Rheological properties of micro-nano magneto-rheological fluid

2019 ◽  
Vol 9 (7) ◽  
pp. 827-830
Author(s):  
Hongbo Wang ◽  
Xinyi Liang ◽  
Jifan Guo ◽  
Chungeng Zhu
Keyword(s):  
Mass Fraction ◽  
Mechanical Performance ◽  
Nano Particles ◽  
Testing System ◽  
Mr Fluid ◽  
Mechanical Performances ◽  
Magneto Rheological ◽  
Nonmagnetic Particles ◽  
Magnetic Induction Intensity ◽  
Constant Shear Rate

In this paper, a novel micro-nano Magneto-rheological Fluid (MR) is proposed, and its mechanical performance, mainly including the shear torque and normal stress, is studied. Here, the magnetic particle in this kind of smart fluid is composed by the micro and nano particle, that is, produced by adding some nano magnetic or nonmagnetic particles into the traditional MR fluid (its particle size about 1–10 μm). A set of testing system, mainly including the plate-on-plate shearing test rig, is built to investigate the effect of the added percent of particles on the mechanical performances of MR fluid. In the condition of a constant shear rate, if the mass fraction of the nano particles is a constant, for example 4%, with the increasing of the magnetic induction intensity, the shear torque will also increase. The normal force increases rapidly with the increasing of mass fraction of the nano particles and decrease gradually.

scholarly journals The impact of thermal reprocessing of 3D printable polymers on their mechanical performance and airborne pollutant profiles

2021 ◽  
Vol 28 (11) ◽  
Author(s):  
Antti Juho Kalevi Väisänen ◽  
Lauri Alonen ◽  
Sampsa Ylönen ◽  
Isa Lyijynen ◽  
Marko Hyttinen
Keyword(s):  
3D Printing ◽  
Mechanical Performance ◽  
Plastic Material ◽  
Ultrafine Particle ◽  
Poly Lactic Acid ◽  
Testing System ◽  
Multiple Materials ◽  
Airborne Pollutant ◽  
Mechanical Performances ◽  
The Impact

AbstractThe alterations in volatile organic compound (VOC) and ultrafine particulate (UFP) matter emission profiles following thermal reprocessing of multiple materials were examined. Additionally, mechanical performance of the materials was studied. The VOCs were identified by collecting air samples with Tenax® TA tubes and analyzing them with a GC–MS system. UFP concentrations were monitored with a portable ultrafine particle counter. Total VOC emissions of all materials were reduced by 28–68% after 5 thermal cycles (TCs). However, slight accumulation of 1,4-dioxane was observed with poly(lactic acid) materials. UFP emissions were reduced by 45–88% for 3D printing grade materials over 5 TCs but increased by 62% in the case of a waste plastic material over 3 TCs. The mechanical performance of the materials was investigated by measuring their tensile strengths (TSs) and elastic moduli (EM) with an axial-torsion testing system. The reprocessed materials expressed fluctuations in their 3D printing qualities and mechanical performances. The mechanical performances were observed to reduce only slightly after 5 TCs, and the trend was observable only after the data was mass-normalized. The TSs of the samples were reduced by 10–24%, while the EM were reduced by 1–9% after 5 TCs. The TS and EM of one material were increased by 14 and 33%, respectively. In conclusion, recycled polymers are plausible 3D printing feedstock alternatives as they possess acceptable mechanical performance and low emittance according to this study. Furthermore, non-3D printing grade polymers may be applied in a 3D printer with caution.

Bidisperse Perfluorinated Polyether (PFPE)-Based Magneto-Rheological Fluids in a Prosthetic Knee

2009 ◽  
Author(s):  
Fjola Jonsdottir ◽  
Ketill H. Gudmundsson ◽  
Freygardur Thorsteinsson ◽  
Oliver Gutfleisch
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Sedimentation Rate ◽  
Total Solid ◽  
Nano Particles ◽  
Solid Concentration ◽  
Mr Fluid ◽  
Prosthetic Knee ◽  
Magneto Rheological ◽  
Perfluorinated Polyether

