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1st French national conference on composite materials
modulus of gut changed little with tension whereas in nylon and other polymerics it increased rapidly with increasing tension. Using stills from the high speed photography of a ball shot at a clamped racquet Skelton demonstrated that the residence time of a ball on the racquet face was only 3-4 ms - a time so brief that it was difficult to appreciate how any control was achieved or how a variation in response due to variation in string or racquet construction mattered! This paper was followed by a presentation from C.N. Reid and G. Anderson of the Open University on 'The development of the first aluminium-framed squash racquet': Dr Anderson described the design and development of the first commercial racquet of this type made from AIHE30. Dr Reid went on to identify the source of failure which occurred in a few racquets alter 9 months use. These racquets developed cracks radially to the string holes and at 90 ° to one another, all of which bore all the signs of fatigue. When examined by scanning electron microscopy the crack surfaces revealed the striations typical of shear failure. Dr Reid went on to discuss the racquet head in terms of a beam stressed in bending and torsion, and to describe the test rig designed and constructed to subject extrusion profiles to such forces. Following Dr Reid, N.A. Waterman of Fulmer Research Institute Limited gave his paper 'Skateboards - a triumph of materials technology'. In this he described how three elements of modern materials technology were combined to make the best skateboards: the hot casting of polyetherbased polyurethane for the wheels; improved casting techniques for the light alloy 'trucks' (the wheel mountings); and the use of advanced composite materials (including aluminium honeycomb structures developed for aerospace applications) for the decks. He continued with an indication of the principles of materials selection as they applied to skateboards giving consideration to market demand, design and the production methods. T. Hudson Director of Bath University's Department of Physical Recreation began the second session of the day with a talk on 'The development of synthetic sports surfaces'. He described the criteria upon which the development of a multipurpose sports surface for Bath University was based. This surface which is a composition of polyurethane and granulated waste rubber was developed in conjunction with the Avon Rubber Company only after extensive study of sports surfaces involving visits to Europe (including the Munich Olympic site) and the USA when consideration was given to materials such as Cherron, Polysport, Dri-play, Regosol, Recotan and others. Mr Hudson's colleague at Bath, W.C. Clark went on to define the key properties of any sports surface which included wear, slip, resilience, roughness, appearance and the variation of properties with moisture and temper-
ature. He pointed to the difficulties of reconciling the requirements of different games in a multisports surface bounce, for example, differed from one game to another. D. Enoch's paper 'Substrates for synthetic sports surfaces' which followed discussed a system which avoided this difficulty, for the substrate was 'tuned' to a specific game in this case cricket. Mr Enoch, who is with the Cement and Concrete Research Association, reported on the development of a glass fibre-reinforced cement/polystyrene foam/glass fibre-reinforced cement sandwich for use as a substrate for all weather cricket pitches. The product gave a true stump-high bounce to the cricket ball; could be fabricated on site or at works in sections; and was of low cost. One can but speculate as to when it might be used for a Test Match wicket! -
The final session of the conference contained two papers on the use of carbon fibre-reinforced materials in sports equipment. The first paper was read by D. Carlton, of the Grafil Division of Courtaulds Limited, who explained how the sports goods industry now accounts for almost half the world's consumption of carbon fibre. He said that the real commercial breakthrough came in 1973 when over 50000 golf shafts were manufactured in the USA and this application alone used 40 tonnes of prepreg material. Carbon fibre composites have now been used in fishing reels, fishing rods, ski poles, tennis, badminton and squash racquets, using fabrication techniques such as filament winding, pultrusion and injection moulding. L.N. Phillips, of the Royal Aircraft Establishment continued this theme in the final paper of the conference, 'High performance racing sculls'. He described the design and development of racing sculls at the RAE and commented on the problems associated with weaving glass and carbon fibre together into the cloth used as the reinforcement of the sandwich construction of the sculls. Although the novel sandwich hull above was 5 kg lighter than the conventional hull Mr Phillips stressed the importance of looking at the whole system. To reduce weight the RAE specified high tensile strength aluminium alloy rigging and lightweight rowing shoes (which were produced by a ballet shoe manufacturer). The racing sculls, now manufactured by Carbocraft, are significantly lighter than the conventional wooden boats produced in Switzerland and Germany and have the added bonus of being up to 25 % cheaper. Drawing the conference to a close K. Hodd thanked all the speakers for their interesting papers and congratulated them on the excellent standard of their presentation; he also commented on the lively discussion throughout the conference and upon the intensity of the audience participation perhaps more noticeable on the squash courst adjacent to the Conference hall!
