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A new theory of laminated plate
Bonding composites Lees, W.A~International Journal of Adhesion and Adhesives Vol 6 No 3 (1986) pp 171-180 The relevant characteristics of both composites and metals are discussed with reference to their ability to form good joints both to themselves and each other. The relationship between these adherends and a variety of suitable adhesive types is also reviewed with particular reference to the ductility/brittleness/toughness of the various adhesives and their individual capacity to cope with brittle and possibly contaminated surfaces. The theoretical aspects of joint stress distribution are presented as a background to the design of good load-bearing joints. The paper concludes with the innovative suggestion that toughened adhesives may be used as laminating resins where joints are to be very heavily loaded. (Author's abstract)
A computer model of the tensile failure process in unidirectional fibre composites Curtis, P.T. Composites Science and Technology Vol 27 No 1 (1986) pp 63-86 A computer model of the tensile failure process in unidirectional fibre composites that predicts the sequence of fibre failures in a thin layer of composite from the breaking strains of individual fibres, as estimated and from experiment, is presented. The model shows the sequential development of fibre fractures in a composite layer and indicates that only about four fibre fractures in one composite plane are necessary to initiate composite failure. This implies that elimination of the low strain fibres could significantly improve composite strength.
The effective conductivity of composites with imperfect thermal contact at constituent interfaces Benvenisti, Y. and Miloh, T.lnternationalJounal of Engineering Science Vol 24 No 9 (1986) pp 1537-1552 The effective thermal conductivities of a composite material containing dilute concentrations of aligned or randomly oriented prolate spheroidal or oblate particles has been investigated under conditions of imperfect thermal contact at the interfaces. Fundamental concepts are reconsidered and well-known procedures for defining and computing effective moduli are generalized to include imperfect interface effects. The final method of solution is based on expanding the interior and exterior temperature fields in terms of oblate and prolate spheroidal harmonics. Numerical results are presented for different values of the parameter representing the interface condition.
Effective properties of fiber-reinforced composites: effect of polydispersity in fiber diameter Joslin, G.C. and Steel, G. Journal of Applied Physics Vol 60 No 5 (September 1986) pp 16111613 The polydispersity of fibre cross-section may affect some properties of a composite -- thick fibres tend to increase work of fracture and ease of fabrication, whilst thin fibres may reduce matrix cracking and yield. A dispersion of fibre size should allow high volume fractions of fibre to be achieved. Using the Shulz probability density function to model the distribution in fibre cross-section, the authors conclude that transport properties and the elastic modulus are insensitive to polydisperisty in fibre crosssection.
COMPOSITES
. APRIL 1987
An elasticity analysis for the generally and specially orthotropic beams subjected to concentrated loads Sullivan, J.L. and Van Oene, H. Composites Science and Technology Vo12 7 No 2 (1986) pp133155 Classical elasticity equations for the stress and displacement fields of loaded orthotropic beams have been derived and from these the stress distributions in a series of centrally loaded, generally and specially orthotropic beams have been calculated. These stress distributions at selected beam sections and their symmetry about the loading axis are discussed in detail. Fabricating the future with composite materials. Part 1. The basics English, L.K. Materials Engineering (November 1986) pp 29-35 In this the first of a four-part series covering the basics of the important aspects of a wide variety of composites (including ceramic matrix, metal matrix and fibre-reinforced plastics), comparative properties are presented and a variety of fabrication techniques outlined. Finite element analysis of the end notched flexure specimen for measuring Mode II fracture toughness Gillespie Jr, J.W., Carlsson, L.A. and Pipes, R.B. Composites Science and Technology Vol 27 No 3 (1986) pp 177-197 A two-dimensional fibre element analysis of the end-notched flexure (ENF) test specimen for Mode II interlaminar fracture testing of composite material is presented. It has been developed within the constraints of the small deflection theory. The analysis is discussed with respect to contact normal force distribution, stress distribution, ENF compliance and strain energy release rates. It is found that data reduction schemes based upon beam theory underestimate the strain energy release by 20-40%. Thus an improved data reduction scheme which retains the simplicity of the beam theory but includes the accuracy of the FEM is proposed. A microstructural approach to the mechanical response of composite systems with randomly oriented, short fibres. Part 1. Theoretical analysis Haddad, Y.M. Journal of Materials Science Vo121 (1986) pp 3767-3776 A new deformation theory concerning twodimensional composite systems with randomly oriented, short viscoelastic fibres in an elastic matrix has been described. A set of'governing response equations' based on the concepts of statistical theory and probabilistic micromechanics are developed. The notion is introduced of a "material operator' which is a function of the actual microstructural properties of a given composite domain and includes stochastic variables. The deformation process itself is seen as a stochatic process. The theoretical analysis has been developed in a generalized manner and is considered applicable to a large class of fibrous systems. A new theory of laminated plate Ren, J.G. Composite Science and Technology Vol 26 No 3 (1986) pp 225-239 A new laminate plate theory is developed using an assumption based on the theory of composite beams. Exact closed-form solutions are presented and compared with the threedimensional elasticity solutions. The results of the developed theory are found to agree closely with the closed-form solutions.
