Elastic Moduli Of Composite Materials Research Articles

Environmental Effects on the Elastic Moduli of Composite Materials

The buckling moduli of Thornel 300/Fiberite 1034 graphite epoxy composites were measured at temperatures ranging from 105 K to 422 K and at moisture contents ranging from 0% (dry) to 1.5% (fully saturated). The measurements were made using 0°, 90° and π/4 laminates. A survey was also made of the existing data showing the effects of temperature and moisture content on the tensile modulus and the compressive modulus of different composite materials.

Evaluation of elastic moduli of composite materials by linear programming

A method of applying linear programming to evaluate the elastic moduli of unidirectionally fiber-reinforced composite materials is presented. Based on the theory of elasticity, the stresses and displacements of the fiber and of the resin are expressed in terms of harmonic series. The coefficients of the series are determined by the simplex algorithm to minimize the deviations which occur when the stresses and displacements are matched at the fiberresin interface and at the outer boundary of the representative element of the composite. By applying the energy principle, the Young's modulus in the fiber direction and the major Poisson's ratio of the E-glass/resin composite are found to be in good agreement with existing results, while the gap of the bounds for its bulk modulus is considerably narrowed in comparison to earlier results.

Morphology and the elastic modulus of block polymers and polyblends

The theory of the elastic moduli of composite materials in which an inversion of the phases can occur is reviewed. The morphology of the system and the packing fraction of the dispersed phase are important in determining the moduli. The applicability of the theoretical equations is illustrated for four systems of block polymers and polyblends. In three of the systems, phase inversion occurs. Agreement between theory and experiment is good, and where the morphology of the composites is known, the moduliagree with the values expected for that morphology.

The effective modulus of rock as a composite material

An approximation equation for the effective elastic moduli of composite materials including certain rocks was obtained by assuming that the material is composed of elastic granular inclusions surrounded by a matrix having different elastic properties. A cubic element with a granular inclusion at its center was analyzed using the principle of least work and the theorem of minimum potential energy. From comparisons with test results on a variety of composites including artificial rocks, the equation was shown in most cases to give a better approximation than previously developed equations.

Calculation of effective elastic moduli of composite materials with multiphase interactions taken into consideration

The effective tensors of elastic moduli and pliability were calculated by renormalizing the equations of equilibrium and incompatibility. All multiphase interactions were taken into consideration, but the calculation was done approximately by using only the singular parts of derivatives of Green's functions, which is equivalent to the assumption of uniformity of the random components of stress and strain fields within grain boundaries. Solutions derived by two methods are reconciled, making it possible to determine the position of the elastic moduli of shear and of bulk K between the Hashin-Shtrikman bounds. Particular cases in which only the bulk modulus is not uniform, as well as those of composite materials with all of their constituents having the same ratio K=4μ/3 are considered.

Variational principles of elastic moduli of composite materials : Yeh, R. H. T. J Applied Physics, Vol 41, No 8, pp 3353 – 3356 (July 1970)

Variational principles of elastic moduli of composite materials : Yeh, R. H. T. J Applied Physics, Vol 41, No 8, pp 3353 – 3356 (July 1970)

Generalized Equation for the Elastic Moduli of Composite Materials

A generalized equation is proposed for the relative elastic moduli of composite materials. By the introduction of a generalized Einstein coefficient and a function which considers the maximum volumetric peaking fraction of the filler phase, the moduli of many types of composite systems can be calculated.

Variational Principles of the Elastic Moduli of Composite Materials

Variational principles and variational bounds are obtained for the effective elastic moduli of quasiisotropic composite materials.

On the overall elastic moduli of composite materials

The overall elastic moduli of some solid composite materials are evaluated, first by bounding them precisely, and secondly by a ‘self-consistent’ estimate. Transversely isotropic inclusions of ‘needle’ and ‘disc’ shapes are particularly considered, at both random and aligned orientations, and at arbitrary volume concentration.