A micromechanical analysis of a local failure criterion for particle-reinforced composites (original) (raw)
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Micromechanics for Particulate-Reinforced Composites
Mechanics of Advanced Materials and Structures, 1997
A set of micromechanics equations for the analysis of particulate reinforced composites is developed using the mechanics of materials approach. Simplified equations are used to compute homogenized or equivalent thermal and mechanical properties of particulate reinforced composites in terms of the properties of the constituent materials. The microstress equations are also presented here to decompose the applied stresses on the overall composite to the microstresses in the constituent materials. The properties of a "generic" particulate composite as well as those of a particle reinforced metal matrix composite are predicted and compared with other theories as well as some experimental data. The micromechanics predictions are in excellent agreement with the measured values. SYMBOLS C heat capacity E normal modulus G shear modulus K thermal conductivity Vf Volume fraction of particles quantities with tilde refer to particle cell tx coefficient of thermal expansion E strain v Poisson's ratio v density o stress Subscripts b binder p particles pc particulate composite 17. SECURITY CLASSIFICATION
Unit cells for micromechanical analyses of particle-reinforced composites
Mechanics of Materials, 2004
Unit cells are established in this paper for micromechanical analyses of particle-reinforced composites. A range of typical packing systems are examined in a systematic manner for each of them. Only the translational symmetry transformations are employed in establishing these unit cells. There are a number of important advantages resulting from this. The unit cells so derived are capable of dealing with problems involving reinforcing particles of irregular geometries and local imperfections such as debonding between the particles and the matrix, and microcracks in the matrix, provided the regularity of the packing and the orientation of the particles and the imperfections is maintained within the material. Furthermore, all the unit cells established can be subjected to arbitrary combinations of macroscopic stresses or strains using a single set of boundary conditions unlike most available unit cells in the literature, with which individual macroscopic stress or strain components may have to be analysed using different boundary conditions because of the use of reflectional symmetries. Boundary conditions for the unit cells proposed in this paper are derived from appropriate considerations of the conditions resulting from translational symmetry transformations. Applications of loads in terms of macroscopic stresses or strains and thermal loading to the unit cells are described in such a way that they can be implemented in a straightforward manner and the effective properties of composites can be evaluated following a standard and simple procedure without a numerical averaging process. The implementation of the unit cells in the micromechanical finite element analysis of particle-reinforced composites has been demonstrated fully. Spherical particles are assumed and both the particle and the matrix are assumed to be linear elastic materials and the bonding between the particle and the matrix to be perfect. 3D brick elements have been employed to generate the meshes for analysing the unit cells corresponding to various packing systems. The effective properties of the composite represented by the unit cells have been obtained through the analyses and they have been discussed and compared with results in the literature. Stress distributions in the particle and surrounding matrix have been examined. Some interesting characteristics of the different packing systems have been elaborated.
Micromechanical failure in fiber-reinforced composites
This thesis is submitted in partial fulfillment of the requirements for obtaining the degree of Ph.D. in mechanical engineering at the Technical University of Denmark (DTU). The Ph.D. project was funded by the Danish Council for Strategic Research (grant no.: 09-067212) under the Danish Center for Composite Structures and Materials for Wind Turbines (DCCSM) and carried out at the Department of Mechanical Engineering, Solid Mechanics, and the Department of Wind Energy at DTU in the period April 1 st 2011-March 31 st 2014. Supervisors on the project were Associate Professor Ph.D. Brian Nyvang Legarth, Associate Professor Ph.D. Christian F. Niordson and Associate Professor Ph.D. Christian Berggreen from the Mechanical Engineering Department and Professor Dr.techn. Bent F. Sørensen from the Department of Wind Energy, section of Composites and Materials Mechanics. I am very grateful to my supervisors for their inspiring support and for always taking their time to discuss the work and the results during the project. I would also like to thank Professor Javier Llorca and Dr. Carlos González who were hosting me at IMDEA Materials Institute, Madrid, Spain, during my PhD external stay in the period October 2013-January 2014, for our beneficial collaboration.
A micromechanics-based constitutive model for linear viscoelastic particle-reinforced composites
Mechanics of Materials, 2019
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Computational mesomechanics of particle-reinforced composites
Computational Materials Science, 1999
Numerical models of deformation, damage and fracture in particle-reinforced composite materials, based on the method of multiphase ®nite elements (MPFE) and element elimination technique (EET), are presented in this paper. The applicability of these techniques for dierent materials and dierent levels of simulation was studied. The simulation of damage and crack growth was conducted for several groups of composites: WC/Co hard metal alloys, Al/Si and Al/SiC composites on macro-and mesolevel. It is shown that the used modern techniques of numerical simulation (MPFE and EET) are very ecient in understanding deformation and damage evolution in heterogeneous brittle/ ductile materials with inclusions. Ó : S 0 9 2 7 -0 2 5 6 ( 9 9 ) 0 0 0 5 5 -5
International Journal of Engineering Science, 2012
A systematic comparison of inhomogeneity shape effects on the linear elastic, thermoelastic and thermal conduction responses of particle reinforced composites is carried out. For this purpose, multi-particle unit cells that contain randomly positioned and, where applicable, oriented, identical particles having the shapes of spheres, regular octahedra, cubes or regular tetrahedra, respectively, and a volume fraction of 20% are employed. The macroscopic moduli and microscopic responses, such as phase averages, as well as phase-level standard deviations and distribution functions of the microfields are evaluated and compared to analytical estimates. The results indicate the presence of relatively small but consistent effects of the particle shape on the effective behavior of particulate composites. Effects on the microscopic stress and flux fields are predicted to be more pronounced.
