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Journal articles on the topic 'Viscoelastic'

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Author: Grafiati

Published: 4 June 2021

Last updated: 8 June 2024

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1

Egorova, Anna V., Alexey V. Vasiliev, and Lina Bai. "Influence of the quality of viscoelastic removal on phacoemulsification results. Part 1. Type of the postoperative period course depending on the quality of viscoelastic removal in phacoemulsification." Ophthalmology Journal 14, no. 3 (November 15, 2021): 35–40. http://dx.doi.org/10.17816/ov79098.

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BACKGROUND: The reasons for the development of postoperative reactive inflammation under optimal conditions for the operation are errors in the surgical technique and the presence of viscoelastic residues. The likelihood of developing ophthalmic hypertension exists with the use of viscoelastic of any type. Its incomplete evacuation can be explained by the difficult visualization due to its transparency. Analysis of the dependence of the postoperative period course on the quality of viscoelastic removal at phacoemulsification can be considered to be relevant and expedient. AIM: The aim was to study the type of the postoperative period course depending on the quality of viscoelastics removal at phacoemulsification. MATERIALS AND METHODS: 104 eyes of randomly chosen patients who underwent femto-laser assisted phacoemulsification, divided into 2 groups according to ophthalmic viscoelastics characteristics (colored or transparent). Both groups were split into 2 subgroups each depending on method of viscoelastics removal. Tonometry and biomicroscopy were performed 3 hours after phacoemulsification and on the post-op Day 1. Patients with Tyndall effect were examined daily until its disappearance. RESULTS: At comparable preoperative IOP indices, its elevation 3 hours after surgery took place in subgroups 2a and 2b, the highest being in subgroup 2a. The greatest number of eyes with Tyndall effect, at all follow-up periods, was found in subgroup 2a, the lowest in subgroup 1b. The total number of eyes with keratopathy (as epitheliopathy) observed 3 hours after surgery was 7, four of them being from subgroup 2a. CONCLUSIONS: The conducted research showed that the type of early postoperative period course of phacoemulsification depends on visualization possibility of the viscoelastic and of the method of its removal. Minimal changes of hydrodynamics and maximal number of eyes with absence of inflammation took place when using colored viscoelastic and impulse irrigation method.

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Loskutov, Igor A., and Anastasia I. Fedorova. "Phacoemulsification with IOL implantation at a critical level of corneal endothelial cells." Ophthalmology Reports 16, no. 3 (October 17, 2023): 63–69. http://dx.doi.org/10.17816/ov567921.

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BACKGROUND: Cataract phacoemulsification is one of the most frequently performed surgical procedures, and a decrease in the corneal endothelial cell density (ECD) is the main postoperative complication leading to visual impairment. The average cell loss after phacoemulsification is 4.0112.94% within a year, and within 2 months 5.29.1%. The use of viscoelastics helps to reduce this loss, but it is impossible to completely prevent it. AIM: Сomparison of ECD in the pre- and postoperative period of phacoemulsification using viscoelastic of different percentages at a critical level of corneal endothelial cells. MATERIALS AND METHODS: The study included 60 eyes with emmetropic refraction: in the first group: 30 eyes with initial cataract and low ECD level (1694/1218 cells/mm2), an apyrogenic moderately cohesive viscoelastic 1.6% sodium hyaluronate solution (Kogevisk, Solopharm) was used, in the second group: 30 eyes with mature cataract and ECD level (1646/1183 cells/mm2) an apyrogenic, highly purified viscoelastic was used, consisting of medium-molecular fractions of chondroitin sodium sulfate 4% and sodium hyaluronate 3% (Adhevisk, Solopharm). Before surgery and a month after surgery, patients were tested for uncorrected visual acuity in the distance, ECD measurements, and intraocular pressure measurement. RESULTS: In phacoemulsification with IOL implantation, the use of viscoelastics of different percentages shows that the condition of the cornea remained stable a month after surgery. Postoperative ECD loss in all clinical cases, regardless of the stage of cataract, was less than 3%. CONCLUSIONS: Viscoelastics allow to solve the tasks set: in the case of cohesive maintaining the depth of the anterior chamber and the width of the pupil, adhesive protecting the corneal endothelium, good visualization. Rational consistent use of adhesive and cohesive components facilitates basic manipulations during phacoemulsification and IOL implantation. To do this, it is necessary to correctly use and select viscoelastic for a particular operation based on the number of endothelial cells.

