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Acoustically-triggered droplet vaporization (ADV) and tissue deformation are numerically analyzed by extending a numerical model for ADV process based on a level-set method, which considers multiple interfaces between bubble, droplet and ambient water regions, bubble compressibility and droplet-bubble phase change, to include nearby tissue deformation using a full Eulerian formulation. The tissue is assumed to be a viscoelastic neo-Hookean material to properly handle large deformation. The numerical results show that droplet vaporization causes greater tissue deformation than isothermal bubble growth under the same acoustic and initial size conditions. The computations of ADV near a deformable solid demonstrate various bubble-tissue interactions such as mushroom-shaped bubble formation near an elastic tissue, tissue compression due to high-speed liquid jet, and large tissue deformation and perforation caused by the non-spherical bubble re-expansion and bubble entrapment. The effects of droplet-tissue distance and elastic shear modulus on the tissue deformation and perforation are investigated. [ABSTRACT FROM AUTHOR]

This paper presents a novel and comprehensive numerical approach for nonlinear analysis and smart damping control in laminated functionally graded carbon nanotube reinforced magneto-electro-elastic (FG-CNTMEE) plate structures, taking into account multiple physical fields. The approach employs a multi-physical coupling isogeometric formulation based on Non-Uniform Rational Basis Spline (NURBS) to analyze the behavior of laminated FG-CNTMEE plate structures. It incorporates a refined zig-zag theory to accurately capture the Von Kármán nonlinear strain–displacement relationship, as well as the magneto-electro-elastic coupling properties of laminate layers. To achieve nonlinear damped responses, the smart constrained layer damping (SCLD) treatment is applied. Furthermore, to enable smart control of structures using the time-dependent passive/semi-active damping mechanism of viscoelastic materials, the formulation is transformed into the Laplace domain using the Golla–Hughes–McTavish model. The results are then converted back to the time domain through inverse techniques. The proposed approach has been rigorously validated through verification work and demonstrated its effectiveness in simulating and controlling FG-CNTMEE plates in two numerical examples. • A novel numerical method for analysis and smart damping control of FG-CNTMEE plates is proposed. • Incorporate multiphysical coupling IGA formulation with NURBS and refined zig-zag theory. • Utilize smart constrained layer damping for achieving nonlinear damped responses. • Enable time-dependent control using Laplace transformation & inverse conversion to time domain. • Validate and demonstrate effectiveness in analyzing & controlling laminated FG-CNTMEE plates. [ABSTRACT FROM AUTHOR]

• The SPH method is developed for simulating Phan-Thien-Tanner viscoelastic fluid flows. • The mixed symmetric correction algorithm of kernel gradient is implemented. • The artificial stress model is added into the momentum equation. • Both plane Poiseuille flow and the impacting droplet are numerically simulated by SPH. • Influences of PTT rheological parameters on the droplet dynamics are deeply investigated. Numerical simulations of viscoelastic fluid flows are always a hot issue in the field of computational fluid dynamics and the study of their complex rheological properties has important academic and engineering application value. In the present work, we develop a smoothed particle hydrodynamics (SPH) method for simulating transient viscoelastic fluid flows governed by the Phan-Thien-Tanner (PTT) constitutive equation. To improve the computational accuracy of the SPH method, the mixed symmetric correction algorithm of kernel gradient is implemented. To remove the particle clustering and unphysical fracture in fluid stretching which is named as the tensile instability, the artificial stress model is added into the momentum equation. We firstly apply the proposed SPH method to solve the plane Poiseuille flow of a PTT viscoelastic fluid, in which the effectiveness and advantage of the method are verified by comparing the SPH solution with those obtained by the finite volume method (FVM) and analyzing the l2 norm error of different SPH solutions to the FVM solution. Then, the method is employed to simulate the impact behavior of a PTT viscoelastic droplet with a rigid plate. In particular, we not only investigate the spreading behavior of PTT viscoelastic droplet after impacting the rigid plate, but also for the first time capture and analyze the bouncing behavior of droplet by decreasing the Reynolds number. The influences of the Reynolds number, the Weissenberg number, the solvent viscosity ratio, and the PTT elongational parameter on the droplet dynamics behavior are further deeply studied. Numerical results demonstrate that the SPH method proposed in this paper is a powerful computation tool for simulating PTT viscoelastic fluid flows and is capable of effectively describing their complex rheological properties and free surface variation characteristics. [ABSTRACT FROM AUTHOR]

The magnetohydrodynamic (MHD) flow has been concerned widely for its widespread adoption in the field of astrophysics, electronics and many other industries over the years. The purpose of this article is to introduce the variable and distributed order space fractional models to characterize the MHD flow and heat transfer of heterogeneous viscoelastic fluids in a parallel plates. Based on the central difference approximation of Riesz space fractional derivative, the Crank–Nicolson difference scheme for the governing equations is established, and the effectiveness of the algorithm is verified by two numerical examples. We examine the effects of fractional-order model parameters on the velocity and temperature, our investigation indicates that for the constant fractional model, the larger the fractional order parameter, the smaller the velocity and temperature. The variable space fractional method can be used to describe dynamic behavior with time and space dependence, while the distributed space fractional model can describe various phenomena in which the number of differential orders varies over a certain range, characterizing their complex processes over space, and it is also more suitable for simulating the fluid flow and thermal behavior of complex viscoelastic magnetic fluid. [ABSTRACT FROM AUTHOR]

