Characterization of Integrated Functionally Gradient Syntactic Foams

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Kanakaji Chittineni ◽  
Eyassu Woldesenbet
Keyword(s):  
Compressive Strength ◽  
Energy Absorption ◽  
Volume Fraction ◽  
High Strength ◽  
Solid Particles ◽  
Light Weight ◽  
Syntactic Foams ◽  
Stress Plateau ◽  
Functionally Gradient ◽  
Similar Density

Light weight high strength composites can be obtained by reinforcing resin with fillers such as hollow or solid particles and fibers. Composites were fabricated using microballoons (hollow particles) called syntactic foams. These foams can be used in various low density applications such as buoyancy aid materials for deep sea exploration and aerospace vehicles. These foams are usually utilized as light weight core materials for sandwich structures. The present study explores the procedure to fabricate functionally gradient syntactic foams (FGSFs) and further analyze their mechanical properties. The FGSFs produced are gradient structures consisting of four layers with four different types of microballoons, namely, S22, S32, S38, and K46, each having different wall thickness. The volume fraction of all microballoons is maintained constant at 60% to maintain light weight structures. Several FGSF specimens having similar density are fabricated with different layer arrangements. The different layers are integrated before major solidification takes place. Quasistatic compression testing is then performed on the cured FGSF samples using MTS-810 servohydraulic machine. Compressive strength and energy absorption values for each arrangement are compared. The stress plateau in integrated FGSF composites extends from 10% to 60% strain compared with plain syntactic foams. The integrated FGSF shows increment in yield strength and energy absorption compared with adhesively bonded FGSF. It is found that the compressive strength and energy absorption of integrated FGSF composites can be varied based on arrangement of the layers.

Impact Properties of Syntactic Foams and Effect of Microballoon Wall Thickness

2006 ◽  
Author(s):  
Tien-Chih Lin ◽  
Nikhil Gupta
Keyword(s):  
Impact Strength ◽  
Total Energy ◽  
Energy Absorption ◽  
Volume Fraction ◽  
Impact Testing ◽  
Syntactic Foams ◽  
Lower Strength ◽  
Impact Properties ◽  
Different Types ◽  
Pendulum Impact

Hollow particle (microballoon) filled polymeric composites, called syntactic foams, are tested for impact properties in the present work. Izod type pendulum impact testing is carried out on eight types of foams, which are made of four types of microballoons used in volume fractions of 0.5 and 0.6. Variation in the volume fraction of microballoons leads to a difference in the total energy absorbed during fracture of different types of foams. Results show that syntactic foams containing microballoons of lower density show lower impact strength because of the lower strength of these microballoons. An increase in microballoon volume fraction leads to decreased energy absorption and strength.

Dynamic Attenuation and Compressive Characterization of Syntactic Foams

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Bhaskar Ale ◽  
Carl-Ernst Rousseau
Keyword(s):  
High Performance ◽  
Volume Fraction ◽  
Ultrasonic Attenuation ◽  
Dynamic Properties ◽  
High Strength ◽  
Particulate Composites ◽  
Syntactic Foams ◽  
Core Elements ◽  
Marine Applications ◽  
Damping Materials

Hollow particulate composites are lightweight, have high compressive strength, are low moisture absorbent, have high damping materials, and are used extensively in aerospace, marine applications, and in the manufacture of sandwich composites core elements. The high performance of these materials is achieved by adding high strength hollow glass particulates (microballoons) to an epoxy matrix, forming epoxy-syntactic foams. The present study focuses on the effect of volume fraction and microballoon size on the ultrasonic and dynamic properties of Epoxy Syntactic Foams. Ultrasonic attenuation coefficient from an experiment is compared with a previously developed theoretical model for low volume fractions that takes into account attenuation loss due to scattering and absorption. The guidelines of ASTM Standard E 664-93 are used to compute the apparent attenuation. Quasi-static compressive tests were also conducted to fully characterize the material. Both quasi-static and dynamic properties, as well as coefficients of attenuation and ultrasonic velocities are found to be strongly dependent upon the volume fraction and size of the microballoons.

