Structural Adhesives in Engineering II '89

University of Bristol, Bristol, UK, 20 -23 September 1989

Following the response to the First Structural Adhesives in Engineering conference held in Bristol, UK, in 1986, a second meeting was organised In the following report, a member of the organising committee gives a personal account of this second meeting.

Adhesion at Bristol

September of this year saw the second international event on Structural Adhesives in Engineering 'SAE II" at Bristol following the successful meeting three years ago. The organisers took the novel step of preceding the main conference by a one-day tutorial course to provide a background and introduction to the field for those interested but comparatively ignorant of adhesives and the technology associated with them.

This course was well attended with some three dozen following a carefully designed course of talks. Malcolm Bowditch of the Admiralty Research Establishment, Holton Heath, opened proceedings with a brief review of the potential for use of adhesives, illustrated by the new video presentation commisioned by the Institution of Mechanical Engineers. He was followed by Keith Allen of The City University who began by expounding some of the basic principles of adhesion and the involvement of adhesives. A review of some of the essentials was followed by a brief excusion into surface thermodynamics, the relationships of Young and of Duprr, and a glimpse of the depths into which all these can lead. After a pause for much needed coffee, Keith Allen returned to expound some of the mysteries of the chemistry of the various exotic materials now in use in adhesives - - all reduced (hopefully) to a level which might be comprehensible to engineers without being trivial. Then Malcolm Bowditch returned to consider the preparation of surfaces for adhesive bonding, because any useful and durable adhesive bond depends to a large extent on the surfaces involved. So these must be treated so as to bring them into the proper state before any bonding is attempted.

After lunch, Bill Lees of Permabond Adhesives presented some of the concepts necessary for successful design for the use of adhesives in engineering structures, illustrated by examples from his own extensive experience. He was followed by his colleague Dick Moulds who showed how all this can be fitted into practical production schedules. Finally Bob Adams, of the University of Bristol and Chairman of the whole event, rounded it off with a discussion of quality assurance and testing: emphasising the need for

a proper measure of scepticism about all test result and their claims of correlation with service conditions.

Then for the next two and half days, in the Conference proper, a whole series of papers were presented on detailed aspects of the theory and practice of adhesives in engineering. About a hundred people, from a dozen or so different countries, considered thirty-five papers covering the whole range of the subject.

The Conference opened with a keynote address from Professor Adams who began by emphasising the engineering aspects of adhesion and the centrality of this to all the concerns of this particular meeting. The real need was to be able to predict failure loads and modes from the properties of the materials and the structures into which these were fashioned.

This was followed by a group of papers on the effects of design of structures from Paul Fay (Ford Motor Co.), Mr Hashim (Glasgow Marine Technology Centre) and Herr Soetens (TNO Holland). These demonstrated the importance of design of structures to achieve most effective bonding. Then came three papers dealing with the surface preparation for bonding and methods for exploring its effects on the most minute scales. The afternoon ended with four papers on mathematical analysis of the stresses within joints, given by M. Maigret (Aerospatiale, France), Bob Adams (University of Bristol), Andy Crocombe (University of Surrey), and John Clark (Alcan International).

Thursday began with an unusual paper by Jonathan Williams describing an joint initiative by government and industry to increase the exploitation of structural adhesive technology. This was followed by a series of seven papers all dealing with aspects of testing of bonds in various ways and under various conditions. These were given by Alan Hutchinson (Oxford Polytechnic), Ivan Grabovac (DSTO, Australia), Mr Gopalan (National Aeronautical Laboratory, India), Paul Fay (Ford Motor Co.), Brenda Parker (RAE, Farnborough), Steven Shaw (RARDE), and John Comyn (Leicester Polytechnic). Then in the afternoon came a series of talks on various aspects of stress analysis in joints and modes of failure. These speakers were Jean-Pierre Jeandrau (CETIM, France), Kozo Ikegami (Tokyo Institute of Technology, Japan), Mr Mallick (University of Bristol), Hans Groth (The Royal Institute of Technology, Sweden), Ken Liechti (University of Texas, USA), Mr Denison (University of Sheffield), Tony Kinloch (Imperial College), and Herr Roshan (FFA. Switzerland).

INT.J.ADHESlON AND ADHESIVES JANUARY 1990 49

The final sessions on Friday started with three papers on various test methods by Peter Owen (Imperial College), Mr Holownia (Loughborough University), and Mr Mackie (University of Dundee). The last five papers were all accounts of the {successfull use of adhesives in engineering production, given by Eric Lawley (Land Rover Ltd), Herr Strobech (Casco Nobel, Denmark), Mr Hitchen (Brunel University), Colin Watson (Loctite UK). and John Dalling (Dalling Automation).

While the daily sessions of presentation and discussion were often intense and demanding, the evenings were relaxing and totally enjoyable. A reception at Goldney Hall with its superb gardens and grotto, an informal social evening with skittles and singing at the University Social Club and the Conference Dinner at the Pump Rooms at Bath: all ensured that members eventually went home refreshed in body as well as in mind.

