Staff Profiles

My teaching repsonsibilites include lecturing on stress analysis and design for first, second and final year students. I also supervise a number of final year projects, which are often based on the research that I am currently undertaking. 

Modules taught

Module leader for

• Introduction to Stress  (1st Year)

Also teach on

• Stress and Dynamics (2nd Year)
• Advanced stress analysis (3rd Year)
• Group Design Projects (3rd Year)
• Advanced Joining (3rd Year, MSc, MEng)
• Advanced Mechanical Engineering Design (MSc, MEng)

Supervision

I supervise upto 6 MSc student projects each year, with topics that often follow my research interests.

The Joining Technology Research Centre at Oxford Brookes is recognised as one of the leading establishments providing industry with access to a unique combination of engineering and scientific skills in the UK today. The foundations of JTRC go back to 1968 and the Centre has since established an international reputation for its interdisciplinary approach to joining problems. In particular, the research team has undertaken a considerable amount of research and development, and has participated in a wide range of knowledge transfer activities, in the use of adhesives and sealants for the aerospace, automotive and construction sectors.

• Analysis of bonded and sealed joints in the Automotive and Aerospace industries
• Design and analysis of future generation bonded aircraft structures
• Analysis of bonded automotive aluminium joints subject to impact loading
• Structural bonded repair techniques for the Civil Industry
• Development of QC procedures for on-site bonded composite strengthening
• Evaluation and development of design calculations for bonded timber connections and composite strengthened metallic structures
• Durability of bonded timber connections
• Surface pre-treatments of timber, natural fibres and bamboo (corona, flame, silanes)
• Life-time prediction of bonded timber-timber or timber-FRP joints

Research group membership

Joining Technology Research Centre

Cycle Mobility Group

Research grants and awards

• £1.4m TSB part funded project. Advanced composite truss structures (ACTS), TP number TP/8/MAT/6/I/Q1505D, 2007-2011.
• £22k Portuguese Science Foundation, Composite repair systems for timber, LNEC, 2004-2008
• £70k EPSRC (CASE) funded grant. Prediction of the behaviour of rivet-bonded connections in aluminium. EPSRC Grant, 2004-2007

Knowledge Base Lead academic/Supervisor

• KTP with YASA Motors, sponsored by the TSB (£142k) for the development of a mass produced bonded yokeless axial-flux electric motor (started 2011)
• KTP with CMS Industries, sponsored by the TSB (£160k) for the development of rapid assembly technologies (started 2012) Supervisor
• £400k DTI part funded project on the development of the next generation aircraft wing structures. Nodal Optimization of Truss Structures (NOTS), 2003-2006.

Researcher

• £210k DTI MMS funded project on the Classification and qualification of composite materials systems for use in the civil infrastructure. www.compclass.org.uk, 2002-2005.
• £650k EC CRAFT funded project Low Intrusion CONservation Systems for Timber Structures (LICONS). www.LICONS.org, CRAF-1999-71216, 2002-2005
• £50k EPSRC (CASE) funded grant. Multi-modulus adhesive bonding, 2001-2004
• £120k DTI PII, Timber adhesives classification and code user requirements, 2001-2003
• EPSRC funded grant. Design and Fabrication of Low NVH Multi-material Automotive Vehicle Structures. EPSRC Grant GR/S27245/01Design, 2005-2007
• Thematic Network. ‘Design Optimisation and Guidelines for Multi-material Applications’, Contract No. BRRT CT97-5029, 1997-2001
• EPSRC/IMI funded project on Advanced Joining Processes for Lightweight Vehicle Manufacture’, EPSRC Grant Ref, GR/LO3811,1997-2000

Research projects

Current research projects include the development of novel test methods for screening adhesives in realistic environments, development of polymer/ceramic compounds for space and ballistic applications, modelling of multi-material adhesive behaviour and long term performance characteristics.

Research impact

Winner of Engineering Excellence Award, 2014

Finalist in Innovate UK Best of the Best Awards, 2014 

Further information

/ecm/research/engineering/consultancy-for-industry/jtrc/

/ecm/research/engineering/consultancy-for-industry/svec/

Journal articles

• Gentieua, T, Catapanob A, Jumela, J. Broughton J, 'A mean-field homogenisation scheme with CZM-based interfaces describing progressive inclusions debonding'
  Composite Structures 229 (2019)
  ISSN: 0263-8223 eISSN: 1879-1085
  Abstract

  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.
  

