- Email: [email protected]
Initial flexural failure of square, simply supported, angle-ply laminates
Vol 16 (1981 pp 627-632 The shear modulus, strength, and shear strain at failure of CFRP are shown to depend on temperature alone, and also temperature with water uptake. In highly voided specimens the hydrothermal effects are not reversible as is the case with lower void contents. Although the complex effects are not fully explained, the evidence suggests failure of the resin bond. Initial flexurai failure of square, simply supported, angle-ply laminates Turvey, G.J. Fibre Science and Technology Vol 15 No 1 (July 1981) A combination of the Tsai-Hill stress failure criterion with an exact equilibrium solution was used to analyze the flexural failure of the composite plates subjected to uniform square patch loading, at the centre of the plate. A model of passive thermal nondestructive evaluation of composite laminates Charles, J.A. and Wilson, D.W. Polymer Composites Vol 2 No 3 (July 1981) pp 105-111 A numerical model of passive thermal non-destructive testing of composite laminates has been developed, based on a transient, three-dimensional finite difference solution to the heat conduction equations. The model is shown to be of use in characterizing in-plane defects in the laminates and in predicting the laminate response to thermal testing. The theory was verified experimentally using carbon/epoxy and glass/epoxy composites. A parametric study was then conducted to ascertain which variables were critical to the success of passive thermal non-destructive testing: and how flaw resolution might be improved.
presence of the glass fibre, and the VF.
Physical model for the thermal expansion behaviour of fibre-reinforced viscoelastic composites Theocaris, P.S., Papanicolaou, G.C. and Spathis, G.D. Fibre Science and Technology Vol 15 No 3 (November 1981) pp 187-197 An analysis of the thermal expansion coefficients of filled, unidirectional fibre composites was performed using a new theoretical model. This model assumes that interphase material - - the zone between fibres and matrix - - is an inhomogeneous substance with properties varying continuously from the fibre surface to the bulk matrix. The variation of the thermal expansion coefficient in the area of the boundary interphase was analytically studied and expressions for both the longitudinal and transverse coefficients of the composite were derived. The predictions of the continuous-interphase model were found to be in good agreement with those of other workers. Physicochemical properties of epoxidized composite materials from industrial wastes A m i n a b h a v r i , T.M., Patel, R.C. and B i r a d a r , N.S. Materials Science and Engineering Vol 48 No 2 (May 1981) pp 199-206 Four industrial waste materials, sawdust, fly ash, cinder and coke, were used separately with fillers such as silicon carbide, silica and fibrous asbestos, and epoxy resin, to form lightweight composite materials. Tensile strengths of up to 6.05 kgf/cm ~ (for 10% asbestos, 10% carbide, 40% sand/carbide 1:1 mixture, 40% sawdust) and compressive strengths of up to 9.76 kgf/cm ~ (for the same material) were recorded. Good fire, acid and alkali resitance were also observed, and it is concluded that such composites may have potential as low-cost structural materials.
Moisture penetration into composites under external stress Marom, G. and Broutman, L.J. Polymer Composites Vol 2 No 3 (July 1981) pp 132-136 The penetration of water at 95°C, into stressed and unstressed samples of glass and carbon fibre-reinforced epoxy resins was studied, with particular attention being given to the effect of the angle between the stress and the fibre orientation on the diffusivities. It is reported that the application of external stress increases the rate of moisture absorption of the composites, increases the maximum moisture content, and increases the diffusion coefficients. As the angle between the loading and fibre directions increases the rate and maximum value of moisture absorption increase, although their ratio remains constant. The results also indicated that exposure of the composites to water produces a typical damage mechanism which enhances moisture absorption.
Preparation and structure of poly (sulphur nitride) whiskers Stejny, J., Trinder, R.W. and Dlugosz, J. Journal of Materials Science Vol 16 No 11 (November 1981)pp 3161-3170 A method of preparing poly (sulphur nitride) whiskers with diameters down to 400 nm and lengths up to 2 mm is described. Two morphologically different whisker types were produced through the addition of specific impurities to the sulphur dinitride starting material. Both types of whisker were shown to possess a fibrous texture. The fibrils were of irregular shape and composed of microtwins. A vapour-liquid-solid mechanism is proposed for the whisker growth. The possibility of using a correlated polychromatic percolation as a model for the subsequent polymerization of the whiskers is also discussed.
Molding and torsional testing of tubular specimens of glass fiber-reinforced polypropylene Pandit, S.N. and Gupta, V.B. Polymer Composites Vol 2 No 3 (July 1981) pp 121-125 The use of a torsion pendulum device to test tubular samples of i n j e c t i o n - m o u l d e d glass/polypropylene is described. Tests were performed in the temeprature range of - 4 0 ° C to +I00°C. The results obtained indicate that both storage modulus and the logarithmic decrement are affected by the
A probabliistic theory for the strength of short fibre composites Fukuda, H., and Chouw, T.W. Journal of Materials Science Vol 16 (1981) The strength of unidirectional short fibre composites are predicted from a theoretical analysis of 2- and 3-dimensional fibre arrays. The number of adjacent fibre ends, and the resulting stress concentrations are shown to be critical parameters. Predictions are compared with other theoretical and experimental results.
