Fiber Reinforced Metal Matrix Composites Research Articles

Numerical analysis of influence of micro-parameters on macro-micromechanical properties of fiber reinforced metal matrix composites

The properties of fiber reinforced metal matrix composites (MMCs) are anisotropic. These properties can be more appropriately evaluated in polar coordinate. In this paper, the elastic–plastic mechanics model of MMCs is presented based on the combination of macroscopic and meso-scopic analysis in polar coordinate. The influence of micro-parameters such as matrix materials, the fibers and fiber volume fraction of Al/Mg metal matrix composites (MMCs) on the tensile properties of MMCs is also investigated numerically by the representative volume element (RVE) and the numerical results are compared with the experimental data. The results show that the model built in polar coordinate is suitable to the real constructs of MMCs; the fiber plays a major role of load supporting during MMCs stretched. And there is little distinction of the value of maximum stress of MMCs between tests and the numerical analysis.

Effect of interfacial bonding on uniaxial ratchetting of SiC P/6061Al composites: Finite element analysis with 2-D and 3-D unit cells

The effect of interfacial bonding state between particulate and metal matrix on the ratchetting of SiC particulate reinforced 6061Al alloy composites (i.e., SiC P/6061Al composites) in uniaxial cyclic stressing at room temperature was discussed by numerical simulation using a finite element code ABAQUS. In simulation, axi-symmetrical two-dimensional (i.e., 2-D) mono-particle and three-dimensional (i.e., 3-D) multi-particle unit cells were employed, respectively. The ratchetting of un-reinforced matrix alloy was addressed by an elasto-plastic constitutive model with nonlinear kinematic hardening rule, and the particulates were assumed as elastic. Two kinds of interfacial layers were inserted into the unit cells between particulate and matrix, i.e., elastic and elasto-plastic interfacial layers previously employed by Kang et al. [G.Z. Kang, Q. Gao, Composites A 33 (2002) 657–667] in the numerical simulation for monotonic tensile behavior of short fiber reinforced metal matrix composites. Finally, the ratchetting of T6-treated SiC p/6061Al composites was simulated by using 3-D multi-particle unit cell and suitable interfacial property parameters. It is shown that the simulated results are closer to the corresponding experiments than those obtained with assumption of perfect interface. Simultaneously, some microscopic deformation features in the composites and their evolution rules were also revealed by the numerical simulation. Some significant conclusions are obtained, which are useful to establish a constitutive model to describe the ratchetting of the composites.

Estimation of the Elastic-Plastic Fracture Behavior of Fiber Reinforced MMC According to the Change of Interfacial Characteristics

Fiber reinforced metal matrix composites (MMCs) are recently used in automobile, ship, aerospace and manufacturing industry because they have high stiffness and strength. The effective utilization of the strength and stiffness of the fiber reinforced MMCs depends on efficient load transfers from the matrix to fibers through the interfacial region. However, during the fabrication and afterward utilization of composites, so many numbers of micro crack may extend, especially at the interface, even before any load has been applied. Thus, in this study, the interfacial stress state and behavior of the interfacial perpendicular crack for transversely loaded unidirectional fiber reinforced MMCs investigated by using the elastic-plastic finite element analysis.

Load transfer in short fibre reinforced metal matrix composites

The internal load transfer and the deformation behaviour of aluminium–matrix composites reinforced with 2D-random alumina (Saffil ®) short fibres was studied for different loading modes. The evolution of stress in the metallic matrix was measured by neutron diffraction during in situ uniaxial deformation tests. Tensile and compressive tests were performed with loading axis parallel or perpendicular to the 2D-reinforcement plane. The fibre stresses were computed based on force equilibrium considerations. The results are discussed in light of a model recently established by the co-authors for composites with visco-plastic matrix behaviour and extended to the case of plastic deformation in the present study. Based on that model, the evolution of internal stresses and the macroscopic stress–strain were simulated. Comparison between the experimental and computational results shows a qualitative agreement in all relevant aspects.

