Article
Mechanics
Hamid Taghipour, Laurence G. D. Hawke
Summary: The study evaluates the performance of the Rolie-Poly (RP) model in uniaxial elongation and shear, comparing predictions of four RP versions against literature data for monodisperse, entangled polystyrene (PS) chains. The study found that variations in the reptation term do not affect predictions at relaxation after shear and uniaxial elongation, but the FENE treatment has a considerable influence on the model outcomes. Additionally, systematic disagreements are evident when the Rouse Weissenberg (Wi(R)) number exceeds ten. Possible improvements to the model, such as incorporating mechanisms like entanglement loss and chain tumbling, are discussed.
Article
Multidisciplinary Sciences
B. Pialot, J. Gachelin, J. Provost, O. Couture
Summary: New processing techniques for manipulating blood at a microfluidic scale are being implemented, with a focus on in-line evaluation and monitoring of blood properties during extracorporeal circulation being a challenging task. This study demonstrates a non-invasive method for measuring blood hematocrit in a sub-millimeter medical tube using the non-Newtonian behavior of blood velocity profile, with promising results on human blood. The simplicity and effectiveness of this approach suggest its potential impact on in-vitro blood processing.
SCIENTIFIC REPORTS
(2021)
Article
Polymer Science
Seung Heum Jeong, Soowon Cho, Chunggi Baig
Summary: This study presents a detailed analysis of the scaling behavior of chain rotation dynamics in shear flow for melt and dilute linear polymer systems. The results show that dilute systems with hydrodynamic interaction (HI) and excluded volume (EV) effects exhibit two distinct scaling behaviors of chain rotation time between the intermediate and strong flow regimes. In contrast, free-draining dilute polymer systems display a simpler single-scaling behavior throughout the intermediate-to-strong flow regimes. The combined HI and EV effects weaken the structural change of polymer chains and enhance chain rotation dynamics by disturbing chain stretch and alignment to the flow direction. The presence of intermolecular interactions between chains in melt systems leads to two distinct scaling behaviors of chain rotation time as well. The overall scaling behavior of chain rotation is determined by the kinematically stable angular regions near the flow direction, while the kinematically unstable angular regions exhibit affine chain rotation dynamics. This study provides important insights into the understanding of chain rotation dynamics in shear flow.
Article
Engineering, Chemical
Ying Zhang, Xuesong Zhang, Minghao Yang, Yongchao Li, Qi Yang, Jiawei Gong, Xueqin Gao
Summary: This study analyzed the extrusion process of two rubber blends and found wall slip phenomena. The physical parameters and wall slip parameters of the constitutive models were obtained. The results showed that the PTT model was superior to the Bird-Carreau model in predicting the rheological behavior of the extrusion process.
POLYMER ENGINEERING AND SCIENCE
(2023)
Article
Polymer Science
Wangqing Wu, Ke Zeng, Baishun Zhao, Fengnan Duan, Fengze Jiang
Summary: In this study, theoretical modeling and experimental studies were conducted to investigate the factors that influence the accuracy of apparent shear viscosity determination with micro capillary dies. The results indicate that the initial polymer amount in the barrel, pre-compaction pressure, and capillary die diameter significantly affect the micro scale inlet pressure development, which impacts the measurement accuracy at low and medium shear rates. The main factor related to the inaccuracy in the micro scale apparent shear viscosity determination was identified as the varying melt compressibility. Measures such as reducing the initial polymer amount in the barrel and increasing the pre-compaction pressure were suggested to improve measurement accuracy.
Article
Mechanics
Andre Pincot, F. John Burpo, Elahe Javadi, Safa Jamali, Sean Farrington, Matthew J. Armstrong
Summary: A distinctive stress hysteresis phenomenon is observed in human blood rheology, which is related to the longer characteristic time of shear-induced rouleaux breakdown. The hysteresis data is used to fit parameters of the t-ESSTV model, which can predict various blood flow characteristics under different conditions. The correlation between fitting parameters and physiological data helps interpret the model behavior in physical terms.
