Concentration Of Iron Particles Research Articles

Potential for using the ANN-FIS meta-model approach to assess levels of particulate contamination in oil used in mechanical systems

Abstract Mechanical systems need to ensure high levels of quality. Today, greater generic reliability in systems makes it difficult to base any failure prognosis on previous system failures. Predicting the condition of a mechanical system needs to be based, instead, on monitoring the degradation of a system's components. Diagnostic signals can be identified and used as data to estimate the rate of degradation. A key driver for this work is the need to understand the performance of lubricants in systems involving mechanical contact. This article presents methods for studying field data collected with regard to oil. It focuses, in particular, on contaminated oil as this is an excellent source of diagnostic signals and information. However, data on oil present a degree of uncertainty in terms of both their collection and their use in the laboratory. Analysis of oil contaminants was, therefore, performed by applying a fuzzy inference system (FIS) and neural networks. The multilayer perception network was found to be an effective tool. The concentrations of iron and soot particles in used oil were selected as being both illustrative and the most significant model variables. The aim of this study is to acquire information about the condition of both lubricants and the mechanical systems, along with the development of degradation in mechanical equipment and the estimation of residual useful life (RUL). The results obtained will be useful in organizing effective operation of the mechanical systems being studied and modifying their maintenance.

Study of the mechanical properties of Iron-Epoxy composite materials

Iron-Epoxy composite samples were prepared by addeddifferent weight percentages (0, 5, 10, 15, and 20 wt %) from Ironparticles in the range of (30-40μm) as a particle size. The contentswere mixed carefully, and placed a circular dies with a diameter of2.5 cm. Different mechanical tests (Shore D Hardness, Tensilestrength, and Impact strength ) were carried out for all samples. Thesamples were immersed in water for ten weeks, and after two weeksthe samples were take-out and drying to conducting all mechanicaltests were repeated for all samples. The hardness values increasedwhen the Iron particle concentration increased while the Impactstrength is not affected by the increasing of Iron particlesconcentration. The tensile strength results reveal that the tensilestrength and the strain values of composite samples decreases whenthe Iron particles concentration increase. After conductedimmersion processes the results of hardness are reduced wears theresults of tensile strength and the impact strength are increased.

Study of the mechanical properties of Iron-Epoxy composite materials

Iron-Epoxy composite samples were prepared by addeddifferent weight percentages (0, 5, 10, 15, and 20 wt %) from Ironparticles in the range of (30-40μm) as a particle size. The contentswere mixed carefully, and placed a circular dies with a diameter of2.5 cm. Different mechanical tests (Shore D Hardness, Tensilestrength, and Impact strength ) were carried out for all samples. Thesamples were immersed in water for ten weeks, and after two weeksthe samples were take-out and drying to conducting all mechanicaltests were repeated for all samples. The hardness values increasedwhen the Iron particle concentration increased while the Impactstrength is not affected by the increasing of Iron particlesconcentration. The tensile strength results reveal that the tensilestrength and the strain values of composite samples decreases whenthe Iron particles concentration increase. After conductedimmersion processes the results of hardness are reduced wears theresults of tensile strength and the impact strength are increased.

Monitoring sedimentation of magnetorheological fluids using a vertical axis monitoring system with a low aspect ratio sensor coil**This research was conducted at the University of Maryland while the first author was a visiting student.

Adaptive energy absorbers (EAs) utilizing magnetorheological fluids (MRFs) are currently being investigated for severe impact or shock mitigation problems because magnetorheological energy absorbers can adjust stroking load to account for severity of impact and payload mass. Utilizing MRFs in such EAs requires a highly stable suspension that maintains a uniform concentration. Suspension stability of MRFs can be studied using a MRF column and an automated vertical axis inductance monitoring system (AVAIMS), where an inductance sensor is translated up and down the vertical MRF column to track the mud-line, defined as the boundary between the clarified fluid at the top of the column and the MRF below. The rate of descent of the mud-line is typically referred to as the sedimentation rate of the MRF. In this paper, a refined inductance sensor is developed that features a low aspect ratio coil to better localize rapid changes in concentration or sedimentation zone boundaries, as well as to improve symmetry of the applied magnetic field in the MRF sample enclosed by the sensor. This low aspect ratio solenoid (LARS) sensor was developed to measure the vertical distribution of the concentration of carbonyl iron particles in the MRF column. Compared with the high aspect ratio solenoid sensor used in our prior work, the results of FEM simulation and sedimentation experiments demonstrate that the LARS sensor was better able to localize rapid changes in concentration or density. Using the AVAIMS with the refined LARS sensor, a method was developed, based on the measured concentration gradient profile, to identify sedimentation zone boundaries in an MRF column, and these results were compared to our prior work using the measured concentration profile only. Sedimentation zone boundaries that are consistent with Kynch’s sedimentation theory were obtained using the concentration gradient profile method, such as monotonically descending mud-line, linearly ascending gel-line, and linearly ascending cake-line. Key metrics to characterize the time histories of the sedimentation zone boundaries are measured including mud-line descent rate, gel-line ascent rate, and cake-line ascent rate. Identification of sedimentation zone boundaries using the LARS sensor in conjunction with the concentration gradient profile method exhibited two main advantages including the direct measurement and improved localization of the large concentration change that occurs at a sedimentation zone boundary, and the elimination of sensor bias.