Analytical study on the elastoplastic behavior in metal matrix composites

An analytical derivation of composite mechanics to investigate elastoplastic behavior is carried out to predict fiber stresses and fiber/matrix interfacial shear stresses. The model is based on the theoretical development considering stress concentration effects and its formulation is extended to investigate the elastoplastic behavior. The procedure is performed to investigate the stress transfer mechanism in a short fiber reinforced metal matrix composite. For the region of matrix plasticity, slip mechanisms between fiber and matrix which normally take place at the interface are considered for the derivation. Results of predicted stresses for the small scale matrix yielding as well as the large scale matrix yielding are described based on closed form solution. It is found that the proposed model shows the capability to correctly predict the values of fiber stresses and fiber/matrix interfacial shear stresses.

Macroscopic strength estimates for metal matrix composites embedding a ductile interphase

The influence of an interphase region on the macroscopic strength of unidirectional fiber-reinforced metal-matrix composites (MMCs) is investigated. The three phases of the composite are supposed to be elastic-perfectly plastic and to conform with J 2-plasticity. First, theoretical bounds to the macroscopic strength are derived, according to homogenization theory for heterogeneous periodic media: the gap between these bounds is quite narrow for certain stress conditions, volumetric proportions of the constituents, and ratios of the interphase-to-matrix strength. Then, a numerical model previously developed by Taliercio (2005) is employed to predict the macroscopic response of three-phase MMCs under any 3D stress through the analysis of a single representative unit cell. The model is applied to the numerical identification of the macroscopic strength properties of MMCs under uni-, bi- and triaxial stresses, in cases where the theoretical bounds are not sufficiently close to identify the actual macroscopic yield surface. The influence of the weakening interphase on the predicted macroscopic strength is critically discussed. A decrease in interphase strength is found to affect the transverse tensile and shear strength of the composite to a moderate extent, whereas the macroscopic longitudinal shear strength is extremely sensitive to the interphase strength.

THE STRESS ANALYSIS AND THE CRACK BEHAVIOR ACCORDING TO THE CHARACTERISTIC OF THE INTERFACIAL REGION IN FIBER REINFORCED MMC

High performance composite reinforced with unidirectional continuous fibers are used in applications requiring high stiffness, high strength and light weight. Because of the high stiffness of the reinforced continuous fiber, the longitudinal performance of such unidirectional composites is greatly enhanced, but their transverse performance is so weak. The nature of the fiber/matrix interface is one of the important factors which determine the unique properties of the fiber reinforced metal matrix composites (MMCs). So, the current study is focused on the fracture behavior of the interface. Both stress state of the interface and crack parameters of the perpendicular crack to the interface for unidirectional fiber reinforced metal matrix composites under the transverse loading are investigated by using elastic-plastic finite element analysis. Different fiber volume fractions (5~60%) and arrangement (square and hexagon) of fibers were studied numerically. The fiber/matrix interface was treated as multi thin layer with different material properties. The fiber is assumed as linear elastic SiC and the matrix is assumed as elastic-plastic Ti -15-3 Titanium alloy. The results show that the stress distributions of the multi thin layer model have much less changes compared with a single interface case. And the properties of the interfacial zone affect the stress distribution, crack behavior and mechanical behavior of the fiber reinforced metal matrix composite.

Numerical analysis of the transverse strengthening behavior of fiber-reinforced metal matrix composites

The transverse strengthening behavior of fiber-reinforced metal matrix composites is numerically investigated on the basis of micromechanics analysis. Periodic boundary condition is developed and employed in calculations for considering arbitrary loading directions without changing the configuration of the unit cell. The symmetric boundary condition will be naturally attained if the loading is along the symmetric directions of the unit cell if any. Effects of the volume fraction and several more general fiber arrangements on the transverse strengthening of composites are discussed in detail, including single and/or multi-fibers simulations, from which the maps of the strengthening responses in various directions of the composites are obtained. It is concluded that the effect of fiber volume fraction is significantly different in various directions, the maximum strengthening of composites does not always occur in 0° and/or 90° directions whereas the minimum strengthening is always in 45° direction, and the strengthening of composites has a period of 90° which are independent of fiber arrangements.

