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This thesis is motivated by the use of full-depth, precast, prestressed concrete panels to facilitate deck replacement of composite bridges. The shear pockets required in using convention shear stud connections, however, can cause durability problems. The objective of this study is to investigate the possibility of eliminating the use of shear studs, and adhesively bond the concrete and steel sections. The feasibility of the developed polyurethane adhesive joint is defined based on the serviceability and ultimate limit states. The joint must have sufficient stiffness that additional deflection due to slip must not be excessive. The adhesive and bond must also have sufficient strength to allow the development of the full plastic capacity of the composite section. The use of the developed adhesive joint in typical composite bridges was found to be feasible. The behaviour under live load was found to be close to a fully composite section.

This thesis is motivated by the use of full-depth, precast, prestressed concrete panels to facilitate deck replacement of composite bridges. The shear pockets required in using convention shear stud connections, however, can cause durability problems. The objective of this study is to investigate the possibility of eliminating the use of shear studs, and adhesively bond the concrete and steel sections. The feasibility of the developed polyurethane adhesive joint is defined based on the serviceability and ultimate limit states. The joint must have sufficient stiffness that additional deflection due to slip must not be excessive. The adhesive and bond must also have sufficient strength to allow the development of the full plastic capacity of the composite section. The use of the developed adhesive joint in typical composite bridges was found to be feasible. The behaviour under live load was found to be close to a fully composite section.

Bonding composite structures using adhesives offers several advantages over mechanical fastening such as better flow stress, weight saving, improved fatigue resistance and the ability to join dissimilar structures. The hesitation to adopt adhesively bonded composite joints stems from the lack of knowledge regarding damage initiation and propagation mechanisms within the joint. A means of overcoming this hesitation is to continuously monitor damage in the joint. This study proposes a methodology to conduct structural health monitoring (SHM) of an adhesively bonded composite lap joint using acoustic, guided Lamb waves by detecting, locating and predicting the size of damage. Finite element modeling of a joint in both 2D and 3D is used to test the feasibility of the proposed damage triangulation technique. Experimental validation of the methodology is conducted by detecting the presence, location and size of inflicted damage with the use of tuned guided Lamb waves.

A new adhesive bonding method is introduced for microlamination architectures, for producing low-temperature microchannel arrays in a wide variety of metals. Sheet metal embossing and chemical etching processes have been used to produce sealing bosses and flow features, resulting in approximately 50% fewer laminae over traditional methods. These lamina designs are enabled by reduced bonding pressures required for the new method. An assembly process using adhesive dispense and cure is outlined to produce leak-free devices. Feasible fill ratios were determined to be 1.1 in general and 1.25 around fluid headers, largely due to gaps between faying surfaces caused by surface roughness. Bond strength investigation reveals robustness to surface conditions and a bond strength of 5.5-8.5 MPa using a 3X safety factor. Dimensional characterization reveals a two sigma (95%) post-bonded channel height tolerance under 10% (9.6%) after bonding. Patterning tolerance and surface roughness of the faying laminae were found to have a significant influence on the final postbonded channel height. Leakage and burst pressure testing on several samples has established confidence that adhesive bonding can produce leak-free joints. Operating pressures up to 413 kPa have been satisfied, equating to tensile pressure on bond joints of 1.9 MPa. Higher operating pressures can be accommodated by increasing the bond area of devices. A two-fluid counterflow microchannel heat exchanger has been redesigned, fabricated and tested to demonstrate feasibility of the new method. Results show greater effectiveness and higher heat transfer rates, suggesting a smaller device than the original heat exchanger. A maximum effectiveness of 82.5% was achieved with good agreement between theoretical and experimental values. Although thermal performance was improved, higher pressure drops were noted. Pressure drops were predicted with a maximum error of 16% between theoretical and experimental values. Much of the pressure drop was found to be in the device manifolds, which can be improved in subsequent designs. Fluid flow simulation results show a 45-65X reduction in fluid leakage velocity past sealing bosses, thereby mitigating adhesive erosion concerns. Theoretical models indicate that the worst-case adhesive erosion rate is 1/12th the rate of aluminum and 1/7th the rate of stainless steel, implying satisfactory reliability in high fluid velocity applications. Economic comparison indicates an 83% reduction in material cost and 71% reduction in assembly cost with the new adhesive bonding process, when compared to diffusion bonding for the recuperator investigated in this study. Adhesive compatibility with common refrigerants is reviewed through literature references, with no adverse compatibility issues noted. The findings of this research suggest a fairly quick path to commercialization for the new bonding method. Future studies required to pursue commercialization are liquid and gas permeability evaluations, and long term strength and performance testing of adhesives in targeted applications. / Graduation date: 2012 / Access restricted to the OSU Community at author's request from Mar. 26, 2012 - Mar. 26, 2013

