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Composites news
C O M P O S I T E S news •A I
M E Conference (1975)
Further details are available on the AIME-sponsored special symposia on composite materials, to be held in April 1975. The general theme of the symposia will be appraisal of the past twenty years' work on composites, with respect to possible future research and applications. The first meeting will be held in Geneva, Switzerland; the main aim will be to assemble technical people from various parts of the world who are working with advanced composite materials, designs and applications. The emphasis will be on the combined scientific and engineering advancements of composites. The second meeting, to be held in Boston, USA, will consolidate the significant contributions of the Geneva meeting and put them into the context of the work being done in the USA. Information regarding submission of papers can be obtained from: A. R. Scott, Executive Secretary, TMS-AIME 345 East 47 Street, New York, NY 10017, USA, Dr E. Anderson,Battelle Geneva Research Center, 7 route de Drize, CH-1227, Carouge/Geneva, or Dr E. Scala, PO Box 1362, Cortland, NY 1362, Cortland, NY 13045, USA.
Reports from Techlink Techlink, an information link between research and industry in the UK, under the Department of Trade and Industry, recently announced the availability of the following reports:
Selecting resin matrices for improved composite strength ( Techlink No 1438). This gives details of a report prepared by the Lewis Research Center in the USA which presents criteria for selecting resin matrices to improve composite strength. These criteria resulted from theoretical and experimental investigations in which matrix properties such as ultimate strength, ultimate elongation, toughness and fracture toughness were found to be misleading for predicting composite strength. The work indicated that the area under the matrix stress/strain diagram, limited to 1% strain, is a good index for assessing its contribution: the cor-
50
responding initial modulus is considered to be a useful parameter for translating matrix properties to those of the composite. Composite mechanics were used, in conjunction with experimental data either generated as part of the study or taken from the literature, to identify the matrix properties which influence composite unidirectional strength. Unidirectional specimeas were made from carbon fibres and low, intermediate and high modulus resins. They were tested for strength in longitudinal flexure, transverse tension and compression and interlaminar shear. Composite strength data from other sources included values of longitudinal tension and compression, transverse tension and interlaminar shear. Comparisons of the composite strength data with the various matrix properties led to the identification of convenient and practical criteria for assessing the matrix contribution to composite strength.
Fabrication of plastics using nonionizing radiation ( Techlink No 1445). A report from the US Plastics Evaluation Center surveyed the use of ultraviolet, infrared, induction, radiofrequency and microwave radiation heating in the fabrication of plastics. This survey included instruments both in current use and with reasonable commercial potential. The methods are suitable for application to glassreinforced polyesters (eg laminates and pipes), formed sheets, moulded' phenolics, epoxies and other thermosets, urethane foams, etc. The use of non-ionizing radiation processes in the fabrication of plastics products can lead to reduced costs, increased processing speed and improved product quality.
Development o[pyrrone structural foams (Techlink No 1446). An investigation, sponsored by NASA, was carried out on the development of techniques for preparing pyrrone foams for use as a filler for the cells of honeycomb structures. Initially, most of the work was devoted to preparing pyrrone prepolymers, but the high-curing shrinkage of unfilled
pyrrone prepolymers and consequent unsuitability for use in a foam-in-place process led to the production of syntactic foams. These were formulated using carbon microspheres, of 200/.tm nominal diameter, and a technique was devised for introducing syntactic foam formulations into honeycomb structures. Techlink Unit, Technology Reports Centre, Orpington, Kent BR5 3RF, England
