scholarly journals Notch (In)Sensitivity of Aluminum Matrix Syntactic Foams

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 574 ◽  
Author(s):  
Attila Szlancsik ◽  
Bálint Katona ◽  
Dóra Károly ◽  
Imre Orbulov
Keyword(s):  
Fracture Toughness ◽  
Crack Opening ◽  
Matrix Material ◽  
Hollow Spheres ◽  
Aluminum Matrix ◽  
Syntactic Foams ◽  
Complex Investigation ◽  
Pressure Infiltration ◽  
Three Point Bending ◽  
The Matrix

Aluminum alloy (Al99.5 or AlSi12)-based metal matrix syntactic foams (MMSFs) were produced by pressure infiltration with ~65 vol % Globocer filler (33 wt % Al2O3, 48 wt % SiO2, 19 wt % Al2O3∙SiO2). The infiltrated blocks were machined by different geometry tools in order to produce notched samples. The samples were loaded in three-point bending, and the loading force values were recorded against the cross-head displacements and the crack opening displacements. To measure up the notch sensitivity and toughness of the MMSFs, the fracture energies and the fracture toughness values were determined. The results showed that the mentioned quantities are needed to describe the behavior of MMSFs. The fracture energies were shown to be notch-sensitive, while the fracture toughness values were dependent only on the matrix material and were insensitive to the notch geometry. The complex investigation of the fracture surfaces revealed strong bonding between the hollow spheres and the Al99.5 matrix due to a chemical reaction, while this bonding was found to be weaker in the case of the AlSi12 matrix. This difference resulted in completely different crack propagation modes in the case of the different matrices.

scholarly journals Characterisation of Hybrid Metal Matrix Syntactic Foams

2015 ◽  
Vol 812 ◽  
pp. 219-225 ◽  
Author(s):  
Imre Norbert Orbulov ◽  
Kornél Májlinger
Keyword(s):  
Volume Fraction ◽  
Mechanical Energy ◽  
Matrix Material ◽  
Hollow Spheres ◽  
Base Material ◽  
Outer Diameter ◽  
Syntactic Foams ◽  
Compression Tests ◽  
Pressure Infiltration ◽  
Geometrical Properties

High quality aluminium matrix syntactic foams (AMSFs) were produced by pressure infiltration. This method can ensure the maximal volume fraction of the reinforcing hollow spheres and very low amount of unwanted or matrix porosities. By this method hybrid MMSFs with mixed metal and ceramic hollow spheres were also produced. The matrix material was AlSi12 alloy and two different types – produced by Hollomet GmbH in Germany – of hollow spheres were used: Globomet (GM) and Globocer (GC). The geometrical properties of the hollow spheres were similar (average outer diameter), but their base material was pure iron and Al2O3+SiO2 in the case of GM and GC hollow spheres respectively. The volume fraction of the reinforcing hollow spheres were maintained at ~65 vol%, but the ratio of them was altered in 20% steps (100% GM + 0% GC, 80% GM + 20% GC...). The results of the compression tests showed, that the compressive strength, yield strength, plateau strength, structural stiffness and the absorbed mechanical energy values increased with higher ceramic hollow sphere reinforcement ratio. The fracture strains of the investigated MMSFs decreased with the higher GC ratio. Generally the strength values also increased with higher diameter to height (H/D) ratio from H/D=1 to H/D=1.5 and 2.

scholarly journals Investigation of Bimodal Aluminium Matrix Syntactic Foams Filled with Ceramic Hollow Spheres

2020 ◽  
Vol 13 (1) ◽  
pp. 110-113
Author(s):  
Borbála Leveles ◽  
Alexandra Kemény ◽  
Imre Norbert Orbulov
Keyword(s):  
Metal Foam ◽  
Mechanical Energy ◽  
Matrix Material ◽  
Hollow Spheres ◽  
Volume Ratio ◽  
Syntactic Foams ◽  
The Matrix ◽  
Static Mechanical ◽  
Specific Mechanical Energy ◽  
Energy Absorbing

