scholarly journals Measurement of Residual Stresses in Metal Matrix Composites

1994 ◽  
Vol 116 (3) ◽  
pp. 605-610 ◽  
Author(s):  
P. K. Wright

Metal matrix composites (MMC) are expected to develop internal residual stresses on cooling from fabrication due to the large thermal expansion mismatch between reinforcing fibers and the matrix. This work was undertaken to measure experimentally these residual stresses and compare them with analytical calculations in order to establish clearly their levels and dependence on material parameters. Two techniques for residual stress measurement were investigated: (1) X-ray diffraction (sin2-psi method) and (2) neutron diffraction. Both techniques gave results in good agreement with analytical predictions for several systems (SCS-6/Ti-24Al-11Nb, W/NiAl, and Al2O3NiAl). The results obtained showed a dependence of residual stresses on thermal expansion coefficients, elastic moduli, volume fraction fibers, and matrix yield strengths. The fibers showed compressive stress states, and the matrix, tension. Average stresses were higher in the fiber direction than transverse to fibers.

Author(s):  
P. K. Wright

Metal matrix composites (MMC) are expected to develop internal residual stresses on cooling from fabrication due to the large thermal expansion mismatch between reinforcing fibers and the matrix. This work was undertaken to experimentally measure these residual stresses and compare them with analytical calculations in order to clearly establish their levels and dependence on material parameters. Two techniques for residual stress measurement were investigated: 1) Xray diffraction (sin2 psi method) and 2) neutron diffraction. Both techniques gave results in good agreement with analytical predictions for several systems (SCS-6/Ti-24Al-11Nb, W/NiAl, and Al2O3NiAl). The results obtained showed a dependence of residual stresses on thermal expansion coefficients, elastic moduli, volume fraction fibers, and matrix yield strengths. The fibers showed compressive stress states, and the matrix, tension. Average stresses were higher in the fiber direction than transverse to fibers.


Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2143
Author(s):  
Shaimaa I. Gad ◽  
Mohamed A. Attia ◽  
Mohamed A. Hassan ◽  
Ahmed G. El-Shafei

In this paper, an integrated numerical model is proposed to investigate the effects of particulate size and volume fraction on the deformation, damage, and failure behaviors of particulate-reinforced metal matrix composites (PRMMCs). In the framework of a random microstructure-based finite element modelling, the plastic deformation and ductile cracking of the matrix are, respectively, modelled using Johnson–Cook constitutive relation and Johnson–Cook ductile fracture model. The matrix-particle interface decohesion is simulated by employing the surface-based-cohesive zone method, while the particulate fracture is manipulated by the elastic–brittle cracking model, in which the damage evolution criterion depends on the fracture energy cracking criterion. A 2D nonlinear finite element model was developed using ABAQUS/Explicit commercial program for modelling and analyzing damage mechanisms of silicon carbide reinforced aluminum matrix composites. The predicted results have shown a good agreement with the experimental data in the forms of true stress–strain curves and failure shape. Unlike the existing models, the influence of the volume fraction and size of SiC particles on the deformation, damage mechanism, failure consequences, and stress–strain curve of A359/SiC particulate composites is investigated accounting for the different possible modes of failure simultaneously.


1994 ◽  
Vol 350 ◽  
Author(s):  
D. B. Miracle ◽  
P. R. Smith ◽  
J. A. Graves

AbstractA significant materials-based activity to develop Ti-aluminide metal matrix composites for high temperature aerospace structural applications is now underway. A review of the approaches, progress, and status of the development of continuously-reinforced Ti-aluminide metal matrix composites with matrices which contain a significant volume fraction of the ordered orthorhombic Ti2AlNb phase will be presented. The principal application considered is a gas turbine compressor rotor ring, and this influences the development approaches and properties goals. Specific development activity that will be presented includes modification and control of the matrix composition and microstructure, fiber coating treatments to control interdiffusion between the fiber and the matrix, and to improve the ability of the interface to support a mechanical load, and efforts to improve the properties of SiC monofilaments used as reinforcements. Critical issues that define the requirements for additional studies will be presented.


