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Water-filled polyester foams combine high density, low cost
SCII0M BER, R. W. and GALE, W. R. Causes of variability in hand layup RP part 1
tures of up to about IlO°C. It is especially suitable for lining pipes, storage tanks and process tanks (69/5/24)
Modern Plastics, 46, No 8 pp 82 - 84 (..lug~tst 1969} A statistical analysis of several major factors affecting variability of mechanical properties of wet layups RP is presented. Laminator variability is shown to be a key fa.ctor, although production methods play an important role. Results presented on the effects of testing technique are ificonclusive although the authors suggest that further investigation might prove fruitful. A marked decrease in property variability is achieved in simulated production runs by standardizing reinforcement and production methods. (69/5/22)
THEBERGE, J. E. and HALL, N. T. Impact behaviour of glass-fortified thermoplastics Modern Plastics, 46, No 7, pp 114 - 122 (July 1969} Notched and un-notched Izod and tensile-impact values are presented for a wide selection of glass-reinforced thermoplastics. These values show that un-notched lzod and tensile-impact strengths provide no basis for toughness comparisons but is useful in evaluating notch-sensitivity. Other conclusions are that long fibres offer no improvement in toughness over short fibres and that with the exception of polypropylene, all the glassreinforced thermoplas'tics tested show an increase in fiTS and toughness with increasing strain-rate. Toughness rankings are reported for all materials tested. (69/5/23)
WALKER, R. A. Reinforcement sheet,
of
Clean water through plastics Modern Plastics, 46, No 7, pp 50 - 54 (July 1969} Certain plastics possess unique properties which make them ideal for use as membranes in the purification of polluted water by the techniques of reverse osmosis, ultrafiltration and electro-dialysis. A brief description of these three techniques is followed by illustrations of some ingenious composite materials designed to make optimum use of both the strength and permeability o f plastics. An example of this ingenuity is demonstrated in a permeation unit made up of bundles of minute, hollow nylon fibres encapsulated in an epoxy binder. The 30 million "fibres give a total membrane area of 85,000ft 2", the strength, corrosion-resistance and permeability o f nylon are adequately exploited, support being provided by the epoxy. Several other such composites are described and the economic benefits, both to the plastics producer and the water-purifier are discussed in some detail. (69/5/25)
SURVEY O F MORGANITE FIBRES Properties fibres
of high modulus carbon
Reinforced Plastics, [,4 ugust 1969)
pp
324 - 327
A general survey o f the properties of the Modmor range o f carbon fibres manufactured by Morganite Research and Development Ltd together with properties of carbon reinforced plastics. (69/5/27)
polypropylene
Rubber and Plastics Age, 50, No 8, pp 585 - 586 (August 1969) A new material has been developed which consists of polypropylene sheet reinforced with a specially woven cloth of glass and polypropylene fibres. ]'he material retains the chemical resistance of polypropylene and yet can be readily bonded to other materials. It can be used in tempera-
126
WOOD, S.
COMPOSITESDecember 1969
EDITORIAL
resin with 3% by volume of continuous silica fibre were strained at rates from 0.051 to 510ram/rain. The region o f fibre fracture deviated from the matrix crack by increasing amounts as the strain rate was reduced. This effect is explained semiquantitatively in terms of the variation of the resin modulus with loading rate. (6915128)
REVIEW ARTICLE Reinforced plastics developments Bri'tish ,Plastics, 42, No 8, pp 51 - 56 (August 1969} A brief but fairly comprehensive review of tiae matrix materials, reinforcements and fabrication techpiques in the field of reinforced thermosetting plastics. Examples of applicational trends in the construction and transport industries are listed, together with some uses for these materials in the manufacture o f electrical goods and chemical plant. (69/5/29)
Structures
DAVIDS, N. and GUPTA, B.P.. Internal plastic expansion of composite spheres under explosive loading of cavities Fibre Science and Technology, 1, No 4, p 285 (April 1969} Deformation due to the explosive expansion of internal cavities occurs so rapidly that the inertia of the material causes it to flow after the load has been removed. The dynamic plastic expansion of spherical and cylindrical cavities which takes inertia into account is analysed by a finite element method assuming an incompressible and rigid-plastic material. It is shown that inclusion of inertia effects give appreciably better agreement with experimental results and extensions of the analysis to composite laminates of aluminium and plastic are made. (69/5/2)
Fracture of fibre reinforced materials Nature, 223, No 5209, p 941 (August 1969} The importance of loading rate on the fracture characteristics o f a unidirectional composite has been demonstrated by a simple experiment. Notched bar specimens of flexiblised epoxy
FABIAN, R. J. Water-filled polyester foams combine high density, low cost Materials 1969}
Engineering,
p
18
(July