AbstractIn this study bimodal A413 matrix syntactic foams filled with ceramic hollow spheres (CHSs) were produced and examined by computer tomography (CT) and quasi-static mechanical testing to determine the mixing properties of the hollow spheres and the strength of the metal foam. Two hollow spheres of different nominal diameters (d1 = 2.4 mm and d2 = 7.0 mm) were used in equal volume ratio. The produced metal foams have a density of 1.61±0.03 g/cm3, with smaller inclusions and some defective hollow spheres in the structure. The foams have an average compressive strength of 120 MPa and a specific mechanical energy absorbing capacity of 43.5 J/cm3. As a result of the upsetting tests, the matrix material is separated from the CHSs, breaking the connection between them.

Structure and Properties of Aluminum Matrix Composites Reinforced by Al2O3 Particles

2008 ◽  
Vol 591-593 ◽  
pp. 188-192 ◽  
Author(s):  
Leszek Adam Dobrzański ◽  
M. Kremzer ◽  
Klaudiusz Gołombek
Keyword(s):  
Composite Materials ◽  
Matrix Material ◽  
Aluminum Matrix ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
Ceramic Fibers ◽  
Pressure Infiltration ◽  
Ceramic Phase ◽  
The Matrix ◽  
Infiltration Method

The work presents the research results of modern composite materials. The matrix material was EN AC AlSi12 alloy while the reinforcement ceramic preforms, obtained through sintering process of Al2O3 Alcoa CL 2500 powder with addition of carbon fibers as pore forming agent burned out during sintering. The composites were produced with use of porous material pressure infiltration method. The main limitation of base technology is a difficulty in obtaining composite materials with volumetric participation of ceramic phase in amount not less than 20%. Obtained on the base of ceramic preforms composite materials were tested with scanning electron microscopy. Additionally, hardness and tensile test was performed for acquired materials. Achieved results indicate the possibility of producing, with use of pressure infiltration method, porous preforms composed of Al2O3 particles, new composite material with desired microstructure and properties, being a cheaper alternative for materials with base of ceramic fibers.

Analytical and Numerical Study of Crushing of Syntactic Foams Under Uniaxial Compression

2008 ◽  
Author(s):  
Prabhakar Marur
Keyword(s):  
Finite Element ◽  
Uniaxial Compression ◽  
Numerical Study ◽  
Bulk Material ◽  
Hollow Spheres ◽  
Syntactic Foam ◽  
Particulate Composites ◽  
Syntactic Foams ◽  
The Matrix ◽  
Crushing Behavior

Syntactic foams are a class of particulate composites made with hollow microspheres dispersed uniformly in a matrix. By the inclusion of hollow spheres in the matrix, the bulk mechanical properties are improved by limiting the bending of cell edges and localization of inelastic deformation, which is the cause of failure in the case of low-density foams. For the general class of cellular materials, several analytical and experimental methods are available in the literature to characterize the material. In the case of syntactic foams, relatively few methods exist for the computation of effective elastic properties and methods for analyzing the crush behavior of the syntactic foams are rather limited. In this research, the quasi-static crushing behavior of syntactic foam under uniaxial compression is investigated using analytical and numerical methods. To better understand the bulk behavior of syntactic foam, a micromechanical study is conducted to analyze the crushing of hollow spheres in dilute concentration. Initially the stress fields around dilute concentration are derived using continuum mechanics principles and subsequently a limit analysis is performed. To gain further insight into the deformation fields and deformations of cell walls leading to densification, a finite element (FE) analysis is performed. Assuming a periodic repetition of a representative volume of the material would correspond to the bulk material, axisymmetric and 3D finite element models are developed. The numerical computations are compared with the analytical results obtained in this study, and with experimental data reported in the literature. Using the FE models, a parametric study is conducted to investigate the influence of microsphere strength and elastic mismatch between the matrix and the inclusions on the crush behavior of syntactic foam.