Energy absorbing composites The Technical Products Division of the Brunswick Corporation have developed a class of materials which they have called 'energy absorbing composites' for damping and/or isolation of vibrations in structures. These materials are primarily metallic and consist of at least two elements, one of which displays elastic properties and the other damping characteristics. Brunswick claim that their materials are superior to conventional elastomeric materials and viscous.type dampers because they offer greater design flexibility. Other advantages claimed are a wide operational temperature range ( 196°C to 427°C), ability to withstand operating stresses up to 2 GN/m 2 and operating frequencies up to 100 Hz. Fatigue lives of up to 7.5 x 106 cycles have been obtained on composites which exhibited relatively low damping capacities (15%) at low strain amplitudes. At resonant frequency conditions, lives of l0 s cycles have been measured for relatively large damping capacities (40%) at large strain a~nplitudes. The metallic characteristics of these composites can also be utilized to isolate vibrations at frequencies well above resonance. Two basic situations are involved: firstly, the transmission of forces from a small to a large mass (eg from a car to the frame), and, secondly, the transmission of forces from a large to a small mass (eg from a car to the passenger). Both types are normally controlled by the introduction of resilient mounts between the source and the receiver. The use of Brunswick's material can provide a damping coefficient of up to 40% per cycle, with resonant transmissibilities as low as 3-for a double input amplitude of 2.54 mm. Brunswick say that a significant feature of their energy absorbing composites is their simple design compared with the more
COMPOSITES . MARCH 1974
complex systems commonly in use. Thus, a single structur~ may be able to replace a complicated arrangement of several components. A wide variety of configurations such as. wire, rod, bar, sheet and strip is available. Brunswick Corporation, 1 Brunswick Plaza, Skokie, Illinois 60076, USA
Composite superconductor The Atomic Energy Research Establishment at HarweU have developed a technique for preparing stabilized superconducting composite materials using A15-structure compounds (eg Nb3Sn, V3Ga ). Until now, mechanical fabrication techniques could not be used, the compounds being too hard and brittle. This problem has been overcome at Harwell by forming Nb3Sn by a solid state reaction between tin from a bronze matrix and niobium. The niobium, in the form of rods, is embedded in the required geometry, in an ingot of bronze: this is mechanically reduced until the niobium is sufficiently thin and then heat treated to form Nb3Sn. After reaction to form the Nb3Sn the bronze still contains some tin, and if pure copper is required for stabilization in the composite it can be incorporated with a ductile barrier to prevent contarnination by tin from the bronze. Fig.1 shows the distribution of the niobium rods in the bronze matrix, x 250: Enquiries to: P. E. Madsen, AERE Harwell, Didcot, Berkshire, England.
Fig.1
Distribution of niobium rods in
bronze matrix
Courses at Harwell Amongst the many courses to be held at the HarweU Education Centre, in 1974, are the following, which have topics relevant to composite materials technology included in them:
Introduction to plastics technology, 1-5 April), which provides a basic introduction to the uses of both thermal and reinforced plastics for pro-
COMPOSITES . MARCH 1974
duction managers, design staff and others new to the field. Topics covered include processing, manufacture, non-destructive and destructive testing methods, designing in reinforced plastics and tribOlogical and long-term performance aspects.
Materials science, (29 April-3 May) This is a graduate level course intended for scientists, engineers and technologists already working in this field who require an opportunity to extend their knowledge beyond their own speciality. It also meets the requirements of others wishing to familiarize themselves with current developments in materials science. Topics include unusual materials and their uses, ceramics, plastics, metals, composites, adhesi~'es, physical properties, compatibility, non-destructive testing and fabrication techniques: emphasis is given to recent technological advances.
Modem physical techniques in materials technology, (20-24 May). This enables scientists engaged in research and development work to become familiar with a broad range of modern physical techniques important in the field of materials technology:~These include x-ray,electron and neutron diffraction, optical and electron microscopy, electron microprobe analysis, Auger spectroscopy and analytical techniques.
fl i!iii~iii~i
Fig.2 AGA grp buoy, showing the novel underwater profile
sure and allow water to flow underneath: this, combined with a low centre of gravity, reduces the heeling effect in strong currents which are likely to be encountered in the locations for which the buoy was developed, such as in harbours and rivers. AGA Navigation Aids Limited, Beacon Works, 77 High Street, Brentford, Middlesex, England
Resin for chemical
plant
Further details, of all the courses, are available from the Harwell Education Centre, AERE Harwell, Didcot, Berkshire, England.
