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.

Micromechanical Analysis of Nonlinear Viscoelastic Unidirectional Fiber-Reinforced Composites

2011 ◽  
Vol 110-116 ◽  
pp. 1166-1170 ◽  
Author(s):  
Hasan Behzadpoor ◽  
Saeed Masoumi ◽  
Manouchehr Salehi
Keyword(s):  
Three Dimensional ◽  
Fiber Reinforced Composites ◽  
Elastic Fibers ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Creep Tests ◽  
Unidirectional Fiber ◽  
Viscoelastic Matrix ◽  
Nonlinear Viscoelastic ◽  
Micromechanical Approach

The micromechanical approach of Simplified Unit Cell Method (SUCM) in closed-form three dimensional solutions is used for predicting creep response of unidirectional fiber reinforced composites. The composite consist of elastic fibers reinforcing nonlinear viscoelastic resin. The nonlinear viscoelastic matrix behavior is modeled by using Schapery single integral viscoelastic constitutive equation. Off-axis specimens of graphite/epoxy with 45 and 90 fiber orientations were subjected to 480 minutes creep tests and the results is compared with experimental data and MOC results available in the literature. There is good agreement with experimental results due to using SUCM.

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.

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.

scholarly journals An Energy-Based Model of Longitudinal Splitting in Unidirectional Fiber-Reinforced Composites

1999 ◽  
Vol 67 (3) ◽  
pp. 437-443 ◽  
Author(s):  
K. Oguni ◽  
G. Ravichandran
Keyword(s):  
Volume Fraction ◽  
Effective Properties ◽  
Confining Pressure ◽  
Fiber Reinforced Composites ◽  
Fiber Direction ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
Unidirectional Fiber ◽  
Longitudinal Splitting

Unidirectional fiber-reinforced composites are often observed to fail in a longitudinal splitting mode in the fiber direction under far-field compressive loading with weak lateral confinement. An energy-based model is developed based on the principle of minimum potential energy and the evaluation of effective properties to obtain an analytical approximation to the critical stress for longitudinal splitting. The analytic estimate for the compressive strength is used to illustrate its dependence on material properties, surface energy, fiber volume fraction, fiber diameter, and lateral confining pressure. The predictions of the model show good agreement with available experimental data. [S0021-8936(00)02003-1]

scholarly journals Natural Composite Reinforced by Lontar (Borassus flabellifer) Fiber: An Experimental Study on Open-Hole Tensile Strength

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Jefri Bale ◽  
Kristomus Boimau ◽  
Marselinus Nenobesi
Keyword(s):  
Tensile Strength ◽  
Unsaturated Polyester ◽  
Specific Area ◽  
Matrix Cracking ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
Hole Configuration ◽  
The Matrix

A research has been conducted in the present study to investigate the effect of hole configuration on tensile strength of lontar fiber-reinforced composites. The lontar fiber-reinforced composites used in this study were produced by hand lay-up process. The lontar fiber-reinforced composites consist of short random fiber of 5 cm that contains 32% of nominal fiber volume as the reinforcement and unsaturated polyester as the matrix. The results show that the differences of hole configuration have an effect on tensile strength of lontar fiber-reinforced composites. It is found that the specific area of four-hole specimens experiences smaller strain propagation due to the redistributed stress and no stress passes through the hole. The damage of lontar fiber-reinforced composites with different hole configurations in tension is fairly straight and transverse to the loading axis, where the initial damage occurs in the form of matrix cracking, propagates into interfacial failure in form of delamination, and ultimately failed mainly due to the fiber breakage.

scholarly journals A Stochastic Homogenized Peridynamic Model for Intraply Fracture in Fiber-Reinforced Composites

2019 ◽  
Author(s):  
Javad Mehrmashhadi ◽  
Ziguang Chen ◽  
Jiangming Zhao ◽  
Florin Bobaru
Keyword(s):  
Failure Modes ◽  
Volume Fraction ◽  
Crack Opening ◽  
Computational Cost ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
Peridynamic Model ◽  
Loading Case

The quasi-static transverse fracture behavior in unidirectional fiber-reinforced composites (FRCs) is investigated using a new intermediately-homogenized peridynamic (IH-PD) model and a fully homogenized peridynamic (FH-PD) model. The novelty in the IH-PD model here is accounting for the topology of the fiber-phase in the transverse sample loading via a calibration to the Halpin-Tsai model. Both models can capture well the measured load-displacement behavior observed experimentally for intraply fracture, without the need for an explicit representation of microstructure geometry of the FRC. The IH-PD model, however, is more accurate and produces crack path tortuosity as well as a non-monotonic load-crack-opening softening curve, similar to what is observed experimentally. These benefits come from the preservation of some micro-scale heterogeneity, stochastically generated in the IH-PD model to match the composite’s fiber volume fraction, while its computational cost is equivalent to that of an FH-PD model. We also present a three-point bending transverse loading case in which the two models lead to dramatically different failure modes: the FH-PD model shows that failure always starts from the off-center pre-notch, while the IH-PD model, when the pre-notch is sufficiently off-center, finds that the composite fails from the center of the sample, not from the pre-notch. Experiments that can confirm these findings are sought.

Tensile Properties of Random Distribution Short SMA Fiber Reinforced Composites

2011 ◽  
Vol 488-489 ◽  
pp. 686-689
Author(s):  
Hong Shuai Lei ◽  
Bo Zhou ◽  
Zhen Qing Wang ◽  
Xiao Qiang Wang
Keyword(s):  
Random Distribution ◽  
Volume Fraction ◽  
Effective Elastic Modulus ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
Equivalent Inclusion Method ◽  
Equivalent Inclusion ◽  
Three Phase

Shape memory alloy (SMA) reinforced composites have been widely used in aerospace engineering fields. In this paper, four basic assumptions were presented to simply the research model based on the Eshelby’s equivalent inclusion method and Mori-Tanaka scheme. Based on the three-phase equivalent system and two-step equivalent process, the effective elastic modulus and thermal expansion coefficient of unidirectional random distribution short SMA fiber reinforced composites were derived. The tensile mechanical properties of composites with fiber volume fraction (15%), size (L=3, D=1; L=5, D=1), and number (N= 30, 50), were simulated using software ANSYS12.0, and discussed the failure mode of the composites.

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