Material Modeling of High-Pressure Compliant Syntactic Foams

2015 ◽  
Author(s):  
Elliott Gruber ◽  
Kenneth Cunefare
Keyword(s):  
Internal Pressure ◽  
Syntactic Foam ◽  
Material Modeling ◽  
Syntactic Foams ◽  
Expansion Chamber ◽  
Control Effectiveness ◽  
Effective Bulk Modulus ◽  
System Pressure ◽  
Approximate Order ◽  
Overall Performance

Syntactic foam, specifically a host urethane embedded with hollow microspheres, has been shown to be an effective method to treat pressure pulsations, also known as noise, within a hydraulic system; however, the current generation of foam becomes less effective with increasing system pressure, particularly ineffective above 7 MPa. Material modeling predicts that increasing the initial internal pressure of a microsphere will allow voids within the foam to retain their size at pressures up to 35 MPa and the foam will remain compliant at those pressures. Noise is attenuated by an expansion chamber lined with syntactic foam when the system pressure causes embedded microspheres to collapse, which leaves a gaseous void within the host urethane, greatly reducing the effective bulk modulus of the foam. Predicted material properties are then used in conjunction with a previously developed linear acoustic model to predict the effectiveness of developmental syntactic foams. Changing the mechanical properties of the current host urethane does not have a drastic impact on the overall performance unless the properties have been reduced to the approximate order as the properties of the void. The factors with the most consequence on noise control effectiveness are the internal pressure of the microspheres and system pressure.

The Processing and Structure of Steel Matrix Syntactic Foams Prepared by Infiltration Casting

2018 ◽  
Vol 933 ◽  
pp. 129-135
Author(s):  
Quan Zhan Yang ◽  
Yan Peng Wei ◽  
Zhi Quan Miao ◽  
Peng Gao ◽  
Bo Yu
Keyword(s):  
Metal Matrix ◽  
Heat Insulation ◽  
Hollow Spheres ◽  
Syntactic Foam ◽  
Average Diameter ◽  
Steel Matrix ◽  
Syntactic Foams ◽  
Minimum Diameter ◽  
Microstructure Characteristics ◽  
Multifunctional Properties

Metal matrix syntactic foams are consisting of metal matrix and hollow spheres in closely or randomly packed, which own multifunctional properties with lightweight, damping, heat insulation, energy absorption and have a vast application prospect. Steel matrix can extend the potential of syntactic foams as a materials class to several new fields of application. In this paper, the hollow alumina spheres were introduced into the steel matrix by infiltration casting, the minimum diameter of hollow spheres for infiltration is analyzed in theory, the steel matrix syntactic foams were successfully prepared, which contain two different sphere types with average diameter sizes 3.97mm and 4.72mm, and the average densities of syntactic foams were calculated to be 4.39 (spheres occupy 43.7% of the volume) and 3.74 g/cm3 (spheres occupy 52.1% of the volume), respectively. The microstructure characteristics of the steel matrix syntactic foam were analyzed by means of scanning electron microscopy and energy spectrum.

Preparation and Characteristic of Different Hollow Microspheres Filled Syntactic Foams

2014 ◽  
Vol 809-810 ◽  
pp. 237-242
Author(s):  
Xin Jin ◽  
He Yi Ge ◽  
Ping Wang ◽  
Zhong Yuan Pan ◽  
Juan Chen
Keyword(s):  
Interfacial Adhesion ◽  
Syntactic Foam ◽  
Weight Fraction ◽  
Hollow Microspheres ◽  
Syntactic Foams ◽  
Polystyrene Microspheres ◽  
Compressive Properties ◽  
Hollow Glass Microspheres ◽  
Important Improvement ◽  
The Impact

In this study, hollow glass microspheres (HGM) and hollow polystyrene microspheres (HPSM) have been employed as fillers in epoxy resin to prepare the syntactic foam. A kind of good performance composite was prepared. The effects of presence of various hollow microspheres on the impact and compressive properties of syntactic foams are studied. Weight fraction of HPSM and HGM for the syntactic foams varies up to 2.0 wt% and 25 wt%, respectively. The results show that the coupling agent can induce the interfacial adhesion between the HGM and the resin and help HGM uniformly disperse in the resin and hence result in better mechanical properties of composite. On the other hand, the effect of HPSM for the composite density is greater than that of HGM. The addition of a small percentage of HPSM helps produce an important improvement in the low density of syntactic foam. The syntactic foam has uniform stability component and the excellent integrative performances. Fabricated syntactic foams had compression strength of 51.96 MPa and density of 0.671 g/cm3.

