CHARACTERIZING THE EFFECT OF TEMPERATURE AND MAGNETIC FIELD STRENGTHS ON THE COMPLEX SHEAR MODULUS PROPERTIES OF MAGNETORHEOLOGICAL (MR) FLUIDS

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1318-1324 ◽  
Author(s):  
W. W. CHOOI ◽  
S. O. OYADIJI
Keyword(s):  
Magnetic Field ◽  
Shear Modulus ◽  
Complex Modulus ◽  
Loss Modulus ◽  
Excitation Frequency ◽  
Effect Of Temperature ◽  
Complex Shear Modulus ◽  
Mr Fluids ◽  
Complex Shear ◽  
Frequency Coverage

When a magnetic field is applied across MR fluids, a yield stress is developed, and their rheological properties can then be categorized into two distinct regimes; pre-yield and post-yield. This paper concerns the viscoelastic behaviour of MR fluids in the pre-yield region. Oscillatory tests were carried out to determine the complex shear modulus properties of MR fluids between the temperature range of -20°C and +50°C. The test results show that the storage modulus and loss modulus increased in value as the excitation frequency was increased from 5Hz to 50Hz. The complex modulus was also found to be influenced by changes in temperature; the higher the temperature, the lower the complex modulus. This is consistent with the behaviour of viscoelastic polymers. The sets of temperature-dependent and frequency-dependent data were subsequently condensed using the method of reduced variables into master curves of complex modulus which effectively extended the frequency coverage of the data at the reference temperature.

Identification of Complex Shear Modulus of MR Layer Placed in Three-Layer Beam – Part 2: Algorithm

2015 ◽  
Vol 759 ◽  
pp. 15-25
Author(s):  
Mateusz Romaszko ◽  
Jacek Snamina ◽  
Sebastian Pakuła
Keyword(s):  
Magnetic Field ◽  
Shear Modulus ◽  
Field Data ◽  
Free Vibrations ◽  
Complex Shear Modulus ◽  
Mr Fluid ◽  
Magnetic Field Data ◽  
Complex Modes ◽  
Complex Shear ◽  
The Magnetic Field

The paper presents the procedure of identification of a complex shear modulus which describes properties of MR fluid in the pre-yield regime as a function of magnetic field. Data necessary for identification were collected basing on measurements of free vibrations of a three-layered cantilever beam at a special laboratory stand. Magnetic field exerting on MR fluid placed in the beam was generated by electromagnet. In the next step, complex modes of beam vibrations for various places of applying the magnetic field and its strength were calculated.

scholarly journals Evaluation of Rheological Characteristics of Graphite Modified Bitumen

2021 ◽  
Vol 11 ◽  
pp. 51-57
Author(s):  
Odunayo Olayemi Oladunjoye ◽  
Olugbenga Joseph Oyedepo ◽  
Ebenezer Omoniyi Olukanni ◽  
Sombo Philiph Akande
Keyword(s):  
Shear Modulus ◽  
Phase Angle ◽  
Dynamic Viscosity ◽  
Loss Modulus ◽  
Rheological Parameters ◽  
Dynamic Shear ◽  
Complex Shear Modulus ◽  
Modified Bitumen ◽  
Dynamic Shear Rheometer ◽  
Complex Shear

The level of performance of asphalt concrete has a close relationship with the properties of bitumen used. This research evaluates the rheological parameters of graphite modified bitumen. Index properties tests were conducted on bitumen and graphite to determine their suitability. Dynamic viscosity and dynamic shear rheometer were conducted on bituminous binder modified with four different proportion of graphite ranging from 2% to 10% by bitumen weight. Dynamic viscosity test was conducted on bitumen and graphite modified bitumen at temperature of 1350C and 1650C using Brookfield Viscometer. The rheological properties are centered on phase angle (δ) and complex shear modulus (G*) which were determined on bitumen and graphite modified bitumen at temperature ranging from 520C – 700C at 10 rad/s frequency using Dynamic Shear Rheometer in accordance with ASTM D7175-15. The storage modulus (G'), loss modulus (G") and rutting parameters were then evaluated from phase angle and complex shear modulus. The bitumen and graphite modified bitumen showed that graphite modified bitumen has the highest complex shear modulus and rutting parameter of 8984 (kPa) and 33387 (kPa) at 10% graphite content. The results of viscosity helped to determine the mixing and compaction temperatures. Dynamic shear rheometer test results determined the elastic and viscous behaviour at various temperature. The higher the complex shear modulus and rutting parameter the stiffer the binder will resist deformation and rutting.