Compressive Stress of Syntactic Foam: Effect of rNBR Particles Reinforced Epoxy Macrospheres (rNBR-EM)

2018 ◽  
Vol 280 ◽  
pp. 301-307
Author(s):  
Z. Zakaria ◽  
C.Y. Yao
Keyword(s):  
Compressive Strength ◽  
Physical Properties ◽  
Compressive Stress ◽  
Energy Absorption ◽  
Wall Thickness ◽  
Syntactic Foam ◽  
Radius Ratio ◽  
Butadiene Rubber ◽  
Syntactic Foams ◽  
Compressive Properties

This research focuses on the effect of rejected nitrile butadiene rubber (rNBR) gloves particles reinforced epoxy macrospheres (EM) on the physical properties and compressive stress of syntactic foam. Adding rNBR particles on the surface of macrospheres can increase the energy absorption as a result of improving the compressive properties of syntactic foam. Three types of macrospheres have been produced for the fabrication of syntactic foam, namely EM without rNBR, 1-layer rNBR-EM and 2-layer rNBR-EM. The results showed that increased rNBR particles layer on macrospheres has increased the wall thickness, and reduced the radius ratio of macrospheres as well as increased the density of syntactic foams. The compressive strength and modulus of syntactic foam with 2-rNBR-EM increased compared to the syntactic foams of 1-rNBR-EM and EM without rNBR. In addition, the toughness of the 2-rNBR-EM increased compared to the syntactic foams of 1-rNBR-EM and EM without rNBR.

Compressive Strength and Splitting Tensile Strength of Steel Fiber Reinforced Ultra High Strength Concrete (SFRC)

2010 ◽  
Vol 34-35 ◽  
pp. 1441-1444 ◽  
Author(s):  
Ju Zhang ◽  
Chang Wang Yan ◽  
Jin Qing Jia
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
High Strength Concrete ◽  
Steel Fiber ◽  
Volume Fraction ◽  
High Strength ◽  
Splitting Tensile Strength ◽  
Steel Fibers ◽  
Fiber Reinforced ◽  
Strength Concrete

This paper investigates the compressive strength and splitting tensile strength of ultra high strength concrete containing steel fiber. The steel fibers were added at the volume fractions of 0%, 0.5%, 0.75%, 1.0% and 1.5%. The compressive strength of the steel fiber reinforced ultra high strength concrete (SFRC) reached a maximum at 0.75% volume fraction, being a 15.5% improvement over the UHSC. The splitting tensile strength of the SFRC improved with increasing the volume fraction, achieving 91.9% improvements at 1.5% volume fraction. Strength models were established to predict the compressive and splitting tensile strengths of the SFRC. The models give predictions matching the measurements. Conclusions can be drawn that the marked brittleness with low tensile strength and strain capacities of ultra high strength concrete (UHSC) can be overcome by the addition of steel fibers.

Controlling of Distribution of Mechanical Properties in Functionally-Graded Syntactic Foams for Impact Energy Absorption

2012 ◽  
Vol 706-709 ◽  
pp. 729-734 ◽  
Author(s):  
Masahiro Higuchi ◽  
Tadaharu Adachi ◽  
Yuto Yokochi ◽  
Kenta Fujimoto
Keyword(s):  
Mechanical Properties ◽  
Density Distribution ◽  
Energy Absorption ◽  
Impact Energy ◽  
Volume Fraction ◽  
Functionally Graded ◽  
Syntactic Foams ◽  
Compression Tests ◽  
Density Distributions ◽  
Control Distribution

In the study, novel fabrication processes of functionally-graded (FG) syntactic foams were developed to control distribution of the mechanical properties in the FG foams for highly impact energy absorption. In order to control mechanical properties, the density distributions in FG foams were graded by floating phenomenon of the light-weight micro-balloons in matrix resin during curing process. The density distribution in the foam could be controlled by adjusting the average volume fraction and the turning procedure of the mold before grading the micro-balloons in the foam. The compression tests of the fabricated FG foams suggested that the foams had high absorption of impact energy since the foams collapsed progressively due to the grading of the density distribution.

