scholarly journals The Dynamic Compressive Response of an Open-Cell Foam Impregnated With a Non-Newtonian Fluid

2009 ◽  
Vol 76 (6) ◽  
Author(s):  
M. A. Dawson ◽  
G. H. McKinley ◽  
L. J. Gibson
Keyword(s):  
Newtonian Fluid ◽  
Colloidal Silica ◽  
Dynamic Compression ◽  
Shear Thickening ◽  
Local Strain ◽  
Strain Rates ◽  
Parallel Plates ◽  
Compressive Response ◽  
Instantaneous Strain ◽  
Open Cell Foam

The response of a reticulated, elastomeric foam filled with colloidal silica under dynamic compression is studied. Under compression beyond local strain rates on the order of 1 s−1, the non-Newtonian, colloidal silica-based fluid undergoes dramatic shear thickening and then proceeds to shear thinning. In this regime, the viscosity of the fluid is large enough that the contribution of the foam and the fluid-structure interaction to the stress response of the fluid-filled foam can be neglected. An analytically tractable lubrication model for the stress-strain response of a non-Newtonian fluid-filled, reticulated, elastomeric foam under dynamic compression between two parallel plates at varying instantaneous strain rates is developed. The resulting lubrication model is applicable when the dimension of the foam in the direction of fluid flow (radial) is much greater than that in the direction of loading (axial). The model is found to describe experimental data well for a range of radius to height ratios (∼1–4) and instantaneous strain rates of the foam (1 s−1 to 4×102 s−1). The applicability of this model is discussed and the range of instantaneous strain rates of the foam over which it is valid is presented. Furthermore, the utility of this model is discussed with respect to the design and development of energy absorption and blast wave protection equipment.

scholarly journals Interface-resolved simulations of particle suspensions in Newtonian, shear thinning and shear thickening carrier fluids

2018 ◽  
Vol 852 ◽  
pp. 329-357 ◽  
Author(s):  
Dhiya Alghalibi ◽  
Iman Lashgari ◽  
Luca Brandt ◽  
Sarah Hormozi
Keyword(s):  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Shear Thickening ◽  
Fluid Phase ◽  
Local Strain ◽  
Reynolds Numbers ◽  
Mean Value ◽  
Strain Rates ◽  
Local Shear ◽  
The Mean

We present a numerical study of non-colloidal spherical and rigid particles suspended in Newtonian, shear thinning and shear thickening fluids employing an immersed boundary method. We consider a linear Couette configuration to explore a wide range of solid volume fractions ($0.1\leqslant \unicode[STIX]{x1D6F7}\leqslant 0.4$) and particle Reynolds numbers ($0.1\leqslant Re_{p}\leqslant 10$). We report the distribution of solid and fluid phase velocity and solid volume fraction and show that close to the boundaries inertial effects result in a significant slip velocity between the solid and fluid phase. The local solid volume fraction profiles indicate particle layering close to the walls, which increases with the nominal $\unicode[STIX]{x1D6F7}$. This feature is associated with the confinement effects. We calculate the probability density function of local strain rates and compare the latter’s mean value with the values estimated from the homogenisation theory of Chateau et al. (J. Rheol., vol. 52, 2008, pp. 489–506), indicating a reasonable agreement in the Stokesian regime. Both the mean value and standard deviation of the local strain rates increase primarily with the solid volume fraction and secondarily with the $Re_{p}$. The wide spectrum of the local shear rate and its dependency on $\unicode[STIX]{x1D6F7}$ and $Re_{p}$ point to the deficiencies of the mean value of the local shear rates in estimating the rheology of these non-colloidal complex suspensions. Finally, we show that in the presence of inertia, the effective viscosity of these non-colloidal suspensions deviates from that of Stokesian suspensions. We discuss how inertia affects the microstructure and provide a scaling argument to give a closure for the suspension shear stress for both Newtonian and power-law suspending fluids. The stress closure is valid for moderate particle Reynolds numbers, $O(Re_{p})\sim 10$.

