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Engineering（科研） 2013年第1期5卷 67-72页

作者： Utpal Jyoti Das 不详

An analysis of oscillatory flow of a viscoelastic fluid and mass transfer along a porous oscillating channel with radiative heat transfer in presence of first-order chemical reaction is considered. The problem is concerned with the flow through a channel in which the viscoelastic fluid is injected on one boundary of the channel with a constant velocity, while it is sucked off at the other boundary with the same velocity. The two boundaries are considered to be in close contact with the two plates placed parallel to each other. The effect of temperature oscillations at the plate (upper wall) where the suction takes place is taken into consideration. The plates are supposed to be oscillating with a given velocity in their own planes. Analytical expressions for velocity profile, the temperature, concentration profile, wall shear stress on the upper wall are obtained. The profiles of the velocity and skin friction have been presented graphically for different values of the viscoelastic parameters with the combination of the other flow parameters encountered in the problem under investigation. It is observed that velocity decrease with the increasing values of the viscoelastic parameter in comparison with Newtonian fluid. Also, the wall shear stress increase with the increasing values of the viscoelastic parameter.

关键词： viscoelastic Fluid First-Order Chemical Reaction Porous Wall Oscillating Channel Radiative Heat Transfer

viscoelastic Evaluation of Different Hyaluronic Acid Based Fillers Using Vibrational Optical Coherence Tomography

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Materials Sciences and Applications 2019年第5期10卷 423-431页

作者： Frederick H. Silver Ruchit G. Shah Nikita Kelkar Dominick Benedetto Dale DeVore Justin Cohen Department of Pathology and Laboratory Medicine Robert Wood Johnson Medical School Rutgers The State University of New Jersey Piscataway NJ USA OptoVibronex LLC Mt. Bethel Pa USA Graduate Program in Biomedical Engineering Rutgers The State University of New Jersey Piscataway NJ USA Center for Advanced Eye Care Vero Beach FL USA DV Consulting Chelmsford MA USA Glasgold Group Princeton NJ USA

Hylauronic acid (HA) is used as a viscoelastic in Ophthalmology during cataract surgery based on its high viscosity at rest, its ability to shear thin and dissipate energy during phacoemulsification. However, these properties of HA solutions would make them susceptible to migration when used as dermal filler materials. In this study, we apply a new technique termed vibrational optical coherence tomography (VOCT) to compare the physical properties of different HA solutions and fillers used in facial aesthetics. Results presented in this study suggest that HA solutions and HA dermal fillers have markedly different physical properties. HA solutions are highly viscoelastic with high % viscous losses while fillers tend to have lower viscous energy dissipation properties. Clinical observations suggest that the high loss fillers are injected more superficially in the face where tension and internal and external forces are more likely minimized giving tissue of the hands and lips more volume and allowing more natural movement. In contrast, the lower loss gels that are used to lift tissue, generally have a higher G’, and are injected deeper into the face where injection and internal forces are likely to be higher. It is concluded that HA filler gel design can be optimized by use of VOCT to evaluate the % viscous energy loss both in vitro and in vivo.

关键词： Hyaluronic Acid Injectable Filler Dermal Filler Plastic Surgery Cosmetic Surgery viscoelastic Mechanical Properties Facial Surgery Optical Coherence Tomography Vibrational Optical Coherence Tomography

viscoelastic Response of Graphite Platelet and CTBN Reinforced Vinyl Ester Nanocomposites

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Materials Sciences and Applications 2011年第11期2卷 1667-1674页

作者： Brahmananda Pramanik P. Raju Mantena 不详

Developing stronger, safer and more cost-effective structural materials for the new generation naval ships is the focus of ongoing research at University of Mississippi. The light-weight nanoparticle reinforced glass/carbon polymeric based composites and structural foams for blast, shock and impact mitigation are emphasized in this research. Derakane 510A-40 brominated vinyl ester nanocomposite resin systems are considered to be used in the composite face sheets of sandwich structures with fire-resistant foam core to reduce flammability along with optimal flexural rigidity, vibrational damping and enhanced energy absorption. In this work, the viscoelastic performance of 1.25 and 2.5 weight percent exfoliated graphite nanoplatelet (xGnP) added with 10 weight percent Carboxy Terminated Butadiene Nitrile (CTBN) reinforced brominated vinyl ester nanocomposites are studied. A Dynamic Mechanical Analyzer (DMA) - TA Instruments Model Q800 was used to obtain the viscoelastic properties, modulus (stiffness), creep/stress relaxation, and damping (energy dissipation), of the exfoliated graphite platelet and CTBN reinforced brominated vinyl ester. Effects of frequency (time) on the viscoelastic behavior were investigated by sweeping the frequency over three decades: 0.01, 0.1, 1.0 and 10 Hz, temperature range from 30°C to 15°C at 4°C per minute step rate. Master curves were generated by time-temperature superpositioning (TTS) of the experimental data at 50°C reference temperature. Addition of CTBN in xGnP reinforced brominated vinyl ester composites resulted in greater intrinsic material damping, indicating the possibility of higher energy absorption with the new configuration.