In this paper we present an extension of a multiscale smoothed particle hydrodynamics (SPH) method to transient viscoelastic injection molding processes. Specifically, we use the method presented by Xu and Yu, J. Non-Newtonian Fluid Mech. 229 (2016) pp. 27–42, in which the bead-spring chain model is employed to describe the viscoelastic behavior of the fluid without resort to a closed-form constitutive equation. Moreover, to resolve the heavy computation and the time-consuming problem, an efficient parallel algorithm, including parallelizations of both SPH particles and Brownian configuration fields, is developed. To validate the algorithm, we first simulate the viscoelastic Couette flow based on Hookean dumbbell, FENE dumbbell, and FENE chain models. The SPH results are compared with the analytical solutions or those obtained by other methods. The parallel performances of the algorithm are analyzed. Then, we extend the method to the challenging injection molding problem. A number of numerical examples including the injection molding of an F-shaped cavity in two dimensions and a door handle in two and three dimensions are investigated. Some molecular information such as the molecular stretch, the orientation angle, and the mean configuration thickness are displayed. It is found that the injection molding processes could be successfully investigated by SPH from a micro perspective. The proposed parallel algorithm is essential for the efficient simulation of injection molding processes. The maximum speedup can reach more than 130 for the case of the door handle in three dimensions. [ABSTRACT FROM AUTHOR]

This paper presents an efficient stabilized meshless technique with a hybrid kernel to simulate the fractional Rayleigh–Stokes problem for an edge in a viscoelastic fluid. The proposed method approximates the unknown solution through two phases. Firstly, the temporal discretization of the govern model is performed by integrating both sides of it, and then the space discretization is obtained by making use of the local hybrid Gaussian-cubic kernel meshless. The localized approach considers merely neighboring collocation nodes, while avoiding the ill-conditioning occurring in other techniques with dense and large matrix systems. The semi-discretized approach in terms of the convergence and stability properties is discussed theoretically in the weighted H 1 -norm and confirmed numerically. Two illustrative examples are given to show the efficiency and applicability of the proposed strategy. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to investigate the effects of the shear-thinning viscoelastic behavior of the surrounding matrix on droplet deformation by weakly compressible smoothed particle hydrodynamics (WC-SPH). Also, the effect of the presence of another droplet is examined. Design/methodology/approach: A modified consistent weakly compressible SPH method is proposed. After code verification, a complete parameter study is performed for a drop under the simple shear flow of a Giesekus liquid. The investigated parameters are 0.048≤Ca ≤ 14.4, 0.1≤c ≤ 10, 0.04≤De ≤ 10, 0≤α ≤ 1 and 0.12≤Re ≤ 12. Findings: It is demonstrated that the rheological behavior of the surrounding fluid could dramatically affect the droplet deformation. It is shown that the droplet deformation is increased by increasing Re and Ca. In contrast, the droplet deformation is decreased by increasing a, De and polymer content. Also, it is indicated the presence of another droplet could drastically affect the flow field, and the primary stress difference (N1) is resonated between two droplets. Originality/value: The main originality of this paper is to introduce a new consistent WC-SPH algorithm. The proposed method is very versatile for tackling the shear-thinning viscoelastic multiphase problems. Furthermore, a complete parameter study is performed for a drop under the simple shear flow of Giesekus liquid. Another novelty of the current paper is studying the effect of the presence of a second droplet. To the best of the authors' knowledge, this is performed for the first time. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to develop a comprehensive size-dependent piezoelectric thermo-viscoelastic coupling model that accounts for two fundamentally distinct size-dependent models that govern fractional dual-phase lag heat transfer and viscoelastic deformation, respectively. Design/methodology/approach: The fractional calculus has recently been shown to capture precisely the experimental effects of viscoelastic materials. The governing equations are combined into a unified system, from which certain theorems results on linear coupled and generalized theories of thermo-viscoelasticity may be easily established. Laplace transforms and state–space approach will be used to determine the generic solution when any set of boundary conditions exists. The derived formulation is used to two concrete different problems for a piezoelectric rod. The numerical technique for inverting the transfer functions is used to generate observable numerical results. Findings: Some analogies of impacts of nonlocal thermal conduction, nonlocal elasticity and DPL parameters as well as fractional order on thermal spreads and thermo-viscoelastic response are illustrated in the figures. Originality/value: The results in all figures indicate that the nonlocal thermal and viscoelastic parameters have a considerable influence on all field values. This discovery might help with the design and analysis of thermal-mechanical aspects of nanoscale devices. [ABSTRACT FROM AUTHOR]

The paper presents an efficient numerical approach to deal with the hybrid damping vibration control of laminated functionally graded carbon-nanotube reinforced composite plates (FG-CNTRC) structures. In order to evaluate the damped response, a smoothed finite element model has been derived to simulate the laminated FG-CNTRC plate integrated with active constrained layer damping (ACLD) treatment patches consisting of 1-3 piezoelectric composite (1-3 PZC) layer and a viscoelastic layer. The constrained layer of the ACLD patch is modeled as viscoelastic materials by using the complex modulus. In order to enhance the efficiency of the numerical approach, the proposed framework integrates the zig-zag theory into the cell-based smoothed discrete shear gap method (CS-DSG3) to help increase the accuracy and reduce the computational cost. The accuracy and reliability of the present study are validated by comparing its numerical results to those of other available numerical methods. Moreover, the effect of CNT distribution, nanotube volume fraction, and CNT orientation on the damping behavior of FG-CNTRC plates are investigated. Additionally, the influence of symmetrical and asymmetrical damping treatment configuration for controlling the vibration is also examined in detail. • An efficient numerical approach for the hybrid damping of FG-CNTRC plates is proposed. • Proposed framework helps increase the accuracy and reduce computational cost. • Effects of CNT distribution, volume fraction, and orientation on the damping behavior are examined. • Influence of symmetrical and asymmetrical configuration is examined. [ABSTRACT FROM AUTHOR]

A new report from the Autonomous University of Nuevo Leon in Mexico discusses the use of autologous internal limiting membrane (ILM) flap techniques to increase the success rate of closing large traumatic macular holes (TMHs). The report describes a modified ILM packing technique called "fill in the hole" and presents the anatomical and visual results in two cases. The research also includes a step-by-step video demonstrating the technique. For more information, the full research article can be accessed for free online. [Extracted from the article]

Researchers at the University of Waterloo in Canada have developed a new design for magnetically actuated helical micro-robots that can transport cargo in Newtonian fluids without making contact with the cargo. These micro-robots have the potential to be used in medical procedures and drug delivery, as they can navigate through different types of fluids. The researchers propose a design consisting of three helical sections with alternating handedness, which can transport both straight filaments and those with intrinsic curvature or a spherical payload. This non-contact method of delivering cargo could lead to more effective micro-robots for medical applications. [Extracted from the article]

