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Optimization of the thermal shock resistance of carbon-carbon composites
Abstracts of journals Compiled by Dr H. A. Barker, I. Bell, B. Gill and R. Warren
CARBON MA TRICES
The flash method is extended to measure directly the thermal diffusivity of graphite/carbon fibre in unidirectionCVD/PAN felt carbon/carbon ally reinforced composites and also in composites fibre bundles for a range of fibre types. Lieberman, M. L. et al. Journal of MOD-3 is a three-dimensional orthoComposite Materials, Vol 9 (Oct 1975) gonal-reinforced carbon/carbon pp 33 7-346 composite whose thermal diffusivity Carbon fibre reinforced/carbon matrix materials of particular interest for applic- was measured in order to compute the ations which require high thermal shock thermal conductivity in the three resistance. The preparation of a CVD/ orthogonal directions. PAN carbon/carbon frustum and its evaluation are described. The thermal gradient infiltration technique has successfully yielded a matrix composed primarily of the desired rough laminar micro- GENERAL structure. Characterisation of the composite includes thermal and mechanical Acoustic emission from stress rupture properties as functions of temperature, and fatigue of an organic fiber as well as room temperature crystallocomposite graphic parameters. Hamstad, M. A. and Chiao, T. T.
Optimization of the thermal shock resistance of carbon-carbon composites Guess, T. R. and Butler, B. L. Conference on Composite Reliability, ASTM STP 580 (American Society for Testing and Materials, 1975) pp 229246 A three-dimensional rule of mixtures model was developed to calculate the room temperature thermal and mechanical properties of carbon-carbon composites whose constituents have anisotropic properties. The model was used, along with the properties of different carbon fibres and pyrocarbon matrices, to determine the fibre-matrix combination, constituent volume fractions, and constituent orientations that maximise expected composite thermal shock resistance of heat shields. The results indicate that a composite having a low volume fraction of high-modulus carbon fibres, arranged in a 3D array, and coated with anisotropic, heat-treated pyrocarbon matrix, will have the maximum thermal shock resistance. Confidence in the model was established by good agreement between model predictions and experimental data on actual carbon-carbon composites. Thermophysical properties of carbon/ graphite fibres and MOD-3 fibrereinforced graphite Lee, H. J. and Taylor, R. E. Carbon, Vo113 (1975)pp 521-527 200
Conference on Composite Reliability, ASTM STP 580 (American Society for Testing and Materials, 1975) pp 191201 A series of tests was carried out to determine the scatter in acoustic emission data gathered during stress rupture and fatigue testing of a simple fibre-reinforced epoxy composite. It was found that, during the stress rupture and fatigue tests, the plots of summation of acoustic emission counts versus time were found to resemble metal creep curves in that primary, secondary and tertiary regions could be distinguished. Because of a significant amount of scatter, however, only a limited correlation could be made between the slope of the summation curve and the specimen life during the tests. Flawed specimens were easily sorted out during the tension tests. It is suggested that the acoustic emission data gathered during composite fatigue and stress rupture testing might be useful for life prediction.
Analysis for beams made of bi-modulus elastic orthotropic materials Tabaddor, F. Fibre Science & Technology, Vol 6, No 1 (Jan 1976) pp 51-62 Beams of orthotropic bi-modulus composites were subjected to lateral loading and their stress/strain characteristics analysed. It was found that the analysis is more complex than that of classical theory.
Application of a special X-ray nondestructive testing technique for monitoring damage zone growth in composite laminates Chang, F. H. et al. Conference on Composite Reliability, ASTM STP 580 (American Society for Testing and Materials, 1975) pp 176-190 A modified X-ray non-destructive testing technique was used to study matrix cracks parallel to fibres between plies in a graphite/epoxy composite material. A tetrabromoethane opaque additive, applied at the source of the damage zones, was used to enhance the image of the flaw. The buckling of transversely isotropic beams on elastic foundations Das Gupta, S. Fibre Science & Technolog?2, Vol 6, No 1 (Jan 1976)pp 11-17 An analysis of buckling for beams made of transversely isotropic material, and resting on Winkler-type foundations, is presented. It shows that for a high E/G ratio and a low slenderness ratio, the effect of shear can be significant for beams with either simply supported or fixed ends. In both cases, including the shear effect lowers the critical load value.