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3

&NA;. "Viscoelastic." Reactions Weekly &NA;, no. 387 (February 1992): 8. http://dx.doi.org/10.2165/00128415-199203870-00032.

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4

ROSEN, E. S. "Viscoelastic." British Journal of Ophthalmology 83, no. 6 (June 1, 1999): 759c. http://dx.doi.org/10.1136/bjo.83.6.759c.

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5

Stoll, Robert D. "Bottom sediments—Viscoelastic, poroelastic, or poro‐viscoelastic?" Journal of the Acoustical Society of America 84, S1 (November 1988): S151. http://dx.doi.org/10.1121/1.2025872.

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6

Li, ZL, DG Sun, BH Han, B. Sun, X. Zhang, J. Meng, and FX Liu. "Response of viscoelastic damping system modeled by fractional viscoelastic oscillator." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 231, no. 17 (April 6, 2016): 3169–80. http://dx.doi.org/10.1177/0954406216642477.

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The fractional model considering geometric factor of viscoelastic damping systems is proposed by adopting fractional viscoelastic oscillator. To obtain dynamic responses of the fractional model, a numerical method is derived based on matrix function theory and Grumwald–Letnikov discrete form of fractional derivative. As a special engineering application example, the vibration response of the viscoelastic suspension installed in heavy crawler-type vehicles is studied through the proposed model. Furthermore, the parameter influence on the vibration control capability of the viscoelastic suspension is researched. The results indicate that the fractional viscoelastic oscillator is a favorable choice to characterize the dynamic behavior of viscoelastic damping structures. Additionally, the parameters in fractional viscoelastic oscillator namely geometric factor and fractional order exert considerable impact on the dynamic response of viscoelastic damping structures.

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7

Nemoto, Norio. "Viscoelastic Measurements." Kobunshi 40, no. 8 (1991): 540–43. http://dx.doi.org/10.1295/kobunshi.40.540.

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8

Takahashi, Masaoki. "Viscoelastic Measurements." Kobunshi 42, no. 12 (1993): 972–75. http://dx.doi.org/10.1295/kobunshi.42.972.

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9

Natrajan, Srinivas. "VISCOELASTIC MATERIAL." Optometry and Vision Science 67, no. 2 (February 1990): 153. http://dx.doi.org/10.1097/00006324-199002000-00019.

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10

Florén, Ingrid. "Viscoelastic Purity." Journal of Cataract & Refractive Surgery 24, no. 2 (February 1998): 145–46. http://dx.doi.org/10.1016/s0886-3350(98)80185-5.

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11

Hill, R. M., and L. A. Dissado. "Viscoelastic response." Rheologica Acta 24, no. 5 (September 1985): 537–39. http://dx.doi.org/10.1007/bf01462503.

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12

Vrentas, J. S., and C. M. Vrentas. "Viscoelastic diffusion." Journal of Polymer Science Part B: Polymer Physics 39, no. 13 (2001): 1529–47. http://dx.doi.org/10.1002/polb.1126.

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13

Goles, Nikola, Marko Nerancic, Sanja Konjik, Brigitte Pajic-Eggspuehler, Bojan Pajic, and Zeljka Cvejic. "Phacoemulsification and IOL-Implantation without Using Viscoelastics: Combined Modeling of Thermo Fluid Dynamics, Clinical Outcomes, and Endothelial Cell Density." Sensors 21, no. 7 (March 30, 2021): 2399. http://dx.doi.org/10.3390/s21072399.