In this paper, the elastic-like surface Green's functions for an anisotropic viscoelastic half-plane are derived using the time-stepping method. Using the elastic-like surface Green's functions as the core analytical solutions, we develop semi-analytical models (SAMs) and apply them to solve two different contact problems with anisotropic viscoelastic materials. As new modeling approaches, the SAMs developed here can provide fast and efficient approaches to solving contact problems. These methods enable us to consider contact problems with generally anisotropic viscoelastic solids, in which the contact surface is frictional and either smooth or rough, and the applied loads and boundaries can be time-variant. The correctness of the derived surface Green's functions is demonstrated by comparing the numerical results obtained by SAMs and those achieved from the analytical solutions or boundary element methods. Using the obtained numerical results, the impacts of time step size, anisotropy, frictional coefficient, roughness, and applied loads on the contact responses are further analyzed and discussed. [ABSTRACT FROM AUTHOR]

This paper aims to investigate a thermal frictional contact model with damage and long memory effects. We consider a deformable body made of viscoelastic material and assume the process to be dynamic. The material is expected to adhere to the Kelvin–Voigt constitutive law, with damage and thermal effects incorporated. The variational formulation of the model results in a coupled system comprising a history-dependent hemivariational inequality governing the displacement field, a parabolic variational inequality describing the damage field and an evolution equation for the temperature field. In the analysis of this system, we initially introduce a fully discrete scheme, and then concentrate on deriving error estimates of numerical solutions. An optimal order error estimate is attained under some appropriate solution regularity assumptions. At the tail of this manuscript, numerical simulations are provided for the contact problem to validate the theoretical results. • We have studied a complex thermoviscoelastic contact model with damage and long memory. • The variational formulation gives rise to a differential hemivariational inequality. • We focus on optimal error estimates of numerical solutions. • Theoretical analysis and numerical simulation have faced considerable challenges. [ABSTRACT FROM AUTHOR]

A recent study conducted at the University of California San Francisco (UCSF) has found that peroxidase-mediated mucin cross-linking drives the formation of pathologic mucus gel in IL-13-stimulated airway epithelial cells. Mucus plugs that obstruct airflow in asthma are known to occur in the context of type 2 inflammation, and this study shows that IL-13-activated airway epithelial cells can generate pathologic mucus independently of immune cells. The researchers used a magnetic microwire rheometer to characterize the viscoelastic properties of the mucus and found that IL-13-activated cells exhibited solid-like behavior caused by mucin cross-linking. The study also found an increase in peroxidase activity in IL-13-activated cells and an increase in gene expression for thyroid peroxidase (TPO) in patients with asthma. These findings suggest that IL-13-activated airway epithelial cells autonomously generate pathologic mucus through peroxidase-mediated cross-linking of mucin polymers. [Extracted from the article]

We develop an error-in-constitutive-relation (ECR) approach toward the full-field characterization of linear viscoelastic solids described within the framework of standard generalized materials. To this end, we formulate the viscoelastic behavior in terms of the (Helmholtz) free energy potential and a dissipation potential. Assuming the availability of full-field interior kinematic data, the constitutive mismatch between the kinematic quantities (strains and internal thermodynamic variables) and their "stress" counterparts (Cauchy stress tensor and that of thermodynamic tensions), commonly referred to as the ECR functional, is established with the aid of Legendre–Fenchel gap functionals linking the thermodynamic potentials to their energetic conjugates. We then proceed by introducing the modified ECR (MECR) functional as a linear combination between its ECR parent and the kinematic data misfit, computed for a trial set of constitutive parameters. The affiliated stationarity conditions then yield two coupled evolution problems, namely (i) the forward evolution problem for the (trial) displacement field driven by the constitutive mismatch, and (ii) the backward evolution problem for the adjoint field driven by the data mismatch. This allows us to establish compact expressions for the MECR functional and its gradient with respect to the viscoelastic constitutive parameters. For generality, the formulation is established assuming both time-domain (i.e. transient) and frequency-domain data. We illustrate the developments in a two-dimensional setting by pursuing the multi-frequency MECR reconstruction of (i) piecewise-homogeneous standard linear solid, and (b) smoothly-varying Jeffreys viscoelastic material. [ABSTRACT FROM AUTHOR]

This paper investigates a new general nonlinear system, which comprises a fractional differential equation and a history-dependent quasivariational inequality with a variable constraint set, as well as a quasivariational–hemivariational inequality with a variable constraint set. Such a general nonlinear system can be used to describe a nonlinear quasistatic thermoelastic frictional contact problem of viscoelastic materials with long memory, wear and implicit obstacles. By employing the fixed point theorem of the set-valued mapping, the solvability for such a general nonlinear system is proved under some mild conditions. Moreover, our abstract result is applied to obtain the solvability of a new nonlinear quasistatic thermoelastic frictional contact problem with long memory, wear and implicit obstacles. • A new general fractional differential system with variable constraint sets is introduced and studied. • A solvability theorem is given for such a system by using the fixed point theorem for a set-valued map. • A solvability theorem is obtained for a new nonlinear quasistatic thermoelastic frictional contact problem. [ABSTRACT FROM AUTHOR]