Hodd
Paris, France (19-21 September 1978)
1st French national conference on composite materials Organised by the Centre des Mat~riaux This first french national conference on composite materials proved to be a considerable success,attracting about three hundred participants including representatives
COMPOSITES. APRIL 1979
from several countries. The aim of the meeting was to give research workers and all those interested in the scientific study of composite materials a chance to meet and discuss
67
the state of knowledge in this field. The broad themes chosen were 'behaviour', 'design' and 'control' of which the first two subjects were well represented by papers of a high scientific level. There were regrettably few which dealt with control of the material, although there were numerous demands that more effort should be directed in this direction. This probably reflects the actual situation where there are many questions being asked about the control of composites but few answers forthcoming. An encouraging aspect of the conference was the large number of participants from industry (and not only from the aerospace firms) which indicates the lively and growing interest of general industry in composites. It shows a readiness to take what has been found for aerospace application and apply it to more down to earth structures. Industry was also well represented in the list of authors, although not surprisingly the aerospace and the nuclear power industries dominated. Other papers came from industrial research institutes and academic establishments.
the time of the next conference in this series, which will be held in 1980. A.R. Bunsell Papers p r e s e n t e d de Charentenay, F.X. et al. 'Acoustic emission study of delamination in multilayer composites' Favre, J.P. 'Resistance of composites to shock and damage' Martin, Ch. 'Techniques for measuring fibre-matrix adhesion and the shear strength of composite materials' Bathias, C. 'Application of fracture mechanics to cfrp' Maillot, B. and Massard, T. 'Study of failure modes in cfrp' Pailler, R. and Naslain, R. 'Correlation between the chemical interactions and the fibre/matrix interface and the mechanical properties of boron titanium' Hearn, D., Favry, Y. and Bunsell, A.R. 'Manufacture of boron/ aluminiurn tubes' Vauterin-Leddet, I. and Bunsell, A.R. 'Fatigue damage of boron aluminium'
The number of papers had been limited to thirty three so as Dudragne, F. et al. 'Use of the epoxy system-polybutadiene for to avoid the need for parallel sessions, and more than half Kevlar composites' were devoted to the mechanical behaviour and the failure Magnin, G. 'Mixt composites carbon/Kevlar' of composites. The first session included papers on delaminBurgade, G. 'The hybrid of carbon/Kevlar and glass/Kevlar' ation in grl~ the shock resistance of composites, techniques for measuring fibre matrix adhesion and shear, the applications Massot, J.J. 'Creep of unidirectional grp' of fracture mechanics and the mechanisms of failure of Laroche, D. and Bunsell, A.R. 'Long term behaviour of cfrp' cfrp. The following session had papers on boron/aluminium Phang, C., Vong, T.S. and Verchery, G. 'Study of shear tests for composites, the chemical interaction at the interface, unidirectional composites' mechanisms of fatigue damage and the means of fabricating Deleuze, M., Doucelance, C. and Chretien, N. 'Non-destructive tubes in B-AI for use in structures. There were also three control of (Si-3D) composite materials after shock damage' papers which dealt with Kevlar and hybrid composites. The Lenain, J.C. 'Characterisation by acoustic emission of the mechsecond day produced papers on the reliability of composites anisms of damage in composites as a means of non destructive control' and the assessment of damage. In the first session, the creep of grp was considered, as was the long term behaviour of Gacougnolle, J.L., Parisot, J. and Riviere, A. 'Measurement of internal damping and of modulus to study the mechanical cfrp using the acoustic emission (AE) technique to follow properties of homogeneous and composite materials' the state of internal damage; one paper considered more Bentejac, J.P. 'The quality of composites' closely the usefulness of AE in testing composites, and another compared ultrasonic and AE techniques for Blach~re and Coffy 'Optimisation of beams loaded in bending fatigue' evaluating shock damage. The final paper in this session Louwman et al. 'Properties of filament wound grp tubes' showed how measurement of internal damping can be Diernaz, E. and Verchery, G. 'Experimental and theoretical study useful on determining the mechanical properties of of the conditions for the support of fibre reinforced containers composites. Following this was a session devoted to on 2 elastic support' industrial aspects, which again included quality control, Pouzols, G. 'The polyaminobismal(~imides: different ways of as well as optimisation of composite beams to be used obtSining composites with high mechanical and thermal properties' in bending, the properties of grp tubes and the problems Pabiot, J. 'Mechanical and chemical aging of grp' involved in the use of grp reservoirs. The final day started with three papers on mechanical properties, dealing with ageing of grp; the effect of the environment and electrical stresses on grp; and high performance resins. The rest of the day was given to problems of design, finite element techniques, viscoelastic behaviour, calculation of deformations and stresses in multilayer plates and their fracture criteria, design of reservoirs, the importance of considering non linear behaviour in design, calculation of stresses in cylinders made from composites and, finally, the dispersion of elastic waves in anistropic composite beams. It is clear from the interest generated by this conference that the awareness of composite materials in France is rapidly developing and portends well for the future. It is to be hoped that one of the aims of the conference that of promoting contacts in this field - will be fulfilled; and not only in France, but also with workers in other countries. It will be interesting to see what progress has been made by