Article
Engineering, Multidisciplinary
Ayelet Goldstein, Ofer Eyal
Summary: The study proposes a simple method for examining the local behavior of velocity and shear stresses near a triple point in two-phase flow. By focusing on the vicinity of the TP and simplifying calculations, the method can be extended to other areas for application.
APPLIED MATHEMATICAL MODELLING
(2021)
Article
Chemistry, Multidisciplinary
Charinee Winotapun, Thidarat Makmoon, Chuanchom Aumnate, Dumrong Thanomjitr, Wuttipong Rungseesantivanon, Hiroshi Ito
Summary: Micropatterns were fabricated on polypropylene surfaces using hot embossing technique. The replication quality was evaluated based on the effective filling ratio. The results showed that the filling ratio increased with increasing embossing temperature and applied force. The effect of different melt flow indexes of polypropylene on the filling ratio was also investigated. Micropatterned polypropylene sheets demonstrated easy-opening properties for packaging applications.
Article
Mechanics
Ali Rezghi, Ping Li, Junfeng Zhang
Summary: This article simulates the lateral migration process of a viscoelastic capsule in tube flow and investigates the effects of viscosity ratio, membrane shear viscosity, and capillary number on the migration dynamics. The migration process is characterized by an initial transient phase and a subsequent reduction in deformation and migration velocity. The capsule also undergoes continuous rotation during migration, which gradually slows down. The interior-exterior fluid viscosity and membrane viscosity have similar effects on reducing capsule deformation and inclination angle, while a high membrane viscosity may introduce significant oscillations in deformation, inclination, and migration velocity. The migration velocity and rotation period are found to be slower for capsules with higher viscosity contrast and/or membrane viscosity, and the influence of membrane viscosity becomes more pronounced at higher capillary numbers.
Article
Polymer Science
Wei Wang, Linlin Wang
Summary: The study evaluates the viscoelastic flow of low-density polyethylene melts using the S-MDCPP model combined with different approaches, demonstrating that the model accurately captures the rheological behaviors of branched polymers in complex flow.
Article
Polymer Science
E. Farotti, E. Mancini, A. Lattanzi, M. Utzeri, M. Sasso
Summary: The mechanical behavior of polymers is greatly influenced by temperature and strain rate conditions. This study proposes a constitutive law for characterizing polymers that exhibit shear banding during compression loading, and the validity of this method is confirmed through numerical calculations and experimental observations.
Article
Polymer Science
Mir Hamid Reza Ghoreishy, Foroud Abbassi Sourki
Summary: This study simulated the pressure flows of a thermoplastic elastomer vulcanizate (TPV) melt in the die region of a single-screw extruder using the finite-element method. COMSOL software was used to develop the finite-element model and solve the working equations. The rheological behavior of the polymer melt was described using the ACross-WLF rheological equation of state. A new augmented Navier's slip equation was developed to consider the effect of wall slip on solution variables. The results showed that using no-slip condition or a constant slip coefficient in the Navier's slip equation leads to significant errors in predicting mass flow rates and pressure.
IRANIAN POLYMER JOURNAL
(2023)
Article
Materials Science, Multidisciplinary
Zhecheng Zhou, Qi Wang, Ruirun Chen, Xu Wang, DeZhi Chen, Hengzhi Fu
Summary: The variations in flow stress at elevated temperature for Nb-20Ti-16Si-0.5Gd alloy were studied through thermal simulation experiment. The results showed that the flow stress decreased with increasing deformation temperature, but increased with increasing strain rate. The constitutive equation of the alloy was derived using the Arrhenius hyperbolic sine function, accurately fitting the relationship between strain rate, stress, and temperature.
INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
(2023)
Article
Mechanics
H. Koochi, Jonatan Mac Intyre, M. Korhonen, A. Puisto, N. Maleki-Jirsaraei, M. J. Alava
Summary: The impact of thixotropy on the settling behavior of a solid sphere is studied using a finite element-computational fluid dynamics simulation. The flow behavior is evaluated by coupling the Navier-Stokes equations with the dynamic evolution of an initially heterogeneous fluid's microstructure. The study identifies different settling regimes based on the degree of structuring, associated heterogeneity, local morphology of the microstructure, and stress induced by the sphere. The results show that the competition between orthokinetic and perikinetic build-up and shear-induced break-down of the microstructure plays a vital role in understanding the connection between flow curve and settling behavior of the fluids.
Article
Chemistry, Physical
Nicolas Cuny, Eric Bertin, Romain Mari
Summary: Our study focuses on the rheology of jammed suspensions of soft elastic particles, predicted by a constitutive model derived from particle-level dynamics. The orientation of microstructural anisotropy, influenced by advection and contact elasticity, plays a crucial role in yielding and flow processes. This model generates normal stress differences and explains various transient behaviors observed in shear rate increases, flow cessation, and creep. Additionally, it elucidates the collapse of storage modulus in yielded suspensions measured through parallel superposition.
Article
Mechanics
Richard S. Graham
JOURNAL OF RHEOLOGY
(2019)
Article
Chemistry, Physical
Muhammad Anwar, Richard S. Graham
JOURNAL OF CHEMICAL PHYSICS
(2019)
Article
Engineering, Chemical
Voon-Loong Wong, Katerina Loizou, Phei-Li Lau, Richard S. Graham, Buddhika N. Hewakandamby
CHEMICAL ENGINEERING RESEARCH & DESIGN
(2019)
Article
Polymer Science
Muhammad Anwar, Richard S. Graham
JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS
(2019)
Article
Chemistry, Physical
Ying Zhou, Kenny Jolley, Rhiannon Phillips, Roger Smith, Houzheng Wu
Article
Materials Science, Multidisciplinary
James G. McHugh, Kenny Jolley, Pavlos Mouratidis
JOURNAL OF NUCLEAR MATERIALS
(2020)
Article
Physics, Multidisciplinary
Daniel J. Read, Claire McIlroy, Chinmay Das, Oliver G. Harlen, Richard S. Graham
PHYSICAL REVIEW LETTERS
(2020)
Article
Engineering, Manufacturing
Andrea Costanzo, Roberto Spotorno, Maria Virginia Candal, Maria Mercedes Fernandez, Alejandro J. Muller, Richard S. Graham, Dario Cavallo, Claire McIlroy
ADDITIVE MANUFACTURING
(2020)
Article
Chemistry, Physical
Jack Broad, Simon Preston, Richard J. Wheatley, Richard S. Graham
Summary: This paper outlines a strategy to reduce the number of training points required to model intermolecular potentials using Gaussian processes, without compromising accuracy. By using an asymptotic function and learning the crossover distance from training data, the technique successfully reduces the number of training points by up to 49% compared to previous sequential learning methods. The approach can be easily applied to other statistical prediction or modeling problems.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
James G. McHugh, Pavlos Mouratidis, Anthony Impellizzeri, Kenny Jolley, Dogan Erbahar, Chris P. Ewels
Summary: Dislocations are crucial for understanding plastic deformation and damage evolution in materials. In this study, the prismatic dislocations in graphite were investigated using density functional theory calculations. The energetics, structure, and mobility of different prismatic core structures were evaluated. The role of interlayer stacking in dislocation glide and climb was also considered. The results suggest that the prismatic dislocation core is stable at high temperatures and its breaking can facilitate damage recovery.
Article
Chemistry, Physical
James G. McHugh, Pavlos Mouratidis, Kenny Jolley
Summary: This study investigated the behavior of ruthenium nanoclusters on graphene using first-principles calculations. The results demonstrated that intercalated atoms can shear the lattice and form an AA stacking configuration at high density of single Ru atom interstitials, with this effect weakening with increasing cluster size. The interlayer stacking configuration also significantly influenced cluster diffusion.