Novel Rheometer for Superposed Constant and Oscillatory Shear Rate

2007 ◽  
Vol 345-346 ◽  
pp. 1605-1608
Author(s):  
Sandro Dinser ◽  
Klaus Haeusler ◽  
Jürg Dual
Keyword(s):  
Shear Rate ◽  
Shear Modulus ◽  
Normal Force ◽  
Complex Modulus ◽  
Nonlinear Behavior ◽  
High Sensitivity ◽  
Complex Viscosity ◽  
Complex Shear Modulus ◽  
Complex Shear ◽  
Viscoelastic Liquids

A newly developed resonator in combination with a UDS 200 rheometer allows performing different kinds of measurements. The characteristics of the resonator are its resonant frequency slightly above conventional rheometers, the high sensitivity allowing measurement of fluids with viscosities as low as that of water and the very small oscillation amplitudes. The nonlinear behavior of viscoelastic liquids can be analyzed using parallel superposition of shear. It is known that the parallel complex shear modulus differs from the complex modulus of a fluid at rest. First measurements have shown the ability of the instrument to quantify this effect. At the same time, normal force, shear rate viscosity and complex viscosity can be measured on a sample.

A Hybrid Model for Characterizing Pre-Yield Properties of MR Fluids

2014 ◽  
Author(s):  
Mehdi Eshaghi ◽  
Ramin Sedaghati ◽  
Subash Rakheja
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Shear Modulus ◽  
Hybrid Model ◽  
Applied Magnetic Field ◽  
Sandwich Beams ◽  
Complex Shear Modulus ◽  
Mr Fluid ◽  
Field Dependent ◽  
Complex Shear

This study aims to present a field dependent phenomenological model to characterize the Magneto-Rheological (MR) fluid in the pre-yield region under varying frequency and applied magnetic field. Systematic analytical and experimental studies are proposed to formulate a hybrid model for representing complex shear modulus of a typical MR fluid (MR 122EG from Lord Corporation) as a function of both applied magnetic field and frequency. Two fully treated MR based sandwich beams with aluminum and copper face layers and MR fluid as the core layer are designed and fabricated. Uniform magnetic flux across the sandwich beam is provided using two permanent magnets. The fabricated MR based sandwich beams are then tested on an electrodynamic shaker under sweep sine excitation and different applied magnetic field to realize the effect of external excitation frequency and applied magnetic field on the stiffness and damping properties of the structure. The finite element model based on classical plate theory is also developed to analyze vibration response of the designed MR based sandwich beams incorporated with MR fluid. Then, by correlating the finite element results with those of the experiment, the frequency and field dependent complex shear modulus of the MR fluid is identified.

Evaluating the Properties of Bitumen Stabilized with Carbon Nanotubes

2013 ◽  
Vol 723 ◽  
pp. 312-319 ◽  
Author(s):  
Wynand JvdM Steyn ◽  
Tanya E. Bosman ◽  
Samantha Galle ◽  
Jacques van Heerden
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Shear Modulus ◽  
Rheological Properties ◽  
Complex Modulus ◽  
Fatigue Cracking ◽  
Complex Shear Modulus ◽  
Multi Walled Carbon Nanotube ◽  
Complex Shear ◽  
Plastic Sample