Fluid-Structural Interaction Analysis of the MMC-Thixoforging Process

High mechanical properties in combination with low density are key features for lightweight constructions in automotive and aerospace applications. The combination between the innovative thixoforging process and the potential of fibre or particle strengthened composites with metallic matrices (MMCs) provides an efficient manufacturing process of structural components with continuous or gradient reinforcements. The scope of the Center of Competence for Casting and Thixoforging Stuttgart (CCT) contains new semi-solid manufacturing methods for metal matrix composites which have been developed and applied for patent pending. While previous research projects were focussed on fabrication of continuous fibre reinforced metal matrix composites, the local reinforcement insertion, located in the center of high force and torsion load zones, is going to be the next evolution step of the CCT research team. Therefore it is essential to verify, to simulate and to reproduce the process during infiltration of the semi-sold matrix metal into the textile layer experimentally. This paper illustrates investigations regarding the infiltration process of the thixotropic cast-alloys AlSi7Mg0.3 (A365) into laminated fibre woven fabrics by computational fluid dynamics and fluid-structure interaction analysis, taking account into specific manufacturing technology, the rheological behaviour of the alloy with special focus on infiltration behavior.

Fabrication of fiber reinforced metal matrix composites by squeeze casting technology

Squeeze forming process is a special casting technique that combines the advantages of traditional high pressure die casting, gravity permanent mold die casting and common forging technology. It is a relatively new casting process. It is otherwise called squeeze forming, liquid forging, liquid pressing, extrusion casting, liquid metal stamping, pressure crystallization and corthias casting. The above said process was first discovered by the Russians and later it was developed in countries like USA, Europe and Japan. This advanced casting method is applied for processing of both ferrous and non-ferrous materials besides composites. The major advantages of this technology are elimination of porosity and shrinkage, 100% casting yield, attainment of greater part details, good surface finish, good dimensional accuracy, high strength to weight ratio, improved wear resistance, higher corrosion resistance, higher hardness, resistance to high temperature, improved fatigue and better creep strength. The components manufactured by this casting method requires lesser post machining operation and they have improved mechanical properties like higher strength and ductility. In squeeze casting process the liquid metal is pressurized while they solidify and hence near net shapes can be produced with sound and dense quality. The microstructural refinement of squeeze cast products is desirable for many critical applications. This process is simple, economical and it can be automated easily. The process generates the highest mechanical properties attainable in a cast product. So this process has been adopted to make composite castings at an affordable cost. This paper reviews about the principles of squeeze casting technology, which can be applied to process discontinuous fiber reinforced metal matrix composite castings. Besides this article highlights the type of engineering components produced by this advanced casting method.

Micromechanical finite element analysis of metal matrix composites using nonlocal ductile failure models

Finite element studies of ductile damage in the matrix of particle and fiber reinforced metal matrix composites are presented. Three material models capable of supporting such simulations at the constituent level are discussed within a unified framework. They comprise an element removal technique triggered by a ductile damage indicator as well as versions of the ductile rupture models of Gurson and Rousselier. Nonlocal averaging is employed for reducing the mesh dependence typically displayed by continuum damage methods upon the onset of local softening. Implementation issues specific to the use of nonlocal damage models in a continuum micromechanics framework are discussed. The efficacy of the approach in limiting the mesh sensitivity of the predicted behavior of composites subject to matrix damage is demonstrated for a simple three-dimensional matrix-particle configuration. Applications of the method to multi-particle and multi-fiber unit cells subjected to uniaxial tensile loads are presented and effects of microgeometrical parameters on the mechanical response are discussed.