Particle shape influence on elastic-plastic behaviour of particle-reinforced composites
Archives of materials science and engineering, 2014
Particle-reinforced composite materials very often provide unique and versatile properties. Modelling and prediction of effective heterogeneous material behaviour is a complex problem. However it is possible to estimate an influence of microstructure properties on effective macro material properties. Mentioned multi-scale approach can lead to better understanding of particle-reinforced composite behaviour. The paper is focused on prediction of an influence of particle shape on effective elastic properties, yield stress and stress distribution in particle-reinforced metal matrix composites. Design/methodology/approach: This research is based on usage of homogenization procedure connected with volume averaging of stress and strain values in RVE (Representative Volume Element). To create the RVE geometry Digimat-FE software is applied. Finite element method is applied to solve boundary value problem, in particular a commercial MSC.Marc software is used. Findings: Cylindrical particles provide the highest stiffness and yield stress while the lowest values of stiffness and yield stress are connected with spherical particles. On the other hand stress distribution in spherical particles is more uniform than in cylindrical and prismatic ones, which are more prone to an occurrence of stress concentration. Research limitations/implications: During this study simple, idealised geometries of the inclusions are considered, in particular sphere, prism and cylinder ones. Moreover, uniform size and uniform spatial distribution of the inclusions are taken into account. However in further work presented methodology can be applied to analysis of RVE that maps the real microstructure. Practical implications: Presented methodology can deal with an analysis of composite material with any inclusion shape. Predicting an effective composite material properties by analysis of material properties at microstructure level leads to better understanding and control of particle-reinforced composite materials behaviour. Originality/value: The paper in details presents in details an investigation of influence of inclusion shape on effective elastic-plastic material properties. In addition it describes the differences between stress distributions in composites with various inclusion shapes.
Experimental and numerical study of the micro-mechanical failure in composites
The fibre/matrix interfacial debonding is found to be the first microscale failure mechanism leading to subsequent macroscale transverse cracks in composite materials under tensile load. In this paper, the micromechanical interface failure in fiber-reinforced composites is studied experimentally and by numerical modeling by means of the finite element analysis. Two fibers embedded in the matrix are subjected to a remote transverse tensile load (see Fig. 1a). The trapezoidal cohesive zone model proposed by Tvergaard and Hutchinson [14] is used to model the fracture of the fiber-matrix interfaces. This study is based on the comparison between the results of numerical modeling and those corresponding to the experimental tests by employing two parameters: The angle from the load direction to the crack tip and the crack normal opening. This comparison aims to investigate the interfacial properties and also assess the progressive fiber-matrix debonding by focusing on the interaction of two fibers with dissimilar interfacial strengths.
Composites Science and Technology, 2004
The effect of particle clustering on the effective response and damage evolution in particle reinforced Al/SiC composites is studied numerically and analytically. A probability of material failure is determined on the basis of the model of a composite as an array of subdomains, and with the use of the probabilistic analysis of failure of matrix ligaments between particles. It was found that the clustered particle arrangement leads to the three times higher probability of specimen failure than the random uniform particle arrangement. Mesomechanical finite element simulations of damage evolution in the composite with clustered and uniform particle arrangements, and different amounts, sizes and volume contents of SiC particles have been carried out. Tensile stress-strain curves and the fraction of failed particles plotted versus the applied far-field strain curves were determined numerically for all the microstructures. It was shown that the failure stress of composites increases with increasing the average nearest-neighbor distance between the particles in the composite, and with decreasing the degree of clustering of particles.
Failures analysis of particle reinforced metal matrix composites by microstructure based models
Materials & Design, 2010
This paper discusses the methodology of microstructure based elastic–plastic finite element analysis of particle reinforced metal matrix composites. This model is used to predict the failure of two dimensional microstructure models under tensile loading conditions. A literature survey indicates that the major failure mechanism of particle reinforced metal matrix composites such as particle fracture, interfaces decohesion and matrix yielding is mainly dominated by the distribution of particles in the matrix. Hence, analyses were carried out on the microstructure of random and clustered particles to determine its effect on strength and failure mechanisms. The finite element analysis models were generated in ANSYS, using scanning electron microscope images. The percentage of major failures and stress–strain responses were predicted numerically for each microstructure. It is evident from the analysis that the clustering nature of particles in the matrix dominates the failure modes of particle reinforced metal matrix composites.