Professor James G Broughton

Cavitation erosion is a major challenge for marine and fluid machinery systems. This study investigated the erosion performance of two as-cast aluminium alloys exposed to acoustic cavitation in water at temperatures of 10–50 °C and those were then compared with an extruded wrought alloy tested specifically at the temperature of maximum erosion. The results showed that the as-cast A380 alloy displayed exceptional resistance to cavitation erosion, with the lowest mass loss and surface roughness. This finding suggests that the as-cast A380 alloy is a suitable choice for lightweight, high-performance components in applications where cavitation resistance is critical.

The specification and use of recycled carbon fibre composites require the generation of reliable data that gives a comprehensive description of the material. Our research dealt with an experimental study of recycled, discontinuous, needle-punched, non-woven carbon fibre/epoxy composites. The property-constituent relationships of these composites require the adaptation of testing practices, coupled with an understanding of their failure mechanisms. The objective was to define a test protocol to determine their shear load limits. Four interlaminar shear test methods were investigated, namely, Short Beam Shear, Double Notch Shear, Double Beam Shear and Iosipescu Shear. A modified Iosipescu shear specimen provided a stress state in the composite that was much closer to pure interlaminar shear than that observed with other test methods. Identification of the weakest shear plane and re-fabrication of the test geometry enabled consistent interlaminar shear failures using the Iosipescu test method. We found that the shear behaviour was dependent on the internal fibre architecture of our particular material, thus enabling potential optimisation of such composites.

The objective of the present study is to describe the progressive debonding of inclusions in particle or fibre reinforced composites. To do so, the mean-field homogenisation scheme of Mori-Tanaka is enriched to take into account imperfect interfaces. The interfaces are modelled by a bilinear Cohesive Zone Model (CZM) taking into account normal and tangential effects. Results obtained with this new mean-field homogenisation scheme are compared to 2D FE-based numerical simulations that are used as reference results. The effects of inclusions volume fraction and size are also observed.

The present study aims at describing the debonding phenomenon of a particle embedded in an elastic matrix. Two types of fracture mechanics approaches are developed and compared in this context. The phenomenon is analytically described using a finite fracture mechanics approach, while numerical simulations are performed using a cohesive zone model to describe the decohesion process. Both methods rely on two mechanical parameters: the interface strength, σmax and the fracture energy, Gc, of the interface. Both modelling approaches produce results that show larger particles tend to debond before smaller ones although noticeable differences are observed, especially concerning the relationship between the critical load and the particle radius: in the framework of the FFM, the critical load is inversely proportional to the square root of the particle radius, while when using CZM, the critical load is inversely proportional to the particle radius.

The recycling, recovery and reuse of End-of-Life Vehicles (ELVs) has raised worldwide 

concerns. This paper identified drivers for new joining solutions in the automotive 

industry and specifically reviewed current use of adhesive technology. From an ELV 

recycling point of view, rapid assembly and disassembly joining solutions were identified 

as key technology drivers. Innovations in adhesive disbonding technologies were 

reviewed and suggestions for the most promising future disbonding technologies have 

been proposed.

The recycling, recovery and reuse of End-of-Life Vehicles (ELVs) has raised worldwide concerns. This paper identified drivers for new joining solutions in the automotive industry and specifically reviewed current use of adhesive technology. From an ELV recycling point of view, rapid assembly and disassembly joining solutions were identified as key technology drivers. Innovations in adhesive disbonding technologies were reviewed and suggestions for the most promising future disbonding technologies have been proposed.

The study presented in this paper was carried out to assess the use of an embedded process zone based model in a commercial finite element code for predicting the behaviour of adhesively bonded structures. The relevant adhesive properties were measured using a variety of test methods and the results applied to the analysis of a single lap joint. Having demonstrated satisfactory accuracy in simulating the behaviour of the single lap joint the same methodology was then applied to a more complex structure. The structure used was a T shaped structure formed from two adhesively bonded aluminium rails. Despite some variability in the test results acceptable correlation with the analysis results was again achieved. The effects of variability in the adhesive material data on the output from the Finite Element analysis were investigated using a statistical study. This showed only a limited sensitivity to the interface toughness parameter

Long-term durability of a structural adhesive joint is an important requirement, because it has to be able to support the required design loads, under service conditions, for the planned lifetime of the structure. Epoxy adhesives, whilst not ideal, are currently the best family of adhesives for in situ repair operations. As long as the bonded joint remains dry and unexposed to high service temperatures, epoxy adhesives produce strong bonds to timber. However, once they are exposed to severe stresses as a result of repeated water soaking and drying cycles, the bonded joint delaminates and does not fulfill the requirements for structural timber adhesives intended for exterior exposure. One way of improving bond durability is through the use of surface treatments prior to bonding. In this study, the effects of corona discharge surface treatment, hydroxymethylated resorcinol (HMR) and γ-glycidoxypropyltrimethoxysilane (GPMS) adhesion promoters on the durability enhancement of pine, iroko, and oak bonded joints were evaluated. The results proved that surface modification methods for adhesion promotion can be adapted to cellulosic substrates with significant improvements in bonded joint durability