The Dynamic Compressive Response of Open-Cell Foam Impregnated With a Newtonian Fluid

2008 ◽  
Vol 75 (4) ◽  
Author(s):  
M. A. Dawson ◽  
G. H. McKinley ◽  
L. J. Gibson
Keyword(s):  
Newtonian Fluid ◽  
Darcy’S Law ◽  
Dynamic Compression ◽  
Boundary Value ◽  
Darcy's Law ◽  
Elastic Buckling ◽  
Additional Contribution ◽  
Low Density ◽  
Strain Rates ◽  
Open Cell

This analysis considers the flow of a highly viscous Newtonian fluid in a reticulated, elastomeric foam undergoing dynamic compression. A comprehensive model for the additional contribution of viscous Newtonian flow to the dynamic response of a reticulated, fluid-filled, elastomeric foam under dynamic loading is developed. For highly viscous Newtonian fluids, the flow in the reticulated foam is assumed to be dominated by viscous forces for nearly all achievable strain rates; Darcy’s law is assumed to govern the flow. The model is applicable for strains up to the densified strain for all grades of low-density, open-cell, elastomeric foam. Low-density, reticulated foam is known to deform linear elastically and uniformly up to the elastic buckling strain. For strains greater than the elastic buckling strain but less than the densified strain, the foam exhibits bimodal behavior with both linear-elastic and densified regimes. The model presented in this analysis is applicable for all strains up to the densified strain. In the bimodal regime, the model is developed by formulating a boundary value problem for the appropriate Laplace problem that is obtained directly from Darcy’s law. The resulting analytical model is more tractable than previous models. The model is compared with experimental results for the stress-strain response of low-density polyurethane foam filled with glycerol under dynamic compression. The model describes the data for foam grades varying from 70ppito90ppi and strain rates varying from 2.5×10−3to101s−1 well. The full model can also be well approximated by a simpler model, based on the lubrication approximation, which is applicable to analyses where the dimension of the foam in the direction of fluid flow (radial) is much greater than the dimension of the foam in the direction of loading (axial). The boundary value model is found to rapidly converge to the lubrication model in the limit of increasing aspect ratio given by the ratio of the radius R, to the height h, of the foam specimen with negligible error for aspect ratios greater than R∕h∼4.

Dynamic compressive response of 3D GFRP composites with shear thickening fluid (STF) matrix as cushioning materials

2021 ◽  
pp. 002199832098424
Author(s):  
Mohsen Jeddi ◽  
Mojtaba Yazdani
Keyword(s):  
Shear Thickening ◽  
Low Velocity Impact ◽  
Gfrp Composites ◽  
High Concentration ◽  
Low Velocity ◽  
Shear Thickening Fluid ◽  
Compressive Response ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Shear Thickening Fluids

Whereas most previous studies have focused on improving the penetration resistance of Shear Thickening Fluids (STFs) treated composites, in this study, the dynamic compressive response of single and multi-ply 3 D E-Glass Fiber Reinforced Polymer (GFRP) composites with the STF matrix was investigated by using a drop-weight low-velocity impact test. The experimental results revealed the STF improved the compressive and cushioning performance of the composites such that with increasing its concentration, further improvement was observed. The five-ply composite containing the STF of 30 wt% silica nanoparticles and 1 wt% carbon nanotubes (CNTs) reduced the applied peak force by 56% and 26% compared to a steel plate and five-ply neat samples, respectively. A series of repeated impacts was performed, and it was found that the performance of high-concentration composites is further decreased under this type of loading.

Heat Transfer and Entropy Generation Characteristics of a Non-Newtonian Fluid Squeezed and Extruded Between Two Parallel Plates

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
P Kaushik ◽  
Pranab Kumar Mondal ◽  
Sukumar Pati ◽  
Suman Chakraborty
Keyword(s):  
Heat Transfer ◽  
Newtonian Fluid ◽  
Entropy Generation ◽  
Bejan Number ◽  
Engineering Systems ◽  
Power Law Model ◽  
Parallel Plates ◽  
Unsteady Heat Transfer ◽  
Thermodynamic Performance ◽  
Fluid Rheology

This study investigates the unsteady heat transfer and entropy generation characteristics of a non-Newtonian fluid, squeezed and extruded between two parallel plates. In an effort to capture the underlying thermo-hydrodynamics, the power-law model is used here to describe the constitutive behavior of the non-Newtonian fluid. The results obtained from the present analysis reveal the intricate interplay between the fluid rheology and the squeezing dynamics, toward altering the Nusselt number and Bejan number characteristics. Findings from this study may be utilized to design optimal process parameters for enhanced thermodynamic performance of engineering systems handling complex fluids undergoing simultaneous extrusion and squeezing.