Preparation and Characterization of Hybrid Aluminum Matrix Composites Reinforced with MWCNT Using Powder Metallurgy Process

2015 ◽  
Vol 813-814 ◽  
pp. 620-624
Author(s):  
S. Dhandapani ◽  
T. Rajmohan ◽  
K. Palanikumar ◽  
Charan Mugunthan
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Metal Matrix ◽  
Matrix Material ◽  
Aluminum Matrix ◽  
Nano Particles ◽  
Aluminum Matrix Composites ◽  
The Matrix ◽  
Carbon Nano Tubes

Metal Matrix Nano Composites (MMNC) consist of a metal matrix reinforced with nano-particles featuring physical and mechanical properties very different from those of the matrix. Especially carbon Nano tubes (CNT) can improve the matrix material in terms of wear resistance, damping properties and mechanical strength. The present investigation deals with the synthesis and characterization of aluminium matrix reinforced with micro B4C particles, and Multi Wall Carbon nano Tubes (MWCNT) were prepared by powder metallurgy route. Powder mixture containing fixed weight (%) of B4C and different wt% of MWCNT as reinforcement constituents that are uniaxial cold pressed and later green compacts are sintered in continues electric furnace. Microstructure and Mechanical properties such as micro hardness and density are examined. Micro structure of samples has been investigated using scanning electron microscope (SEM) .The results indicated that the increase in wt % of MWCNT improves the bonding and mechanical properties.

scholarly journals Structural Damages in Syntactic Metal Foams Caused by Monotone or Cyclic Compression

2017 ◽  
Vol 61 (2) ◽  
pp. 146 ◽  
Author(s):  
Bálint Katona ◽  
Imre Norbert Orbulov
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Metal Matrix ◽  
High Strain ◽  
Hollow Spheres ◽  
Syntactic Foams ◽  
Pressure Infiltration ◽  
Cyclic Compression ◽  
Significant Difference ◽  
Strain Rate Compression

Closed cell, high strength metallic foams, like ceramic hollow spheres filled metal matrix foams are promising materials to build lightweight but high specific strength structural parts. The aim of this study is to investigate the damage of the foam structure during monotone or cyclic compression. The tested metal matrix syntactic foams were produced by inert gas pressure infiltration. Four different alloys as matrix and two different ceramic hollow spheres as filler material were applied. The cylindrical specimens were investigated in quasi-static and high strain rate compression and in cyclic compression. The higher strain rates were ensured by a Split-Hopkinson pressure bar system, while the fatigue tests were performed on a closed loop universal hydraulic testing machine. The failure modes of the foams have explicit differences showing barreling and shearing in the case of quasi-static and high strain rate compression respectively. In the case of the fatigue loading, there was a significant difference between the damage mechanisms of the unalloyed and the Si alloyed matrix syntactic foams. This can be explained by the difference between the yield strength of the matrix material and the ceramics hollow spheres.

Composite Materials Based on EN AW-Al Cu4Mg1(A) Aluminum Alloy Reinforced with the Ti(C,N) Ceramic Particles

2006 ◽  
Vol 530-531 ◽  
pp. 243-248 ◽  
Author(s):  
Leszek Adam Dobrzański ◽  
Anna Włodarczyk-Fligier ◽  
Marcin Adamiak
Keyword(s):  
Aluminum Alloy ◽  
Composite Materials ◽  
Uniform Distribution ◽  
Matrix Material ◽  
Aluminum Matrix ◽  
Tensile Tests ◽  
Reinforcing Particles ◽  
Hardness Tests ◽  
Strength Tests ◽  
The Matrix