Effect of iron particles concentration and additives on properties of Magneto rheological Fluids

Effect of iron particles concentration and additives on properties of Magneto rheological Fluids

Stiffness and damping characteristics of MR fluid-based sandwich beams: experimental study

The study investigates the behaviour of three-layered cantilever sandwich beams filled with magnetorheological fluids (MRFs) differing in the iron particle content by volume. Outer layers are made of aluminium, the space between them is sealed with silicone rubber. Two types of beams are considered: fully filled beams and partially filled beams, subjected to the magnetic field. The aim of the study is to determine stiffness and damping characteristics in relation to the magnetic field strength and the actual location where the magnetic field acts upon the beam. For this purpose, measurements have been taken of the beam free vibration response for various magnetic field strength levels and for various positions of the electromagnet located along the beam axis. Basing on the developed measurement data processing algorithm, the influence of the vibration amplitude on the natural frequency and a dimensionless damping coefficient have been determined. Finally, the equivalent natural frequency and the dimensionless damping coefficient have been derived accordingly, and the stiffness and damping ratio have been determined in function of the magnetic field strength, the electromagnet position and the MRF iron particle content by volume.

Complex vibration modes in magnetorheological fluid-based sandwich beams

The study investigates the complex vibration modes of sandwich beams filled with magnetorheological fluids (MRFs). An approach is suggested involving both experiments and calculation procedures to determine the complex modes of the beams’ free vibrations. Testing was done on three-layered cantilever beam filled with MRF and exposed to the magnetic field generated by an electromagnet. The purpose of the work is to analyse the influence of MRF on the beam motion and to determine the complex modes. Measurements of free vibrations of two beams filled with MRFs differing in the iron particle content by volume were taken in a purpose-built experimental set-up. Vibrations of the beam were registered under magnetic field varying in strength and for varied electromagnet’s positions with respect to the beam fixed end. Thus obtained measurement data were utilised to derive the dependence of magnetic field strength and electromagnet position on beam stiffness and damping. Complex modes were obtained with the use of finite element (FE) proposed by the authors for the investigated beams. Results are given as plots of modulus and argument of the complex vibration mode against the co-ordinate defining the position along the beam axis. Results revealed major discrepancies between the values of real and imaginary parts of the beams’ vibrations modes.

Magnetic circuit analysis to obtain the magnetic permeability of magnetorheological elastomers

The magnetic permeability of magnetorheological elastomers must be known for their long-term use in the actual engineering systems. In this article, the magnetic permeability of both isotropic and anisotropic magnetorheological elastomers has been determined using a new method. The magnetic induction was measured and a closed magnetic circuit analysis was carried out to obtain the magnetic permeability of magnetorheological elastomers for both isotropic and anisotropic magnetorheological elastomers with 10%–50% volume concentration of carbonyl iron particles. The magnetic permeability was increased with increasing particle concentration for both isotropic and anisotropic magnetorheological elastomers as we could expect. The isotropic permeability is always lower than the anisotropic permeability. The maximum relative permeability value of 6.6 was obtained for 50% particle volume concentration. The experimental results also show a good agreement with theoretical predictions and previous investigations.