Experimental study of the out-of-plane dynamic behaviour of adhesively bonded composite joints using split Hopkinson pressure bars

2018 ◽  
Vol 52 (21) ◽  
pp. 2875-2885 ◽  
Author(s):  
S Sassi ◽  
M Tarfaoui ◽  
H Benyahia
Keyword(s):  
Strain Rate ◽  
Dynamic Behaviour ◽  
Dynamic Compression ◽  
Strain Rates ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Adhesively Bonded Joints ◽  
Out Of Plane ◽  
Bonded Composite ◽  
Strong Material

The effect of the strain rate on the mechanical behavior and the damage of adhesively bonded joints is one of the most important factors to consider in designing them. Vast research has been carried out on the dynamic behaviour of adhesives at different strain rates; however, the investigation about the dynamic behaviour of the adhesively bonded joints is limited. In this paper, the main objective is to study and assess the effect of the strain rate on the out-of-plane mechanical behaviour of adhesively bonded joints under dynamic compression using Hopkinson bars. These joints are studied using glass/vinylester composite materials which are commonly used in naval applications. The experimantal results have shown a strong material sensitivity to strain rates. Moreover, damage investigations have revealed that the failure mainly occurred in the adhesive/adherent interface because of the brittle nature of the polymeric adhesive. Results have shown good agreement with the dependency of the dynamic parameters on strain rates.

Comparative studies of the constitutive models for tungsten heavy alloy (95W-3.5Ni-1.5Fe) at high strain rates

2021 ◽  
pp. 095440622110451
Author(s):  
Xiuwen Lai ◽  
Zhanjiang Wang ◽  
Na Qin
Keyword(s):  
Threshold Stress ◽  
Dynamic Compression ◽  
Constitutive Models ◽  
Heavy Alloy ◽  
Tungsten Heavy Alloy ◽  
Strain Rates ◽  
Stress Model ◽  
Static Compression ◽  
Mechanical Threshold ◽  
Wide Range

The plastic behaviors’ description of a tungsten heavy alloy (95W-3.5Ni-1.5Fe) at temperatures of 298–773 K and strain rates of 0.001–11,000 s−1 is systematically studied based on four constitutive models, that is, Zerilli-Armstrong model, modified Zerilli-Armstrong model, Mechanical Threshold Stress model, and modified Mechanical Threshold Stress model. The quasi-static compression experiments using an electronic universal testing machine and the dynamic compression experiments using a split Hopkinson pressure bar apparatus are employed to obtain the true stress–strain curves at a total of three temperatures (298 K, 573 K, and 773 K) and a wide range of strain rates (0.001–11,000 s−1). The parameters of the four constitutive models are obtained by the above fundamental experimental data and Grey Wolf Optimizer. The correlation coefficient and average absolute relative error are used to evaluate the predicted performance of these models. Modified Mechanical Threshold Stress model is found to have the highest predicted performance in describing the flow stress of the 95W-3.5Ni-1.5Fe alloy. Eventually, two compression experiments whose loading conditions are not in the fundamental experiments are conducted to validate the four models.

Microstructural and Dynamic Mechanical Characterization of Biodegradable Magnesium-Calcium Alloy for Orthopedic Implants

2014 ◽  
Author(s):  
V. S. Brooks ◽  
Y. B. Guo
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Compression ◽  
Orthopedic Implants ◽  
Strain Rates ◽  
High Strain Rates ◽  
Static Compression ◽  
Metallic Biomaterial

Magnesium-Calcium (Mg-Ca) alloy is an emerging metallic biomaterial for manufacturing biodegradable orthopedic implants. However, very few studies have been conducted on mechanical properties of the bi-phase Mg-Ca alloy, especially at the high strain rates often encountered in manufacturing processes. The mechanical properties are critical to design and manufacturing of Mg-Ca implants. The objective of this study is to study the microstructural and mechanical properties of Mg-Ca0.8 (wt %) alloy. Both elastic and plastic behaviors of the Mg-Ca0.8 alloy were characterized at different strains and strain rates in quasi-static tension and compression testing as well as dynamic split-Hopkinson pressure bar (SHPB) testing. It has been shown that Young’s modulus of Mg-Ca0.8 alloy in quasi-static compression is much higher than those at high strain rates. Yield strength and ultimate strength of the material are very sensitive to strain rates and increase with strain rate in compression. Strain softening also occurs at large strains in dynamic compression. Furthermore, quasi-static mechanical behavior of the material in tension is very different from that in compression. The stress-strain data was repeatable with reasonable accuracy in both deformation modes. In addition, a set of material constants for the internal state variable plasticity model has been obtained to model the dynamical mechanical behavior of the novel metallic biomaterial.

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