Regaining biomechanical function, comfort and quality of life is a prime consideration when designing prosthetic limbs. Recently, microprocessor-controlled prosthetic knees, which rely on magneto-rheological (MR) technology, have become available and have the potential to meet these needs. One of these promising products is a prosthetic knee manufactured by the company Ossur Inc. The knee is a synergy of artificial intelligence, advanced sensors and MR actuator technology. A critical factor in the success of the prosthetic knee is the composition of the MR fluid. In the prosthetic actuator, the fluid is used in shear mode in a micron-sized fluid gap. The characteristics of the MR fluid, such as, the off-state viscosity, the field-induced shear yield stress, the post-yield viscosity, and the particle sedimentation rate, determine the properties of the prosthetic knee. This paper describes a novel perfluorinated polyether (PFPE)-based MR fluid with properties that are tailored for the requirements of the prosthetic knee actuator. Rheological measurements of monodisperse and bidisperse PFPE-based fluid mixtures are presented. The monodisperse fluid consists of micron-sized carbonyl iron particles and the bidisperse mixture contains micron- and nano-sized particles. A few different concentrations of nano particles are investigated; first by holding the total solid concentration constant, and then by increasing the total solid concentration, to exceed that of the MR fluid containing only micron-sized particles. An MR fluid composition is sought that has a suitable balance between field-induced strength, off-state viscosity and sedimentation rate, for the proposed application. This balance is determined by desired qualities of the prosthetic knee and relate directly to the MR fluid. The field-induced shear stress of MR fluid samples is measured as a function of the magnetic flux density along with the off-state viscosity as a function of the shear-rate. The shear stress and off-state viscosity at high-shear rates are of particular interest, since the working shear rate in the prosthetic knee is high, due to the micron-sized gap between the blades in the fluid chamber of the actuator. Mathematical models are presented that describe how the MR fluid properties relate to the behavior of the prosthetic knee. The paper shows how a tailored design of an MR fluid can further the success of the MR prosthetic knee.

scholarly journals Advanced mechanical and thermal characterization of 3D bioextruded poly(e-caprolactone)-based composites

2018 ◽  
Vol 24 (4) ◽  
pp. 731-738 ◽  
Author(s):  
Hanxiao Wang ◽  
Marco Domingos ◽  
Fabio Scenini
Keyword(s):  
Mechanical Performance ◽  
Raw Materials ◽  
Thermal Characterization ◽  
Nano Particles ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Content Type ◽  
Bioactive Scaffolds ◽  
3D Printed ◽  
Mechanical Performances

Purpose The purpose of this paper is to study the effect of nano hydroxyapatite (HA) and graphene oxide (GO) particles on thermal and mechanical performances of 3D printed poly(ε-caprolactone) (PCL) filaments used in bone tissue engineering (BTE). Design/methodology/approach Raw materials were prepared by melt blending, followed by 3D printing via 3D Discovery (regenHU Ltd., CH) with all fabricating parameters kept constant. Filaments, including pure PCL, PCL/HA and PCL/GO, were tested under the same conditions. Several techniques were used to mechanically, thermally and microstructurally evaluate properties of these filaments, including differential scanning calorimetry, tensile test, nano indentation and scanning electron microscope. Findings Results show that both HA and GO nano particles are capable of improving mechanical performance of PCL. Enhanced mechanical properties of PCL/HA result from reinforcing effect of HA, while a different mechanism is observed in PCL/GO, where degree of crystallinity plays an important role. In addition, GO is more efficient at enhancing mechanical performance of PCL compared with HA. Originality/value For the first time, a systematic study about effects of nano HA and GO particles on bioactive scaffolds produced by additive manufacturing for BTE applications is conducted in this work. Mechanical and thermal behaviors of each sample, pure PCL, PCL/HA and PCL/GO, are reported, correlated and compared with literature.

Adaptable Fixturing Heads for Swarm Fixtures: Discussion of Two Designs

2012 ◽  
Author(s):  
Serena Gagliardi ◽  
Xiong Li ◽  
Matteo Zoppi ◽  
Luis de Leonardo ◽  
Rezia Molfino
Keyword(s):  
Life Cycle ◽  
Hydrostatic Pressure ◽  
Phase Change ◽  
European Commission ◽  
Mr Fluid ◽  
End Effector ◽  
Innovative Project ◽  
Life Cycle Design ◽  
Multi Agent ◽  
Magneto Rheological

