scholarly journals Field–Frequency-Dependent Non-linear Rheological Behavior of Magnetorheological Grease Under Large Amplitude Oscillatory Shear

2021 ◽  
Vol 8 ◽  
Author(s):  
Huixing Wang ◽  
Tianxiao Chang ◽  
Yancheng Li ◽  
Shaoqi Li ◽  
Guang Zhang ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Large Amplitude ◽  
Three Dimensional ◽  
Viscoelastic Behavior ◽  
Shear Thickening ◽  
Oscillatory Shear ◽  
Large Amplitude Oscillatory Shear ◽  
Field Frequency ◽  
Frequency Dependent ◽  
Non Linear

This article investigates the influence of frequency on the field-dependent non-linear rheology of magnetorheological (MR) grease under large amplitude oscillatory shear (LAOS). First, the LAOS tests with different driving frequencies were conducted on MR grease at four magnetic fields, and the storage and loss moduli under the frequency of 0.1, 0.5, 1, and 5 Hz were compared to obtain an overall understanding of the frequency-dependent viscoelastic behavior of MR grease. Based on this, the three-dimensional (3D) Lissajous curves and decomposed stress curves under two typical frequencies were depicted to provide the non-linear elastic and viscous behavior. Finally, the elastic and viscous measures containing higher harmonics from Fourier transform (FT)-Chebyshev analysis were used to quantitatively interpret the influence of the frequency on the non-linear rheology of MR grease, namely, strain stiffening (softening) and shear thickening (thinning), under LAOS with different magnetic fields. It was found that, under the application of the magnetic field, the onset of the non-linear behavior of MR grease was frequency-dependent. However, when the shear strain amplitude increased in the post-yield region, the non-linear rheology of MRG-70 was not affected by the oscillatory frequency.

scholarly journals Viscoelastic Rheological Behaviors of Polypropylene and LMPP Blends

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3485
Author(s):  
Feichao Zhu ◽  
Sohail Yasin ◽  
Munir Hussain
Keyword(s):  
Large Amplitude ◽  
Viscoelastic Behavior ◽  
Nonlinear Behavior ◽  
Oscillatory Shear ◽  
Large Amplitude Oscillatory Shear ◽  
Mechanical Responses ◽  
Nonlinear Viscoelastic ◽  
Linear Viscoelastic ◽  
Viscoelastic Behaviors ◽  
Linear And Nonlinear

Dynamic oscillatory shear testing is used to investigate polymeric viscoelastic behaviors. Small and large amplitude oscillatory shear tests are the canonical method for characterizing the linear and nonlinear viscoelastic behaviors of any polymeric material. With prominent and abundant work on linear viscoelastic studies, the nonlinear behavior is evasive in terms of generating infinite higher harmonics in the nonlinear regime. For this reason, intrinsic nonlinearities from large amplitude oscillatory shear (LAOS) studies have recently been used for insights on microstructural behaviors. This study is carried out for linear and nonlinear viscoelastic behavior with a main focus on LAOS of isostatic polypropylene (iPP) and relatively new low molecular weight and low modulus polypropylene-based polyolefin (LMPP) blends. The morphological results showed reduced spherulitic crystal nucleus size and increased distribution in blends with increasing LMPP. The blends showed subtle linear viscoelastic responses with strong nonlinear mechanical responses to variant strain and stress compared to pure iPP. The intracycle strain thickening and intracycle strain stiffening of high-content LMPP blends were comparatively dominant at medium strain amplitudes.

Rheological properties of soy protein isolate – carboxymethyl flaxseed gum mixed dispersions under large amplitude oscillatory shear

2020 ◽  
Vol 16 (7) ◽  
Author(s):  
Yu-xi Ma ◽  
Jin-lei Niu ◽  
Dong Li ◽  
Li-jun Wang
Keyword(s):  
Rheological Properties ◽  
Soy Protein ◽  
Large Amplitude ◽  
Soy Protein Isolate ◽  
Shear Thickening ◽  
Shear Thinning ◽  
Protein Isolate ◽  
Oscillatory Shear ◽  
Large Amplitude Oscillatory Shear ◽  
Flaxseed Gum