关键词： Nanocomposite CTBN viscoelastic TTS Material Damping Energy Absorption

Reflective cracking viscoelastic response of asphalt concrete under dynamic vehicle loading

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Journal of Southeast University(English Edition) 2009年第3期25卷 391-394页

作者：赵岩荆倪富健东南大学交通学院南京210096

In order to investigate the mechanical response of reflective cracking in asphalt concrete pavement under dynamic vehicle loading, a finite element model is established in ABAQUS. The viscoelastic behavior is described by a prony series which is calculated through nonlinear fitting to the creep test data obtained in the laboratory. Based on the viscoelastic theory, the time-temperature equivalence principle, fracture mechanics and the dynamic finite element method, both the Jintegral and the mix-mode stress intensity factor are utilized as fracture evaluation parameters, and a half-sine dynamic loading is used to simulate the vehicle loading. Finally, the mechanical response of the pavement reflective cracking is analyzed under different vehicle speeds, different environmental conditions and various damping factors. The results indicate that increasing either the vehicle speed or the structure damping factor decreases the maximum values of fracture parameters, while the structure temperature has little effect on the fracture parameters. Due to the fact that the vehicle speed can be enhanced by improving the road traffic conditions, and the pavement damping factor can become greater by modifying the components of materials, the development of reflective cracking can be delayed and the asphalt pavement service life can be effectively extended through both of these ways.

关键词： asphalt pavement viscoelastic finite element method reflective cracking dynamic vehicle loading

PHASE INVERSION AND ITS MECHANICAL MODEL STUDIES FOR THE TWO-PHASE POLYMER BLEND SYSTEMS (Ⅱ)——DYNAMIC viscoelastic RESPONSE

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Science China Chemistry 1992年第4期35卷 385-390页

作者：陈大俊周涵新孙桐 Department of Chemical Fiber Technology China Textile University Shanghai 200051 PRC

The dynamic viscoelastic response of the two-phase polymer blend systems shows the characteristics of the thermorheologically complex materials. In this paper theoretical equations for describing the dynamic viscoelastic response of such polymer blend systems have been established by means of the mechanical modeling technique. The dynamic viscoelastic response of the blend systems at any blend composition can be predicted theoretically by using the equations established, provided that the dynamic viscoelastic response of the two pure components and the mechanical model parameters are known in advance. Thus, we provide an effective method for studying the dynamic mechanical properties and the molecular relaxation characteristics of the two-phase polymer blend systems.

关键词： polymer blend system mechanical model dynamic viscoelastic response.

Finite Element Modelling of Car Seat with Hyperelastic and viscoelastic Foam Material Properties to Assess Vertical Vibration in Terms of Acceleration

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Engineering（科研） 2020年第3期12卷 177-193页

作者： Purnendu Mondal Subramaniam Arunachalam School of Architecture Computing and Engineering University of East London (Docklands Campus) London UK

Primary objective of automobile seats is to offer adequate level of safety and comfort to the seated human occupant, primarily against vibration. Ideally, any sort of automotive seat is constructed by mechanical framework, cushion, backrest and headrest. The frame structures are made of metallic alloys, while the cushion, backrest and headrest are made of polyurethane foam material. During the design phase of automotive seat, the greatest challenge is to assign realistic material properties to foam material;as it is non-linear in nature and exhibit hysteresis at low level stress. In this research paper, a car seat has been modelled in finite element environment by implementing both hyperelastic and viscoelastic material properties to polyurethane foam. The car seat has been excited with the loads due to car acceleration and human object and the effects of vibration in terms of vertical acceleration at different locations have been measured. The aims of this simulation study are to establish a car seat with the foam material properties as accurately as possible and provide a finite element set up of car seat to monitor the vertical acceleration responses in a reasonable way. The RMS acceleration values for headrest, backrest and cushion have been found to be 0.91 mm/sec2, 0.54 mm/sec2 and 0.47 mm/sec2, respectively, which showed that the car seat foam can effectively be modelled through combined hyperelastic and viscoelastic material formulations. The simulation outputs have been validated through real life testing data, which clearly indicates that this computerized simulation technique is capable of anticipating the acceleration responses at different car seat segments in a justified way.