Driven by the trend of life-cycle design and sustainable production, an innovative project called self-reconfigurable intelligent swarm fixtures (SwarmItFIX) funded by the European Commission is being developed. The project investigates the application of robotic multi agent fixtures for the support of automotive and airplane body panels during their manufacturing and assembly processes. This paper addresses the exploration and development of the adaptable heads, which are the end-effector of the intelligent fixture. The head is able to adapt to the shape of the workpiece and freeze its shape after adaptation to provide stable support. Two kinds of head designs are discussed. The first design uses the pseudo-phase-change properties of a volume of bulk grains (metal sand) which can be clustered using a hydrostatic pressure to conform to a given workpiece shape. The second design investigated uses phase-change magneto-rheological (MR) fluid in a network of channels to allow and block the motion of a crown of miniature pistons. The initial experiments are carried out and their results show the effectiveness of the design.

scholarly journals Mechanical Performance of Glass-Based Geopolymer Matrix Composites Reinforced with Cellulose Fibers

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2395 ◽  
Author(s):  
Gianmarco Taveri ◽  
Enrico Bernardo ◽  
Ivo Dlouhy
Keyword(s):  
Fly Ash ◽  
Mechanical Performance ◽  
Fiber Surface ◽  
Cellulose Fiber ◽  
Maximum Effect ◽  
Matrix Composites ◽  
Curing Conditions ◽  
Chevron Notch ◽  
Geopolymer Matrix ◽  
Mechanical Performances

Glass-based geopolymers, incorporating fly ash and borosilicate glass, were processed in conditions of high alkalinity (NaOH 10–13 M). Different formulations (fly ash and borosilicate in mixtures of 70–30 wt% and 30–70 wt%, respectively) and physical conditions (soaking time and relative humidity) were adopted. Flexural strength and fracture toughness were assessed for samples processed in optimized conditions by three-point bending and chevron notch testing, respectively. SEM was used to evaluate the fracture micromechanisms. Results showed that the geopolymerization efficiency is strongly influenced by the SiO2/Al2O3 ratio and the curing conditions, especially the air humidity. The mechanical performances of the geopolymer samples were compared with those of cellulose fiber–geopolymer matrix composites with different fiber contents (1 wt%, 2 wt%, and 3 wt%). The composites exhibited higher strength and fracture resilience, with the maximum effect observed for the fiber content of 2 wt%. A chemical modification of the cellulose fiber surface was also observed.

scholarly journals Assessments on the Performance of Asphalt Mixtures Prepared with Adhesion Promoters

2019 ◽  
Vol 8 (3S3) ◽  
pp. 332-339
Keyword(s):  
Mechanical Performance ◽  
Water Immersion ◽  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Asphalt Mixtures ◽  
Adhesion Promoters ◽  
Modified Asphalt ◽  
Service Characteristics ◽  
Bonding Properties ◽  
Mechanical Performances

Asphalt pavement is typically susceptible to moisture damage. However, it could be improved with the incorporation of additives or modifiers through binder modifications. The objective of the study is to assess the effect of adhesion promoters, namely PBL and M5000, onto the Hot Mix Asphalt (HMA). The performance of asphalt mixture has been assessed in terms of the service characteristics, the bonding properties, and mechanical performances. The service characteristics were assessed through the Workability Index (WI) and Compaction Energy Index (CEI) to evaluate the ease of asphalt mixture during the mixing and compaction stage. The bonding properties of the modified asphalt mixtures were determined using the boiling water test and static water immersion test to signify the degree of coating after undergoing specific conditioning period and temperature. The mechanical performances of the modified asphalt mixture were evaluated via Marshall stability, semi-circular bending, and modified Lottman tests. All specimens were prepared by incorporating adhesion promoters at the dosage rates of 0.5% and 1.0% by weight of asphalt binder. From the investigation, the bonding properties significantly improved for the modified asphalt mixture compared to the control mixture. The WI of the modified asphalt mixture increased while the CEI decreased in comparison to the control specimen. This implies the workability of modified asphalt mixture is better and requires less energy to be compacted. Modified asphalt mixture generally had better mechanical performance. Therefore, it can be deduced that the asphalt mixture with adhesion promoters have better overall performance than the control mixture.

scholarly journals Polymeric Nanocomposites: Compounding and Performance

2008 ◽  
Vol 8 (4) ◽  
pp. 1582-1596 ◽  
Author(s):  
L. A. Utracki
Keyword(s):  
Mechanical Performance ◽  
Extensional Flow ◽  
Polyamide 6 ◽  
Nano Particles ◽  
Polymeric Nanocomposites ◽  
Organic Salts ◽  
Melt Compounding ◽  
Twin Screw ◽  
And Performance ◽  
Kinetics Of

