Elastic Moduli of Thickly Coated Particle and Fiber-Reinforced Composites

1991 ◽  
Vol 58 (2) ◽  
pp. 388-398 ◽  
Author(s):  
Y. P. Qiu ◽  
G. J. Weng
Keyword(s):  
Shear Modulus ◽  
Bulk Modulus ◽  
Elastic Moduli ◽  
Poisson Ratio ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Two Phase ◽  
Coated Particle ◽  
Replacement Method

Based on the models of Hashin (1962) and Hashin and Rosen (1964), the effective elastic moduli of thickly coated particle and fiber-reinforced composites are derived. The microgeometry of the composite is that of a progressively filled composite sphere or cylinder element model. The exact solutions of the effective bulk modulus κ of the particle-reinforced composite and those of the plain-strain bulk modulus κ23, axial shear modulus μ12, longitudinal Young’s modulus E11, major Poisson ratio ν12, of the fiber-reinforced one are derived by the replacement method. The bounds for the effective shear modulus μ and the effective transverse shear modulus μ23 of these two kinds of composite, respectively, are solved with the aid of Christensen and Lo’s (1979) formulations. By considering the six possible geometrical arrangements of the three constituent phases, the values of κ, and of κ23, μ12, E11, and ν12 are found to always lie within the Hashin-Shtrikman (1963) bounds, and the Hashin (1965), Hill (1964), and Walpole (1969) bounds, respectively, but unlike the two-phase composites, none coincides with their bounds. The bounds of μ and μ23 derived here are consistently tighter than their bounds but, as for the two-phase composites, one of the bounds sometimes may fall slightly below or above theirs and therefore it is suggested that these two sets of bounds be used in combination, always choosing the higher for the lower bound and the lower for the upper one.

Coefficients of thermal expansion of unidirectional fiber-reinforced composites using unit-cell model

2018 ◽  
Vol 53 (11) ◽  
pp. 1425-1436
Author(s):  
PC Upadhyay ◽  
JP Dwivedi ◽  
VP Singh
Keyword(s):  
Thermal Expansion ◽  
Cell Model ◽  
Unit Cell ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Unit Cell Model ◽  
Fiber Reinforced ◽  
Two Phase ◽  
Thermal Expansion Coefficients ◽  
Three Phase

Coefficients of thermal expansion of some uniaxially fiber-reinforced composites have been evaluated using three-phase unit-cell model. Results have been compared with the values predicted by two other models based on composite cylinders assembly (CCA), and also with some earlier reported experimental values. An extension of the two-phase unit-cell model has also been presented for the evaluation of thermal expansion coefficients of three-phase composites. The formulation has been used to evaluate the overall coefficients of thermal expansion of AS-graphite/epoxy system with a low modulus coating on the fibers. The results have been compared with the results obtained from the Sutcu's recursive concentric cylinders model for composites containing coated fibers. From the comparison of results of the unit-cell models (both, two-phase and three-phase) with the results obtained from some other models available in the literature, it is concluded that the overall thermal properties of fiber-reinforced composites evaluated by the unit-cell model can be used as effectively as by any other model.

scholarly journals Optimization of elasticity of unidirectionnal non-overlapping fiber reinforced materials

2019 ◽  
Vol 286 ◽  
pp. 03004
Author(s):  
L. Lakhal ◽  
Y. Brunet ◽  
T. Kanit
Keyword(s):  
Elastic Properties ◽  
Elastic Moduli ◽  
Volume Averaging ◽  
Distribution Functions ◽  
Fiber Reinforced Composites ◽  
Effective Elastic Moduli ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Fiber Reinforced Materials ◽  
Local Stresses

The aim of this work is to efficiently select samples of non-overlapping parallel fiber reinforced composites with regard to their elasticity and their fiber distribution in the composite cross-section. The samples were built with the help of the simulated annealing technique according to chosen Radial Distribution Functions. For each sample the fields of local stresses were simulated by finite element method, then homogenized by volume averaging in order to investigate their elastic properties. The effect of RDF shape on elastic properties was quantified. The more the fiber distributions deviate from Poisson’s Law the higher the effective elastic moduli are. A method to select samples of real fiber reinforced composites according to their elasticity is proposed.

The Effective Dilatational Response of Fiber-Reinforced Composites With Nonlinear Interface

1996 ◽  
Vol 63 (2) ◽  
pp. 357-364 ◽  
Author(s):  
A. J. Levy
Keyword(s):  
Elastic Moduli ◽  
Characteristic Length ◽  
Normal Component ◽  
Fiber Reinforced Composites ◽  
Elastic Fibers ◽  
Separation Mechanism ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
Nonlinear Force

This paper presents a model of the dilatational response of fiber-reinforced composites for situations where the fibers interact with the matrix through a nonlinear interfacial separation mechanism. The solution to a planar solitary fiber-interface-matrix problem is employed together with the geometrically consistent composite cylinders model to obtain an exact solution for the bulk response of an elastic matrix reinforced with unidirectional elastic fibers. In the solitary fiber problem interface characterization assumes the form of a nonlinear force-separation law which couples the normal component of displacement jump to the normal component of interface traction and which requires a characteristic length for its prescription. Under decreasing values of characteristic length to inclusion radius ratio ductile or brittle decohesion or closure can occur provided the applied load, interface strength and elastic moduli of fiber and matrix are within the required bounds. Interaction effects due to finite fiber volume concentration, along with the phenomenon of brittle decohesion arising in the solitary fiber problem from the bifurcation of equilibrium separation at the fiber matrix interface, are shown to precipitate instability in the composite. An inequality relating the elastic moduli and interface properties is provided which governs the smooth or abrupt transition in composite response from rigid interface behavior to void behavior. The results are shown to apply equally well for composite geometry based on the three-phase model.

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