In this paper we propose a new vibration isolator system, which combines the advantages of a quasi-zero stiffness (QZS) isolator, a damper exhibiting fractional properties and an inerter, to reduce the vibrations of a multi-span continuous beam bridge excited by moving loads. The inerter produces a fictitious mass amplification effect to improve the controller performance and the fractional order takes into account the previous state of the viscoelastic material. After formulating the dynamics equation using beam theory, the amplitude response is determined analytically using the averaging method. The results obtained from the analytical study are validated using the direct numerical simulation method (Newton–Leipnik method). By comparing the isolation performance of the FQZS (fractional quasi-zero stiffness) isolator and the IFQZS (inerter fractional quasi-zero stiffness) isolator, it is shown that the addition of inertance can significantly suppress the tendency of the curve to slope to the right, allowing us to have a wider isolation frequency range on force transmissibility while improving the efficiency of the isolator. One also shows that increasing the fractional parameter contributes to a decrease in the vibration amplitude of the structure, the amplitude of the force transmitted and the area in which unstable solutions appear. However, beyond a certain value of the fractional parameter, we observe an increase in the latter. In order to further extend the study, bifurcation diagram, phase portrait, time history and power spectral density are explored. • Beam bridge with inerter fractional quasi-zero stiffness (IFQZS) isolator. • Dynamics response when subjected to moving load. • Isolator take into account memory effect and fictitious mass amplification. • Inertance of inerter improves the efficiency of the isolator. • For some parameter of the IFQZS influence consequently the response of the system. [ABSTRACT FROM AUTHOR]

Inventor Maurice Haff has filed a patent application for a "Radially Cross-Aligned Nanofiber Membrane." The application discusses the use of electrospinning to create small diameter fibers and nonwoven webs, which have applications in filtration, textiles, and medical uses. The invention aims to improve the uniformity and cross-alignment of fibers on a collector, which is important for tissue engineering and cell alignment. The application also mentions the potential benefits of the invention in wound dressings for chronic wound care, such as burns and ulcerated skin. The invention provides a cost-effective and efficient process for producing these membranes, eliminating manual steps and allowing for the fabrication of larger-size membranes. The membranes consist of multiple layers of nanofibers that are cross-aligned at oblique angles, creating a structure suitable for wound healing. The nanofibers can be made from various materials and can be loaded with agents such as antimicrobial or regenerative substances. The invention also includes a segmented collector and a controller for controlling the electrospinning process. [Extracted from the article]

A recent report from "Carol Davila" University of Medicine and Pharmacy discusses the use of viscoelastic materials in ophthalmic surgery. These materials have properties of both viscosity and elasticity, making them valuable tools for surgeons. They have been found to protect ocular structures and reduce complications during and after surgery. However, no single agent fulfills all the necessary properties for every surgical technique and situation. This research provides valuable insights into the use of viscoelastic materials in oral rehabilitation. [Extracted from the article]

This paper presents a Convolution Quadrature Time-Domain Boundary Element Method (CQBEM) for antiplane anisotropic viscoelastodynamics. The proposed CQBEM formulation employs the standard linear viscoelastic model and the fundamental solution developed by Wang and Achenbach for expressing viscoelastic and anisotropic properties, respectively. This fundamental solution, which involves integration over the unit circle, is evaluated numerically. After offering a comprehensive overview of the proposed CQBEM formulation, we demonstrate the effectiveness of the proposed method by analyzing the scattering of elastic waves by cavities in certain types of anisotropic viscoelastic materials. Additionally, the use of group velocity curves further validates the numerical results, confirming the anisotropic and viscoelastic effects and thus substantiates the proposed CQBEM for antiplane anisotropic viscoelastic wave propagation. [ABSTRACT FROM AUTHOR]

A patent application by inventor Richard Deslauriers describes a new method for delivering Tumor Treating Fields (TTFields) to solid tumors. TTFields are low-intensity alternating electric fields that disrupt mitosis and are used to treat glioblastoma multiforme (GBM). Currently, TTFields are delivered through transducer arrays that require a layer of conductive medical gel to make contact with the patient's skin. However, this gel has drawbacks such as drying out, varying conductive properties, and skin irritation. Deslauriers' invention proposes using a non-hydrogel skin-interface material as an alternative to the gel, which would eliminate these issues. The patent application provides detailed descriptions of the method and the materials involved. [Extracted from the article]

A patent application has been submitted for a biodegradable patient support device for positioning during a surgical procedure. The device is made of a biodegradable viscoelastic foam material and includes a pad with a flat surface for the patient and an opposing flat surface to hold the device in position on the medical procedure table. The foam material is designed to degrade over time through chemical reactions and/or the action of living organisms. The device can be secured to the table using straps and is suitable for procedures performed with the patient in a Trendelenburg or reverse Trendelenburg position. [Extracted from the article]

Due to large amount of engineering applications, the flow of viscoelastic fluid due to stretched surfaces has turned out to be very famous among the challenging research field of fluid mechanics. Therefore, the main idea of this paper is to classify the instantaneous significances of thermo-physical parameters on the flow of an electrically conducting second grade fluid flow caused by stretched needle. Flow is generated due to a needle which is stretched vertically. The dimensionless transformations are used to change the leading partial differential equations including energy, mass and momentum conservation into ordinary differential form. The newly formed equations along with boundary constraints are solved by employing built in Bvp4c Matlab package. Moreover, the solutions for dimensionless concentration, fluid velocity and energy distributions are analyzed graphically. The thermo-physical embedded parameters controlling the mass, flow and heat transfer characteristics are the magnetic parameter, variable thickness parameter, second grade fluid parameter, small parameter, variable diffusivity parameter and Prandtl number. [ABSTRACT FROM AUTHOR]

The current numerical study investigates the thermal performance of four mono-component (i.e., blade-shaped Al 2 O 3 , brick-shaped Al 2 O 3 , cylinder-shaped Al 2 O 3 or platelet-shaped Al 2 O 3 nanoparticles in 50:50 water–ethylene glycol (EG) base fluid) and four bi-component nanofluids (i.e., blade-shaped Al 2 O 3 + SiO 2 /EG–water, cylinder-shaped Al 2 O 3 + SiO 2 /EG–water, brick-shaped Al 2 O 3 + SiO 2 /EG–water, and platelet-shaped Al 2 O 3 + SiO 2 /EG–water hybrid nanofluids) with the help of mathematical modeling. The non-Newtonian nature of these nanofluids is modeled using second grade viscoelastic fluid model accompanied by the energy equation. The highly non-linear coupled differential equations are solved by shooting method accompanied by 4th order Runge–Kutta method in MATLAB software. The numerical simulations are performed by procuring the data for thermophysical properties from the experimental studies. The effective thermal conductivity and viscosity of the four distinct alumina nanofluids are calculated by the models obtained from the experimental studies. The numerical results reveal that the nanofluid with platelet-shaped Al 2 O 3 nanoparticles is the best heat transporter among the four alumina nanofluids The addition of SiO 2 nanoparticles further accelerates the rate of heat transfer in all four alumina nanofluids. The numerical results that illustrate the influence of nanoparticle volume fraction and thermofluidic parameters on the heat transport phenomenon are also discussed. The MATLAB code developed for the numerical solution is validated against the substantial published literature. • Impact of shape of nanoparticles on Alumina-Silica hybrid nanofluid is studied. • A non-Newtonian fluid flow model is employed for the study. • Thermal conductivity and viscosity models from the experimental studies are used. • A comparative study of the base fluid, nanofluid and hybrid nanofluids is performed. [ABSTRACT FROM AUTHOR]