Scott Bader have introduced a specially developed addition to their range of Crystic resins. Called Crystic 600 PA, the new resin has been formulated for use in the manffacture of chemical plant, and con'On-line' prepreg tape sists of a modified bisphenol polyCourtaulds Limited have superseded their ester. It is said to impregnate readily range of prepreg tapes and sheets with a the glassfibre reinforcement, enabling new Grafil ;on-line' prepreg tape. Preit to be used in filament winding, liminary datasheets are available for the pultrusion, centrifugal moulding tape, which consists, at present, of Grafd and contact moulding applications. A-S fibre in Shell DX 210/BF 3 MEA Fully cured mouldings made from epoxy resin. However, the range is to be Crystic 600 PA are claimed to have extended to include Grafil A-S, HT-S and both outstanding resistance to many HM-S fibres in both this resin and in aggressive chemical environments and '3501', which is an easily handled, high high structural performance. Other temperature epoxy resin with good room claimed advantages are strength retemperature properties. tention in many chemical environments at temperature up to about Courtaulds Limited, Carbon Fibres 98°C, and consistency of both mechUnit, PO Box 16, Coventry CV6 5AE, anical and chemical properties of the England laminates made with the resin. Typical applications suggested for the Novel grp buoy design resin include fume stacks, scrubbing AGA Navigation Aids have produced towers, ducting, reaction vessels, a grp buoy having an unconventional sewage pipes, storage tanks and design, see Fig.2. The four legs built equipment in chemical, civil engineerinto the base of the buoy can, it is ing and food processing industries. claimed, reduce the underwater presCrystic 600 PA can also be used as a
51
lining material for vessels made with other materials. Full details of the new resin', including fabrication, mechanical properties and chemical compatibilities, are given in data sheets available from Scott Bader.
special publications listed in the catalogue is considerable, with topics as diverse as sensory evaluation, education and oceanography. A complete list of out of print publications that are available from a microfilm store is also given.
Scott Bader Company Limited, Wollaston, WeUingborough, Northants NN9 9RL, England
ASTM, 1916 Race Street, Philadelphia, Pennsylvania 19103, USA
BSI Standard for pressure vessels The British Standards Institution (BSI) have published a new standard, BS 4994, which, they claim, is the most advanced design and construction code in the world for the manufacture of grp vessels and tanks. The standard is called 'Vessels and tanks in reinforced plastics', and covers materials using either epoxide or polyester resins, with hand Or machine lay-up techniques other than filament windhag. Provision is made for the incorporation of chemically resistant linings, such as pvc, where necessary. The committee responsible for the new standard hope that it will attain a similar status to BS 1515 for steel pressure vessels. British Standards Institution, 2 Park Street, London WlA 2BS, England
ASTM news The ASTM have published a catalogue of their publications for 1973-74, which include the 1974 Annual book of ASTM standards, in 47 parts. The range of subjects covered by the
52
Improved roving product Owens-Coming Fiberglas Corp. in the USA have introduced an improved glass fibre roving that, they say, is adaptable for nearly all spray-up applications: the company have designated the new product '447 roving'. Testing has indicated good choppability, even dispersion in use, ease of air removal and good conformability to the mould. '447 roving' is classified as an optimum roving product by Owens-Coming, in that is has demonstrated consistent performance in a variety of spray-up equipment and a wide range of applications. Typical uses suggested are in marine, consumer, recreation, electrical and transportation products. Owens-Coming Fiberglas Corp. have also introduced a new glass fibre mat product, called M-715 mat. This, they claim, drapes better than mats currently on the market, conforms immediately to complex shapes and impregnates with resin faster than competitive products. The new mat has been designed for marine or other
applications that demand high strength with intricate contouring. Owens-Coming Fiberglas Corp., Fiberglas Tower, Toledo, Ohio 43659, USA
British Celanese This company, a member of the Courtaulds Group, has published a 4-page leaflet, 'Polypropylene in chemical engineering', which deals with various chemical engineering applications of their products, specifically their 'Celmar' polypropylene/glass fibre laminates and 'Propylex' polypropylone sheet. The products have been used in aluminium, dyestuffs, antibiotics, pharmaceuticals and paper manufacturing processes, as well as gas Cleaning and chemical-wastes storage and transport. Copies of the leaflet can be obtained from: British Celanese Limited, Plastics Group Sales, Spondon, Derby DE2 7BP, England
Slingsby Sailplanes A wholly-owned division of the Vickers Shipbuilding Group, Slingsby Sailplanes have produced a catalogue of some of their products, which includes marine buoys, grp pipe couplings, pressure vessels, gliders and general grp structures. Details are also given of the company's design, test and technical services which are available to industry in general. Slingsby Sailplanes, Composite Materials Division, Kirbymoorside, Yorkshire YO6 6EZ, England
COMPOSITES . MARCH 1974
M E Conference (1975)
Further details are available on the AIME-sponsored special symposia on composite materials, to be held in April 1975. The general theme of the symposia will be appraisal of the past twenty years' work on composites, with respect to possible future research and applications. The first meeting will be held in Geneva, Switzerland; the main aim will be to assemble technical people from various parts of the world who are working with advanced composite materials, designs and applications. The emphasis will be on the combined scientific and engineering advancements of composites. The second meeting, to be held in Boston, USA, will consolidate the significant contributions of the Geneva meeting and put them into the context of the work being done in the USA. Information regarding submission of papers can be obtained from: A. R. Scott, Executive Secretary, TMS-AIME 345 East 47 Street, New York, NY 10017, USA, Dr E. Anderson,Battelle Geneva Research Center, 7 route de Drize, CH-1227, Carouge/Geneva, or Dr E. Scala, PO Box 1362, Cortland, NY 1362, Cortland, NY 13045, USA.