A material consisting of an easily foamed polyester with uniformly distributed closed cells which contain water is described and thought to combine the best features of plastic foam and wood. Its uses at the moment are in the manufacture of articles such as lamps, plaques and statues but it is thought to have potential in furniture manufacture were greater density is required. The deterioration in mechanical properties such as flexural and tensile strength with an increase in water content is noted as is the possibility of filling the hydrated foams with glass fibres. (69/5/3)
mechanical analysis has assumed one or both of the regular geometric arrays, namely square or hexagonal, to represent fibre packing. Experimental results obtained have in general shown a closer agreement with predictions using the square array than those for the hexagonal array, which has led to a preference for the square array in theoretical prediction of composite properties. Micrographical evidence, however, shows fibre packing to be random and not regular and to be more hexagonal than square in nature. The authors develop a micro-mechanical model for square and hexagonal random arrays and very good agreement is shown between experimental results and predictions using the random hexagonal packing model. (69/1/6)
FUJII, T., MIZUKAWA, K., YOSHIDA, S. and YAMAGUCHI, Y. Fatigue characteristics of an FRP sandwich structure with a PVC foam core
Proceedings o f the 12th Japenese congress on materials research, p ] 71 (1969} A study has been made of fatigue in sandwich structures used to impart rigidity to FRP components in the aerospace and ship industries etc. Fatigue was induced by three point bend and cantilever bending under alternating stress. Inserts were put in all specimens to protect the core from large compression deformation by local stresses. Fracture occured more rapidly in the low strength PVC core than in the face plates. It is calculated that the static and dynamic bending strength of a sandwich structure can be increased by adequate inserts which prevent undesirable local deformation. (69/5/4)
ped in nitrile rubber latex and Cured, a relationship between lifetime in flexure and creep data is established. By comparison of time to failure in flexure an effective force may be found from a creep curve which shows good correlation with the modulus as measured on a Gurley stiffness tester. The effective force in conjuction with flexural modulus and specimen thickness may be used to predict the flexure lives of other samples. It is demonstrated that flexure failure time is independent of cycling rate and can be approximately reproduced by an equivalent dead load. (69• 1/8)
IREMONGER, M. J. and WOOD, W. G.
Effects of geometry on stresses in discontinous fibre composite materials CHEW, P. E. and LIN, J. M. Transverse properties of fibrous composites
Materials Research and Standards 9, No 8, pp 29 - 33 (August 1969} The finite-element method and the yon Mises-Hencky criterion are used to calculate the transverse stiffness and strength of unidirectional fibre-reinforced composites, assuming both square and hexagonal fibre configurations. Theoretical predictions of transverse properties as a function of fibre-volume are presented for the limiting cases of perfect bonding and total debonding. The experimental results obtained from tests on metal/ metal and glass/epoxy composites fit within these limits according to the relative strength of the fibre]matrix bonding for the particular system. In no case does the transverse composite strength exceed the matrix strength. (69/I/7)
Journal o f Strain Analysis, 4 No 2, p 121 (1969) The stresses in a plane unidirectional discontinuous-fibre composite loaded axially with the fibres are investigated and the results of an examination of the effects of fibre spacing and nature of discontinuities given. It is found that stress concentrations whose magnitude depends on the size and nature of the end gaps occur around fibre discontinuities and that matrix or interfaeial yielding at low stress levels can result. Analyses of models with different fibre-volume fractions and different distances between fibre ends are discussed and the results confirmed by photoelastie analysis. (69/1/9)
McGUIRE, M. A., BEAUMONT, P. W. R. and HARRIS, B.
The scanning electron microscope (and its use in the study of composites)
Design Engineering, pp 3 6 - 43 {July 1969}
Gdneral ADAMS, D. F. and TSAI, S. W. FULMER, G. E. and GUTHRIE, J. L.
The influence of random filament packing on the transverse stiffness of unidirectional composites
Flex-life and long-term strength of composite materials
Journal o f Composite Materials, 3, pp 368 - 381 (July 1969)
Journal o f Applied Polymers Science, 13, No 3, p 445 (1969)
All previous work on the prediction of composite properties using micro
From the results of experiments on bulky, porous cotton linter webs dip-
After a brief, simplified description of the microscope, its usefulness in the examination of composite materials is demonstrated. Work on the fracture of metal/metal and carbon fibre/ polyester composites is described and illustrated with many electron micrographs showing the resolution and depth of focus obtainable with the SEM (69/1/10) models is described.
