Continuous Fiber Reinforced Metal Matrix Research Articles

Microstructure and mechanical properties of steel wire reinforced Mg matrix composites fabricated by composite extrusion

The Steel/Mg composites were prepared using the composite extrusion method, where AZ31 Mg alloy was used as the matrix and Zn-coated steel wire as the reinforcement. The microstructure evolution and mechanical properties of these composites were systematically studied. The results show that there is an interdiffusion phenomenon of Mg and Zn elements at the interface of the prepared Steel/Mg composites, and an interdiffusion layer with a width of about 15 μm is formed and MgZn and Mg7Zn3 compounds are produced. The inclusion of steel wire in the Mg alloy matrix can significantly reduce its texture strength. Steel/Mg composites have higher tensile and compressive strength than Mg–R. This study provides a novel, time-saving and low-cost method for the manufacture of continuous fiber reinforced metal matrix composites(CFRMMCs), and expands the application of metal composites.

Evaluation on dimensional stability of Cf/AZ91D composite based on the micro-yield strength

The dimensional instability caused by irreversible micro-plastic deformation can be evaluated with the micro-yield strength. Cf/Mg composite material prepared by liquid-solid extrusion following vacuum infiltration(LSEVI) process was taken as testing material and its dimensional stability was evaluated. The load-unload cycle test method is used to explore the stress range for the Cf/Mg composite to generate residuals plastic strain in static conditions. The results show that micro-plastic deformation for Cf/Mg composite material occurred in the stress range between 35 and 45 MPa. When the micro-plastic strain reaches 10−5, the micro-yield strength of the Cf/Mg composite material is evaluated as 79MPa. Compared with matrix alloy, the micro-yield strength has increased by more than 89%, which is the same level as beryllium alloy. This paper provides an effective strategy for characterize the dimensional stability of continuous fibre reinforced metal matrix composites.

A fast numerical method of introducing the strengthening effect of residual stress and strain to tensile behavior of metal matrix composites

Thermal residual stress and strain (TRSS) in particle reinforced metal matrix composites (PRMMCs) are believed to cause strengthening effects, according to previous studies. Here, the representative volume element (RVE) based computational homogenization technique was used to study the tensile deformation of PRMMCs with different particle aspect ratios (AR). The influence of TRSS was assessed quantitatively via comparing simulations with or without the cooling process. It was found that the strengthening effect of TRSS was affected by the particle AR. With the average strengthening effect of TRSS, a fast method of introducing the strengthening effect of TRSS to the tensile behavior of PRMMCs was developed. The new method has reduced the computational cost by a factor 2. The effect of TRSS on continuous fiber-reinforced metal matrix composite was found to have a softening-effect during the entire tensile deformation process because of the pre-yield effect caused by the cooling process.

3D Printing of Continuous Fiber Reinforced Low Melting Point Alloy Matrix Composites: Mechanical Properties and Microstructures.

A novel 3D printing route to fabricate continuous fiber reinforced metal matrix composite (CFRMMC) is proposed in this paper. It is distinguished from the 3D printing process of polymer matrix composite that utilizes the pressure inside the nozzle to combine the matrix with the fiber. This process combines the metallic matrix with the continuous fiber by utilizing the wetting and wicking performances of raw materials to form the compact internal structures and proper fiber-matrix interfaces. CF/Pb50Sn50 composites were printed with the Pb50Sn50 alloy wire and modified continuous carbon fiber. The mechanical properties of the composite specimens were studied, and the ultimate tensile strength reached 236.7 MPa, which was 7.1 times that of Pb50Sn50 alloy. The fracture and interfacial microstructure were investigated and analyzed. The relationships between mechanical properties and interfacial reactions were discussed. With the optimized process parameters, several composites parts were printed to demonstrate the advantages of low cost, short fabrication period and flexibility in fabrication of complex structures.

Fiber Traction Printing: A 3D Printing Method of Continuous Fiber Reinforced Metal Matrix Composite

A novel metal matrix composite freeform fabrication approach, fiber traction printing (FTP), is demonstrated through controlling the wetting behavior between fibers and the matrix. This process utilizes the fiber bundle to control the cross-sectional shape of the liquid metal, shaping it from circular to rectangular which is more precise. The FTP process could resolve manufacturing difficulties in the complex structure of continuous fiber reinforced metal matrix composites. The printing of the first layer monofilament is discussed in detail, and the effects of the fibrous coating thickness on the mechanical properties and microstructures of the composite are also investigated in this paper. The composite material prepared by the FTP process has a tensile strength of 235.2 MPa, which is close to that of composites fabricated by conventional processes. The complex structures are printed to demonstrate the advantages and innovations of this approach. Moreover, the FTP method is suited to other material systems with good wettability, such as modified carbon fiber, surfactants, and aluminum alloys.