On phenomenologieal failure criteria for composite bolted joint analyses Wilson, D.W. and Tsujimoto, Y. Composites Science and Teehnology Vo126 No 4 (l 986) pp 283305 Existing phenomenological strength models with various refinements are examined and compared. It is suggested that extreme caution needs to be exercised in applying these models for the analysis bolted joints in composite materials to assure that the model is properly configured for the specific material, laminate and geometric conditions under analysis. The potential of composites in structural automotive applications Beardmore, P. and Johnson, C.F. Composites Science and Technology Vo126 No 4 (1986) pp 251281 This paper summarizes the current state of development of high-performance composites suitable for automotive applications. Availability and suitability of types of fibre-reinforced plastic materials are discussed. Emphasis is placed upon the two main categories of materials response: fatigue (durability) and energy absorption. Requirements of methods of fabrication are examined. It is suggested that high speed resin transfer moulding may meet the high-volume, high-performance requirements. It is not thought that technological breakthroughs are required, but a concerted effort to bring existing scattered knowledge and techniques together. Scattering of elastic waves by spherical inclusions with application to low frequency wave propagation in composites Norris, A.N. International Journal of Engineering Science Vo124 No 8 (1986) 1271-1282 A unified treatment of the scattering of elastic waves by spherical inclusions for both compressional and shear incidence is presented. Explicit formulae are given for the effective wave speeds and attenuations when the inclusions are voids. The study of the internal structure of composites using computational tomography Barakhov, V.I., Dimitrienko, I.P., Goncharov, V.i., Stepanov, A.P. and Nicolayev, V.A. AllUnion Scientific-Technological Journal of Engineering Physics Vol 51 No 6 (December 1986) pp 1021-1027 The results of tomographic studies of the internal structure of composites are presented. The studies are based on the possibility to obtain composite density matrices in the test cross-section. The interpretation of the statistical data on the elementary cell density allowed estimation of its distribution over the material thickness and qualitative estimation of voidage. (Authors' abstract -- article in Russian) The transverse moduli of fibre-composite material Spencer, A. Composites Science and Technology Vo127 No 2 (1986) pp 93-109 The elastic moduli of uniaxial fibre-reinforced composite material are reviewed. A single lormula is derived for the calculation of the two matrix-dependent moduli: Young's modulus and the axial-transverse shear modulus. The formula takes into consideration the need for a simple equation but draws attention to the variation of packing array with fibre volume fraction. Its accuracy is demonstrated by comparison with existing Ibrmula based on HalpinTsai and by verifying its trends for the extremes of fibre volume fraction.
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A computer model of the tensile failure process in unidirectional fibre composites Curtis, P.T. Composites Science and Technology Vol 27 No 1 (1986) pp 63-86 A computer model of the tensile failure process in unidirectional fibre composites that predicts the sequence of fibre failures in a thin layer of composite from the breaking strains of individual fibres, as estimated and from experiment, is presented. The model shows the sequential development of fibre fractures in a composite layer and indicates that only about four fibre fractures in one composite plane are necessary to initiate composite failure. This implies that elimination of the low strain fibres could significantly improve composite strength.
The effective conductivity of composites with imperfect thermal contact at constituent interfaces Benvenisti, Y. and Miloh, T.lnternationalJounal of Engineering Science Vol 24 No 9 (1986) pp 1537-1552 The effective thermal conductivities of a composite material containing dilute concentrations of aligned or randomly oriented prolate spheroidal or oblate particles has been investigated under conditions of imperfect thermal contact at the interfaces. Fundamental concepts are reconsidered and well-known procedures for defining and computing effective moduli are generalized to include imperfect interface effects. The final method of solution is based on expanding the interior and exterior temperature fields in terms of oblate and prolate spheroidal harmonics. Numerical results are presented for different values of the parameter representing the interface condition.
Effective properties of fiber-reinforced composites: effect of polydispersity in fiber diameter Joslin, G.C. and Steel, G. Journal of Applied Physics Vol 60 No 5 (September 1986) pp 16111613 The polydispersity of fibre cross-section may affect some properties of a composite -- thick fibres tend to increase work of fracture and ease of fabrication, whilst thin fibres may reduce matrix cracking and yield. A dispersion of fibre size should allow high volume fractions of fibre to be achieved. Using the Shulz probability density function to model the distribution in fibre cross-section, the authors conclude that transport properties and the elastic modulus are insensitive to polydisperisty in fibre crosssection.