Rehabilitation of timber structures - preparation and environmental service condition effects on the bulk performance of epoxy adhesives Epoxy adhesives have been used for many years in the rehabilitation of timber structures and are currently the most appropriate adhesive type for on-site operations. However, because they exhibit excellent initial joint strength when tested in standard climate conditions, there has not been a major concern about their service durability. In order to contribute to the ongoing discussion on the reliability of these adhesives, a study was conducted to evaluate the effect of environmental service conditions on the durability of four commercial two-component structural epoxy adhesives, as well as the effect that the type of mixing, curing and post-curing conditions, as well as the presence of moisture have on the adhesives viscoelastic properties. It was found that the preparation conditions, cure schedule and moisture have a significant effect on the performance of the bulk adhesives. Moreover, it was found that under ambient conditions there is potential for under-cure or slow progression of cure for the epoxy adhesive products typically employed in these applications, which in turn can compromise the durability of a bonded joint.

Long-term durability of a structural adhesive joint is an important requirement, because it has to be able to support the required design loads, under service conditions, for the planed lifetime of the structure. One way of improving bond durability is through the use of surface treatments prior to bonding, which will activate the adherends" surface, making it more receptive to the adhesive. In this study, the effects of two surface pre-treatments (corona discharge and flame ionization) on three timbers (maritime pine, iroko, and European oak) were evaluated quantitatively through contact angle measurements. These measurements allowed the determination of the changes in the timber surface thermodynamic characteristics, thus indicating which pre-treatment performed better. The results showed that both techniques increased each timber's surface free energy, which could translate into a durability enhancement of bonded joints. Overall, the corona-discharge treatment looks more promising, since this treatment leads to a bigger increase in the timber's surface energy, especially in its polar component, whilst also tended to be less species specific, less susceptible to variation, and the treatment effects lasted longer for this type of treatment.

Adhesive bonding technology has played an essential role in the development and growth of the rehabilitation and repair of timber structures. The ability of a structural joint to maintain satisfactory long-term performance, often in severe environments, is an important requirement of a structural adhesive joint, as the joint should be able to support design loads, under service conditions, for the planned life time of the structure. A number of factors determining the durability of structural adhesive joints have been identified and can be grouped in three categories: environment, materials and stresses. The environment is dominated by temperature and moisture. The materials category includes the adherend, the adhesive, and the inter-phase between them both. The last category refers to the stresses to which the bond is subjected during or after exposure to service environment, affecting both longevity and residual strength. Since this subject in relation to timber bonding is very disperse within the literature, this paper will focus briefly on each of the aforementioned factors, thus providing a general understanding on the factors that influence the durability of bonded timber joints.

Adhesively bonded lap shear joints have been investigated widely and several ideas have been proposed for improving joint strength by reducing bondline stress concentrations. These include application of adhesive fillets at the overlap ends and use of adhesive with graded properties in the overlap area. Another, less common, approach is to deform the substrates in the overlap area in order to obtain a more desirable bondline stress distribution. Previous work carried out by the authors on a number of different substrate materials indicated that a reverse-bent joint geometry is useful for increasing joint strength. Results from static stress analysis and experimental testing demonstrated that significant improvements could be achieved. This paper presents results of further work carried out to assess the fatigue performance of reverse-bent joints. Substrates with different yield and plastic deformation characteristics were used and the effects of different overlap lengths on strength were examined. The results of this research show that the improvements obtained under static tests conditions translate to even higher benefits in fatigue. The paper also explains the failure mechanism of the joints under fatigue loading.

Adhesive bonding is used increasingly by the automotive industry to join structural components of metallic and composite materials. The most common joint configuration is the lap-shear joint, which has been investigated widely and several ideas have been proposed to improve its performance. For example, the introduction of fillets at the overlap ends or tapering of the substrates can reduce the peel stresses at the overlap end. Other approaches include the use of"reverse-bent" substrates and"wavy joints" to reduce peel stresses. This paper compares the stress distribution of the"reverse-bent" and the"wavy joint" , with the stresses of the traditional lap-shear joint, using finite element analysis (FEA). A parametric study was carried out showing trends influencing stresses in the adhesive layer. Experimental tests were conducted to evaluate the assumptions used in, and the findings of, the FEA. The joint strength of"reverse-bent" joints was found to be up to 40% higher compared to flat joints using various substrate materials, adhesives and overlap lengths.