The chemical vapour deposition of carbon on carbon fibres Pierson, H. O. and Lieberman, M. L. Carbon, Vol 13 (June 1975)pp 159166 The relationship between chemical vapour deposition (CVD) parameters and the resultant pyrolytic carbon microstructures have been examined for matrix deposition in fibrous carbon substrates. Temperature, pressure, C/H ratio, total flow rate and carbonfelt density are the parameters considered. Most of the data obtained are in agreement with the CVD model for carbon. Damage analysis in composite materials Rose, J. L. and Shelton, W. Conference on Composite Reliability, ASTM STP 580 (American Society for Testing and. Materials, 1975) pp 215-226 Two non-destructive evaluation test methods, radiography and ultrasonics, are examined for potential use in corn-
COMPOSITES, JULY 1976
CARBON MA TRICES
The flash method is extended to measure directly the thermal diffusivity of graphite/carbon fibre in unidirectionCVD/PAN felt carbon/carbon ally reinforced composites and also in composites fibre bundles for a range of fibre types. Lieberman, M. L. et al. Journal of MOD-3 is a three-dimensional orthoComposite Materials, Vol 9 (Oct 1975) gonal-reinforced carbon/carbon pp 33 7-346 composite whose thermal diffusivity Carbon fibre reinforced/carbon matrix materials of particular interest for applic- was measured in order to compute the ations which require high thermal shock thermal conductivity in the three resistance. The preparation of a CVD/ orthogonal directions. PAN carbon/carbon frustum and its evaluation are described. The thermal gradient infiltration technique has successfully yielded a matrix composed primarily of the desired rough laminar micro- GENERAL structure. Characterisation of the composite includes thermal and mechanical Acoustic emission from stress rupture properties as functions of temperature, and fatigue of an organic fiber as well as room temperature crystallocomposite graphic parameters. Hamstad, M. A. and Chiao, T. T.
Optimization of the thermal shock resistance of carbon-carbon composites Guess, T. R. and Butler, B. L. Conference on Composite Reliability, ASTM STP 580 (American Society for Testing and Materials, 1975) pp 229246 A three-dimensional rule of mixtures model was developed to calculate the room temperature thermal and mechanical properties of carbon-carbon composites whose constituents have anisotropic properties. The model was used, along with the properties of different carbon fibres and pyrocarbon matrices, to determine the fibre-matrix combination, constituent volume fractions, and constituent orientations that maximise expected composite thermal shock resistance of heat shields. The results indicate that a composite having a low volume fraction of high-modulus carbon fibres, arranged in a 3D array, and coated with anisotropic, heat-treated pyrocarbon matrix, will have the maximum thermal shock resistance. Confidence in the model was established by good agreement between model predictions and experimental data on actual carbon-carbon composites. Thermophysical properties of carbon/ graphite fibres and MOD-3 fibrereinforced graphite Lee, H. J. and Taylor, R. E. Carbon, Vo113 (1975)pp 521-527 200
Conference on Composite Reliability, ASTM STP 580 (American Society for Testing and Materials, 1975) pp 191201 A series of tests was carried out to determine the scatter in acoustic emission data gathered during stress rupture and fatigue testing of a simple fibre-reinforced epoxy composite. It was found that, during the stress rupture and fatigue tests, the plots of summation of acoustic emission counts versus time were found to resemble metal creep curves in that primary, secondary and tertiary regions could be distinguished. Because of a significant amount of scatter, however, only a limited correlation could be made between the slope of the summation curve and the specimen life during the tests. Flawed specimens were easily sorted out during the tension tests. It is suggested that the acoustic emission data gathered during composite fatigue and stress rupture testing might be useful for life prediction.
Analysis for beams made of bi-modulus elastic orthotropic materials Tabaddor, F. Fibre Science & Technology, Vol 6, No 1 (Jan 1976) pp 51-62 Beams of orthotropic bi-modulus composites were subjected to lateral loading and their stress/strain characteristics analysed. It was found that the analysis is more complex than that of classical theory.
Application of a special X-ray nondestructive testing technique for monitoring damage zone growth in composite laminates Chang, F. H. et al. Conference on Composite Reliability, ASTM STP 580 (American Society for Testing and Materials, 1975) pp 176-190 A modified X-ray non-destructive testing technique was used to study matrix cracks parallel to fibres between plies in a graphite/epoxy composite material. A tetrabromoethane opaque additive, applied at the source of the damage zones, was used to enhance the image of the flaw. The buckling of transversely isotropic beams on elastic foundations Das Gupta, S. Fibre Science & Technolog?2, Vol 6, No 1 (Jan 1976)pp 11-17 An analysis of buckling for beams made of transversely isotropic material, and resting on Winkler-type foundations, is presented. It shows that for a high E/G ratio and a low slenderness ratio, the effect of shear can be significant for beams with either simply supported or fixed ends. In both cases, including the shear effect lowers the critical load value.
The chemical vapour deposition of carbon on carbon fibres Pierson, H. O. and Lieberman, M. L. Carbon, Vol 13 (June 1975)pp 159166 The relationship between chemical vapour deposition (CVD) parameters and the resultant pyrolytic carbon microstructures have been examined for matrix deposition in fibrous carbon substrates. Temperature, pressure, C/H ratio, total flow rate and carbonfelt density are the parameters considered. Most of the data obtained are in agreement with the CVD model for carbon. Damage analysis in composite materials Rose, J. L. and Shelton, W. Conference on Composite Reliability, ASTM STP 580 (American Society for Testing and. Materials, 1975) pp 215-226 Two non-destructive evaluation test methods, radiography and ultrasonics, are examined for potential use in corn-
COMPOSITES, JULY 1976