scholarly journals Characterisation of Aluminium Matrix Syntactic Foams under Static and Dynamic Loading

2011 ◽  
Vol 82 ◽  
pp. 142-147 ◽  
Author(s):  
Mohamed Altenaiji ◽  
Graham K. Schleyer ◽  
Yo Yang Zhao
Keyword(s):  
Compressive Strength ◽  
Porous Ceramic ◽  
Syntactic Foam ◽  
Absorption Capacity ◽  
Core Material ◽  
Aluminium Matrix ◽  
Test Machine ◽  
Syntactic Foams ◽  
Pressure Infiltration ◽  
Energy Absorbing

Development of a lightweight, strong and energy-absorbing material that has potential application for the protection of vehicles and occupants against impact and blast, is a difficult challenge facing the materials community. Aluminium matrix syntactic foams will be investigated as a possible core material as part of a multi-layered protection system for military vehicles. Aluminium matrix syntactic foams are composite materials consisting of an aluminium matrix implanted with hollow or porous ceramic particles. This paper investigates the mechanical properties of aluminium matrix syntactic foam with different sizes of ceramic micro-spheres and different grades of aluminium, fabricated by the pressure infiltration method. The static crushing behaviour of the foam was investigated under two test conditions using an Instron 4505 machine. Results are compared and discussed. The dynamic compressive response was investigated using a drop-weight impact test machine. It was found that the particle size of the ceramic micro-spheres and the grade of the aluminium metal have a significant effect on the energy absorption capacity of the material. The compressive strength of the syntactic foam was found to increase with increasing compressive strength of the metal matrix.

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.

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.

scholarly journals Mechanical Behavior of Syntactic Foams for Deep Sea Thermally Insulated Pipeline

2010 ◽  
Vol 24-25 ◽  
pp. 97-102 ◽  
Author(s):  
Dominique Choqueuse ◽  
Peter Davies ◽  
Dominique Perreux ◽  
Laurent Sohier ◽  
Jean Yves Cognard
Keyword(s):  
Syntactic Foam ◽  
Test Methods ◽  
Shear Loading ◽  
Hydrostatic Compression ◽  
Shear Stresses ◽  
Syntactic Foams ◽  
Oil Exploitation ◽  
Service Behavior ◽  
Offshore Oil

Ultra Deep offshore oil exploitation (down to 3000 meters depth) presents new challenges to offshore engineering and operating companies. Flow assurance and particularly the selection of insulation materials to be applied to pipe lines are of primary importance, and are the focus of much industry interest for deepwater applications. Polymeric and composite materials, particularly syntactic foams, are now widely used for this application, so the understanding of their behavior under extreme conditions is essential. These materials, applied as a thick coating (up to 10-15 cm), are subjected in service to: - high hydrostatic compression (up to 30 MPa) - severe thermal gradients (from 4°C at the outer surface to 150°C at the inner wall), and to high bending and shear stresses during installation. Damageable behavior of syntactic foam under service conditions has been observed previously [1] and may strongly affect the long term reliability of the system (loss of thermal properties).This study is a part of a larger project aiming to model the in-service behavior of these structures. For this purpose it is important to identify the constituent mechanical properties correctly [2, 3]. A series of tests has been developed to address this point, which includes: - hydrostatic compression - shear loading using a modified Arcan fixture This paper will describe the different test methods and present results obtained for different types of syntactic foams.

Electromagnetic Properties of Syntactic Foam Composites

1994 ◽  
Vol 372 ◽  
Author(s):  
Paul J. Kemper ◽  
Rick Moore
Keyword(s):  
Surface Morphology ◽  
Effective Medium Theory ◽  
Finite Thickness ◽  
Syntactic Foam ◽  
Frequency Dispersion ◽  
Electromagnetic Properties ◽  
Syntactic Foams ◽  
Sphere Surface ◽  
Medium Theory ◽  
Permittivity Measurements

AbstractA numerical model based upon renormalized effective medium theory will be described. The model successfully predicts the frequency dispersive permittivity of finite thickness dielectric/ conducting microsphere composites, electrically lossy syntactic foams, where the conducting particulates have volumetric fraction of 0 to 50%. The composites display unique frequency dispersions which are associated with the composite dimensionality and fractal-like sphere surface morphology. Theory and measurement show the composites have critical volume fractions which can be 20% above theoretical values for conducting spheres, i.e 27-–31% and the frequency dispersion of the composite permittivity can be varied by controlling the nanoscale surface morphology and composite thickness. Supporting permittivity measurements in the frequency range of 1–100 GHz will be presented.