  Website 
• Timothée Gentieu, Dr Julien Jumel, Dr Anita Catapano, Prof James G Broughton, 'Size effect in particle debonding: Comparisons between Finite Fracture Mechanics and Cohesive Zone Model'
  Composite Materials (2018)
  ISSN: 0021-9983 eISSN: 1530-793X
  Abstract

  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.
  

  Website 
• Gentieu T, Catapano A, Jumel J, Broughton J, 'Computational modelling of particulate-reinforced materials up to high volume fractions: Linear elastic homogenisation'
  Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 233 (6) (2017) pp.1101-1116
  ISSN: 1464-4207 eISSN: 2041-3076
  Abstract This work focuses on the analysis of the micro and macroscopic mechanical response of particle-reinforced composites. A particular attention is paid to the influence of two fundamental design parameters, i.e. the particles shape and their volume fraction (up to very high values ranging from 0 to almost 0.8), on the overall mechanical response of the structure as well as on the resulting elastic symmetry of the material. The strain energy-based homogenisation technique of periodic media is here applied to a 2D finite element model of a representative volume element of the composite. Different algorithms are developed to generate, with a good level of accuracy, the real microstructure of the composite material characterised by circular as well as polygonal particles. Moreover, for each studied configuration, a link between the geometrical parameters of the microstructure (particles shape, size, distribution, and volume fraction) and the size of the representative volume element is also provided in order to properly describe the constitutive behaviour of the composite at the macroscopic scale. The numerical results are compared with analytical models taken from the literature to prove on the one hand the limitations of the analytical approaches and on the other hand the effectiveness of the proposed numerical models.
   