Reports from Techlink Techlink, an information link between research and industry in the UK, under the Department of Trade and Industry, recently announced the availability of the following reports:
Selecting resin matrices for improved composite strength ( Techlink No 1438). This gives details of a report prepared by the Lewis Research Center in the USA which presents criteria for selecting resin matrices to improve composite strength. These criteria resulted from theoretical and experimental investigations in which matrix properties such as ultimate strength, ultimate elongation, toughness and fracture toughness were found to be misleading for predicting composite strength. The work indicated that the area under the matrix stress/strain diagram, limited to 1% strain, is a good index for assessing its contribution: the cor-
50
responding initial modulus is considered to be a useful parameter for translating matrix properties to those of the composite. Composite mechanics were used, in conjunction with experimental data either generated as part of the study or taken from the literature, to identify the matrix properties which influence composite unidirectional strength. Unidirectional specimeas were made from carbon fibres and low, intermediate and high modulus resins. They were tested for strength in longitudinal flexure, transverse tension and compression and interlaminar shear. Composite strength data from other sources included values of longitudinal tension and compression, transverse tension and interlaminar shear. Comparisons of the composite strength data with the various matrix properties led to the identification of convenient and practical criteria for assessing the matrix contribution to composite strength.
Fabrication of plastics using nonionizing radiation ( Techlink No 1445). A report from the US Plastics Evaluation Center surveyed the use of ultraviolet, infrared, induction, radiofrequency and microwave radiation heating in the fabrication of plastics. This survey included instruments both in current use and with reasonable commercial potential. The methods are suitable for application to glassreinforced polyesters (eg laminates and pipes), formed sheets, moulded' phenolics, epoxies and other thermosets, urethane foams, etc. The use of non-ionizing radiation processes in the fabrication of plastics products can lead to reduced costs, increased processing speed and improved product quality.
Development o[pyrrone structural foams (Techlink No 1446). An investigation, sponsored by NASA, was carried out on the development of techniques for preparing pyrrone foams for use as a filler for the cells of honeycomb structures. Initially, most of the work was devoted to preparing pyrrone prepolymers, but the high-curing shrinkage of unfilled
pyrrone prepolymers and consequent unsuitability for use in a foam-in-place process led to the production of syntactic foams. These were formulated using carbon microspheres, of 200/.tm nominal diameter, and a technique was devised for introducing syntactic foam formulations into honeycomb structures. Techlink Unit, Technology Reports Centre, Orpington, Kent BR5 3RF, England
Energy absorbing composites The Technical Products Division of the Brunswick Corporation have developed a class of materials which they have called 'energy absorbing composites' for damping and/or isolation of vibrations in structures. These materials are primarily metallic and consist of at least two elements, one of which displays elastic properties and the other damping characteristics. Brunswick claim that their materials are superior to conventional elastomeric materials and viscous.type dampers because they offer greater design flexibility. Other advantages claimed are a wide operational temperature range ( 196°C to 427°C), ability to withstand operating stresses up to 2 GN/m 2 and operating frequencies up to 100 Hz. Fatigue lives of up to 7.5 x 106 cycles have been obtained on composites which exhibited relatively low damping capacities (15%) at low strain amplitudes. At resonant frequency conditions, lives of l0 s cycles have been measured for relatively large damping capacities (40%) at large strain a~nplitudes. The metallic characteristics of these composites can also be utilized