68
Mailfert, R. et al. 'Evolution of electrical and mechanical properties of unidirectional grp under prolonged electrical, mechanical and climatic conditions'
Boubal, G. 'Calculation of the Hooke matrix for a continuum from a model of the basic finite element' Hamelin, G. and Debicki, G. 'Study of the time dependent behaviour of grp' Chhim, V., Roelandt, J.M. and Verchery, G. 'Calculation of deformations and stresses in sandwich structures; a comparison between small and large numbers of layers' Le Nizerhy, D. 'Design of pressure vessels in grp taking into account geometrical and rheological non linearities' Lemoine, L. 'Design of structures. Necessity to take into account physical and geometrical non-linearities' Hamelin, P and Debicki, G. 'Study of methods of calculation applicable to the design of rotatin~;;structures in grp' Massard, T. 'Calculation of stresses and deformations in a cylindrical anistropic composite structure with the aid ~of a mixt variable technique' Vinh, T. 'The dispersion of elastic waves in anistropic composite beams'
C O M P O S I T E S . A P R I L 1979
ature. He pointed to the difficulties of reconciling the requirements of different games in a multisports surface bounce, for example, differed from one game to another. D. Enoch's paper 'Substrates for synthetic sports surfaces' which followed discussed a system which avoided this difficulty, for the substrate was 'tuned' to a specific game in this case cricket. Mr Enoch, who is with the Cement and Concrete Research Association, reported on the development of a glass fibre-reinforced cement/polystyrene foam/glass fibre-reinforced cement sandwich for use as a substrate for all weather cricket pitches. The product gave a true stump-high bounce to the cricket ball; could be fabricated on site or at works in sections; and was of low cost. One can but speculate as to when it might be used for a Test Match wicket! -
The final session of the conference contained two papers on the use of carbon fibre-reinforced materials in sports equipment. The first paper was read by D. Carlton, of the Grafil Division of Courtaulds Limited, who explained how the sports goods industry now accounts for almost half the world's consumption of carbon fibre. He said that the real commercial breakthrough came in 1973 when over 50000 golf shafts were manufactured in the USA and this application alone used 40 tonnes of prepreg material. Carbon fibre composites have now been used in fishing reels, fishing rods, ski poles, tennis, badminton and squash racquets, using fabrication techniques such as filament winding, pultrusion and injection moulding. L.N. Phillips, of the Royal Aircraft Establishment continued this theme in the final paper of the conference, 'High performance racing sculls'. He described the design and development of racing sculls at the RAE and commented on the problems associated with weaving glass and carbon fibre together into the cloth used as the reinforcement of the sandwich construction of the sculls. Although the novel sandwich hull above was 5 kg lighter than the conventional hull Mr Phillips stressed the importance of looking at the whole system. To reduce weight the RAE specified high tensile strength aluminium alloy rigging and lightweight rowing shoes (which were produced by a ballet shoe manufacturer). The racing sculls, now manufactured by Carbocraft, are significantly lighter than the conventional wooden boats produced in Switzerland and Germany and have the added bonus of being up to 25 % cheaper. Drawing the conference to a close K. Hodd thanked all the speakers for their interesting papers and congratulated them on the excellent standard of their presentation; he also commented on the lively discussion throughout the conference and upon the intensity of the audience participation perhaps more noticeable on the squash courst adjacent to the Conference hall!
Hodd
Paris, France (19-21 September 1978)
1st French national conference on composite materials Organised by the Centre des Mat~riaux This first french national conference on composite materials proved to be a considerable success,attracting about three hundred participants including representatives
COMPOSITES. APRIL 1979
from several countries. The aim of the meeting was to give research workers and all those interested in the scientific study of composite materials a chance to meet and discuss
67
the state of knowledge in this field. The broad themes chosen were 'behaviour', 'design' and 'control' of which the first two subjects were well represented by papers of a high scientific level. There were regrettably few which dealt with control of the material, although there were numerous demands that more effort should be directed in this direction. This probably reflects the actual situation where there are many questions being asked about the control of composites but few answers forthcoming. An encouraging aspect of the conference was the large number of participants from industry (and not only from the aerospace firms) which indicates the lively and growing interest of general industry in composites. It shows a readiness to take what has been found for aerospace application and apply it to more down to earth structures. Industry was also well represented in the list of authors, although not surprisingly the aerospace and the nuclear power industries dominated. Other papers came from industrial research institutes and academic establishments.