  Website 
• Lu YC, Broughton J, Winfield P, 'Surface modification of thermally expandable microspheres for enhanced performance of disbondable adhesive'
  International Journal of Adhesion and Adhesives 66 (2016) pp.33-40
  ISSN: 0143-7496
  Abstract This research successfully improved the compatibility between thermally expandable microspheres (TEMs) and an adhesive system for enhanced performance. TEMs were grafted with poly(glycidyl methacrylate) (PGMA) chains via atom transfer radical polymerisation (ATRP) with activators regenerated by electron transfer (ARGET) or ARGET ATRP technique. The temperature effect on the surface modification of TEMs was investigated for an optimum modification condition. Compared to adhesive incorporating unmodified TEMs, up to 15.8% increase in tensile lap shear strength and 24.0% increase in ultimate tensile strength (UTS) were achieved. Most notably, after environmental conditioning, the UTS of the adhesive system containing modified TEMs was 8.0% higher than the strength of unmodified TEMs before environmental conditioning.Website 
• Lu Y, Broughton J, Winfield P, 'A Review of Innovations in Disbonding Techniques for Repair and Recycling of Automotive Vehicles'
  International Journal of Adhesion and Adhesives 50 (2014) pp.119-127
  ISSN: 0143-7496
  Abstract
  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.
  Website 
• Broughton J G, Rodrigues D D, 'Silane surface modification of boron carbide epoxy composites'
  International Journal of Adhesion and Adhesives 46 (2013) pp.62-73
  ISSN: 0143-7496
  Abstract Boron carbide (BC) is a boron-rich ceramic material used as a radiation absorber for shielding parts in the nuclear industry and for particle physics experimentation. BC parts are generally manufactured using the sintering process, which tends to limit the size and shape of components and imparts high cost. Low temperature and lower pressure moulding using a BC polymer matrix composites (PMC) provides an alternative process for developing lower cost parts whilst accommodating increased complexity of geometry and size. However, a lack of adhesion exhibited between BC and the resin led to a composite with limited mechanical strength and durability. In this study a silane coupling agent was used to improve the adhesion between the epoxy resin and BC. An improvement in mechanical strength was observed in the treated composite by means of three-point bending, Iosipescu and double v-notch tests. Initial investigation of the surface chemistry also showed the presence of hydroxyl groups and B–O bonds, which may promote improved adhesion through silane condensation and the formation of covalent bonds.Website 
• Clarke M, Broughton J, Hutchinson A, Buckley M, 'Application of the design of experiments procedure to the behaviour of adhesively bonded joints with plastically deformable adherends to enable further understanding of stain-rate sensitivity'
  International Journal of Adhesion and Adhesives 44 (-) (2013) pp.226-231
  ISSN: 0143-7496
  Abstract The study presented in this paper was carried out to investigate further the effects of strain rate on the strength of adhesively bonded single lap shear joints. Tests were carried out on two different configurations of adhesively bonded joints that were designed to exhibit different behaviours. In one configuration both adherends were made from a relatively low strength grade of aluminium such that both would exhibit significant plastic deformation prior to adhesive failure. The other configuration used one adherend that was significantly stronger such that only elastic deformation was exhibited prior to failure of the adhesive. The joint specimens were tested at several different strain rates using a servo-hydraulic test machine and the results analysed using statistical methods. To further understand the results Finite Element models of the joints were created using a Cohesive Zone Model to predict damage development and failure in the adhesive. The Design of Experiments procedure was used to study the effects of material parameters relating to both the adherends and the adhesive in the Finite Element models. The results of the testing suggested that the strength of joints formed from two adherends that exhibited plastic deformation prior to failure did not show statistically significant sensitivity to strain rate. Interpretation of the results of the Finite Element analyses suggested that the adherend yield was the main factor influencing failure load in the adhesive for joints of this type.Website 
• Hooper M, Hutchinson A, Broughton J, Taylor M, 'Development of a novel test rig for the evaluation of aircraft fuel tank sealant'
  Journal of Testing and Evaluation 40 (1) (2012) pp.1-7
  ISSN: 0090-3973
  Abstract A key concept for the future evaluation of sealant materials for commercial aircraft is to expose realistic sealed joint systems to typical dynamic and environmental parameters representative of actual flight conditions. The development of a mechanism to undertake the full range of test parameters for the evaluation of sealants for current and future aircraft is described in this paper. This mechanism, or model sealed system (MSS), consists of an axial stress machine into which vibrational fatigue, high and low temperatures and pressures can be programmed for automatic operation. The test coupons, within the MSS, can be stressed to simulate flight conditions along with the flight pressures and temperatures. The MSS is described and the results of sealant evaluation to date are presentedWebsite 
• Custódio J, Broughton J, Cruz H, 'Rehabilitation of timber structures: novel test method to assess the durability of bonded-in rod connections'
  Materials and Structures 45 (1-2) (2012) pp.199-221
  ISSN: 1359-5997
  Abstract Rehabilitation/restoration systems involving bonded-in rods represent an efficient alternative method for the repair and/or reinforcement of structural timber members. However, in spite of their advantages, their use is still restrained by the lack of knowledge about their long-term performance. In order to correct this situation it is necessary to gain a greater understanding of their durability, creep and fatigue behaviour. However, reliable and realistic accelerated ageing tests do not yet exist, and the application of the existing European or American standards to epoxy bonded products are much too penalising, since they merely impose severe conditions that are not verified in service although these may be suitable for other adhesives. To address these concerns a test procedure to assess long-term behaviour of bonded-in rod connections was developed with the aim of providing a simple method for the selection of candidate repair system materials for specific applications. The data collected so far using the realistic performance assessment test (RPAT) appears to predict correctly the end-use performance for different adhesives as well as for different timbers.Website 
• Clarke M, Broughton J, Hutchinson A, Buckley M, 'An investigation into the use of an embedded-process zone model for predicting the structural behaviour of adhesive bonded joints'
  International Journal of Vehicle Structures and Systems 3 (3) (2012) pp.203-209
  ISSN: 0975-3060
  Abstract

  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

  Website 
• Custódio J, Broughton J, Cruz H, 'Rehabilitation of timber structures ' preparation and environmental service condition effects on the bulk performance of epoxy adhesives'
  Construction and Building Materials 25 (8) (2011) pp.3570-3582
  ISSN: 0950-0618
  Abstract

  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.