关键词： Car Seat Hyperelastic Material viscoelastic Material Finite Element Vertical Acceleration Vertical Vibration

Virtual Biopsy and Physical Characterization of Tissues, Biofilms, Implants and viscoelastic Liquids Using Vibrational Optical Coherence Tomography

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World Journal of Mechanics 2019年第1期9卷 1-16页

作者： Frederick H. Silver Ruchit G. Shah Dominick Benedetto Abhinav Dulur Thomas Kirn Department of Pathology and Laboratory Medicine Robert Wood Johnson Medical School Rutgers The State University of New Jersey Piscataway NJ USA Graduate Program in Biomedical Engineering Rutgers The State University of New Jersey Piscataway NJ USA Center for Advanced Eye Care Vero Beach FL USA

Tissue biopsies and implant analysis during animal testing or clinical studies are a requirement for development of new surgical materials and procedures. In this paper we report the use of vibrational OCT (VOCT) to evaluate the viscoelastic behavior of tissues, polymeric materials, biofilms, and viscoelastic solutions of macromolecules. Our results suggest that VOCT is a useful technique to characterize the behavior of cellular tissues and biofilms, polymeric implant materials and viscoelastic solutions used in medicine. It is demonstrated that the modulus and resonant frequency squared per unit thickness is a feature that can be used to characterize a variety of tissues. Further work is needed to understand the generalized behavior of synthetic polymers and viscoelastic solutions.

关键词： Optical Coherence Tomography Vibrational Optical Coherence Tomography Biofilm viscoelastic Solutions Mechanical Properties Modulus Stiffness Tissues Hyaluronic Acid

Decay Rate for a viscoelastic Equation with Strong Damping and Acoustic Boundary Conditions

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Journal of Applied Mathematics and Physics 2017年第4期5卷 922-932页

作者： Zhiyong Ma College of Science Shanghai Second Polytechnic University Shanghai China

This paper is concerned with a nonlinear viscoelastic equation with strong damping: . The objective of the present paper is to provide some results on the long-time behavior to this equation with acoustic boundary conditions. By using the assumptions on the relaxation function due to Tatar [1], we show an arbitrary rate of decay with not necessary of an exponential or polynomial one and without the assumption condition. The result extends and improves some results given in Cavalcanti [2].

关键词： viscoelastic Equation Decay Rate Acoustic Boundary Condition

Glucocorticoid-induced alterations in titin, nebulin, myosin heavy chain isoform content and viscoelastic properties of rat skeletal muscle

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Advances in Biological Chemistry 2013年第1期3卷 70-75页

作者： Maire Aru Karin Alev Helena Gapeyeva Arved Vain Raivo Puhke Ando Pehme Priit Kaasik Anne Selart Teet Seene Institute of Exercise Biology and Physiotherapy University of Tartu Tartu Estonia Institute of Mathematical Statistics University of Tartu Tartu Estonia Institute of Physics University of Tartu Tartu Estonia Institute of Sport Pedagogy and Coaching University of Tartu Tartu Estonia

viscoelastic properties of skeletal muscle are associated with a complex network of cytoskeletal proteins where titin and nebulin play a substantial role. The need for evaluation of muscle viscoelastic properties is widely accepted in clinical use to evaluate the effect of treatment or progression of muscle pathology (atrophy). We tested the hypothesis that the viscoelastic properties (elasticity, tone and stiffness) change in atrophied muscles with concomitant changes in cytoskeletal proteins (titin, nebulin) and contractile protein (myosin heavy chain) proportion. Sixteen 24- week-old male rats of the Wistar strain were randomly allocated to two groups: dexamethasone group treated each day for 10 consecutive days with dexamethasone in order to induce atrophy and control group. Skeletal muscle viscoelastic properties (elasticity, tone and stiffness) were determined using a myotonometer. Titin, nebulin and myosin heavy chain content were quantified using SDS-PAGE electrophoresis. We found that glucocorticoid-induced muscle atrophy is accompanied by reduced elasticity and increased tone and stiffness, with concomitant changes in titin, nebulin and myosin heavy chain con- tent. The elasticity decreased by 10.9% (P P < 0.05), and stiffness was significantly lower in dexamethasone group (627.3 N/m vs 758.6 N/m);(P < 0.05). Compared with the control group, the content of titin, nebulin and myosin heavy chain in atrophied muscle was 76.4%, 70.6% and 82.3%, respectively. Our results may lead to a better understanding of the mechanism of muscle atrophy and provide better guidance for rehabilitation practices and help to find rational therapeutic intervention in the future.

关键词： viscoelastic Properties Skeletal Muscle Atrophy Myotonometry Cytoskeletal Proteins Glucocorticoids

Quantum Effects on the Rayleigh-Taylor Instability of viscoelastic Plasma Model through a Porous Medium

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Journal of Modern Physics 2011年第10期2卷 1146-1155页

作者： Gamal A. Hoshoudy 不详

The stability of stratified of incompressible, viscoelastic plasma through a porous medium in the presence of the quantum mechanism is considered. The dispersion relation is obtained using the normal mode technique. The behavior of growth rate with respect to the quantum effect, strain retardation time and stress relaxation time are examined in the presence of porosity of the porous medium, the medium permeability, kinematic viscosity. It is shown that, the presence of quantum term stabilizes a certain wave number band, whereas the system is unstable for all wave numbers in the absence of quantum term. The considered parameters beside the quantum term will bring about more stability on the considered system.

关键词： Rayleigh-Taylor Instability viscoelastic Quantum Plasm