The article talks about stickiness and the mechanisms that control it. Topics covered include examples of plants that are considered as sticky-makers, such as sundews which produce glistening drops of sticky, sweet mucilage to attract and entrap their prey, two very distinct ways to unstick a solid or a liquid, and the sticking methods used in glues and adhesives.

The present work involves the development of micromechanics based model of the woven fabric reinforced polymer composites and studying their dynamics. A higher-order finite element model of woven fibre composite beam is established after considering the modulus operator for both fibre and matrix. This micromechanical model is further validated with two other methods. In the first method, equivalent composite samples are prepared and tested in dynamic mechanical analyser to obtain the storage modulus and loss factor for a defined range of frequency. The experimental data are used to calculate viscoelastic parameters of the modulus operator and further utilised to bring down the equations of motion. In another method, modal testing of the same composite beam is conducted using an impact hammer connected to the Bruel & Kjaer FFT analyser. Modal parameters obtained from three techniques are compared to show the correctness of the mathematical model. The proposed micromechanics based model may be useful to accurately estimate the material characteristics of the viscoelastic composite without fabricating the samples or conducting explicit experiments. [Display omitted] • Micromechanical models are developed to study the dynamics of woven fibre composite. • Two operator based approaches are used to study damping of viscoelastic composite. • Modal damping parameters are evaluated using the finite element method. • The two theoretical models are validated with impact hammer experiments. [ABSTRACT FROM AUTHOR]

There seems to be a basic misconception in several recent papers concerning the material symmetry of bodies in configurations that are pre-stressed. In this short paper we point to the source of the error and show that the material symmetry that is possible depends on the nature of the pre-stress. We also extend the results for material symmetry which have been well-known within the context of simple elastic solids to the general class of simple materials. This generalization has relevance to the material symmetry of biological solids that are viscoelastic. [ABSTRACT FROM AUTHOR]

The prediction of compressible nonisothermal flows of viscoelastic fluids is important in many industrial processes. Until relatively recently, there was a lack of tractable thermodynamically consistent mathematical models for this class of flows. In this paper a stabilised finite element scheme is presented for the models developed by the authors Mackay and Phillips (2019) which incorporates compressibility and nonisothermal effects. Numerical results are presented for variants of a couple of benchmark problems: the lid driven cavity and the natural convection problems. The temporal discretisation is based on the Taylor–Galerkin method. A compressible version of the discrete elastic viscous split stress (DEVSS) formulation is used to stabilise the numerical scheme. The combined and separate influence of compressible, viscoelastic and thermal effects on the characteristics of these benchmark flows is studied for the first time. • Numerical schemes for compressible, nonisothermal viscoelastic flows are presented. • The influence of stabilisation methods on convergence is explored. • The influence of compressible, viscoelastic and thermal effects is studied. • For lid-driven cavity flow, viscoelasticity increases elastic energy while compressibility decreases it. • Viscoelasticity reduces overall heat transfer in a convection cell. [ABSTRACT FROM AUTHOR]

A patent has been issued to the University of Central Oklahoma for a radially cross-aligned nanofiber membrane. The patent describes an apparatus and method for collecting fiber threads in an electrospinning device to achieve a more uniform and cross-aligned distribution of fibers on a collector. The invention aims to create a fiber membrane with electrospun nanofibers arranged in oblique angles and crossing at distinct points of intersection, allowing for cell migration and exudate flow from a wound. This technology has potential applications in tissue engineering and wound care. [Extracted from the article]

• Development a CC-FV nanotube model incorporating magnetic interactions in both local and nonlocal states. • Applying multiple scale technique and numerical integration methods to solve and verity the nonlinear nonlocal problem. • A detailed study of the effects of magnetic field on the presence of nonlocal damping, viscosity damping of viscoelastic media and nonlinear damping of viscoelastic materials. • The effects of all important parameters are investigated on axial viscoelastic nanotubes in the presence of nonlinear elastic media. This study presents innovative results on a nonlinear dynamic model of a ferromagnetic-viscoelastic nanotube (FVN) whose dissipation effects are captured by material behavior with a linear dissipation law operating in a nonlinear geometric regime. It investigates a possible system derived from a Kelvin–Voigt type dissipation model that describes internal viscoelastic damping in the form of a parallel spring and a dashpot. In addition, a class of losses by linear viscous media in local and nonlocal damping is presented in the modeling. Magnetic load effects are studied using axial rod theory regardless of rotational inertia and shear effects. The governing equation is derived by Hamilton's principle for the FVN subjected to a transverse magnetic field resting on a nonlinear elastic foundation with viscose effects. Formulas have been developed to obtain the nonlinear damping characteristics of a single-walled nanotube. Then, multiple scale method (MSM)-based solutions and Eringen elasticity theory are applied to demonstrate the aforementioned effects on a narrow clamped-clamped (CC) nanotube in detail. The approximate analytical solution is verified by numerical integration methods and a good agreement between the approximate analytical and numerical results is observed. The effect of all important parameters such as local and nonlocal viscosity damping, nonlinear damping coefficient, linear and nonlinear stiffness of the elastic medium due to changes in amplitude vibration of the magnetic field (AVMF) and displacement responses (DR) have been investigated. The original research proposed in this paper may enable the systematic study of nonlinear damping in nanomechanical oscillators, which may help to reveal the underlying physical mechanism. [ABSTRACT FROM AUTHOR]