Structure Properties Relationship Studies of Vinyl Ester Hybrid Syntactic Foam

2021 ◽  
pp. 368-394
Author(s):  
Pravin R. Kubade ◽  
Amol N. Patil ◽  
Hrushikesh B. Kulkarni
Keyword(s):  
Vinyl Ester ◽  
Syntactic Foam ◽  
Fracture Mechanisms ◽  
Syntactic Foams ◽  
Static Compression ◽  
Molding Method ◽  
Deformation And Fracture ◽  
The Matrix ◽  
Fly Ash Cenosphere ◽  
Izod Impact

Syntactic foam is the porous composite produced by mixing prefabricated hollow spherical particle into the matrix. Syntactic foams are used as energy absorption sandwich core for several applications like marine, automotive, and aerospace. In this work, low density hollow glass microspheres are hybridized with fly ash cenosphere in Bisphenol-A epoxy-based vinyl ester matrix. Hybrid syntactic foams is created with 60% total filler content. Within these hybrid systems internal composition of two fillers were varied in a step of 25 vol% with respect to each other. Hybrid syntactic foams are prepared by the hand lay-up (molding) method. The physical characterization parameter contains density and matrix porosity whereas tensile, quasi-static compression, flexural (3-point bending), Izod impact, and micro Vickers hardness are grouped as mechanical characterization parameters. Scanning electron microscopy was performed on fractured surfaces to examine deformation and fracture mechanisms related with each loading condition.

Microscopic Studies of Syntactic Foams Tested Under Three-Point Bending Conditions

2002 ◽  
Author(s):  
Nikhil Gupta ◽  
Eyassu Woldesenbet
Keyword(s):  
Moisture Absorption ◽  
Syntactic Foam ◽  
Local Stress ◽  
Core Material ◽  
Syntactic Foams ◽  
Compression Tests ◽  
Three Point Bending ◽  
Microscopic Studies ◽  
Stress States ◽  
Point Bend

Use of syntactic foam as core material in the sandwich structured composites is increasing due to its higher compressive strength, damage tolerance and low moisture absorption compared to the open cell structured foams. Extensive microscopic examination of the syntactic foams tested under compressive and three-point bending conditions is undertaken in this study. The aim of the investigation is to determine the local fracture mode and correlate it with the microscopic structure of the material. Local stress states are identified in the material based on the microscopic fracture features. Syntactic foam tested in the study has resin to microballoons ratio of 1.52 by weight. Compression tests were conducted on the syntactic foam specimens having two different aspect rations, which were 0.4 and 0.91. Three-point bend tests were conducted on the sandwich structures containing syntactic foam as core material and glass fabric as the skin material.

Dynamic Mechanical Properties of Polypropylene Syntactic Foam with Polymer Microballoons

2007 ◽  
Vol 7-8 ◽  
pp. 289-294
Author(s):  
Hiroyuki Mae ◽  
Masaki Omiya ◽  
Kikuo Kishimoto
Keyword(s):  
Mechanical Properties ◽  
Syntactic Foam ◽  
Environmental Scanning Electron Microscopy ◽  
Tensile Tests ◽  
Dynamic Mechanical Properties ◽  
Environmental Scanning ◽  
Strain Rates ◽  
Syntactic Foams ◽  
Bulk Specimen ◽  
Polypropylene Matrix

The main objective of this study is to measure and characterize the mechanical properties of the thermoplastic syntactic foams at the intermediate and high strain rates. The syntactic foam consists of the elastically deformable microballoons in the polypropylene matrix. The four types of syntactic foams and one polypropylene bulk specimen are prepared at same manufacturing process: 0, 20, 30, 40 and 50 volume percent of microballoons. Tensile tests are conducted at nominal strain rates ranging from 10-1 to 102 (1/sec). Elastic modulus, yield stress and rupture strain are measured and the effects of microballoons on the mechanical properties are studied. In addition, fracture surfaces are observed with ESEM (Environmental Scanning Electron Microscopy). Finally, the changes of fracture mode due to microballoons are discussed.

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