COMPOSITES
. APRIL 1987
An elasticity analysis for the generally and specially orthotropic beams subjected to concentrated loads Sullivan, J.L. and Van Oene, H. Composites Science and Technology Vo12 7 No 2 (1986) pp133155 Classical elasticity equations for the stress and displacement fields of loaded orthotropic beams have been derived and from these the stress distributions in a series of centrally loaded, generally and specially orthotropic beams have been calculated. These stress distributions at selected beam sections and their symmetry about the loading axis are discussed in detail. Fabricating the future with composite materials. Part 1. The basics English, L.K. Materials Engineering (November 1986) pp 29-35 In this the first of a four-part series covering the basics of the important aspects of a wide variety of composites (including ceramic matrix, metal matrix and fibre-reinforced plastics), comparative properties are presented and a variety of fabrication techniques outlined. Finite element analysis of the end notched flexure specimen for measuring Mode II fracture toughness Gillespie Jr, J.W., Carlsson, L.A. and Pipes, R.B. Composites Science and Technology Vol 27 No 3 (1986) pp 177-197 A two-dimensional fibre element analysis of the end-notched flexure (ENF) test specimen for Mode II interlaminar fracture testing of composite material is presented. It has been developed within the constraints of the small deflection theory. The analysis is discussed with respect to contact normal force distribution, stress distribution, ENF compliance and strain energy release rates. It is found that data reduction schemes based upon beam theory underestimate the strain energy release by 20-40%. Thus an improved data reduction scheme which retains the simplicity of the beam theory but includes the accuracy of the FEM is proposed. A microstructural approach to the mechanical response of composite systems with randomly oriented, short fibres. Part 1. Theoretical analysis Haddad, Y.M. Journal of Materials Science Vo121 (1986) pp 3767-3776 A new deformation theory concerning twodimensional composite systems with randomly oriented, short viscoelastic fibres in an elastic matrix has been described. A set of'governing response equations' based on the concepts of statistical theory and probabilistic micromechanics are developed. The notion is introduced of a "material operator' which is a function of the actual microstructural properties of a given composite domain and includes stochastic variables. The deformation process itself is seen as a stochatic process. The theoretical analysis has been developed in a generalized manner and is considered applicable to a large class of fibrous systems. A new theory of laminated plate Ren, J.G. Composite Science and Technology Vol 26 No 3 (1986) pp 225-239 A new laminate plate theory is developed using an assumption based on the theory of composite beams. Exact closed-form solutions are presented and compared with the threedimensional elasticity solutions. The results of the developed theory are found to agree closely with the closed-form solutions.
On phenomenologieal failure criteria for composite bolted joint analyses Wilson, D.W. and Tsujimoto, Y. Composites Science and Teehnology Vo126 No 4 (l 986) pp 283305 Existing phenomenological strength models with various refinements are examined and compared. It is suggested that extreme caution needs to be exercised in applying these models for the analysis bolted joints in composite materials to assure that the model is properly configured for the specific material, laminate and geometric conditions under analysis. The potential of composites in structural automotive applications Beardmore, P. and Johnson, C.F. Composites Science and Technology Vo126 No 4 (1986) pp 251281 This paper summarizes the current state of development of high-performance composites suitable for automotive applications. Availability and suitability of types of fibre-reinforced plastic materials are discussed. Emphasis is placed upon the two main categories of materials response: fatigue (durability) and energy absorption. Requirements of methods of fabrication are examined. It is suggested that high speed resin transfer moulding may meet the high-volume, high-performance requirements. It is not thought that technological breakthroughs are required, but a concerted effort to bring existing scattered knowledge and techniques together. Scattering of elastic waves by spherical inclusions with application to low frequency wave propagation in composites Norris, A.N. International Journal of Engineering Science Vo124 No 8 (1986) 1271-1282 A unified treatment of the scattering of elastic waves by spherical inclusions for both compressional and shear incidence is presented. Explicit formulae are given for the effective wave speeds and attenuations when the inclusions are voids. The study of the internal structure of composites using computational tomography Barakhov, V.I., Dimitrienko, I.P., Goncharov, V.i., Stepanov, A.P. and Nicolayev, V.A. AllUnion Scientific-Technological Journal of Engineering Physics Vol 51 No 6 (December 1986) pp 1021-1027 The results of tomographic studies of the internal structure of composites are presented. The studies are based on the possibility to obtain composite density matrices in the test cross-section. The interpretation of the statistical data on the elementary cell density allowed estimation of its distribution over the material thickness and qualitative estimation of voidage. (Authors' abstract -- article in Russian) The transverse moduli of fibre-composite material Spencer, A. Composites Science and Technology Vo127 No 2 (1986) pp 93-109 The elastic moduli of uniaxial fibre-reinforced composite material are reviewed. A single lormula is derived for the calculation of the two matrix-dependent moduli: Young's modulus and the axial-transverse shear modulus. The formula takes into consideration the need for a simple equation but draws attention to the variation of packing array with fibre volume fraction. Its accuracy is demonstrated by comparison with existing Ibrmula based on HalpinTsai and by verifying its trends for the extremes of fibre volume fraction.
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