Based on the thin plate theory and D'Alembert's principle to establish the equilibrium equation for viscoelastic axially moving plates, this paper establishes the ternary governing equation of variable fractional order for viscoelastic axially moving plates by using a variable fractional order constitutive relationship for viscoelastic materials. Shifted Chebyshev wavelets are introduced for approximating the deflection function, and numerical solutions for the governing equations are given. The effectiveness and accuracy of the algorithm in this paper is illustrated by convergence analysis, error correction and numerical examples. Finally, the algorithm is used to simulate the vibration of axially moving plates with different moving speeds and different boundary conditions. Meanwhile, Gaussian white noise was introduced to investigate the vibration of the viscoelastic axially moving plate under pure noise environment, simple harmonic load-same direction noise environment and simple harmonic load-opposite direction noise environment, respectively. And the vibration comparison of PP material plate and LLDPE material plate is also carried out. The above research conclusions are consistent with the existing literature, indicating that algorithm proposed by this paper is applicable to numerical simulation and research on viscoelastic axially moving plates. • This algorithm solves the fractional axially moving plate equation in time domain. • The simulated plate vibration matches reality under Gaussian white noise. • Research shows PP boards are stiffer than LLDPE boards. • Research shows tighter clamping reduces board vibration. • Algorithm's accuracy and effectiveness shown via analysis and error correction. [ABSTRACT FROM AUTHOR]

A recent report from Sardar Vallabhbhai National Institute of Technology in Surat, India, discusses the development of photo-responsive wormlike micelle mediated viscoelastic materials (WMMVMs) for various applications. These materials have fine-tunable structures and stimuli-tunable characteristics, making them useful in soft robotics, actuators, tissue engineering, optical devices, molecular switches, and biosensors. The researchers found that the WMMVMs exhibited reversible changes in viscoelastic properties in response to pH and temperature, as well as irreversible photo-responsive behavior when exposed to UV light. The study concludes that these materials can serve as a useful model for understanding photo-responsiveness and have potential applications in various fields. [Extracted from the article]

A patent application by inventor Gregory Vinton Matthews has been made available online for a device and method related to the storage and loading of intraocular lenses (IOLs). The invention aims to provide a more efficient and safe way to introduce an IOL into a delivery device without manual manipulation or risk of damage. The device includes a base member, splaying member, and loading member, while the method involves reconfiguring the haptics of the IOL for delivery. The patent application was filed by Alcon Inc., a medical technology company based in Switzerland. [Extracted from the article]

• A novel strategy for implementing integral-based viscoelastic constitutive theories is proposed. • Schapery-type constitutive theories and higher-order finite difference (FD) schemes are used. • The proposed incremental approach is used along with the meshfree RPIM. • The CTM is utilized for accurate evaluation of the integrals. • Very accurate and efficient numerical solutions are obtained with the presented method. In the present work, an improved meshfree radial point interpolation method (RPIM) is developed for the analysis of homogeneous, as well as non-homogeneous viscoelastic problems. A novel strategy for implementing integral-based viscoelastic constitutive theories using the meshfree methods is presented. This strategy makes use of the integral formulation of Schapery-type constitutive theories and higher-order finite difference (FD) schemes. The Cartesian transformation method (CTM) is adopted for accurate and efficient calculation of the domain integrals in the formulation of the meshfree RPIM. The superior performance of this modified algorithm is assessed through some benchmark examples and by comparing the obtained results with the existing analytical or numerical solutions. Through these comparisons, an improvement over the conventional integral-based recursive strategies of viscoelastic materials is observed. [ABSTRACT FROM AUTHOR]

The article focuses on incremental removal of small portions of the Beilby layer, nearperfect optical surfaces has created. Topics include the supply of low-roughness surfaces rely on traditional loose abrasive finishing methods that create subsurface damage (SSD), the technique has been shown to produce excellent results in fused silica, and the silica has considered to be insoluble due in large part to the formation of this diffusion layer.

The efficient use of resources is one of the most important things in the current development. In the field of lightweight constructions, rubber and reinforced polymer composite materials become more and more important. This constantly increases the demands on the simulation software. The development of robust and efficient algorithms for these simulations is the aim of this paper. The application of higher order finite elements in space has a good influence on solution quality in space, but causes a higher computational cost compared to linear elements. We propose higher order finite elements in space and time in combination with a reinforced viscoelastic material formulation in a variational framework. Therefore, a higher order approximation in space and time is applied. The application of variational based time integrators guarantees the preservation of the total balance of linear momentum and the total balance of angular momentum. In order to fulfill the total balance of energy, an extension with discrete gradients is developed for the variational framework. The achieved time stepping scheme represents a very robust and consistent algorithm for the application of transient finite element simulations with reinforced viscoelastic materials and boundary conditions. In an implementation, however, the higher order approximation in space and time combined with the viscoelastic material suffers from a high computational effort. Hence, an efficient implementation is required in order to reduce the computational time to a minimum. In our approach, we face this problem by using a GPU and the programming architecture Cuda from NVIDIA, which allows a massive parallelization of time-consuming parts of the simulation. We introduce a pipeline design for the GPU implementation, which provides multiple advantages. This design allows a simple porting of an already existing implementation by means of self-managing pipeline-stages. However, a significant speedup is still achieved due to further optimizations which exploit the architecture of GPUs. In addition, when combining both hardware resources GPU and CPU the computational time can be reduced significantly once more. Therefore, our GPU implementation easily allows a distribution of computational effort between both GPU and CPU. Finally, we show in numerical examples the reached speedup of this approach, and the impact of combining the GPU and the CPU is studied in detail. [ABSTRACT FROM AUTHOR]