COMPOSITES. APRIL 1982
On the pull-out ot" nbres wire enmrgeu enus Phan-Thien, N. Fibre Science and Technology Vol 15 No 2 (September 1981) pp 111-116 An approximate solution to the pull-out of an enlarged-end fibre from a semi-infinite matrix is developed, with the aim of quantifying the effects of the enlarged end of the fibre. It is assumed that the fibre rod is nearly rigid and slender, so that previous theoretical results based on the slenderbody theory can be used. The enlarged end was modelled by a rigid spherical bead. Linear viscoelastic effects are also discussed. Reinforced plastics aim at cost efficiency Wehrenberg II, R.H. Materials Engineering (May 1981) pp 47-52 A review is presented of recent advances in the field of composite materials from the industrial viewpoint. Emphasis in the article is placed on materials savings, reduced labour and ease of processing. Review: Some physical defects arising in composite materials fabrication Johnson, W., and Ghosh, S.K. Journal of Materials Science Vol 16 (1981) pp 285-301 This review surveys a range of defects which arise in the fabrication and subsequent processing of composite materials including fibre-reinforced materials, metal-matrix composites, ceramic-matrix composites, and sandwich, clad and bonded materials. A semi-dry method for the production of lightweight glass fibre-reinforced gypsum Evans, T.J., Majumdar, A.J. and Ryder, J.F. International Journal of Cement Composites and Lightweight Concrete Vol 3 No 1 (February 1981) pp 41-44 Expanded perlite, chopped glass fibre and water are premixed and hemihydrate gypsum plaster is then added to the premix. This forms a semi-dry, crumbly mix which, on pressing, produces a low density composite having good insulation and fireresistance properties, albeit with low strength. It is suggested that the material would be particularly suitable for some indoor applications, such as ceiling tiles, or for decorative texturing or lamination with wood or plastic. The production method itself requires less capital investment and labour than the spray dewatering technique. Some observations on the cured shape of thin unsymmetrie laminates Hyer, M.W. Journal of Composite Materials Vol 15 (March 1981) pp 175-194 Thin unsymmetric composite laminates were found to cure into the shape of a right circular cylinder rather than being saddle-shaped as predicted by classical lamination theory. Using an analysis based on Mohrs circle of curvature laminates of the (0/902/0)T, (02/0~)T , (04/04)T families were investigated for this behaviour. The principal, curvature directions of the cylindrical shapes being both predictable and repeatable. Thicker laminates conformed to the predictions of classical theory. Spray metal composite tooling Thorpe, M.L. and Minge, J.W. 26th National SAMPE Symposium Proceedings (April 1981) pp 374-387 Some examples of the successful use of-the arc spray metal tooling concept, in which metal is sprayed onto a model or pattern, are presented.
211
presence of the glass fibre, and the VF.
Physical model for the thermal expansion behaviour of fibre-reinforced viscoelastic composites Theocaris, P.S., Papanicolaou, G.C. and Spathis, G.D. Fibre Science and Technology Vol 15 No 3 (November 1981) pp 187-197 An analysis of the thermal expansion coefficients of filled, unidirectional fibre composites was performed using a new theoretical model. This model assumes that interphase material - - the zone between fibres and matrix - - is an inhomogeneous substance with properties varying continuously from the fibre surface to the bulk matrix. The variation of the thermal expansion coefficient in the area of the boundary interphase was analytically studied and expressions for both the longitudinal and transverse coefficients of the composite were derived. The predictions of the continuous-interphase model were found to be in good agreement with those of other workers. Physicochemical properties of epoxidized composite materials from industrial wastes A m i n a b h a v r i , T.M., Patel, R.C. and B i r a d a r , N.S. Materials Science and Engineering Vol 48 No 2 (May 1981) pp 199-206 Four industrial waste materials, sawdust, fly ash, cinder and coke, were used separately with fillers such as silicon carbide, silica and fibrous asbestos, and epoxy resin, to form lightweight composite materials. Tensile strengths of up to 6.05 kgf/cm ~ (for 10% asbestos, 10% carbide, 40% sand/carbide 1:1 mixture, 40% sawdust) and compressive strengths of up to 9.76 kgf/cm ~ (for the same material) were recorded. Good fire, acid and alkali resitance were also observed, and it is concluded that such composites may have potential as low-cost structural materials.
