- Email: [email protected]
Preparation and structure of Sarancarbon fibres
Direct observations of the internal structure of carbon fibres Wicks, B. J. Journal o f Materials Science, Vol 6, No 2, pp 173 - 175 (February 1971) This is a short report of some observations of carbon fibre structure as a function of graphitizing temperature. The work is part of an investigation into the deterioration of fibre strength properties with increasing graphitization temperature above an optimum of about 1600 C. This note contains an intense amount o f information concerning structure development during graphitization. (71 / 1/29) O
.
Elastic-plastic behaviour of polycrystalline metals and composites Hutchinson, J. W. Proceedings of the Royal Society, Vol 319, p 247 (October 1970) The stress-strain behaviour of polycrystals and composites is analysed mathematically by means of self consistent models based on these properties of the single crystal constituents. Tensile stress-strain curves are calculated for polycrystals and composites and single crystal anisotropy and work hardening are taken into account. (71 / 1/30)
Elastoplastic analysis of residual stresses and axial loading in composite cylinders Hecker, S. S., Hamilton, C. H. and Ebot, L. J. Journal o f Materials, Vol 5, No 4, pp 868 - 900 (December 1970) A model developed previously b y the authors is applied to the stresses caused b y cooling from fabrication temperature and b y axial loading of composite cylinders. Model copper/ steel composites were studied. Transverse stresses which resulted from the difference in contractile tendencies of the two materials were increased by axial loading, resulting in failure at stresses below those predicted b y the rule of mixtures. The authors suggest that in many respects the mechanical behaviour of filamentary composites can be expected to be similar to, but more complex than, that of composite cylinders. (71 / 1/31 )
The hardening rate of fibrestrengthened materials Tanaka, B. and Mori, T. Philosophical Magazine, Vol 23, No 183, p 737 (1971) By consideration of the change in elastic energy due to internal stress and that of the external potential due to the interaction of the internal and
124
COMPOSITES June 1971
applied stresses the hardening rate of a unidirectional metallic composite was calculated. Application of this analysis technique to a copper matrix reinforced with tungsten wires showed good agreement with the experimental results of Kelly and Lilholt. (71/1/32)
Longitudinal shear deformation of composites - effective shear modulus Sendeckyj, G. P. Journal o f Composite Materials, Vol 4, pp 5 0 0 - 5 1 2 (October 1970) An exact analytical solution is given for a case of longitudinal shear loading of a unidirectional fibre-reinforced composite. The analysis takes into account random spacing between fibres, random variation of fibre radii and the variation in shear modulus from fibre to fibre. An exact expression is derived for the effective shear modulus of the composite which simplifies considerably in the case of an exact array of equal fibres. Excellent agreement is found with numerical solutions. Extension of the results to viscoelastic composites is indicated. (71/1/33)
On non-structural applications of composites Bever, M. B., Duwez, P. E. and Tiller, W. A. Materials Science and Engineering, Vol 6, No 3, p 149 (September 1970) The potential non-structural applications o f composites which include electrical, magnetic, optical, thermal, acoustic, nuclear and chemical are reviewed and a useful list o f references is appended. The general characteristics of composites are examined from the point o f view o f their unusual combinations of properties such as anisotropy, the vibrational and electronic states o f the atoms at the interfaces, and the ability o f one phase to isolate different interconnected arrays. The practical and potential non-structural applications of these materials are considered. (71 / 1/34)
Optimum reinforcement of concrete slab elements Morley, C. T. Magazine o f concrete research, Vol 22, No 72, pp 155-162 (September 1970) A method is presented for finding the optimum arrangement o f reinforcement in a concrete slab subjected to combinations of moments and membrane forces. F o r certain simple combinations the solution can be found easily and in the special cases of membrane forces only, or moments only, the equations reduce to previously published results. (71 / 1/35)
Preparation and structure of Sarancarbon fibres Boucher, E. A., Cooper, R. W. and Everett, D. H. Carbon, Vol 8, No 5, pp 597 - 605 (November 1970) In an attempt to obtain more fundamental information about the process of producing carbon fibres from polymeric precursors, the authors have selected a Saran (vinylidene chloride• vinyl chlorfde) precursor which has a simple decomposition chemistry. Changes in structure and morphology occurring during carbon formation and subsequent heat treatment to 2500°C have been followed by x-ray diffraction, optical and electron microscopy, and have been related to the chemistry of decomposition. Three stages in the decomposition are defined and the resulting carbon fibres have markedly inferior mechanical properties to those produced from PAN or rayon precursors. However, the crystallite size is similar to that of a PAN-carbon-fibre and it is hoped that this study will lead to a greater understanding of that more complex system. (7111/36)
Propagation of stress waves in a laminated plate composite Lundergan, C. D. and Drumheller, D. S. Journal o f Applied Physics, Vo142, No 2, pp 669 - 675 (February 1971) The propagation of a dilatational stress wave in a laminated composite was investigated theoretically and experimentally. The composite consisted of ten bilaminar plates oriented normal to the direction of propagation of the wave. Agreement between theory and experiment was generally good, but the analysis indicates a need to account for the influence of fracture phenomena such as debonding of the layers of the composite, and nonlinearities in the comvonents of the composite. (71/1/37)
Some aspects of the evaluation of the impact behaviour of low temperature fibre composites Morris, A. W. H. and Smith, R. S. Fibre Science and Technology, Vol 3, No 3, p 219 (January 1971) Miniature Charpy and ballistic impact tests for composite materials are described and results of their application in the examination of glass-fibrereinforced/polyester-resin and boronreinforced/aluminium composites are reported. It is noted that under ballistic impact conditions internal damage and debonding and/or fibre breakage occurs even though little surface damage is apparent: bend and tensile strengths are adversely affected. (71/1/38)
.