Overall. the whole event was well worthwhile and the organisers - - both the technical committee and Butterworths who sponsored it - - are to be congratulated on another valued contribution to the total effort to extend the knowledge and use of adhesive technology more widely. It is perhaps a pi~' that more engineers from the real world of industry, did not attend, for whatever reasons.

Papers presented

Day 1 'The redesign of adhesively bonded box beam sections for improved impact performance' P.A. Fay and G.D. Suthurst (Ford Motor Company Ltd, UK)

'Design and assessment methodologies for adhesively bonded structural connections' S.A. Hashim, M.J. Cowling and I.E. Winkle (Glasgow Marine Technology Centre, UI~

"Adhesive joints in aluminium alloy structures' F. Soetens (TNO Institute, The Netherlands)

'Novel techniques for oxide characterisation within adhesively bonded aluminium joints" R.J. Davies and D.A. Moth (Admiralty Research Establishment UK)

"The surface pretreatment of aluminium and lithium aluminium alloys for structural bonding' J.A. Bishopp (Ciba-Geigy Plastics, UK)

'Surface treatment and analysis for adhesive bonding' J. Comyn (Leicester Polytechnic, UK}

'An expert system for the study of high duty bonded joints in aerospace structures' J.P. Maigret (Aerospatiale, France)

'Adhesives joint strength predictions for real boundary conditions' X. Zhao and R.D. Adams (University of Bristol, UK] 'Structural assessment of bonded joint design' A.D. Crocombe (University of Surrey, UK)

.The application of fracture mechanics to adhesive bonding' J.D. Clark, J.S. Crompton, G.C. Wasseh and R.F. Dixon (Alcan International Ltd, UK)

Day 2

'Industrial exploitation of structural adhesive technology - - a UK initiative' J.J.E. Williams (Centre for Exploitation of Science and Technology, UI~ 'A compression test for determining adhesive materiel properties' A.R. Hutchinson and D.E. Lees (Oxford Polytechnic, UK)

'A new shear test for structural adhesives' I. Grabovac and C.E.M. Morris (DSTO, Victoria, Australia)

'Hygrothermal effects on shear stress-strain characteristics of thin adhesives' R. Gopalan (National Aeronautical Laboratory, Banga/ore, India)

'Durability of adhesively bonded steel under salt spray and hydrothermal stress conditions' P.A. Fay and A, Madison (Ford Motor Company, UI~

'The strength of bonded carbon fibre composite joints exposed to high humidity' B.M. Parker (RAE, Famborough, UK)

'Organosilanes for durability enhancement' R.A. Gledhill, S.J. Shaw and D.A. Tod (RARDE, Waltham Abbey, UK)

'Durability of joints in aluminium alloy bonded with epoxide and phenolic adhesives' J. Comyn (Leicester Polytechnic, UIQ

'New concepts for designing structural adhesively bonded joints' J.P. Jeandrau (CETIM, France)

'Strength of adhesively bonded scarf joints between glass fibre reinforced plastics and metals' K. Ikegami, T. Takeshita, K. Matsuo and T. Sugibayashi (Tokyo Institute of Technology, Japan)

'Strength prediction of lap joints with elasto-plastic adhesives using linear closed form methods' V. Mallick and R.D. Adams (University of Bristol UK)

'Viscoelastic and vicoplastic stress analysis of adhesive joints' H.L. Groth (The Royal Institute of Technology, Stockholm, Sweden)

'The effect of adhesive layer thickness on interfacial crack initiation' K.M. Liechti and Y-M Lang (The University of Texas, Austin, USA)

'An investigation of internal adhesive failure in composites using a 10 KN straining stage, scanning electron microscopy and SIMS' P. Denison. F.R, Jones and A.J. Paul (University of Sheffield, UI~ 'Mechanisms and mechanics of the environmental failure of aluminium- alloy joints' A.J. Kinloch, R.J. Davies and H. Mirzali (Imperial College, London, U/~

'Tongue and slot joints in composite sandwich panels' G.R. Roshan (FFA, Flugzeugwerke, Switzerland)

Day 3

'Ultrasonic spectroscopy for the nondestructive measurement of the cohesive properties of adhesive joints' P.N. Owen. M.J. Hodson and P. Cawley (Imperial College, London, UK)

'Comparison of peel-test and holographic NOT method for water ingression into metal joints' B.P. Holownis (Loughborough University of Technology, UK) 'A numerical study of the coin-tap test' R.I. Mackie and A.E. Vardy (University of Dundee, UK) 'Bonding - - the automatic challenge of the 1990's' E.D. Lawley (Land Rover Ltd,, UK)

'Polyurethane adhesive technology in Scandinavia" C. Strobech (Casco Nobel Denmark)

'The automated application of two-part epoxide adhesive beads' C. Hitchen and R.J. Grieve (Brune/ University, Uxbridge, UK) Adhesive case histories for the designer and production engineer - - how

to produce more profit' C. Watson (Loctite UI~ UK~ Refrigerated vehicle construction" J. Dalling (Dalling Automation, UK)

50 INT.J.ADHESlON AND ADHESIVES JANUARY 1990