Polymeric nanocomposites (PNC) are binary mixtures of strongly interacting, inorganic platelets dispersed in a polymeric matrix. For full exfoliation, the thermodynamic miscibility is required. There are three basic methods of organically-modified clay dispersion that might result in PNC: (1) in polymer solution (followed by solvent removal), (2) in a monomer (followed by polymerization), and (3) in molten polymer (compounding). Most commercial PNC are produced by the second method, but it is the third one that has the greatest promise for the plastics industry. Similarly as during the manufacture of polymer blends, the layered silicates must be compatibilized by intercalation with organic salts and/or addition of functionalized macromolecules. Compounding affects the kinetics of dispersion process, but rarely the miscibility. Melt compounding is carried out either in a single-screw (SSE) or a twin-screw extruder (TSE). Furthermore, an extensional flow mixer (EFM) might be attached to an extruder. Two versions of EFM were evaluated: (1) designed for polymer homogenization and blending, and (2) designed for dispersing nano-particles. In this review, the dispersion of organoclay in polystyrene (PS), polyamide-6 (PA-6) or in polypropylene (PP) is discussed. The PNC based on PS or PA-6 contained two components (polymer and organoclay), whereas those based on PP in addition had a compatibilizer mixture of two maleated polypropylenes. Better dispersion was found compounding PNC's in a SSE + EFM than in TSE with or without EFM. The mechanical performance (tensile, flexural and impact) was examined.

Effect of Centrifugal Force Effect on Magneto-Rheological Fluid Clutches

2002 ◽  
Author(s):  
Vijay A. Neelakantan ◽  
Gregory N. Washington
Keyword(s):  
Magnetic Fields ◽  
Design Methodology ◽  
Volume Fraction ◽  
The Other ◽  
Particle Orientation ◽  
Centrifugal Forces ◽  
Mr Fluid ◽  
Set Up ◽  
Magneto Rheological ◽  
Very High

The property of magnetorheological fluids to change their yield stress depending on applied magnetic fields can be employed to develop many controllable devices one of them being MR fluid based clutches. One major problem however with MR fluid based clutches is that at high rotational speeds, the iron/ferrous particles in the MR fluid centrifuge due to very high centrifugal forces. Thus the particles move outward as the speed increases thereby making the fluid non-homogeneous. Many times however the initial analysis assumes fluid homogeneity, which is really not the case. In this paper this problem is addressed by assuming various volume fraction profiles describing the fluid particle orientation. Two cases, one with a linear profile and the other with an exponential profile are discussed. Expressions for the torque transmitted are derived at for both disc shaped and cylindrical shaped clutches. In addition, the use of a MR sponge based clutch that may indeed reduce the effect of centrifugal forces significantly is described. The design methodology and configuration for the sponge clutch are also discussed. An experimental set up used to test the clutch is also described.

Development of a boring bar with magneto rheological fluid damping and assessment of its dynamic characteristics

2017 ◽  
Vol 24 (14) ◽  
pp. 3094-3106 ◽  
Author(s):  
CV Biju ◽  
MS Shunmugam
Keyword(s):  
Modal Parameters ◽  
Model Parameters ◽  
Excitation Current ◽  
Mr Fluid ◽  
Boring Bar ◽  
Chatter Suppression ◽  
Damping Characteristics ◽  
Fluid Damping ◽  
Variable Damping ◽  
Magneto Rheological

The boring operation is prone to chatter as the boring bar is slender and has an overhang. For chatter suppression, passive, semi-active or active control methods can be employed. In the present work, a boring bar has been specially designed to transfer vibration to a cantilever bar surrounded by magneto rheological (MR) fluid. The MR fluid when exposed to electromagnetic flux changes its rheological property within a certain range. Thus, the boring bar is able to exhibit variable damping characteristics by changing the excitation current. The modal parameters are experimentally obtained through an impact test and a shaker test. The variation of modal parameters with excitation current is discussed. A stability lobe diagram is also developed from the model parameters, showing safe and unsafe regions for operation. The semi-active boring bar developed in the present work can be used for the suppression of chatter during the boring operation.

Sign in / Sign up

Export Citation Format

Share Document