Moisture penetration into composites under external stress Marom, G. and Broutman, L.J. Polymer Composites Vol 2 No 3 (July 1981) pp 132-136 The penetration of water at 95°C, into stressed and unstressed samples of glass and carbon fibre-reinforced epoxy resins was studied, with particular attention being given to the effect of the angle between the stress and the fibre orientation on the diffusivities. It is reported that the application of external stress increases the rate of moisture absorption of the composites, increases the maximum moisture content, and increases the diffusion coefficients. As the angle between the loading and fibre directions increases the rate and maximum value of moisture absorption increase, although their ratio remains constant. The results also indicated that exposure of the composites to water produces a typical damage mechanism which enhances moisture absorption.
Preparation and structure of poly (sulphur nitride) whiskers Stejny, J., Trinder, R.W. and Dlugosz, J. Journal of Materials Science Vol 16 No 11 (November 1981)pp 3161-3170 A method of preparing poly (sulphur nitride) whiskers with diameters down to 400 nm and lengths up to 2 mm is described. Two morphologically different whisker types were produced through the addition of specific impurities to the sulphur dinitride starting material. Both types of whisker were shown to possess a fibrous texture. The fibrils were of irregular shape and composed of microtwins. A vapour-liquid-solid mechanism is proposed for the whisker growth. The possibility of using a correlated polychromatic percolation as a model for the subsequent polymerization of the whiskers is also discussed.
Molding and torsional testing of tubular specimens of glass fiber-reinforced polypropylene Pandit, S.N. and Gupta, V.B. Polymer Composites Vol 2 No 3 (July 1981) pp 121-125 The use of a torsion pendulum device to test tubular samples of i n j e c t i o n - m o u l d e d glass/polypropylene is described. Tests were performed in the temeprature range of - 4 0 ° C to +I00°C. The results obtained indicate that both storage modulus and the logarithmic decrement are affected by the
A probabliistic theory for the strength of short fibre composites Fukuda, H., and Chouw, T.W. Journal of Materials Science Vol 16 (1981) The strength of unidirectional short fibre composites are predicted from a theoretical analysis of 2- and 3-dimensional fibre arrays. The number of adjacent fibre ends, and the resulting stress concentrations are shown to be critical parameters. Predictions are compared with other theoretical and experimental results.
COMPOSITES. APRIL 1982
On the pull-out ot" nbres wire enmrgeu enus Phan-Thien, N. Fibre Science and Technology Vol 15 No 2 (September 1981) pp 111-116 An approximate solution to the pull-out of an enlarged-end fibre from a semi-infinite matrix is developed, with the aim of quantifying the effects of the enlarged end of the fibre. It is assumed that the fibre rod is nearly rigid and slender, so that previous theoretical results based on the slenderbody theory can be used. The enlarged end was modelled by a rigid spherical bead. Linear viscoelastic effects are also discussed. Reinforced plastics aim at cost efficiency Wehrenberg II, R.H. Materials Engineering (May 1981) pp 47-52 A review is presented of recent advances in the field of composite materials from the industrial viewpoint. Emphasis in the article is placed on materials savings, reduced labour and ease of processing. Review: Some physical defects arising in composite materials fabrication Johnson, W., and Ghosh, S.K. Journal of Materials Science Vol 16 (1981) pp 285-301 This review surveys a range of defects which arise in the fabrication and subsequent processing of composite materials including fibre-reinforced materials, metal-matrix composites, ceramic-matrix composites, and sandwich, clad and bonded materials. A semi-dry method for the production of lightweight glass fibre-reinforced gypsum Evans, T.J., Majumdar, A.J. and Ryder, J.F. International Journal of Cement Composites and Lightweight Concrete Vol 3 No 1 (February 1981) pp 41-44 Expanded perlite, chopped glass fibre and water are premixed and hemihydrate gypsum plaster is then added to the premix. This forms a semi-dry, crumbly mix which, on pressing, produces a low density composite having good insulation and fireresistance properties, albeit with low strength. It is suggested that the material would be particularly suitable for some indoor applications, such as ceiling tiles, or for decorative texturing or lamination with wood or plastic. The production method itself requires less capital investment and labour than the spray dewatering technique. Some observations on the cured shape of thin unsymmetrie laminates Hyer, M.W. Journal of Composite Materials Vol 15 (March 1981) pp 175-194 Thin unsymmetric composite laminates were found to cure into the shape of a right circular cylinder rather than being saddle-shaped as predicted by classical lamination theory. Using an analysis based on Mohrs circle of curvature laminates of the (0/902/0)T, (02/0~)T , (04/04)T families were investigated for this behaviour. The principal, curvature directions of the cylindrical shapes being both predictable and repeatable. Thicker laminates conformed to the predictions of classical theory. Spray metal composite tooling Thorpe, M.L. and Minge, J.W. 26th National SAMPE Symposium Proceedings (April 1981) pp 374-387 Some examples of the successful use of-the arc spray metal tooling concept, in which metal is sprayed onto a model or pattern, are presented.
211