Elastic-plastic behaviour of polycrystalline metals and composites Hutchinson, J. W. Proceedings of the Royal Society, Vol 319, p 247 (October 1970) The stress-strain behaviour of polycrystals and composites is analysed mathematically by means of self consistent models based on these properties of the single crystal constituents. Tensile stress-strain curves are calculated for polycrystals and composites and single crystal anisotropy and work hardening are taken into account. (71 / 1/30)
Elastoplastic analysis of residual stresses and axial loading in composite cylinders Hecker, S. S., Hamilton, C. H. and Ebot, L. J. Journal o f Materials, Vol 5, No 4, pp 868 - 900 (December 1970) A model developed previously b y the authors is applied to the stresses caused b y cooling from fabrication temperature and b y axial loading of composite cylinders. Model copper/ steel composites were studied. Transverse stresses which resulted from the difference in contractile tendencies of the two materials were increased by axial loading, resulting in failure at stresses below those predicted b y the rule of mixtures. The authors suggest that in many respects the mechanical behaviour of filamentary composites can be expected to be similar to, but more complex than, that of composite cylinders. (71 / 1/31 )
The hardening rate of fibrestrengthened materials Tanaka, B. and Mori, T. Philosophical Magazine, Vol 23, No 183, p 737 (1971) By consideration of the change in elastic energy due to internal stress and that of the external potential due to the interaction of the internal and
124
COMPOSITES June 1971
applied stresses the hardening rate of a unidirectional metallic composite was calculated. Application of this analysis technique to a copper matrix reinforced with tungsten wires showed good agreement with the experimental results of Kelly and Lilholt. (71/1/32)
Longitudinal shear deformation of composites - effective shear modulus Sendeckyj, G. P. Journal o f Composite Materials, Vol 4, pp 5 0 0 - 5 1 2 (October 1970) An exact analytical solution is given for a case of longitudinal shear loading of a unidirectional fibre-reinforced composite. The analysis takes into account random spacing between fibres, random variation of fibre radii and the variation in shear modulus from fibre to fibre. An exact expression is derived for the effective shear modulus of the composite which simplifies considerably in the case of an exact array of equal fibres. Excellent agreement is found with numerical solutions. Extension of the results to viscoelastic composites is indicated. (71/1/33)
On non-structural applications of composites Bever, M. B., Duwez, P. E. and Tiller, W. A. Materials Science and Engineering, Vol 6, No 3, p 149 (September 1970) The potential non-structural applications o f composites which include electrical, magnetic, optical, thermal, acoustic, nuclear and chemical are reviewed and a useful list o f references is appended. The general characteristics of composites are examined from the point o f view o f their unusual combinations of properties such as anisotropy, the vibrational and electronic states o f the atoms at the interfaces, and the ability o f one phase to isolate different interconnected arrays. The practical and potential non-structural applications of these materials are considered. (71 / 1/34)
Optimum reinforcement of concrete slab elements Morley, C. T. Magazine o f concrete research, Vol 22, No 72, pp 155-162 (September 1970) A method is presented for finding the optimum arrangement o f reinforcement in a concrete slab subjected to combinations of moments and membrane forces. F o r certain simple combinations the solution can be found easily and in the special cases of membrane forces only, or moments only, the equations reduce to previously published results. (71 / 1/35)
Preparation and structure of Sarancarbon fibres Boucher, E. A., Cooper, R. W. and Everett, D. H. Carbon, Vol 8, No 5, pp 597 - 605 (November 1970) In an attempt to obtain more fundamental information about the process of producing carbon fibres from polymeric precursors, the authors have selected a Saran (vinylidene chloride• vinyl chlorfde) precursor which has a simple decomposition chemistry. Changes in structure and morphology occurring during carbon formation and subsequent heat treatment to 2500°C have been followed by x-ray diffraction, optical and electron microscopy, and have been related to the chemistry of decomposition. Three stages in the decomposition are defined and the resulting carbon fibres have markedly inferior mechanical properties to those produced from PAN or rayon precursors. However, the crystallite size is similar to that of a PAN-carbon-fibre and it is hoped that this study will lead to a greater understanding of that more complex system. (7111/36)
Propagation of stress waves in a laminated plate composite Lundergan, C. D. and Drumheller, D. S. Journal o f Applied Physics, Vo142, No 2, pp 669 - 675 (February 1971) The propagation of a dilatational stress wave in a laminated composite was investigated theoretically and experimentally. The composite consisted of ten bilaminar plates oriented normal to the direction of propagation of the wave. Agreement between theory and experiment was generally good, but the analysis indicates a need to account for the influence of fracture phenomena such as debonding of the layers of the composite, and nonlinearities in the comvonents of the composite. (71/1/37)
Some aspects of the evaluation of the impact behaviour of low temperature fibre composites Morris, A. W. H. and Smith, R. S. Fibre Science and Technology, Vol 3, No 3, p 219 (January 1971) Miniature Charpy and ballistic impact tests for composite materials are described and results of their application in the examination of glass-fibrereinforced/polyester-resin and boronreinforced/aluminium composites are reported. It is noted that under ballistic impact conditions internal damage and debonding and/or fibre breakage occurs even though little surface damage is apparent: bend and tensile strengths are adversely affected. (71/1/38)