Mechanical Properties of Modified Polypropylene Coarse Fiber-Reinforced, High-Strength, Lightweight Concrete

2011 ◽  
Vol 374-377 ◽  
pp. 1499-1506
Author(s):  
Rong Hui Zhang ◽  
Jian Li
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Lightweight Concrete ◽  
Volume Fraction ◽  
High Strength ◽  
Lightweight Aggregate Concrete ◽  
Fiber Reinforced ◽  
Fiber Volume

In this study, the effect of micro-expansion high strength grouting material (EGM) and Modified polypropylene coarse fiber (M-PP fiber) on the mechanical properties of lightweight concrete are investigated. The influence of EGM and M-PP fiber on compressive strength , flexural strength and drying shrinkage of concrete are researched, and flexural fracture toughness are calculated. Test results show that the effect of EGM and M-PP fiber volume fraction (Vf) on flexural strength and fracture toughness is extremely prominent, compressive strength is only slightly enhanced, and the rate of shrinkage is obviously decreased. It is observed that the shape of the descending branch of load-deflection and the ascending branch of shrinkage-age tends towards gently with the increase of Vf. And M-PP fiber reinforced lightweight aggregate concrete is more economical.

scholarly journals Effects of Low Volume Fraction of Polyvinyl Alcohol Fibers on the Mechanical Properties of Oil Palm Shell Lightweight Concrete

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Ming Kun Yew ◽  
Hilmi Bin Mahmud ◽  
Bee Chin Ang ◽  
Ming Chian Yew
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Polyvinyl Alcohol ◽  
Oil Palm ◽  
Lightweight Concrete ◽  
Volume Fraction ◽  
High Strength ◽  
Palm Shell ◽  
Oil Palm Shell ◽  
Low Volume

This paper presents the effects of low volume fraction(Vf)of polyvinyl alcohol (PVA) fibers on the mechanical properties of oil palm shell (OPS) high strength lightweight concrete mixtures. The slump, density, compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity under various curing conditions have been measured and evaluated. The results indicate that an increase in PVA fibers decreases the workability of the concrete and decreases the density slightly. The 28-day compressive strength of oil palm shell fiber-reinforced concrete (OPSFRC) high strength lightweight concrete (HSLWC) subject to continuous moist curing was within the range of 43–49 MPa. The average modulus of elasticity (E) value is found to be 16.1 GPa for all mixes, which is higher than that reported in previous studies and is within the range of normal weight concrete. Hence, the findings of this study revealed that the PVA fibers can be used as an alternative material to enhance the properties of OPS HSLWC for building and construction applications.

Fabrication and Properties of Syntactic Magnesium Foams

1998 ◽  
Vol 521 ◽  
Author(s):  
M. Hartmann ◽  
K. Reindel ◽  
R. F. Singer
Keyword(s):  
Compressive Strength ◽  
Energy Absorption ◽  
Wall Thickness ◽  
Volume Fraction ◽  
Hollow Spheres ◽  
Three Dimensional ◽  
Syntactic Foam ◽  
Absorption Efficiency ◽  
Casting Technique ◽  
Energy Absorption Efficiency

ABSTRACTSyntactic magnesium foams which consist of thin-walled hollow alumina spheres embedded in a magnesium matrix were fabricated by infiltrating a three-dimensional array of hollow spheres with a magnesium melt by using a gas pressure-assisted casting technique.The resulting composite contains closed cells of homogeneous and isotropic morphology. The densities of the syntactic magnesium foams were between 1.0 and 1.4 g/cm3. The densities were controlled by variations in the bulk density of the hollow spheres with the volume fraction of spheres kept constant at approximately 63 %.Compressive deformation characteristics of the composites were evaluated with respect to the influence of matrix strength and sphere wall thickness on characteristic variables such as compressive strength, plateau stress and energy absorption efficiency. Differences in the strength of the magnesium-based matrix materials investigated (cp-Mg, AM20, AM50, AZ91) had little influence on the compressive strength of the syntactic foam. However, an increasing relative wall thickness of the hollow ceramic spheres led to a significant strength enhancement. In all cases the ratio between compressive and plateau strength rose with increasing composite strength resulting in decreasing energy absorption efficiency.