A fast directional boundary element method for wideband multi-domain elastodynamic analysis is developed. The directional low rank property of the elastodynamic kernel is proved, which serves as the theoretical basis of the fast directional algorithm. The boundary integral evaluation is accelerated domain by domain. For each domain, the octree is divided into low frequency and high frequency regimes according to its S-wave number. The computation in the low frequency regime is the same with the kernel independent fast multipole method, while the high frequency regime is computed efficiently by applying the parabolic low rank property of the kernels on directional wedges. The matrices on only one directional wedge for each level have to be calculated, since that for other directions can be obtained by coordinate frame rotations. Thus the harmonic responses for any frequencies can be computed efficiently. Numerical results show that the computational complexity for wideband multi-domain elastodynamic problems is successfully brought down to O (N log α N). Its applications to viscoelastic materials and inverse problems are also validated. [ABSTRACT FROM AUTHOR]

This paper presents a new numerical method to solve the constitutive equations of fractional-order viscoelastic Euler–Bernoulli beams. Firstly, the constitutive equation of Euler–Bernoulli beams is established by analyzing the constitutive relation between the fractional viscoelastic materials. Secondly, the constitutive equation of the beams is transformed into a matrix equation by skillfully using a Quasi-Legendre polynomial in the time domain, which can greatly simplify the solution process. Then the matrix equation is discretized and solved, and the numerical solutions are obtained. Finally, dynamic analysis of two different fractional viscoelastic materials is carried out by numerical experiments, and the influences of time on displacements are considered for the first time. With the change of time and position, displacements under different external loads are obtained for the polybutadiene beams and butyl B252 beams, and the change law of displacements is found. In addition, the performances of the two materials are compared and analyzed. [ABSTRACT FROM AUTHOR]

New observations have revealed that tiny flakes of detritus in the ocean fall more slowly due to the mucus that surrounds each flake. This mucus, known as "marine snow," is a viscoelastic fluid that affects the sinking speed of the flakes. Understanding the physics of this sticky goo is important for climate research, as it could influence the rate at which carbon gets sequestered deep in the ocean. Scientists hope that these findings can be used to refine climate models and better understand the oceans' impact on climate change. [Extracted from the article]

A recent study conducted by researchers at the University of Glasgow explores the phenomenon of flow-induced self-assembly (FISA) in viscoelastic fluids. FISA involves the chaining of particles in these fluids under shear flow. The researchers used a specialized shear cell to investigate the dynamics of FISA and found that the onset of elastic instability is strongly correlated with an enhancement of FISA. They also observed that particle chains break apart under constant shear for a long period of time and that the elastic component of the fluid fades during continuous shear flows. This research provides new insights into FISA and its potential applications in various fields. [Extracted from the article]

We consider a mathematical model which describes the quasistatic frictionless contact of a viscoelastic body with a rigid-plastic foundation. We describe the mechanical assumptions, list the hypotheses on the data and provide three different variational formulations of the model in which the unknowns are the displacement field, the stress field and the strain field, respectively. These formulations have a different structure. Nevertheless, we prove that they are pairwise dual of each other. Then, we deduce the unique weak solvability of the contact problem as well as the Lipschitz continuity of its weak solution with respect to the data. The proofs are based on recent results on history-dependent variational inequalities and inclusions. Finally, we present numerical simulations in the study of the contact problem, together with the corresponding mechanical interpretations. • Three problems with displacement, stress, and strain fields as unknowns, respectively. • Proof of pairwise duality between introduced variational formulations of the problem. • Accompanying numerical approximation scheme based on the irrational formulation. [ABSTRACT FROM AUTHOR]

The patent application titled "Solvent-Free Liquid From Regenerated Silk Fibroin: A Writeable And Shapeable Material" explores the use of regenerated silk fibroin (RSF) in biomedical and tissue engineering applications. RSF is obtained by removing sericin from silk-worm fibroin through a degumming method. The researchers have investigated methods to retain RSF in its silk I conformation to create stronger and more biocompatible materials. They have developed a process for stabilizing silk fibroin in the form of a powder and a viscoelastic silk liquid that can behave like a liquid or a soft solid. The inventors also describe a process for preparing the silk liquid using a coupling reaction and freeze drying. [Extracted from the article]

A falling film of a weakly viscoelastic liquid (Walters' liquid B ′ ′) is studied in detail for low to moderate values of the Reynolds number. A linear stability analysis within the framework of the Orr–Sommerfeld-type boundary value problem reveals a destabilizing effect of the viscoelastic parameter near the threshold of instability but a stabilizing effect of the viscoelastic parameter on the primary instability far away from the threshold of instability. The surface equation is derived to decipher the existence of nonlinear waves based on the centre manifold approach. However, it renders an unbounded solution in the short-wave regime. In order to avoid singular behaviour found in the surface equation, a regularized equation, a simplified second-order model, and a full second-order model are proposed. In the linear regime, both the regularized equation and the model equations show excellent agreement with the results of the Orr–Sommerfeld-type boundary value problem, i.e., the viscoelastic parameter demonstrates a dual role in the primary instability. In the nonlinear regime, the results of the regularized equation are verified with those of the simplified second-order model. Both the regularized equation and the simplified second-order model show qualitatively similar characteristics of the nonlinear waves. The speed and maximum amplitude corresponding to the steady-state travelling waves attain fixed values in the drag-inertia regime. Moreover, the speed and maximum amplitude acquired from the regularized equation underestimate the results of the simplified second-order model when the Reynolds number lies in the drag-inertia regime. The time-dependent simulation of the regularized equation displays a train of solitary waves downstream to a monochromatic time periodic forcing at the inlet. The separation distance between the first two solitary pulses is computed, and it seems to approach an asymptotic value when the time is very large. This fact assures the possibility of a bound-state formation among the solitary pulses downstream for the weakly viscoelastic liquid. • Numerical solution of the Orr–Sommerfeld equation using AUTO 07p. • Viscoelastic parameter has a dual role in the primary instability. • Viscoelastic parameter accelerates transition from Nusselt solution to solitary wave solution. • Model equations are adequate in exploring the complex wave dynamics. • Second-order viscous diffusion terms are responsible for the stabilizing effect. • Recirculation pattern appears in the core region of the wave profile. • Maximum amplitude and speed increase in the presence of the viscoelastic parameter. [ABSTRACT FROM AUTHOR]