МЕТОДЫ ФОРМИРОВАНИЯ ПОЛУФАБРИКАТОВ ДЛЯ ИЗГОТОВЛЕНИЯ ВОЛОКНИСТЫХ МЕТАЛЛИЧЕСКИХ КОМПОЗИЦИОННЫХ МАТЕРИАЛОВ (обзор)

МЕТОДЫ ФОРМИРОВАНИЯ ПОЛУФАБРИКАТОВ ДЛЯ ИЗГОТОВЛЕНИЯ ВОЛОКНИСТЫХ МЕТАЛЛИЧЕСКИХ КОМПОЗИЦИОННЫХ МАТЕРИАЛОВ (обзор)

连续纤维增强金属基复合材料研究进展及其激光熔覆

连续纤维增强金属基复合材料研究进展及其激光熔覆

Elastoplastic damage micromechanics for continuous fiber-reinforced ductile matrix composites with progressive fiber breakage

An elastoplastic damage micromechanical framework considering evolutionary fiber breakage is proposed to predict the overall material behaviors of continuous fiber-reinforced composites with ductile matrix under external loading. In the present work, we assume that the overall nonlinear behavior of a composite is primarily attributed to the plastic deformation in the matrix as well as the damage evolution due to fiber breakage. The effective elastoplastic deformations are governed by means of the effective yield surface derived from a representative microstructure with elastic fibers embedded in an elastoplastic matrix material. The matrix behaves elastically or plastically depending on the local stress, and the effective elastoplastic deformation obeys the associative plastic flow rule and isotropic hardening law. In addition, taking advantage of the eigenstrain due to fiber breakage together with a Weibull statistic model, the evolutionary fiber breakage mechanism is effectively predicted. Finally, the overall elastoplastic stress–strain responses are reached under the framework of micromechanics and damage mechanics. Comparisons between the proposed theoretical predictions and experimental data are performed to illustrate the capability of the proposed framework. In particular, the proposed model is employed to investigate the overall uniaxial and axisymmetric elastoplastic stress–strain responses of the continuous fiber-reinforced metal matrix composites. Studies of the initial yield surfaces at various damage levels are conducted as well.

Effect of the Yield Criterion of Matrix on the Brittle Fracture of Fibres in Uniaxial Tension of Composites

This paper examines the effect of the yield criterion of the matrix on brittle fracture of the fibre in continuous fibre reinforced metal matrix composites subjected to tension in the direction parallel to the fibres. It is assumed that the matrix obeys quite a general isotropic yield criterion. An approximate approach to predicting the tensile load at which the fibre breaks previously proposed in the literature is adopted. It is shown that this tensile load is practically independent of the yield criterion of the matrix. This is a great advantage for engineering applications since an analytic solution is available in the case of Tresca yield criterion. This solution can be used for a wide range of matrix materials with no loss of the accuracy of the prediction of the tensile load at which the fibre breaks.

Influence of Laminate Scheme on Design of Continuous Fiber Reinforced Composite Turbofan Engine Shaft

Advanced materials and processes are required to meet the performance goals in the design of advanced turbofan engine, SiC/Ti composite is typically used in low pressure turbine shaft (LPTS). Firstly, establish the viability and effectiveness of composite cylinder assemblage (CCA) micro-mechanics model and representative volume element (RVE) micro-mechanics model which are utilized to calculate the mechanical parameter of continuous fiber reinforced metal matrix composite (CFRMMC), respectively. Results show that RVE model is more applicable to calculate continuous fiber reinforced LPTS. Secondly, parameters of mechanics performance calculated by RVE model are taken as input to build mechanics analysis model of fiber reinforced metal matrix composite shaft structure. The optimal solution will be got by design and analysis of CFRMMC shaft structure with 2 kinds of loads. Compared with deformation and stress of shaft structure with different material scheme, then an optimization scheme of SCS/Ti2AlNb composite of LPTS can be obtained.

Modeling of Damage Evolution and Failure in Fiber-Reinforced Ductile Composites Under Thermomechanical Fatigue Loading

In this article, a methodology based upon micromechanical analysis of multiple damage-plasticity events is developed to predict nonlinear cyclic stress-strain response and fatigue failure of continuous fiber-reinforced metal matrix composites under cyclical thermomechanical loading. Microscopic damage-plasticity events in composite are described by fiber fracture, local cyclic plasticity of matrix and interface as well as interfacial debonding. A superposition method under the framework of shear-lag arguments is developed to analyze cyclic stress and deformation in the composites. A simulation scheme coupled with Monte-Carlo method is proposed to investigate evolution of damage-plasticity, cyclic behavior, and fatigue life of the composites. The statistic variations in fiber strength, local thermoplasticity of matrix properties, and interface characters between fiber and matrix have been taken into account. The model can predict the crossover behavior of the S-N curves observed in experiments for the in-phase and out-of-phase thermomechanical fatigue loads. The underlying mechanisms controlling the cross-over behavior have been revealed by the simulation.

Modeling of Progressive Failure in Ductile Matrix Composites Including Local Matrix Yielding

In this article a theoretical model based upon micromechanical analysis of damage is developed to predict nonlinear stress-strain response and progressive failure of continuous fiber-reinforced metal matrix composites (MMCf). A micromechanically analytical model using an influence function superimposition technique is developed to derive stress profiles for any configuration of breaks in MMCf under tensile loading, by considering local matrix tensile yield and interface yield (or sliding). Several hundred Monte Carlo simulations including these failure mechanisms have been executed to simulate failure process and determine statistically the ultimate strength distributions of the composites. Site discretization, material sizes and shape parameter in Weibull distribution are studied to investigate the dependence of ultimate strength on these factors. It is shown that the size dependence of composite ultimate strength is dominated by fiber strength statistics and stress redistribution due to progressive microdamage.