Atomic-level finishing of aluminum alloy by chemo-mechanical magneto-rheological finishing (CMMRF) for optical applications

Nanofinished aluminum alloys are widely used in optics as metallic mirrors, micro-electronics and micro-mechanical assemblies. In general, the ductile materials like aluminum and copper are being machined by diamond turn machining (DTM) process to get the nanometric surface finish. However, it is impossible to achieve an atomic level surface finish by conventional random finishing processes like lapping. With a newly developed chemo mechanical magnetorheological finishing (CMMRF) process, an experimental investigation has been carried out on Al-alloy by implementing suitable chemical reactions on the superficial layer of the workpiece. A full experimental design has been performed to optimize the process by varying several parameters such as concentration of chemicals, concentration of abrasives, concentration of carbonyl iron particles and working gap. Effect of different parameters has been studied an average surface roughness value (Ra) of less than 2 nm was achieved, which was further improved by optimizing the process parameters. The best result of CMMRF finished aluminum (0.597 nm) was way better than DTM and chemo-mechanical polishing process. In terms of reflectance, in the range of 300–2200 nm the processed surface was found to have 5% higher value in comparison with sputtered counterpart. Also, it was observed that finishing of aluminum caused its surface to shift from hydrophilic to hydrophobic and then to the super-hydrophilic region with a contact angle of 16°. By this experimentation, more than 98% improvement on surface finish has been observed. Therefore, it has been concluded that the CMMRF process can finish aluminum alloy of the order of few angstrom (Å).

Magnetomechanical properties of composites and fibers made from thermoplastic elastomers (TPE) and carbonyl iron powder (CIP)

Magnetoactive elastomers (MAE) made from composites of five thermoplastic elastomers (TPE) of different stiffness with carbonyl iron powder (CIP) as magnetic component were investigated. The composites were produced by melt blending of the magnetic particles with the TPEs in a twin-screw extruder. The resulting materials were characterized by ac permeability testing, stress–strain measurements with and without external magnetic field and magnetically controlled bending of long cylindrical rods in a homogenous magnetic field. The magnetic field necessary for deflection of the rods decreases with decreasing modulus and increasing iron particle content. This effect can be used e.g. for magnetically controlled actuation. Some highly filled MAE show a magnetic field induced increase of Young’s modulus. Filaments could be spun from some of the composites.

The rapid response of forming medium’s properties to variable loading types of magnetic field and consequent field-dependent sheet formability

Previous studies show that forming medium with adjustable mechanical properties may be used to achieve the controllable sheet formability. Magneto-rheological (MR) fluid was once adopted as property-adjustable forming medium to achieve the variable sheet formability. Yet, as a key process parameter in this process, the loading types of magnetic field may affect the sheet formability significantly, which is emphatically evaluated in this paper. Finite element analysis of bulge tests using three kinds of MR fluids with different mechanical properties were carried out. The field-dependence of sheet formability in this process is clarified by the finite element results. On the basis of that, bulge tests of Al1060-O sheet under different loading types of magnetic field were implemented. The sudden drop and swift recovery of forming load were observed, which is used to indicate the rapid response of forming load to external magnetic field. Deviation of forming load curves under different loading types of magnetic field was verified to be influenced by iron particle content of MR fluid. Geometry of bulged specimens and thickness strain under different loading types of magnetic field were measured. Forming limit surface was presented to show the variation of sheet forming limit. The loading types of magnetic field are considered to be responsible for the extent of formability increase in MRPF process. Optimized types of magnetic field are essential for the practical application of this process.

Axial squeeze strengthen effect on rotary magneto-rheological damper

Pressure is an important factor to influence the performance of an magneto-rheological (MR) apparatus. The effect of the axial squeeze strengthen effect on rotary MR damper is investigated theoretically and experimentally in this study. First, a theoretical analysis in a microscopic view is proposed. It indicates that a concentrated increment of iron particle content in the working gap results in the effect. Then, a pressure-controlled rotary MR damper with the axial squeeze strengthen effect is designed, manufactured and tested. The results show that the axial squeeze strengthen effect on rotary MR damper is remarkable for the damper with lower particle content in MR fluids. In addition, there is an optimal pressure to obtain the maximum axial squeeze strengthen effect on the rotary MR damper.

Property-adjustable forming medium induced extension of sheet metal formability under variable magnetic field

Deformation states of sheet metals are determined by the in-plane stress distribution, which is closely related to forming load transmitted by forming medium. Mechanical properties of conventional forming medium, such as mineral oil, gas, and polyurethane, can hardly be controlled during the whole forming process. However, if the mechanical properties of forming medium can be freely altered, the stress state of sheet metal may become controllable. As a result, the magneto-rheological (MR) fluid was employed as a property-adjustable forming medium in this paper, which attempted to extend sheet formability in a controllable way. Effects of magnetic flux density (B) and iron particle content (φ) on yield stress of MR fluid in compression mode were analyzed at first. Magneto-rheological pressure bulging (MRPB) tests for Al1060-O sheet were conducted under different sets of parameters. Effects of B and φ on forming load were presented to show the adjustable mechanical properties of forming medium. Extended forming limit diagram (e-FLD) was proposed to describe the variation of sheet forming limit. The results indicate that sheet forming limit can be extended by monotonously increasing B in a certain range. The appropriate range of B is correlated to φ. The through-thickness shear stress caused by the transverse friction between MR fluid and sheet metal is considered to be responsible for this increase. The proposed process is demonstrated to be an efficient method to control the sheet formability, and more practical application may be expectable.