scholarly journals High Strength Concrete Beams Reinforced with Hooked Steel Fibers under Pure Torsion

2022 ◽  
Vol 8 (1) ◽  
pp. 92-104
Author(s):  
Haleem K. Hussain ◽  
Mustafa Shareef Zewair ◽  
Mazin Abdulimam Ahmed
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
High Strength Concrete ◽  
Concrete Beams ◽  
Volume Fraction ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
Pure Torsion ◽  
Fiber Volume ◽  
Strength Concrete

A study of the behavior of fibers in high-strength reinforced concrete beams is presented in this paper. Twelve reinforced concrete beams were tested under a pure torsion load. Different compressive strengths (45.2, 64.7, and 84.8 MPa) and fiber volume fractions (0, 0.25, 0.5, and 0.75) with variable spacing between transverse reinforcements have been used. It was discovered that the maximum torque of a high-strength concrete beam is increased by about 20.3, 25.6, and 27.1% when the fractional volume of fiber is increased from 0 to 0.25, 0.5 and 0.75 respectively (when the compressive strength is 45.2 MPa and the transverse reinforcement spacing is 100 mm). The test results show that the ultimate torsional strength becomes higher when the concrete compressive strength increases, and this percentage increase becomes higher with increasing steel fiber volume fraction. When the spacing between transverse reinforcements decreases from 150 to 100 mm, the ultimate torque increases by 19.9%. When the spacing between transverse reinforcements decreases from 100 to 60 mm, the ultimate torque increases by 17.0%. In these beams, the fibers’ compressive strength and volume fraction were kept constant at 45.2 MPa and 0.75, respectively. Doi: 10.28991/CEJ-2022-08-01-07 Full Text: PDF

Unit Cell Approach as a Multi Scale Modeling Technique for Predicting the Behaviour of Fiber Reinforced High Strength Concrete Under Compression

2011 ◽  
Author(s):  
Sunir Hassan ◽  
C. Lakshmana Rao ◽  
K. Ganesh Babu
Keyword(s):  
Compressive Strength ◽  
Volume Fraction ◽  
High Strength ◽  
Unit Cell ◽  
Fiber Reinforced ◽  
Material Behaviour ◽  
Strength Concrete ◽  
Volume Fractions ◽  
Coarse Aggregates ◽  
Fine Aggregates

Fiber reinforced concrete has been identified as a particulate composite consisting of hardened cement paste, fine aggregates, coarse aggregates, particulate fibers etc. and each constituent plays a significant role in the combined quasi brittle behaviour of the material. From the view point of a numerical modeler, a two phase model consisting of a matrix phase and a coarse aggregate phase is simple and sufficient enough to take care of the heterogeneity without affecting the capability of the model to predict the material behaviour as reported by Ghouse et al [1]. Thus the unit cell under consideration is modeled as a square with an inner circle (Fig. 1), the square representing the total volume fraction of combined properties of cement paste, fine aggregates, particulate fibers and water. The inner circle represents the total volume fraction of coarse aggregates in the material. This representative volume fraction is assigned with periodic boundary conditions to ensure uniformity in deformation and to avoid any discontinuities in the material once the unit cell has been repeatedly arranged to build up the macro sized material and has undergone deformation in elastic range. Ghouse et al [1] could identify only slight variations in the compressive strength of normal low strength concrete with varying aggregate volume fractions. A comparatively decreasing trend in compressive strength has also been observed initially when glass fiber reinforced high strength cement composite (GFRCC) was analyzed by Sunir et al [2]. Investigations proceed in the direction of predicting the material behaviour by replacing the glass fiber and its volume fraction with polypropylene fibers considered by Pavan [3] as being significant in improving the mechanical characteristics of the macro composite under consideration. An analysis of polymer fiber reinforced high strength concrete (PFRC) with similarly varying aggregate volume fractions could predict significantly decreasing trends in compressive strength for lower volume fractions. In future, the ease with which the unit cell approach predicts the behaviour of fiber reinforced plain mortar is also to be investigated in a similar manner.

Sign in / Sign up

Export Citation Format

Share Document