The aim of this paper is to investigate the rheological properties of Multi-Walled Carbon NanoTube (MWCNT) enhanced bitumen. The rheological properties of bitumen samples with a range of MWCNT applications are evaluated. The shear complex modulus of the samples increased after ageing, and also increased as the percentage of MWCNTs increased. The viscous component of the complex shear modulus was found to be dominant at higher temperatures, but as the concentration of MWCNTs increased, it was found that the elastic portion started to dominate at higher temperatures. At higher temperatures a change in the phase angle was found, with increased concentrations of MWCNTs causing a decrease in δ, representing a more plastic sample. It is shown that addition of MWCNTs as a modifier did not increase the cracking resistance of the bitumen. Thus, if fatigue cracking is of concern in a certain area it is not recommended to use MWCNTs as a modifier. As the quantity of MWCNTs increased, the temperature at which rutting would start to occur, increased.

Dynamic Mechanical Properties of PEG 4000 + Quartz Composites

2015 ◽  
Vol 1112 ◽  
pp. 385-388 ◽  
Author(s):  
Fauziyah Nur Aini ◽  
Musyarofah ◽  
Triwikantoro ◽  
Mashuri ◽  
Sukma Firdaus ◽  
...  
Keyword(s):  
Shear Modulus ◽  
Complex Modulus ◽  
Strain Relaxation ◽  
Silica Sand ◽  
Heating Process ◽  
Processing Temperature ◽  
Complex Shear Modulus ◽  
Dynamic Mechanical ◽  
Peg 4000 ◽  
Complex Shear

The complex shear modulus of polyethylene glycol (PEG) 4000 + quartz compositesas a variation of processing temperature and applied temperature has been investigated using a Dynamic Mechanical Analysis (DMA) instrument. The quartz, obtained by processing silica sand from Tanah Laut, South Kalimantan, of as much as 40% by weight was used as the filler of the composite. The processing temperature was room temperature, 50°C, and 70°C after considering the theoretical melting point of PEG 4000. Results showed that such temperaturesgave several phenomena related with the complex modulus values from the pure PEG 4000 and the composite, i.e.they dropped with time indicating the presence of relatively rapid strain relaxation and were in the range of 50-300MPa. Furthermore, theaddition of quartz improved the values wherethe most improvement occurred on the 70°C sample,i.e. almost twice from the pure PEG 4000. Increasing the heating process, however, significantly reduced the values. The reduction was confirmed by further investigation where the result showed that the complex shear modulus value both in the pure PEG 4000 and the composite dropped with applied temperature at around 42°C and 45°C, respectively, whichcan be related to the melting PEG. A severe drop was particulartly observed in the composite which was believed caused by the addition of quartz in a lose powder form.

Analytical Approach to Recovering Bone Porosity From Effective Complex Shear Modulus

2009 ◽  
Vol 131 (12) ◽  
Author(s):  
Carlos Bonifasi-Lista ◽  
Elena Cherkaev ◽  
Yener N. Yeni
Keyword(s):  
Shear Modulus ◽  
Cancellous Bone ◽  
Spectral Measure ◽  
Complex Modulus ◽  
Ct Images ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Complex Shear Modulus ◽  
Human Cancellous Bone ◽  
Complex Shear

This work deals with the study of the analytical relations between porosity of cancellous bone and its mechanical properties. The Stieltjes representation of the effective shear complex modulus of cancellous bone is exploited to recover porosity. The microstructural information is contained in the spectral measure in this analytical representation. The spectral function can be recovered from the effective measurements over a range of frequencies. The problem of reconstruction of the spectral measure is very ill-posed. Regularized algorithm is derived to ensure stability of the results. The proposed method does not use any specific assumptions about the microgeometry of bone. The approach does not rely on correlation analysis, it uses analytical relationships. For validation purposes, complex shear modulus over a range of frequencies was calculated by the finite element method using micro-computed tomography (micro-CT) images of human cancellous bone. The calculated values were used in numerical algorithm to recover bone porosity. At the microlevel, bone was modeled as a heterogeneous medium composed of trabeculae tissue and bone marrow treated as transversely isotropic elastic and isotropic viscoelastic materials, respectively. Recovered porosity values are in excellent agreement with true porosity found from the corresponding micro-CT images.

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