Properties Of Multiphase Composites Research Articles

Iterative Method to Predict Effective Elastic Moduli of Multiphase Particulate Composites

AbstractIn multiphase particulate composites, the deviation and mismatch of the elastic moduli of different particles may significantly affect the overall mechanical performance of the composites. This study investigates the effects of such deviations on the macroscopic properties of multiphase composites via an iterative micromechanics-based method. The elastic properties of the particles are assumed to obey certain statistical distributions. In the proposed iterative method, the composites are divided into multiple two-phase composites and their strain concentration tensors are derived by means of the inclusion matrix–reference medium model, which is a modification of the generalized self-consistent method. Iterative solutions are established that take into account the effects of the variation in the elastic properties of the particles in terms of the effective shear and bulk moduli. The findings show that the proposed iterative method converges quickly and that the results agree well with the experimen...

Synthesis and Measurement of the Thermoelectric Properties of Multiphase Composites: ZnSb Matrix with Zn4Sb3, Zn3P2, and Cu5Zn8

We synthesized a series of samples with composition around 52 at.% zinc (Zn), 44 at.% antimony (Sb), 4 at.% phosphorus (P), and up to 3 at.% copper (Cu) by melting the elements and subsequent annealing. This resulted in dense and almost crack-free samples. X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) revealed composites with a majority phase of ZnSb containing varying amounts of Zn3P2 and Cu5Zn8, in addition to Zn4Sb3 in some of the samples. We measured the Seebeck coefficient, electrical conductivity, and thermal conductivity as a function of temperature. The thermoelectric performance tended to improve with increasing Cu content. At Cu content of 2 at.%, a reduced resistivity allows for the highest dimensionless figure of merit, with a maximum zT value of 0.18 at around 573 K.

Effective Mechanical Properties for Composites with Three-Phase Randomly Distributed Aggregates Predicted by Multi-Step Mori-Tanaka Method

Multi-step Mori-Tanaka method (MMT) is applied to the estimation of the effective mechanical properties for composites with three-phase randomly distributed aggregates in this paper. The Multi-phase Homogenization Theory (MHT) which is based on mathematical homogenization method and is employed to verify the results of MMT method. Results show that MMT method is reasonable and practicable to predict the effective mechanical properties of composites with several phases, and the Young’s moduli and Poisson’s ratios of each phase may have some effects on the effective mechanical properties of multi-phase composites.

A polarization‐based FFT iterative scheme for computing the effective properties of elastic composites with arbitrary contrast

SUMMARYIt is recognized that the convergence of FFT‐based iterative schemes used for computing the effective properties of elastic composite materials drastically depends on the contrast between the phases. Particularly, the rate of convergence of the strain‐based iterative scheme strongly decreases when the composites contain very stiff inclusions and the method diverges in the case of rigid inclusions. Reversely, the stress‐based iterative scheme converges rapidly in the case of composites with very stiff or rigid inclusions but leads to low convergence rates when soft inclusions are considered and to divergence for composites containing voids. It follows that the computation of effective properties is costly when the heterogeneous medium contains simultaneously soft and stiff phases. Particularly, the problem of composites containing voids and rigid inclusions cannot be solved by the strain or the stress‐based approaches. In this paper, we propose a new polarization‐based iterative scheme for computing the macroscopic properties of elastic composites with an arbitrary contrast which is nearly as simple as the basic schemes (strain and stress‐based) but which has the ability to compute the overall properties of multiphase composites with arbitrary elastic moduli, as illustrated through several examples. Copyright © 2011 John Wiley & Sons, Ltd.

Magneto-electro-elastic Eshelby tensors for a piezoelectric-piezomagnetic composite reinforced by ellipsoidal inclusions

The magneto-electro-elastic Eshelby tensors that represent the stress, electric displacement, and magnetic induction in an inclusion resulting from the constraint of the surrounding matrix of piezomagnetic-piezoelectric composites are presented. The tensors provide the basis for analysis of the magneto-electro-elastic response of the composites and have numerous applications such as to the study of defects, overall properties of multiphase composites, and fracture mechanics, etc. For a three-dimensional transversely isotropic piezoelectric/piezomagnetic composite containing spheriodal inclusions, the number of nonzero Eshelby tensors is 41 while among them only 17 are independent. These independent tensors can be divided into three categories. The first category consists of those tensors related to the elastic response, the second involves those related to the piezomagnetic response, while the third includes elastic and magnetic interactive terms. Moreover, the magneto-electro-elastic Eshelby tensors are obtained in the closed forms when both constituents of the composite are transversely isotropic and shapes of the inclusion are elliptic, rod shaped, penny shaped, and ribbon like.

Acoustic and dynamic properties of two-phase media with non-spherical inclusions

Abstract The propagation and attenuation of ultrasonic waves in sintered copper powder with air saturated pores is studied experimentally and theoretically in the long-wavelength approximation using the self-consistent single scattering theory. The overall dynamic and propagation properties of such an example of a two-phase composite are analysed computationally, the properties of the pure matrix material being, in the first step, determined by extrapolation from suitable ultrasonic measurements carried out at low porosities. The results presented confirm the ultrasound to be extremely useful in estimating the influence of the volume concentration and shape of the inclusions on the overall dynamic properties of multi-phase composites.