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.

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%).

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.

Generalised constitutive equations for densification of metal matrix coated fibre composites

The present paper completes a study of constitutive equations for the consolidation processing of continuous fibre reinforced metal matrix composite materials. It builds on an earlier paper in which physically based constitutive equations were derived for the case of symmetrical, isostatic loading. In the present paper, constitutive equations are developed for in plane, general stress states. The total deformation of the consolidating composite is expressed as the sum of a conventional deviatoric creep term, together with a dilatational term, which was derived using a variational method previously published. The equations contain only two material parameters, which are the conventional creep coefficient and exponent for the fibre coating material (in this case, Ti-6Al-4V). The resulting equations have been implemented into finite element software enabling the simulation of practical consolidation processes. The model has been verified by comparing predicted results with those obtained from independent micromechanical models. A number of experimental tests have been carried out, and the model is used to predict the rates of densification for a range of experimental pressure and temperature histories. Good comparisons have been achieved.

Determination of the matrix in situ flow stress of a continuous fibre reinforced metal matrix composite using instrumented indentation

Nanoindentation is employed to determine the flow stress of a pure aluminium matrix of a composite reinforced with continuous alumina fibres. The stress for a given representative strain, which depends on the geometry of the indenter, can be deduced using the reverse method established by Bucaille et al. [Acta Mater. 51 (2003) 1663] assuming that the normal force is proportional to the square of the penetration depth: F=Ch2. During the first stage of this work, nanoindentation experiments were conducted on annealed and cold-worked aluminium using the Berkovich and cube corner pyramids. The apparent hardness of these materials was found to decrease with increasing penetration depth. The evolution of the normal force as a function of penetration depth was therefore modelled by a polynomial equation allowing extrapolation of the mechanical behaviour to the macroscopic scale. Good agreement was found between the flow stress of cold-worked aluminium obtained in this manner and the values obtained from tensile testing. However, for the annealed aluminium, the present method largely overestimates the values. It is suggested that both geometrically necessary dislocations and the microstructure are the main factors responsible for the indentation size effect (ISE). Several scales must therefore be considered in order to extrapolate the behaviour of aluminium from the nano- to the macroscale. In the second stage of this work, nanoindentation tests were carried out in the aluminium matrix of the composite at small penetration depths to avoid any influence of the fibres. By comparison with previous results on bulk aluminium, the flow stress of the matrix was determined and its plastic behaviour was found to be close to that of cold-worked aluminium, in agreement with other studies. This implies that the aluminium matrix is strongly modified by the presence of fibres during the fabrication of the composite.

A different approach for calculation of stress intensity factors in continuous fiber reinforced metal matrix composites

In this paper, a numerical model developed for the analysis of a cylindrical element of matrix containing a single fiber is presented. A ring-shaped crack is assumed at interface of fiber and matrix. Both layers in the model are bonded perfectly with the exception of the crack faces. Contact elements, which have bonded feature, are used between fiber and matrix. Displacement correlation method is used to calculate opening-mode and sliding-mode stress intensity factors. These results obtained from the analysis help to understand the debonding phenomenon between fiber and matrix interface. Effects of the mechanical properties of fiber and matrix on direction of crack propagation are also discussed.

Creep-rupture lifetime simulation of unidirectional metal matrix composites with and without time-dependent fiber breakage

Abstract A numerical simulation for predicting the axial creep-rupture lifetime of continuous fiber-reinforced metal matrix composites is proposed, based on the finite element method. The simulation model is composed of line elements representing the fibers and four-node isoparametric plane elements representing the matrix. While the fibers behave as an elastic body at all times, the matrix behaves as an elasto-plastic body at the loading process and an elasto-plastic creep body at the creep process. It is further assumed in the simulation that the fibers are fractured not only in stress criterion but time-dependently with random nature. Simulation results were compared with the creep-rupture lifetime data of a boron-aluminum composite with 10% fiber volume fraction experimentally obtained. The simulated creep-rupture lifetimes agreed well with the averages of the experimental data. The proposed simulation is further carried out to predict a possibility of creep-rupture for the composite without time-dependent fiber breakage. It is finally concluded that the creep-rupture of a boron-aluminum composite is closely related with the shear stress relaxation occurring in the matrix as well as time-dependent fiber breakage.

Effects of dendrite interphase on the strength of continuous fiber-reinforced metal matrix composites

Many composites have a kind of dendrite interfacial reaction product. The effects of this dendrite interphase on interfacial cracks, fiber strength and the transfer of interfacial loads were demonstrated in terms of the stress concentration factor calculated with the boundary element method (BEM). It was shown that the stress concentration factor is varied with the geometric parameters of the dendrite interphase. The existence of a dendrite interphase along the interface greatly enhanced the interfacial bond strength and the stress concentration and accelerated the premature damage of the composite.