In order to describe the mechanical behaviors of viscoelastic materials that couple memory effects and time-varying viscosity properties toggled between thixotropy and rheopexy, this paper explores and establishes the constitutive equation of a unified Maxwell model with a variable kernel in terms of the ψ -Caputo fractional derivative. By virtue of a Volterra integral equation of the second kind and the ψ -Laplace transform technique, the closed-form expressions of creep and relaxation responses for the proposed model are derived and compared in detail. Furthermore, to enhance practicality, the exponential and power-law time-varying viscosity candidates are embedded into the proposed model, along with exhibiting the corresponding creep and relaxation behaviors in light of illustration and reasoning, respectively. The results may provide a fresh perspective for detecting the relationship between the viscoelastic system with nonlinear time-varying viscosity and generalized fractional calculus. [ABSTRACT FROM AUTHOR]

This paper deals with the unique solvability of some inverse problems for nonlinear Navier–Stokes–Voigt (Kelvin–Voigt) system with memory that governs the flow of incompressible viscoelastic non-Newtonian fluids. The inverse problems that study here, consist of determining a time dependent intensity of the density of external forces, along with a velocity and a pressure of fluids. As an additional information, two types of integral overdetermination conditions over space domain are considered. The system supplemented also with an initial and one of the boundary conditions: stick and slip boundary conditions. For all inverse problems, under suitable assumptions on the data, the global and local in time existence and uniqueness of weak and strong solutions were established. • The inverse problems are equivalent to the direct problems for a nonlinear parabolic equation with nonlinear nonlocal operator of the function u. • The inverse problems have unique weak and strong solutions in local time. • The following inverse problems have unique weak and strong solutions in global time in particular case. [ABSTRACT FROM AUTHOR]

A particular attention is devoted to analyze the effect of the foundation having fractional order viscoelastic material on a response of a beam structure. Periodic responses are computed using the stochastic averaging method, and the effects of fractional order damping on the vibration reduction of the beam are analyzed. The analysis shows that, as the order of the derivative increases, the resonant amplitude of the beam vibration decreases. It means that high order of the fractional derivative appear to be beneficial for the beam vibration control. It is also observed that the multivalued solution only appears for the smallest order and suddenly disappears as the derivative order increases. Further, the additive and parametric wind turbulence contributes to decrease the chance for the beam to reach the resonance of the amplitude oscillations. The analytical predictions are confirmed by numerical simulations. [ABSTRACT FROM AUTHOR]

An improved meshfree radial point interpolation method (RPIM) is formulated for quasi-static and dynamic analyses of 2D inhomogeneous viscoelastic solids. The presented improved RPIM is formulated in time domain, in which, there is no need for the viscoelastic material to obey the correspondence principle and therefore, all kinds of inhomogeneous viscoelastic materials can be analyzed by the method. The domain integrals, appeared in the proposed RPIM, are computed by the Cartesian transformation method (CTM), which is a truly meshfree integration technique. In the implementation of the CTM no background mesh is required and the domain integrals are computed accurately and efficiently. The accuracy of the method is studied by presenting several numerical examples. The results are compared with available analytic or numerical solutions and very good agreement is observed in all cases. [ABSTRACT FROM AUTHOR]

One of most peculiar issues related to soft viscoelastic contacts is the anisotropy induced on the contact solution: when sliding a perfectly isotropic surface over a viscoelastic half-space, the solution in terms of contact areas and displacement distribution is anisotropic. This is due to the different behaviour, in each contact patch, between the leading edge and the trailing one, where the viscoelastic material needs time to relax. Things become even more complicated when the surfaces into contact are already affected by an anisotropic degree, as occurring in many cases due to the manufacturing process. In this paper, by means of a proper Boundary Element Formulation, based on the definition of a viscoelastic periodic Green's function, we carry out, on these topics, a systematic investigation aimed to study the relation between the rigid surface and the deformed half-space anisotropy tensors. In detail, we show that the two tensors are related by means of a linear transformation, based on a rotation and a "stretching" of the roughness anisotropy tensor. The role of anisotropy is, then, studied in relation with the friction force and with the lateral anisotropy induced force originally defined in this study. [ABSTRACT FROM AUTHOR]

Viscoelasticity is an essential mechanical property of soft materials. Many constitutive models have been proposed to capture this mechanical behavior, but few physically based models were developed due to the challenge to incorporate the micro-mechanisms of viscoelasticity into the formulation. In a previous paper, we proposed a constitutive model to characterize the hyperelastic response under different deformation states with only three parameters (Xiang et al., 2018). Based on the above work and the tube theory of polymer dynamics, we develop herein a physically based viscoelastic constitutive model in this paper. We start from a new microscopic picture at the molecular chain scale, and decompose the stress into a hyperelastic part which comes from the elastic ground network (crosslinked network and entanglement network), and a viscous part which is originated from free chains. Utilizing the same scheme from the previous work (Xiang et al., 2018), we are able to decompose the free chains into two parts, the untangled crosslinked network and the entanglement network. The contour length relaxation and disentanglement from the free chain's networks give the viscous behavior. We test VHB 4910 to validate our model. The model is applied to the mechanical behavior of the soft digital materials (DMs). In addition, the model can explain the Shore A index independent relaxation time of DMs and the asymmetry of viscoelasticity under loading and unloading. This viscoelastic model can be used to predict the mechanical response of soft materials. [ABSTRACT FROM AUTHOR]

Abstract The flexibility matrices of transversely isotropic saturated viscoelastic soils are obtained by the extended precise integration method. We use the finite element method (FEM) to derive the stiffness matrix of pile. The pile-soil interface is divided into elements corresponding to the pile elements based on the boundary element method (BEM). The pile-soil interaction equation is established by the coupling of FEM and BEM. The solutions for the equation are achieved by combining the compatibility condition between the pile and the soil. Numerical examples are presented to study the influences of soil and pile properties on the time-dependent behaviour of piles. [ABSTRACT FROM AUTHOR]