Study of thermal conductivity of magnetorheological fluids using the thermal-wave resonant cavity and its relationship with the viscosity

The thermal conductivity and viscosity of a magnetorheological suspension composed of carbonyl iron particles immerse in silicone oil were studied. Thermal wave resonant cavity was employed to measure the thermal diffusivity of the magnetorheological fluid as a function of an externally applied magnetic field. The dynamic viscosity was also measured and its relationship with the concentration of the particles and the magnetic field strength was investigated. The results show that higher concentrations of carbonyl iron particles as well as higher magnetic field intensities lead to a significant increase in thermal conductivity. The relationship between the thermal conductivity and the dynamic viscosity was explored. Our measurements were examined using an analytical relation between the thermal conductivity and the dynamic viscosity. The results show that by using highly viscous materials, the order induced in the micro particles can be kept for a relatively long time and therefore the increase in thermal conductivity can also be maintained.

Enhancement of a magnetorheological PDMS elastomer with carbonyl iron particles

A magnetorheological elastomer based on silicone rubber with carbonyl iron micro-particles was developed. The influence of the different amount of iron particles was experimentally studied by means of XRD, SEM, FTIR, EDS, XPS, uniaxial tension and rheological and cyclic tests. Different contents of carbonyl iron particles (10–40 wt%) were used to obtain the ratio of magnetic particles/silicone rubber that could provide the best mechanical properties on the MRE material. It was found that the composite material can have an increase of about 95% in its tensile strength when adding 20% of carbonyl iron particles to the raw rubber material. SEM analysis indicates a good dispersion of the magnetic particles on the rubber matrix, and the FTIR and XPS techniques confirm, as expected, that there is no chemical interaction between the iron from the carbonyl iron particles and the silicone rubber matrix due to a proper coating of the particles with silicone oil used as coupling agent. The TGA results evidenced that the addition of coated carbonyl iron particles had an impact on the thermal stability of the MRE and on the formation of cross-linked structures. The viscoelastic behavior of the magnetorheological elastomer is described by running experimental test on a rheometer device. Furthermore, cyclic testing were performed on the material sample to characterize the Mullin's effect.

One-step synthesis and magnetic properties of Ni-Fe3O4@PI core–shell composite microspheres

Nickel(Ni)-iron(III) oxide(Fe3O4)@polyimide (PI) composite microspheres were successfully prepared from poly(amic acid) triethylammonium salts and a mixture of Fe(III) and Ni(II) via a facile one-step solvothermal process. Furthermore, the formation mechanism of the composite microspheres has been investigated. The morphology and the structure of the samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and infrared spectroscopy, respectively. It was determined that PI could be successfully coated on the surface of the magnetic microspheres. Based on the results obtained from thermo-gravimetric analysis and vibrating sample magnetometer curves, it was found that the composite microspheres exhibit an excellent thermal stability. The prepared sample, coined NiFe@PI-4, with higher weight content of iron particles in the polymer matrix, showed improved magnetic properties (saturation magnetization = 57.1 emu/g) due to the high saturation magnetization of Fe3O4 and excellent dispersion effects of polyethylene glycol on the nanoparticles in solution.

Force analysis of magnetic abrasive nano-finishing of magnetic and non-magnetic materials

Finishing is the final operation during manufacturing process of a component. It is time consuming, difficult, and usually a costly operation. Finishing cost can be as high as 15 % of the total production cost. Magnetic Abrasive Finishing (MAF) is an advanced finishing process in which a mixture of non-ferromagnetic abrasive particles and ferromagnetic carbonyl iron particles (CIPs) is used to do finishing operation with the aid of magnetic force. The iron particles form a flexible chain matrix in which the abrasive particles are trapped in between or within the chains. This is called flexible magnetic abrasive brush (FMAB), which when given a relative motion against a (metal/non-metal) surface, it finishes the surface. The present work deals with the effect of the process parameters such as applied magnetic field, concentration of abrasive particles and iron particles in FMAB, and rotational speed of magnet on the finishing forces that are generated during vertical MAF of ferromagnetic (EN-8) and non-ferromagnetic material (brass) flat workpieces. Empirical models for force prediction have been developed based on the experimental results. Effect of the applied magnetic field is seen to have the most significant contribution among all the input parameters. Percentage of oil in FMAB is not a significant factor for normal force, but it is a significant factor to the tangential force. The tangential force increases up to 3 % of oil content in FMAB, and it starts decreasing in the range of 3 to 5 % oil content.

