Papers by Keyword: Particulate Composite

Abstract: The particulate composites with glass matrix are widely used in many engineering applications. The mismatch of coefficients of thermal expansion during the fabrication process usually causes the presence of the residual stresses around particles. The influence and the understanding of the effects of residual stresses on the material response is required. The main aim of the present paper was to create a two-dimensional finite element model to analyze the influence of residual stresses on micro-crack behavior of glass and ceramics-based particulate composites. The maximum tangential stress criterion (MTS) was used to predict the direction of the micro-crack propagation. The modelled material was a kind of Low Temperature Co-fired Ceramics (LTCC) containing alumina particles embedded in a glass matrix. The influence of the micro-crack length and magnitude of loading on the micro-crack propagation path were investigated. The finite element software ANSYS was used. Conclusions of this paper can contribute to a better understanding of the propagation of micro-cracks in particulate composites in the field of residual stresses.

Abstract: Particulate composites with polymer matrix and solid fillers are one of important types of materials. Generally, these materials are usually used as construction materials, high-performance engineering materials or protective organic coatings. The main aim of a present paper is an estimation of the micro-crack behavior in the particulate composite with non-linear polymer matrix. The polymer matrix filled by magnesia-based mineral filler is investigated by means of the finite element method. A non-linear material behavior of the matrix was obtained from experiment as well as properties of mineral filler. Numerical model on the base of representative plane element (RPE) was developed. The results show that the presence of interphase between particle and matrix can improve fracture toughness of polymer particle composite through debonding process. The conclusions of this paper can contribute to a better understanding of the behavior of micro-crack in particulate composites with respect to interphase.

Abstract: The main aim of the paper is an estimation of the macroscopic mechanical properties of particulate composites using numerical methods. Matrix of the considered composite was cross-linked polymethyl methacrylate - PMMA in a rubbery state, which exhibits hyperelastic behaviour. The three parameter Mooney Rivlin material model, which is based on the strain energy density function, was chosen for description of the matrix behaviour. Alumina based particles (Al₂O₃) were used as a filler. Numerical modelling based on the finite element method (FEM) was performed to determine stress-strain curve of the considered particulate composite. Representative volume element (RVE) model was chosen for FE analyses as a modelling approach of a composite microstructure. Various geometry arrangements of particles and various directions of loading have been considered and composite anisotropy has been investigated. A good agreement between numerical calculations with damage model and experimental data has been found and the described method may have a great potential for numerical modelling of composite behaviour and design of new particulate composite materials.

Abstract: In this contribution the mechanical behavior of polymer particulate composite is studied. A numerical model is created as three phase continuum when a matrix, particles and an interphase are considered. Size of particles and properties of matrix are determined from experiment. A non-linear behavior of matrix is considered in calculations. The main objective is to estimate mechanical response of particulate composite depending on the change in matrix and interphase properties. The results are evaluated for different volume filler fraction of particles. The finite element commercial code ANSYS is used for calculations. Results indicated that by the change of volume filler fraction and properties of matrix and interphase it can be obtained composite with relatively different properties.

Abstract: In this paper polymer particulate composite was studied. The composite was modeled as a three-phase continuum – soft matrix, interphase and rigid particles. On the basis of fracture mechanics methodology the interaction of micro-crack propagation in the soft matrix filled by rigid particles (covered by the interphase) was analyzed. The properties of soft matrix (elasto-plastic material) were determined from the experiment and they were used for estimations of the crack behavior.

Abstract: The crack tip region in an elastic composite can be separated into three different regions. based on a simple rate-independent phenomenological constitutive model, the path independence of the J-integral and the concept of cracktip shielding, the maximum radii R of the damage saturation zone is obtained. Damage isotropy in the largest saturated damage zone is expressed by utilizing the Monte-Carlo technique to create the uniform distributions of microcrack location and orientation. With the assumption of dilute microcrack concentration, interaction among microcracks are neglected, and the stress intensity factor produced by interaction between main-crack and each microcrack can be superposed. Two sources of loading are analyzed, one is for the main-crack microcrack interaction under an applied remote load, and the other is for the main-crack microcrack interaction accompanied by the relief of residual stresses on the microcrack surfaces. The results show that two sources of loading can shield the main-crack tip, and microcracks behind the main-crack tip can make the most shielding whereas microcracks ahead of the main-crack tip play no role in shielding.

Abstract: . The Young’s modulus of syntactic foams were studied both the experiment and the theory. The compressive test and dynamic mechanical analysis were progressed for a few of specimens, which were made of the syntactic foams with the epoxy resin and hollow glass microspheres (HGMs). the equations for Young’s modulus of concentrated particulate composites were derived using a differential scheme of an infinitely dilute system, and were employed to prediction the Young’s modulus of syntactic foams. The computed effective Young’s moduli were compared with the experimental results, the prediction values were between the lower and upper bounds of the experimental data, and the prediction model was acceptable and can estimate the Young’s modulus of syntactic foams.

Abstract: The performances of aluminum /vinylester particulate-composites were studied in detail in order to investigate its suitability for engineering applications. This study examined the suitability of atomised aluminum particles for particulate reinforcement of a vinyl ester resin. Mechanical properties were obtained for the composite by testing various percentages of aluminium powder (75-150 m) and vinylester resin. It has been found that the inclusion of Al powder has not significantly changed the properties of vinylester resin, however an improvement in the ductility of the composite has been recorded. The optimal performances of the composite were exhibited by 15% Al composition. The properties of the particulate composites were modeled using numerous empirical models. Unfortunately a significant difference was found between some of the experimental and predicted properties of the Al/vinylester particulate composite. This paper intends to detail the variation of mechanical properties with the change of Al volume fraction in the composite and the performances of empirical models in prediction of the properties of particulate composites.

Abstract: The paper presents the results of investigation on the wear of alumina-based composites containing submicrometre particles of other phases in different conditions of work. Three types of phases were used as additives: tungsten carbide, yttria stabilized zirconia and metallic tungsten. The above mentioned phases were used separately or simultaneously as mixes. Two types of tests were performed - the Dry Sand Test and the Miller Test in wet pulp. Coarse silicon carbide grains were used as an abrasive medium in both cases. The results indicate that the optimal wear susceptibility in given work environment could be achieved by the addition of different type of additives.

Abstract: This work presents the investigation of the mechanical behavior of composite materials strengthened with short fibers and particles. A simple model is presented, with the purpose of predicting the fracture strength of this class of composite material. The model consists of the modification of the rule of mixtures, by the introduction of a correction factor, which corresponds to the adhesion of the resin to the fiber and the particles. The experiments were performed on three different composite materials having the same raw material but different mixture ratios. The composite materials produced were tested by the three-point flexural method, according to ASTM standard, in order to determine their mechanical properties. The comparison between theoretical and experimental results were also performed and found to be in reasonable agreement. Other relevant parameters will also be discussed.