the time of the next conference in this series, which will be held in 1980. A.R. Bunsell Papers p r e s e n t e d de Charentenay, F.X. et al. 'Acoustic emission study of delamination in multilayer composites' Favre, J.P. 'Resistance of composites to shock and damage' Martin, Ch. 'Techniques for measuring fibre-matrix adhesion and the shear strength of composite materials' Bathias, C. 'Application of fracture mechanics to cfrp' Maillot, B. and Massard, T. 'Study of failure modes in cfrp' Pailler, R. and Naslain, R. 'Correlation between the chemical interactions and the fibre/matrix interface and the mechanical properties of boron titanium' Hearn, D., Favry, Y. and Bunsell, A.R. 'Manufacture of boron/ aluminiurn tubes' Vauterin-Leddet, I. and Bunsell, A.R. 'Fatigue damage of boron aluminium'
The number of papers had been limited to thirty three so as Dudragne, F. et al. 'Use of the epoxy system-polybutadiene for to avoid the need for parallel sessions, and more than half Kevlar composites' were devoted to the mechanical behaviour and the failure Magnin, G. 'Mixt composites carbon/Kevlar' of composites. The first session included papers on delaminBurgade, G. 'The hybrid of carbon/Kevlar and glass/Kevlar' ation in grl~ the shock resistance of composites, techniques for measuring fibre matrix adhesion and shear, the applications Massot, J.J. 'Creep of unidirectional grp' of fracture mechanics and the mechanisms of failure of Laroche, D. and Bunsell, A.R. 'Long term behaviour of cfrp' cfrp. The following session had papers on boron/aluminium Phang, C., Vong, T.S. and Verchery, G. 'Study of shear tests for composites, the chemical interaction at the interface, unidirectional composites' mechanisms of fatigue damage and the means of fabricating Deleuze, M., Doucelance, C. and Chretien, N. 'Non-destructive tubes in B-AI for use in structures. There were also three control of (Si-3D) composite materials after shock damage' papers which dealt with Kevlar and hybrid composites. The Lenain, J.C. 'Characterisation by acoustic emission of the mechsecond day produced papers on the reliability of composites anisms of damage in composites as a means of non destructive control' and the assessment of damage. In the first session, the creep of grp was considered, as was the long term behaviour of Gacougnolle, J.L., Parisot, J. and Riviere, A. 'Measurement of internal damping and of modulus to study the mechanical cfrp using the acoustic emission (AE) technique to follow properties of homogeneous and composite materials' the state of internal damage; one paper considered more Bentejac, J.P. 'The quality of composites' closely the usefulness of AE in testing composites, and another compared ultrasonic and AE techniques for Blach~re and Coffy 'Optimisation of beams loaded in bending fatigue' evaluating shock damage. The final paper in this session Louwman et al. 'Properties of filament wound grp tubes' showed how measurement of internal damping can be Diernaz, E. and Verchery, G. 'Experimental and theoretical study useful on determining the mechanical properties of of the conditions for the support of fibre reinforced containers composites. Following this was a session devoted to on 2 elastic support' industrial aspects, which again included quality control, Pouzols, G. 'The polyaminobismal(~imides: different ways of as well as optimisation of composite beams to be used obtSining composites with high mechanical and thermal properties' in bending, the properties of grp tubes and the problems Pabiot, J. 'Mechanical and chemical aging of grp' involved in the use of grp reservoirs. The final day started with three papers on mechanical properties, dealing with ageing of grp; the effect of the environment and electrical stresses on grp; and high performance resins. The rest of the day was given to problems of design, finite element techniques, viscoelastic behaviour, calculation of deformations and stresses in multilayer plates and their fracture criteria, design of reservoirs, the importance of considering non linear behaviour in design, calculation of stresses in cylinders made from composites and, finally, the dispersion of elastic waves in anistropic composite beams. It is clear from the interest generated by this conference that the awareness of composite materials in France is rapidly developing and portends well for the future. It is to be hoped that one of the aims of the conference that of promoting contacts in this field - will be fulfilled; and not only in France, but also with workers in other countries. It will be interesting to see what progress has been made by
68
Mailfert, R. et al. 'Evolution of electrical and mechanical properties of unidirectional grp under prolonged electrical, mechanical and climatic conditions'
Boubal, G. 'Calculation of the Hooke matrix for a continuum from a model of the basic finite element' Hamelin, G. and Debicki, G. 'Study of the time dependent behaviour of grp' Chhim, V., Roelandt, J.M. and Verchery, G. 'Calculation of deformations and stresses in sandwich structures; a comparison between small and large numbers of layers' Le Nizerhy, D. 'Design of pressure vessels in grp taking into account geometrical and rheological non linearities' Lemoine, L. 'Design of structures. Necessity to take into account physical and geometrical non-linearities' Hamelin, P and Debicki, G. 'Study of methods of calculation applicable to the design of rotatin~;;structures in grp' Massard, T. 'Calculation of stresses and deformations in a cylindrical anistropic composite structure with the aid ~of a mixt variable technique' Vinh, T. 'The dispersion of elastic waves in anistropic composite beams'
C O M P O S I T E S . A P R I L 1979