COMPOSITES December 1969
| 27
tures of up to about IlO°C. It is especially suitable for lining pipes, storage tanks and process tanks (69/5/24)
Modern Plastics, 46, No 8 pp 82 - 84 (..lug~tst 1969} A statistical analysis of several major factors affecting variability of mechanical properties of wet layups RP is presented. Laminator variability is shown to be a key fa.ctor, although production methods play an important role. Results presented on the effects of testing technique are ificonclusive although the authors suggest that further investigation might prove fruitful. A marked decrease in property variability is achieved in simulated production runs by standardizing reinforcement and production methods. (69/5/22)
THEBERGE, J. E. and HALL, N. T. Impact behaviour of glass-fortified thermoplastics Modern Plastics, 46, No 7, pp 114 - 122 (July 1969} Notched and un-notched Izod and tensile-impact values are presented for a wide selection of glass-reinforced thermoplastics. These values show that un-notched lzod and tensile-impact strengths provide no basis for toughness comparisons but is useful in evaluating notch-sensitivity. Other conclusions are that long fibres offer no improvement in toughness over short fibres and that with the exception of polypropylene, all the glassreinforced thermoplas'tics tested show an increase in fiTS and toughness with increasing strain-rate. Toughness rankings are reported for all materials tested. (69/5/23)
WALKER, R. A. Reinforcement sheet,
of
Clean water through plastics Modern Plastics, 46, No 7, pp 50 - 54 (July 1969} Certain plastics possess unique properties which make them ideal for use as membranes in the purification of polluted water by the techniques of reverse osmosis, ultrafiltration and electro-dialysis. A brief description of these three techniques is followed by illustrations of some ingenious composite materials designed to make optimum use of both the strength and permeability o f plastics. An example of this ingenuity is demonstrated in a permeation unit made up of bundles of minute, hollow nylon fibres encapsulated in an epoxy binder. The 30 million "fibres give a total membrane area of 85,000ft 2", the strength, corrosion-resistance and permeability o f nylon are adequately exploited, support being provided by the epoxy. Several other such composites are described and the economic benefits, both to the plastics producer and the water-purifier are discussed in some detail. (69/5/25)
SURVEY O F MORGANITE FIBRES Properties fibres
of high modulus carbon
Reinforced Plastics, [,4 ugust 1969)
pp
324 - 327
A general survey o f the properties of the Modmor range o f carbon fibres manufactured by Morganite Research and Development Ltd together with properties of carbon reinforced plastics. (69/5/27)
polypropylene
Rubber and Plastics Age, 50, No 8, pp 585 - 586 (August 1969) A new material has been developed which consists of polypropylene sheet reinforced with a specially woven cloth of glass and polypropylene fibres. ]'he material retains the chemical resistance of polypropylene and yet can be readily bonded to other materials. It can be used in tempera-
126
WOOD, S.
COMPOSITESDecember 1969
EDITORIAL
resin with 3% by volume of continuous silica fibre were strained at rates from 0.051 to 510ram/rain. The region o f fibre fracture deviated from the matrix crack by increasing amounts as the strain rate was reduced. This effect is explained semiquantitatively in terms of the variation of the resin modulus with loading rate. (6915128)
REVIEW ARTICLE Reinforced plastics developments Bri'tish ,Plastics, 42, No 8, pp 51 - 56 (August 1969} A brief but fairly comprehensive review of tiae matrix materials, reinforcements and fabrication techpiques in the field of reinforced thermosetting plastics. Examples of applicational trends in the construction and transport industries are listed, together with some uses for these materials in the manufacture o f electrical goods and chemical plant. (69/5/29)
Structures
DAVIDS, N. and GUPTA, B.P.. Internal plastic expansion of composite spheres under explosive loading of cavities Fibre Science and Technology, 1, No 4, p 285 (April 1969} Deformation due to the explosive expansion of internal cavities occurs so rapidly that the inertia of the material causes it to flow after the load has been removed. The dynamic plastic expansion of spherical and cylindrical cavities which takes inertia into account is analysed by a finite element method assuming an incompressible and rigid-plastic material. It is shown that inclusion of inertia effects give appreciably better agreement with experimental results and extensions of the analysis to composite laminates of aluminium and plastic are made. (69/5/2)
Fracture of fibre reinforced materials Nature, 223, No 5209, p 941 (August 1969} The importance of loading rate on the fracture characteristics o f a unidirectional composite has been demonstrated by a simple experiment. Notched bar specimens of flexiblised epoxy
FABIAN, R. J. Water-filled polyester foams combine high density, low cost Materials 1969}
Engineering,
p
18
(July