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Multidisciplinary
Richard S. Graham, Richard J. Wheatley
Summary: Accurate potential energy surfaces (PES) are required for predicting thermophysical properties from molecular principles. This study presents a widely-applicable method that produces first-principles PES using Gaussian Processes (GP) as a machine learning technique. The method accurately interpolates three-body non-additive interaction data and does not require modification for different molecules. It produces highly accurate interpolation from fewer training points and enables more accurate ab initio calculations. The method is exemplified by computing the PES for CO2-Ar mixtures, which allows for accurate first-principles predictions of various thermophysical properties.
CHEMICAL COMMUNICATIONS
(2022)
Article
Materials Science, Multidisciplinary
James G. McHugh, Pavlos Mouratidis, Kenny Jolley
Summary: In this study, basal dislocations and ripplocations in layered materials were investigated using analytical and computational techniques. It was found that the energetic and structural scaling factors of surface ripplocations are closely related to the physics of a classical carpet ruck. Simulations showed that the lowest-energy structure of dislocation pileups in layered materials is the ripplocation, while large dislocation pileups in bulk graphite exhibited multilayer delamination, curvature, and voids, providing a concise explanation for the large volumetric expansion seen in irradiated graphite.
Article
Chemistry, Physical
Muhammad Anwar, Richard S. Graham
Summary: Modelling of flow-induced nucleation in polymers suggests that long chains are enriched in nuclei, affecting the nucleation rate and mechanism, which is crucial for predicting the rate accurately. Through molecular dynamics simulations, it was found that long chains are significantly enriched in nuclei, supporting quantitative predictions from the recent polySTRAND model.
Article
Crystallography
Thomas J. Wicks, Jonathan A. D. Wattis, Richard S. Graham
Summary: The authors conducted Monte Carlo simulations to study the crystallization transition of single-chain square-well homopolymers, employing parallel tempering, a nonstandard choice of tempering levels, a bespoke biasing strategy, and a method for temperature mapping. The simulations showed good mixing for chains of 128 and 256 beads, resolving issues with reproducibility in prior work. Highly reproducible results with low statistical noise were obtained for free energy landscape and inverse temperature, and a method to extract free energy barrier at any temperature was outlined.
POLYMER CRYSTALLIZATION
(2021)
Article
Mechanics
Chen Liu, Jianzhong Lin, Zhenyu Ouyang
Summary: This study simulated the locomotion state and motion type of elliptical squirmers in a channel flow of power-law fluids. The influence of different parameters on the squirmers was explored, and it was found that coupled structures are prone to break and viscosity significantly affects the flow velocity and motion type of squirmers.
Article
Mechanics
E. E. Herrera-Valencia, M. L. Sanchez-Villavicencio, C. Soriano-Correa, O. Bautista, L. A. Ramirez-Torres, V. J. Hernandez-Abad, F. Calderas
Summary: This study investigated the electroosmotic flow of a viscoelastic fluid in a capillary system. The rheology of the fluid was characterized by a novel generalized exponential model equation, and the effect of charge density on the double-layer field and electrical forces was analyzed. Mathematical models were used to describe the rheological properties and flow performance of the fluid, and experimental data were used to make predictions. The study also examined the influence of applied forces on the structure of the fluid.
Article
Mechanics
Stefano Amadori, Giuseppe Catania
Summary: This article presents a multi-step, iterative technique for locally non-parametric identification of the standard linear solid (SLS) material model using fractional order time differential operators. Test input data consists of a set of identified material complex modulus values estimated at different frequency values obtained from input-output experimental measurements and quasi-static relaxation measurements on the same specimen. The proposed technique is based on an algebraic procedure to solve an overdetermined system of linear equations in order to obtain optimal values for the unknown parameters of the model. The procedure is non-parametric, as the order of the SLS model is initially unknown.
