisms are discussed and include a ranking of joining methods with respect to the strength of the basic laminate. Sandwich panels offer a practical substitute for traditional stiffened plating and, with careful consideration of face and core parameters may be more structurally efficient than stiffened single skin structures. Both analytical and experimental techniques were utilised to study the performance characteristics of steel corrugated core sandwich beam elements under static and fatigue loading. Comparisons between the viable alternative fabrication methods showed adhesive bonding to be very acceptable, especially where structures are subjected to fatigue loading. Transverse to the corrugations, the failure modes are complex and dependent on the combination of geometry of the face and core material. The performance of the necessary bonded joints is particularly influenced by the type of the adhesive used and the form of surface preparation prior to bonding. Small scale experiments have highlighted the importance of suitable surface preparation to promote short term static strength and durability. Investigation of the effect of aging in a wet environment is particularly important in a marine environment as a major concern is the sensitivity of the adhesive to the effects of water. The research has shown that a primer can make an important contribution to both the strength and durability of the joint. Other factors influencing overall joint performance are the type of surface preparation chosen for the substrate, geometric details including joint orientation, spew fillet removal and load. Adhesion at the interface between the adhesive and substrate and also bulk adhesive hydrolytic degradation were also investigated to determine the rote each has in influencing the overall durability of an adhesively bonded connection. A novel form of test was successfully developed to rapidly grade the adhesion durability performance at the interface. The results of this research should improve confidence regarding adhesive bonding of materials of types, sections and sizes suitable for marine structures.