AbstractCarboxymethyl flaxseed gum (CMFG) is developed in our laboratory by modifying flaxseed gun through carboxymethylation. The aim of this study is to reveal the rheological properties of soy protein isolate – carboxymethyl flaxseed gum (SPI-CMFG) mixed dispersion in realistic processing conditions by conducting large amplitude oscillatory shear (LAOS) test, with consideration of concentration and degree of substitution (DS) of CMFG. Results showed that increasing CMFG concentration significantly increased storage moduli (Gʹ), loss moduli (Gʺ), and the apparent viscosity of all SPI-CMFG mixed dispersions. LAOS test illustrated that the dispersions experienced a transition from LAOS type IV to type III after increasing the concentration of CMFG, while the behavior converted from LAOS type I to type III by increasing DS. Fourier transform rheology (FTR) exhibited that increasing the concentration or DS of CMFG both induced a conversion from “soft sphere” to “hard sphere” behavior. The strain-stiffening ratio S and the shear-thickening ratio T demonstrated, that all SPI-CMFG dispersions experienced a similar conversion from strain stiffening to strain softening, and from shear thinning to shear thickening behaviors by increasing the concentration of CMFG. Nevertheless, the mixed dispersions presented shear thickening behaviors when DS was no more than 0.520 in the whole range of strain, while a conversion from shear thinning to shear thickening behavior occurred, when DS reached at 0.755 and 0.973.

Shear Thickening of an Amphiphilic Polymer Solution as Studied by Large Amplitude Oscillatory Shear Flow

2008 ◽  
Author(s):  
Ji Wang ◽  
Christophe Chassenieux ◽  
Jean-François Tassin ◽  
Albert Co ◽  
Gary L. Leal ◽  
...  
Keyword(s):  
Shear Flow ◽  
Polymer Solution ◽  
Large Amplitude ◽  
Shear Thickening ◽  
Amphiphilic Polymer ◽  
Oscillatory Shear ◽  
Large Amplitude Oscillatory Shear ◽  
Oscillatory Shear Flow

Characterization of nonlinear viscoelasticity of magnetorheological grease under large oscillatory shear by using Fourier transform-Chebyshev analysis

2020 ◽  
pp. 1045389X2095946
Author(s):  
Huixing Wang ◽  
Tianxiao Chang ◽  
Yancheng Li ◽  
Shaoqi Li ◽  
Guang Zhang ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Stress Response ◽  
Magnetic Fields ◽  
Large Strain ◽  
Viscoelastic Behavior ◽  
Shear Thickening ◽  
Oscillatory Shear ◽  
Weight Percentage ◽  
Higher Harmonic

Magnetorheological (MR) grease, which is a type of magneto-sensitive smart material, exhibits complex viscoelastic behavior under different magnetic fields. Storage and loss moduli from oscillatory test are commonly used to characterize such field-dependent viscoelastic behavior. However, they are not able to represent the higher harmonic nonlinearity appeared in oscillatory responses under large amplitude oscillatory (LAOS) shear. In this paper, an investigation is conducted on the characterization of the filed-dependent nonlinearity of MR grease under LAOS by utilizing of Fourier transform (FT)-Chebyshev analysis. To capture the higher harmonic nonlinearity for the modeling and analysis, a comprehensive test program has been conducted. Firstly, MR grease with 70% weight percentage of carbonyl iron particles (MRG-70) is prepared and the stress response of MRG-70 under the oscillatory shear from small to large strain amplitudes with different magnetic field are measured. Then the higher harmonics in stress response signal are used to detect the intercycle nonlinearity of MRG-70 and compare with the traditional analysis method of dynamic modulus. Further, the elastic and viscous measures from FT-Chebyshev analysis are obtained to capture the inter-/intracycle nonlinear behaviors, that is, strain stiffening/softening, shear thickening/thinning, of MRG-70 under LAOS. It is found that, in the presence of magnetic fields, the onset of the intercycle nonlinearities of MRG-70 is originated from shear thickening of MR grease. With the further increase of the shear strain, MRG-70 exhibits the nonlinearities with different combinations of strain stiffening/softening and shear thickening/thinning.

scholarly journals Non-linear viscoelasticity analysis for CTAB/NaSal wormlike micellar solution in large amplitude oscillatory shear

2015 ◽  
Vol 81 (823) ◽  
pp. 14-00615-14-00615
Author(s):  
Masatoshi ITO ◽  
Yumiko YOSHITAKE ◽  
Shuji FUJII ◽  
Tsutomu TAKAHASHI ◽  
Toru AIKAWA
Keyword(s):  
Large Amplitude ◽  
Linear Viscoelasticity ◽  
Micellar Solution ◽  
Oscillatory Shear ◽  
Large Amplitude Oscillatory Shear ◽  
Non Linear
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