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The thesis is focused on the surface treatment used for the preparation of aluminium alloys for the adhesive bonding. The theoretical part can be divided into three chapters. The first of them deals with aluminium alloys, the second one speaks about the adhesive bonding. The surface treatment itself, especially the conversion coating issues, is discussed in the last chapter. The experimental part is focused on the optimalization of a two-step titanium and zirconium based conversion coating technology. In the first part, the aluminium alloy is analysed by the glow discharge optical emission spectroscopy. The second part of the experiment deals with the first step of the technology, acidic deoxidation. The objective was to examine the influence of the exposure time on the morphology of the alloy surface and the shear strength of adhesive joints. In the last part of the experiment, the conversion coatings are prepared and characterised by the scanning electron microscopy and energy dispersive spectroscopy.

This master’s thesis is divided into two parts. In the first part are these topics: bonding theory, treatment of bonding surface, types of adhesives, adhesives in the transportation industry and construction and stress of bonded joints. In the second part of this thesis is experimental evaluation of the effect of surface of material on strength of bonded joint.

The aim of this master´s thesis is the design chosen for testing bonded joints on the specified galvanized steel sheet in laboratory conditions and obtaining parameters of bonded joints for application in industrial practice. Basic tests for testing bounded joints were presented in the work. Subsequently, two tests were selected and verified in laboratory conditions. The result of these tests are specific numerical values that were compared with values gained during tests linking method clinch.

Structural adhesive bonding offers several advantages over other types of joining. These include improved stress distribution and increased design flexibility. Adhesive bonding is important in aerospace, automotive, and packaging applications. However, the full potential of the technology has not been exploited because the understanding of the basic mechanisms of adhesion and adhesion failure is incomplete. This investigation elucidates the chemical and mechanical mechanisms responsible for durable adhesion of epoxy resins to phosphorus oxo acid treated aluminum alloys. By systematically altering the adherend surface chemistry, surface topography, and adhesive formulation, combined with accelerated testing, the chemical and mechanical factors that influence the properties of adhesively bonded aluminum are isolated and assessed. It is postulated that a combination of two factors determines the strength and environmental durability of epoxy-bonded aluminum. One is the formation of hydrolytically stable, primary bonds between the adhesive and the adherend, and the second is the hydrolytic stability of the surface oxide, which is always present on the surface of aluminum and aluminum alloys. These conditions can best be met by chemical pretreatment of the oxide surface, which renders the oxide insoluble and creates, at the same time, functional surface sites. These sites can form chemical bonds with reactive components of the adhesive. Morphological and mechanical alteration of the metal surface oxide through hydroxide formation requires liquid water. Liquid water can only form by capillary condensation in interfacial gaps from molecularly diffusing water. A hydrolytically stable oxide will prevent bond failure due to mechanical weakening of the substrate surface, while a high density of hydrolytically stable surface bonding sites will minimize the occurrence of capillary gaps at the interface, thus decreasing the formation of liquid water. It is shown that highly chemically active, although not inherently stable, oxide surfaces can provide environmentally stable adhesive bonds. Conversely, certain highly stable oxide surfaces with few chemically active sites provide no environmental stability to adhesive joints, regardless of the topography of the surface. / Ph. D.