to isolate vibrations at frequencies well above resonance. Two basic situations are involved: firstly, the transmission of forces from a small to a large mass (eg from a car to the frame), and, secondly, the transmission of forces from a large to a small mass (eg from a car to the passenger). Both types are normally controlled by the introduction of resilient mounts between the source and the receiver. The use of Brunswick's material can provide a damping coefficient of up to 40% per cycle, with resonant transmissibilities as low as 3-for a double input amplitude of 2.54 mm. Brunswick say that a significant feature of their energy absorbing composites is their simple design compared with the more
COMPOSITES . MARCH 1974
complex systems commonly in use. Thus, a single structur~ may be able to replace a complicated arrangement of several components. A wide variety of configurations such as. wire, rod, bar, sheet and strip is available. Brunswick Corporation, 1 Brunswick Plaza, Skokie, Illinois 60076, USA
Composite superconductor The Atomic Energy Research Establishment at HarweU have developed a technique for preparing stabilized superconducting composite materials using A15-structure compounds (eg Nb3Sn, V3Ga ). Until now, mechanical fabrication techniques could not be used, the compounds being too hard and brittle. This problem has been overcome at Harwell by forming Nb3Sn by a solid state reaction between tin from a bronze matrix and niobium. The niobium, in the form of rods, is embedded in the required geometry, in an ingot of bronze: this is mechanically reduced until the niobium is sufficiently thin and then heat treated to form Nb3Sn. After reaction to form the Nb3Sn the bronze still contains some tin, and if pure copper is required for stabilization in the composite it can be incorporated with a ductile barrier to prevent contarnination by tin from the bronze. Fig.1 shows the distribution of the niobium rods in the bronze matrix, x 250: Enquiries to: P. E. Madsen, AERE Harwell, Didcot, Berkshire, England.
Fig.1
Distribution of niobium rods in
bronze matrix
Courses at Harwell Amongst the many courses to be held at the HarweU Education Centre, in 1974, are the following, which have topics relevant to composite materials technology included in them:
Introduction to plastics technology, 1-5 April), which provides a basic introduction to the uses of both thermal and reinforced plastics for pro-
COMPOSITES . MARCH 1974
duction managers, design staff and others new to the field. Topics covered include processing, manufacture, non-destructive and destructive testing methods, designing in reinforced plastics and tribOlogical and long-term performance aspects.
Materials science, (29 April-3 May) This is a graduate level course intended for scientists, engineers and technologists already working in this field who require an opportunity to extend their knowledge beyond their own speciality. It also meets the requirements of others wishing to familiarize themselves with current developments in materials science. Topics include unusual materials and their uses, ceramics, plastics, metals, composites, adhesi~'es, physical properties, compatibility, non-destructive testing and fabrication techniques: emphasis is given to recent technological advances.
Modem physical techniques in materials technology, (20-24 May). This enables scientists engaged in research and development work to become familiar with a broad range of modern physical techniques important in the field of materials technology:~These include x-ray,electron and neutron diffraction, optical and electron microscopy, electron microprobe analysis, Auger spectroscopy and analytical techniques.
fl i!iii~iii~i
Fig.2 AGA grp buoy, showing the novel underwater profile
sure and allow water to flow underneath: this, combined with a low centre of gravity, reduces the heeling effect in strong currents which are likely to be encountered in the locations for which the buoy was developed, such as in harbours and rivers. AGA Navigation Aids Limited, Beacon Works, 77 High Street, Brentford, Middlesex, England
Resin for chemical
plant
Further details, of all the courses, are available from the Harwell Education Centre, AERE Harwell, Didcot, Berkshire, England.