A material consisting of an easily foamed polyester with uniformly distributed closed cells which contain water is described and thought to combine the best features of plastic foam and wood. Its uses at the moment are in the manufacture of articles such as lamps, plaques and statues but it is thought to have potential in furniture manufacture were greater density is required. The deterioration in mechanical properties such as flexural and tensile strength with an increase in water content is noted as is the possibility of filling the hydrated foams with glass fibres. (69/5/3)
mechanical analysis has assumed one or both of the regular geometric arrays, namely square or hexagonal, to represent fibre packing. Experimental results obtained have in general shown a closer agreement with predictions using the square array than those for the hexagonal array, which has led to a preference for the square array in theoretical prediction of composite properties. Micrographical evidence, however, shows fibre packing to be random and not regular and to be more hexagonal than square in nature. The authors develop a micro-mechanical model for square and hexagonal random arrays and very good agreement is shown between experimental results and predictions using the random hexagonal packing model. (69/1/6)
FUJII, T., MIZUKAWA, K., YOSHIDA, S. and YAMAGUCHI, Y. Fatigue characteristics of an FRP sandwich structure with a PVC foam core
Proceedings o f the 12th Japenese congress on materials research, p ] 71 (1969} A study has been made of fatigue in sandwich structures used to impart rigidity to FRP components in the aerospace and ship industries etc. Fatigue was induced by three point bend and cantilever bending under alternating stress. Inserts were put in all specimens to protect the core from large compression deformation by local stresses. Fracture occured more rapidly in the low strength PVC core than in the face plates. It is calculated that the static and dynamic bending strength of a sandwich structure can be increased by adequate inserts which prevent undesirable local deformation. (69/5/4)
ped in nitrile rubber latex and Cured, a relationship between lifetime in flexure and creep data is established. By comparison of time to failure in flexure an effective force may be found from a creep curve which shows good correlation with the modulus as measured on a Gurley stiffness tester. The effective force in conjuction with flexural modulus and specimen thickness may be used to predict the flexure lives of other samples. It is demonstrated that flexure failure time is independent of cycling rate and can be approximately reproduced by an equivalent dead load. (69• 1/8)
IREMONGER, M. J. and WOOD, W. G.
Effects of geometry on stresses in discontinous fibre composite materials CHEW, P. E. and LIN, J. M. Transverse properties of fibrous composites
Materials Research and Standards 9, No 8, pp 29 - 33 (August 1969} The finite-element method and the yon Mises-Hencky criterion are used to calculate the transverse stiffness and strength of unidirectional fibre-reinforced composites, assuming both square and hexagonal fibre configurations. Theoretical predictions of transverse properties as a function of fibre-volume are presented for the limiting cases of perfect bonding and total debonding. The experimental results obtained from tests on metal/ metal and glass/epoxy composites fit within these limits according to the relative strength of the fibre]matrix bonding for the particular system. In no case does the transverse composite strength exceed the matrix strength. (69/I/7)
Journal o f Strain Analysis, 4 No 2, p 121 (1969) The stresses in a plane unidirectional discontinuous-fibre composite loaded axially with the fibres are investigated and the results of an examination of the effects of fibre spacing and nature of discontinuities given. It is found that stress concentrations whose magnitude depends on the size and nature of the end gaps occur around fibre discontinuities and that matrix or interfaeial yielding at low stress levels can result. Analyses of models with different fibre-volume fractions and different distances between fibre ends are discussed and the results confirmed by photoelastie analysis. (69/1/9)
McGUIRE, M. A., BEAUMONT, P. W. R. and HARRIS, B.
The scanning electron microscope (and its use in the study of composites)
Design Engineering, pp 3 6 - 43 {July 1969}
Gdneral ADAMS, D. F. and TSAI, S. W. FULMER, G. E. and GUTHRIE, J. L.
The influence of random filament packing on the transverse stiffness of unidirectional composites
Flex-life and long-term strength of composite materials
Journal o f Composite Materials, 3, pp 368 - 381 (July 1969)
Journal o f Applied Polymers Science, 13, No 3, p 445 (1969)
All previous work on the prediction of composite properties using micro
From the results of experiments on bulky, porous cotton linter webs dip-
After a brief, simplified description of the microscope, its usefulness in the examination of composite materials is demonstrated. Work on the fracture of metal/metal and carbon fibre/ polyester composites is described and illustrated with many electron micrographs showing the resolution and depth of focus obtainable with the SEM (69/1/10) models is described.
COMPOSITES December 1969
| 27