Long term stability of magnetorheological fluids using high viscosity linear polysiloxane carrier fluids

Stability of magnetorheological fluids (MRFs) or suspensions has been a key issue in the development of various practical applications. In our prior work, it was experimentally confirmed that a high viscosity linear polysiloxane carrier fluid based MRF (hereinafter HVLP MRF) with 26% particle volume fraction (hereinafter 26 vol%) showed high sedimentation stability for 96 days because HVLP carrier fluids have remarkable shear thinning behavior, that is, very high viscosity at low shear rate but low viscosity at high shear rate. In addition, the effects of HVLP carrier fluid viscosity and carbonyl iron (CI) particle concentration on suspension stability were investigated with the objective of synthesizing highly stable HVLP MRFs for practical applications. The HVLP MRFs were synthesized by suspending nominally 32 vol% of CI particles in carrier fluids with different viscosities (i.e., 140, 440, and 800 Pa s). To illustrate the effect of particle concentration on suspension stability, because it is well known that suspension stability increases as particle concentration increases, two low concentrations, 5 and 10 vol%, and two high concentrations, 20 and 32 vol%, were prepared to demonstrate MRFs with relatively severe sedimentation, and stable suspensions, respectively. A vertical axis inductance monitoring system was employed to evaluate the suspension stability of the HVLP MRFs for 365 days by scanning the inductance of the MRF samples in a vertical fluid column, and logging this data with respect to height and time. In addition, the suspension stability of a commercially available MRF (i.e., Lord MRF-132DG) was also measured and compared with similar measurements for HVLP MRFs.

A fractional calculus approach to modeling rheological behavior of soft magnetic elastomers

A fractional calculus approach is applied to model constitutive behavior of magnetorheological elastomers. To test the model results magnetorheological elastomers containing different concentrations of iron particles have been synthesized and their rheological behavior in various magnetic fields has been studied experimentally. The fractional model parameters were found from fitting the experimental data. An excellent agreement between experimental results and the model predictions has been obtained. Correlation between the values of the order of the constitutive equation and structuring of magnetic filler governed by the balance between elastic and magnetic interactions has been formulated. It has been shown that the fractional rheological model can satisfactorily describe dynamic behavior of magnetorheological elastomers in magnetic field.

Extraterrestrial Metallic Iron in the Lacustrine, Epicontinental and Oceanic Sediments: A Review of Thermomagnetic and Microprobe Analyzes Data

The article represents an overview and generalization of the microprobe and thermomagnetic data on the distribution, content and composition of metallic iron in Pleistocene lacustrine sediments of the Darhad Basin, northern Mongolia, in the Upper Miocene sediments of Lake Baikal, epicontinental sediments of Miocene-Late Jurassic, and Early Cambrian ages in different regions of North Eurasia and in Miocene-Late Jurassic oceanic sediments of North- Western Atlantic. Iron particles percentage varies from ~10-5 to 0.05%, their distribution is bimodal with the distinct zero mode, and the accumulation of iron particles is inversely linked with the rate of sedimentation. Pyrite and pyrrhotite are widespread in the studied sediments, and the distribution of metallic iron does not depend on the presence of pyrite (i.e., on redox conditions). The variations in the Curie temperature of iron from 700°C up to 780°C. The nickel admixture in native iron forms three groups, 1) pure iron (main part of particles), 2) iron with mode 5-6% Ni (kamacite), and 3) Fe-Ni alloy with mode 50% Ni (rare), were found in all studied sections. The global pattern of the distribution and composition of the iron particles clearly indicates that their origin is associated with interplanetary cosmic dust. At the same time, the particles of Fe-Ni alloy are very rare, and their concentration does not correlate with the content of other iron particles. Most likely, the particles of Fe-Ni alloy are mainly due to impact events. Correlation between the concentrations of iron particles and terrestrial minerals (magnetite) is absent as a rule. Such correlation (r=0.3-0.7) testifies the redeposition of iron particles.