Scott Bader have introduced a specially developed addition to their range of Crystic resins. Called Crystic 600 PA, the new resin has been formulated for use in the manffacture of chemical plant, and con'On-line' prepreg tape sists of a modified bisphenol polyCourtaulds Limited have superseded their ester. It is said to impregnate readily range of prepreg tapes and sheets with a the glassfibre reinforcement, enabling new Grafil ;on-line' prepreg tape. Preit to be used in filament winding, liminary datasheets are available for the pultrusion, centrifugal moulding tape, which consists, at present, of Grafd and contact moulding applications. A-S fibre in Shell DX 210/BF 3 MEA Fully cured mouldings made from epoxy resin. However, the range is to be Crystic 600 PA are claimed to have extended to include Grafil A-S, HT-S and both outstanding resistance to many HM-S fibres in both this resin and in aggressive chemical environments and '3501', which is an easily handled, high high structural performance. Other temperature epoxy resin with good room claimed advantages are strength retemperature properties. tention in many chemical environments at temperature up to about Courtaulds Limited, Carbon Fibres 98°C, and consistency of both mechUnit, PO Box 16, Coventry CV6 5AE, anical and chemical properties of the England laminates made with the resin. Typical applications suggested for the Novel grp buoy design resin include fume stacks, scrubbing AGA Navigation Aids have produced towers, ducting, reaction vessels, a grp buoy having an unconventional sewage pipes, storage tanks and design, see Fig.2. The four legs built equipment in chemical, civil engineerinto the base of the buoy can, it is ing and food processing industries. claimed, reduce the underwater presCrystic 600 PA can also be used as a
51
lining material for vessels made with other materials. Full details of the new resin', including fabrication, mechanical properties and chemical compatibilities, are given in data sheets available from Scott Bader.
special publications listed in the catalogue is considerable, with topics as diverse as sensory evaluation, education and oceanography. A complete list of out of print publications that are available from a microfilm store is also given.
Scott Bader Company Limited, Wollaston, WeUingborough, Northants NN9 9RL, England
ASTM, 1916 Race Street, Philadelphia, Pennsylvania 19103, USA
BSI Standard for pressure vessels The British Standards Institution (BSI) have published a new standard, BS 4994, which, they claim, is the most advanced design and construction code in the world for the manufacture of grp vessels and tanks. The standard is called 'Vessels and tanks in reinforced plastics', and covers materials using either epoxide or polyester resins, with hand Or machine lay-up techniques other than filament windhag. Provision is made for the incorporation of chemically resistant linings, such as pvc, where necessary. The committee responsible for the new standard hope that it will attain a similar status to BS 1515 for steel pressure vessels. British Standards Institution, 2 Park Street, London WlA 2BS, England
ASTM news The ASTM have published a catalogue of their publications for 1973-74, which include the 1974 Annual book of ASTM standards, in 47 parts. The range of subjects covered by the
52
Improved roving product Owens-Coming Fiberglas Corp. in the USA have introduced an improved glass fibre roving that, they say, is adaptable for nearly all spray-up applications: the company have designated the new product '447 roving'. Testing has indicated good choppability, even dispersion in use, ease of air removal and good conformability to the mould. '447 roving' is classified as an optimum roving product by Owens-Coming, in that is has demonstrated consistent performance in a variety of spray-up equipment and a wide range of applications. Typical uses suggested are in marine, consumer, recreation, electrical and transportation products. Owens-Coming Fiberglas Corp. have also introduced a new glass fibre mat product, called M-715 mat. This, they claim, drapes better than mats currently on the market, conforms immediately to complex shapes and impregnates with resin faster than competitive products. The new mat has been designed for marine or other
applications that demand high strength with intricate contouring. Owens-Coming Fiberglas Corp., Fiberglas Tower, Toledo, Ohio 43659, USA
British Celanese This company, a member of the Courtaulds Group, has published a 4-page leaflet, 'Polypropylene in chemical engineering', which deals with various chemical engineering applications of their products, specifically their 'Celmar' polypropylene/glass fibre laminates and 'Propylex' polypropylone sheet. The products have been used in aluminium, dyestuffs, antibiotics, pharmaceuticals and paper manufacturing processes, as well as gas Cleaning and chemical-wastes storage and transport. Copies of the leaflet can be obtained from: British Celanese Limited, Plastics Group Sales, Spondon, Derby DE2 7BP, England
Slingsby Sailplanes A wholly-owned division of the Vickers Shipbuilding Group, Slingsby Sailplanes have produced a catalogue of some of their products, which includes marine buoys, grp pipe couplings, pressure vessels, gliders and general grp structures. Details are also given of the company's design, test and technical services which are available to industry in general. Slingsby Sailplanes, Composite Materials Division, Kirbymoorside, Yorkshire YO6 6EZ, England
COMPOSITES . MARCH 1974