Elastoplastic Stress Analysis and Residual Stresses in Metal-matrix-laminated Plates under In-plane and Transverse Loading

Fiber-reinforced metal-matrix composites provide high strength, ductility, specific stiffness, yield point, and a good temperature performance. In this study, steel fiber-reinforced aluminum metal-matrix composite-laminated plates are loaded under in-plane and transverse forces. The finite element method is used for obtaining the solution. The Tsai-Hill theory is used as a yield criterion. The laminated plates are oriented symmetrically and antisymmetrically. The orientation angles are chosen as (0/90)2, (15/15)2, (30/30)2, (45/45)2, (60/60)2, (75/75)2, (0/15)2,(0/30)2,(0/45)2,(0/60)2, and (0/75)2 for the in-plane loading. The stress components are calculated for 500 and 700 load steps. The in-plane force is increased 0.08 (N/mm) per step. The transverse loading is carried out on symmetric and antisymmetric (0/90)2, (30/30)2, (45/45)2, and (60/60)2 laminated plates. The expansion of the plastic region is carried out for 100, 300, and 500 load steps. The magnitude of the residual stress components at the midpoint of the plates for different orientation angles are calculated.

An Elastic-Plastic Fracture Behavior of the Interface Using the Property Gradient in MMC

The strong continuous fiber reinforced metal matrix composites (MMCs) are recently used in aerospace and transportation applications as an advanced material due to its high strength and light weight. However, MMC is significantly affected by the interface under the transverse loading. Furthermore, the crack at the interface induces weakness of the characteristics of the overall mechanical response and strength of the MMCs. In order to be able to utilize these MMCs effectively and with safety, it must be determined their elastic plastic fracture behaviors at the interface. The influence of different regular fiber arrangement as like square and hexagonal arrangement on the strength of transversely loaded fiber reinforced matrix is analyzed. And the interface of fiber and matrix is modeled as thin multi layers with properties linearly gradient to distinguish the interface from the fiber and matrix. Different fiber arrangement of square and hexagon type is studied. And fiber volume fraction is changed for several kinds (5%-60%).

Characterization of fiber-reinforced metal matrix composites fabricated by low-pressure infiltration process

The physical and mechanical properties of randomly oriented fiber-reinforced metal matrix composites (FRMMCs) fabricated by LPI process were examined. SiC particles and SiC fibers were used as reinforcement, while Al–4 mass% Cu alloy, Al–7 Si mass% alloy and AZ91 alloy were used as matrix. A mixture consisting of aluminum particles, SiC particles and SiC fibers was prepared as a preform to control the distribution of SiC fibers in FRMMC. Randomly oriented FRMMC specimens were fabricated by infiltrating the molten matrix alloy into the preform by pressing the melt surface with a low pressure of Ar gas. FRMMC specimens showed a high performance in thermal cycling test as well as an excellent wear resistance. The Vickers hardness of FRMMC specimens was almost constant on the different sections and the physical and mechanical properties were found to be isotropic.

Numerical Simulation for High Strain Rate Failure Process of Unidirectional SiCf-Al Composites

This paper presents an analytical approach which combines the modified shear-lag model and Monte Carlo simulation technique to simulate the high strain rate tensile failure process of unidirectional SiC fiber-reinforced metal matrix composites. In the model, the strength of the fiber elements is randomly allocated by the Monte Carlo method, the elastic-plastic properties of the matrix elements and the friction after the interfaces breakage are definitely allocated. Using this model, the deformation, damage and failure process of the SiCf -Al is simulated on the microscopic level, the tensile stress-strain relationship is well predicted. The relationship between mechanical properties of the composites and the original fiber, in situ fiber, interface strength, and fiber strength distribution is discussed. The analysis also shows that, compared with the experimental results, the simulated results using in situ parameters of fiber arrive at good correlation while those using original parameters have much difference (the predicted strength is obviously higher than the experimental strength).