2011 ◽  
Vol 264-265 ◽  
pp. 663-668 ◽  
Author(s):  
B. Karthikeyan ◽  
S. Ramanathan ◽  
V. Ramakrishnan

The demand of today’s and future spacecrafts for a stable platform for critical payloads is the driving force behind the coefficient of thermal expansion (CTE) measurement of different aerospace materials. The CTE of a composite is different from that given by a simple rule of mixtures. This is because of the presence of reinforcement. The expansion coefficient of reinforcement is less than that of the matrix which introduces a mechanical constraint on the matrix. The degree of constraint is also dependent on the nature of the reinforcement. It is important to point out that interface can exert some influence on the value of CTE, especially for very small particle size. In addition to the interface, the CTE of particle reinforced metal matrix composites (MMCs) is affected by several other factors. To cater the needs of various requirements in a spacecraft making, a wide variety of materials are used. Besides, the indigenization efforts and development of new materials for space-use emphasizes the measurement of CTE before their actual use. Stir casting technique was used to fabricate composites containing Si Cp as reinforcements and special thermo physical properties of the material are found. CTE of the composites are measured by TMA. The experiments have been carried out in the temperature range -1400 C to 5750 C.


2002 ◽  
Vol 11 (5) ◽  
pp. 096369350201100
Author(s):  
J. Solis-Romero ◽  
E. R. de los Rios ◽  
C. A. Rodopoulos ◽  
J. R. Yates ◽  
S. P. Godfrey

This pioneer work demonstrates the possible link between surface engineering techniques like shot-peening (SP) and metal matrix composites. The SP process on MMCs aims to reduce the amount of tensile residual stresses developed on the matrix during manufacturing and consequently to allow the matrix to bear significantly higher strains at the crack tip during cycling. Measurements taken from peened 32%, SM 1140/Ti-6-4[ 8 ] revealed notable changes in the profile of the matrix residual stresses. Further experimental work revealed an increase of 45% on the fatigue limit of the peened material.


2021 ◽  
Author(s):  
Mohamed F. Ibrahim ◽  
Hany R. Ammar ◽  
Agnes M. Samuel ◽  
Mahmoud S. Soliman ◽  
Victor Songmene ◽  
...  

The Al-B4C metal matrix composite (MMC) is characterized by its ability to absorb neutrons which makes it the most suitable shielding material for nuclear reactors. The present work was performed on two series of Al-B4C metal matrix composites made using a powder injection apparatus. In one series, commercially pure aluminum (A5) served as the matrix. For the second set, 6063 alloy was used. In all cases the volume fraction of B4C reinforcement particles (grit size 400 mesh, purity 99.5%) was approximately 15%. The volume fraction of the injected B4C particles was determined using a computer driven image analyzer. Measured amounts of Ti, Zr, and Ti + Zr, were added to the molten composites of both series. Microstructural characterization was carried out employing a field emission scanning electron microscope operating at 20 kV and equipped with an electron dispersive x-ray spectroscopic system (EDS). The same technique was applied to characterize the fracture behavior of the tested composites. Mechanical properties of these composites were investigated using impact testing, and ambient and high temperature tensile testing methods. Almost 1000 impact and tensile samples were tested following different heat treatments. The obtained results from these investigations are reported in this Chapter.


Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1400
Author(s):  
Peter Baumli

The paper reviews the preparation of the different metallic nanocomposites. In the preparation of composites, especially in the case of nanocomposites, interfacial phenomena play an important role. This review summarizes the literature on various interfacial phenomena, such as wettability and reactivity in the case of casting techniques and colloidal behavior in the case of electrochemical and electroless methods. The main contribution of this work lies in the evaluation of collected interfacial phenomena and difficulties in the production of metal matrix composites, for both nano-sized and micro-sized reinforcements. This study can guide the composite maker in choosing the best criteria for producing metal matrix composites, which means a real interface with good adhesion between the matrix and the reinforcement. This criterion results in desirable mechanical and physical properties and homogenous dispersion of the reinforcement in the matrix.


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