Investigations of composite materials based on EN AW-Al Cu4Mg1(A) aluminum alloy reinforced with the Ti(C,N) particles with various weight ratios of 5, 10, and 15% are presented. Powders of the starting materials were mixed in the laboratory vibratory ball mill to acquire the uniform distribution of reinforcement particles in the matrix material. The components were initially compacted at cold state in a die with the diameter of ∅ 26 mm in the laboratory vertical unidirectional press – with a capacity of 350 kN. The obtained P/M compacts were heated to a temperature of 480÷500°C and finally extruded – with the extrusion pressure of 500 kN. Bars with a diameter of 8 mm were obtained as the end product. Based on the microstructural examinations of the obtained composite materials, the uniform distribution of the reinforcing particles in the aluminum matrix was revealed. Hardness tests, tensile tests and the ultimate compressive strength tests made it possible demonstrate that all these properties change along with the reinforcing particles concentration change.

Quasi-State Compressive Properties of Functionally Graded Aluminum Matrix Syntactic Foams

2021 ◽  
Vol 1035 ◽  
pp. 878-883
Author(s):  
Ming Ming Su ◽  
Mo Qiu Li ◽  
Thomas Fiedler ◽  
Hai Hao
Keyword(s):  
Volume Fraction ◽  
Hollow Spheres ◽  
Aluminum Matrix ◽  
Stir Casting ◽  
Functionally Graded ◽  
Small Range ◽  
Syntactic Foams ◽  
Compression Tests ◽  
Static Compression ◽  
Plateau Stress

The uniform aluminum matrix syntactic foams (SFs) were prepared by the stir casting method, with alumina hollow spheres (2-3 mm and 3-4 mm) and expanded glass (2-3 mm) as reinforcements, and ZL111 aluminum alloy as matrix. The functionally graded aluminum matrix syntactic foams (FG-SFs) were obtained by superimposing two uniform aluminum matrix syntactic foams. Quasi-static compression tests were performed. The plateau stress of FG-SFs containing only hollow spheres decreased slightly with increasing volume fraction of SF containing 3-4 mm hollow spheres. The FG-SFs containing 2-3 mm hollow spheres and 2-3 mm expanded glass showed the highest plateau stress. The energy absorption behavior of all samples fluctuated in a small range. The initial position of shear band depended on the volume fraction of uniform aluminum matrix syntactic foams, reinforcement type and size. The cracks always appeared first in the uniform aluminum matrix syntactic foams containing expanded glass.

Stiffness Evaluation for Solids Containing Dilute Distributions of Inclusions and Microcracks

1995 ◽  
Vol 62 (1) ◽  
pp. 71-77 ◽  
Author(s):  
Y. Huang ◽  
K. X. Hu ◽  
A. Chandra
Keyword(s):  
Crack Opening ◽  
Matrix Material ◽  
Numerical Approach ◽  
Stiffness Evaluation ◽  
Growing Crack ◽  
Crack Interactions ◽  
The Matrix ◽  
Additional Strain ◽  
Self Similar ◽  
Nonuniform Stress Field

Materials, such as ceramics, intermetallics, and rocks, contain varying amounts of inhomogeneities, and the matrix material is vulnerable to microcracking in the neighborhood around these inhomogeneities. In an attempt to model the micromechanical aspects of this type of material, a solid containing dilute inclusions surrounded by cracks is investigated in this paper. The dilute-inclusion assumption neglects any interactions among different inclusion-crack clusters, but local inclusion-crack and crack-crack interactions are taken into account fully. It is shown that additional strain due to microcracking in a solid containing inclusions can be represented by an integral of crack opening displacements weighted by a nonuniform stress field induced by inclusions alone (in the absence of microcracking). An effective numerical approach is then developed to evaluate the effective moduli and additional macroscopic strain due to microcracking in composites. It is found that an increase in the number of hard inclusions may not always lead to expected strengthening of the materials, if the matrix material is vulnerable to microcracking around inclusions and a relatively large microcracking zone develops. The limited calculations show that a quasi-static crack-growing process can lead to an actively growing crack being arrested or to a stationary crack starting to grow. This suggests that self-similar crack growth may not be enough to describe the behavior of microcracked composites.

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