Finite Element Analysis for the Transverse Mechanical Behavior of Fiber-Reinforced Three-Phase Metal-Matrix Composites

To improve the transverse properties of fiber-reinforced metal matrix composites, a three-phase material model was proposed. In the model the reinforcing fibers are surrounded by a weak metal matrix, which in turn is encircled by another strong metal matrix. The weak matrix acts as a role to protect the fibers from damage and the strong matrix acts as a role to improve the transverse properties of the composite. Based on the material model, FEM model was established and parameter analysis was carried out to determine the influence of matrix strengths and fibers spatial distribution on the transverse mechanical behavior of the three-phase composite. It was found that the yield strength of the three-phase composite was mainly dictated by the matrix directly surrounding fibers and the effect from another matrix on the yield strength can be neglected. The three-phase composite has a higher transverse strength with hexagonal fiber arrangement than with regular square fiber arrangement.

Fibre breakage in short fibre reinforced metal matrix composites during creep and constant strain rate compression testing

The evolution of fibre breakage during compressive deformation of AlZn11Mg0.2 (wt.%) reinforced with “Saffil” short fibres was characterised. Fibre damage is described in terms of the changes in the distribution of fibre lengths as a function of accumulated strain. Cylindrical specimens with different fibre orientations were deformed under constant compressive load at 573 K and constant strain rate at 573 K and room temperature. No significant difference in the damage evolution for specimens tested under different conditions was observed. A final mean fibre length near 40 μm was observed in all cases.

Effect of fiber coating on the longitudinal damping capacity of fiber-reinforced metal matrix composites

A novel model for calculating the damping capacity of continuous fiber-reinforced metal matrix composites (FMMCs) is proposed based on the viewpoint of energy loss. Finite element method (FEM) has been employed to investigate the effect of fiber coating on the longitudinal damping capacity of a composite by varying the thickness and the material properties of the coating. The results show that the damping of a composite containing the elastic coating increases with a decrease in the elastic modulus of the coating, while for the case of plastic coating, the weak coating or the high elastic modulus coating may help in improving the overall damping of composite.

Effect of thermal?mechanical cycling on thermal expansion behavior of boron fiber-reinforced aluminum matrix composite

The thermal expansion behavior of boron fiber-reinforced aluminum matrix composite subjected to thermal–mechanical cycling (TMC) was studied. Experimental results showed that TMC affected greatly the thermal expansion behavior of the composite. Using a simple analysis model of internal stress in the fibers, the stress change during the thermal expansion coefficient measurements of the composite subjected to TMC was calculated. The results indicated that TMC could induce the interfacial degradation of the composite, and the more the numbers of TMC cycles, or the higher the applied stress level of TMC, the more serious the interfacial degradation of the composite became. The proposed one-dimensional analysis model was proved to be a simple and qualitative approach to probing the interfacial degradation of unidirectional fiber-reinforced metal matrix composites during TMC.

Structural analysis of a plasma facing component reinforced with fibrous metal matrix composite laminate

Fiber-reinforced metal matrix composites (FMMC) show improved mechanical performance compared to conventional alloys. Hence, integration of FMMC in plasma facing components (PFC) is expected to improve the structural reliability of the component. A possible design concept for a FMMC-integrated PFC would be such that a cross-ply laminate interlayer consisting of unidirectional FMMC laminae is locally inserted into the highly stressed domain, e.g. bond interface region. To assess the design feasibility of a FMMC-integrated PFC, dual scale stress computation was conducted on a PFC system consisting of tungsten armor/copper-base FMMC laminate interlayer/copper alloy heat sink. Focus was placed on the evolution of stress state, plastic deformation and local damage both on macro- and microscales under heat flux cycling. For this, an incremental micromechanics algorithm was implemented into a finite element code. Results showed that damage in the FMMC would not be critical under fusion-relevant loading condition.