  Website 
• Custódio J, Broughton J, Cruz H, 'Evaluation of adhesion promotion techniques for structural bonded timber joints'
  Journal of Adhesion 87 (4) (2011) pp.331-352
  ISSN: 0021-8464
  Abstract

  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

  Website 
• Custódio J, Broughton J, Cruz H, 'A review of factors influencing the durability of structural bonded timber joints'
  International Journal of Adhesion and Adhesives 29 (2) (2009) pp.173-185
  ISSN: 0143-7496
  Abstract

  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.

  Website 
• Custódio J, Broughton J, Cruz H, Winfield P, 'Activation of timber surfaces by flame and corona treatments to improve adhesion'
  International Journal of Adhesion and Adhesives 29 (2) (2009) pp.167-172
  ISSN: 0143-7496
  Abstract

  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.

  Website 
• Fessel G, Broughton J, Fellows N, Durodola J, Hutchinson A, 'Fatigue performance of metallic reverse-bent joints'
  Fatigue and Fracture of Engineering Materials and Structures 32 (9) (2009) pp.704-712
  ISSN: 8756-758X
  Abstract

  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.

  Website 
• Custódio J, Broughton J, Cruz H, Hutchinson A, 'A review of adhesion promotion techniques for solid timber substrates'
  Journal of Adhesion 84 (6) (2008) pp.502-529
  ISSN: 0021-8464
  Abstract The use of primers, coupling agents, and other surface treatments to enhance adhesion is now common in the aerospace, automotive, and plastics industries, where they are used to develop highly durable bonds to metals, advanced composites, ceramics, and plastics. However, such treatments are virtually non-existent in the wood products industry although they could solve important adhesion problems. In particular, adhesion promoters can enhance the environmental durability of epoxy bonded joints, and they can enhance the reliability of bonds to timber treated with wood preservatives. A review of current findings is provided that attempts to gather the scarce and disperse information available in the literature about adhesion promotion techniques for bonded solid timber joints. A general overview of the research needs on this topic is also given.Website 
• Fessel G, Broughton J, Fellows N, Durodola J, Hutchinson A, 'Evaluation of different lap-shear joint geometries for automotive applications'
  International Journal of Adhesion and Adhesives 27 (7) (2007) pp.574-583
  ISSN: 0143-7496
  Abstract

  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.

  Website 

Book chapters

• Broughton J, Custódio J, 'Understanding timber structural connection systems' in ICE Manual of Construction Materials, Thomas Telford Ltd (2009)
  ISBN: 978-0-7277-3597-3
  Abstract The strength and stability of any timber structure depends heavily on the connections between the structural members. One prime advantage of wood as a structural material is the ease with which wooden structural parts can be joined together, using a wide variety of connecting systems. This chapter discusses how the characteristics of timber as an engineering material affect the performance and hence design of connections in timber structures.Website 

Conference papers

• JG Broughton, AR Hutchinson, P Winfield, 'Dismantlable Adhesive Joints For Decommissioning, Repair and Upgrade'
  (2018)
  ISBN: 9789283721727
  Abstract Adhesive bonding is well established as one the most successful means of joining advanced composite materials, which are increasingly employed to reduce weight and extend service life. It is also well known that adhesives used to sustain structural loads tend to be permanent, cross-linked and irreversible, which raises particular challenges when equipment becomes obsolete or when there is a need for upgrade or repair. This paper reviews the latest published work on dismantlable adhesive technologies, and highlights the criteria needed to evaluate potential disbondable systems. Whilst tailored formulations, originally developed as selfhealing polymers, demonstrate considerable promise for self-repair, re-adjustment and disbonding, it concludes that additives, in the form of expandable reactive agents, offer demonstrable performance and relatively simple adaptation to bonding technology currently employed. These, in conjunction with appropriate design strategies in order to aid design for disassembly, should offer potential solutions for innovation in temporary repair and upgrade scenarios, including adaptive armour or the development of new modular design platforms using advanced composites.
  

Membership of professional bodies

Soceity for Adhesion and Adhesives (SAA)

Institute of Materials (IoM3)

SAMPE UK

COMPOSITES UK

CRYOX