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Phacoemulsification is a widely used surgical method in cataract surgery with a high energy ultrasound source. The viscoelastic is considered to be tissue protective. The aim of this study is to investigate during surgery the impact of using viscoelastic versus no viscoelastic on clinical outcomes, potential complications and effect on endothelial cell density. The study group included 64 patients, who were subjected to phacoemulsification using balanced salt solution (BSS). Control group consisted of 62 patients, who underwent phacoemulsification using Hyaloronic acid 1% Healon 1%. Student’s t-test was applied for statistical analysis. The simulations of temperature changes during phacoemulsification were performed by COMSOL Multiphysics software. In the BSS group, a mean endothelial cell loss (ECL) of 4.5% was measured one month postoperatively, while in the Healon group ECL was 5.3%. Data analysis showed no significant difference in ECL between the groups (Student’s t-test, p = 0.8). No significant difference was observed in endothelial cell morphology and IOP between the two groups pre- and postoperatively (all p > 0.05). The modeling of thermo fluid dynamics showed that the heating of the cornea is slightly less when Healon was used as irrigation fluid. The phacoemulsification technique can be performed by an experienced surgeon with viscoelastics or continuous anterior chamber (AC) irrigation on the same level of safety regarding endothelial cell damage, providing equally satisfying clinical outcomes.

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14

Ge, Teng, Xing-Huai Huang, Ying-Qing Guo, Ze-Feng He, and Zhong-Wei Hu. "Investigation of Mechanical and Damping Performances of Cylindrical Viscoelastic Dampers in Wide Frequency Range." Actuators 10, no. 4 (April 4, 2021): 71. http://dx.doi.org/10.3390/act10040071.

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This paper aims to develop viscoelastic dampers, which can effectively suppress vibration in a wide frequency range. First, several viscoelastic materials for damping performance were selected, and different batches of cylindrical viscoelastic dampers were fabricated by overall vulcanization. Second, the dynamic mechanical properties of the cylindrical viscoelastic dampers under different amplitudes and frequencies are tested, and the hysteretic curves under different loading conditions are obtained. Finally, by calculating the dynamic mechanical properties of the cylindrical viscoelastic dampers, the energy dissipation performance of these different batches of viscoelastic dampers is compared and analyzed. The experimental results show that the cylindrical viscoelastic damper presents a full hysteretic curve in a wide frequency range, in which the maximum loss factor can reach 0.57. Besides, the equivalent stiffness, storage modulus, loss factor, and energy consumption per cycle of the viscoelastic damper raise with the frequency increasing, while the equivalent damping decreases with the increase of frequency. When the displacement increases, the energy consumption per cycle of the viscoelastic damper rises rapidly, and the equivalent stiffness, equivalent damping, storage modulus, and loss factor change slightly.

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15

Xu, Yeshou, Zhaodong Xu, Yingqing Guo, Xinghuai Huang, Yaorong Dong, and Qiangqiang Li. "Dynamic Properties and Energy Dissipation Study of Sandwich Viscoelastic Damper Considering Temperature Influence." Buildings 11, no. 10 (October 13, 2021): 470. http://dx.doi.org/10.3390/buildings11100470.

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Viscoelastic dampers are a kind of classical passive energy dissipation and vibration control devices which are widely utilized in engineering fields. The mechanical properties and energy dissipation capacity of the viscoelastic damper are significantly affected by ambient temperature. In this work, dynamic properties tests of the sandwich type viscoelastic damper at different environmental temperatures are carried out. The equivalent fractional Kelvin model which can characterize the mechanical behavior of the viscoelastic damper with varying frequencies and temperatures is introduced to describe the dynamic properties and energy dissipation capability of the sandwich viscoelastic damper. The self-heating phenomenon of the sandwich viscoelastic damper is studied with a numerical simulation, and the dynamic properties and energy dissipation variation of the viscoelastic damper with self-heating processes are also analyzed. The results show that the dynamic properties of the viscoelastic damper are significantly affected by temperature, excitation frequency and the internal self-generated heating.

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Tringides, Christina M., Nicolas Vachicouras, Irene de Lázaro, Hua Wang, Alix Trouillet, Bo Ri Seo, Alberto Elosegui-Artola, et al. "Viscoelastic surface electrode arrays to interface with viscoelastic tissues." Nature Nanotechnology 16, no. 9 (June 17, 2021): 1019–29. http://dx.doi.org/10.1038/s41565-021-00926-z.

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17

Zhou, Feng, Jianjun Gan, Xin Du, and Ligang Cui. "A Study on Organic Modification of Damping Properties of Polyurethane Materials for Building." MATEC Web of Conferences 175 (2018): 01017. http://dx.doi.org/10.1051/matecconf/201817501017.

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The damping property of viscoelastic dampers is mainly based on the shear hysteretic behaviorof viscoelastic materials, so as to reduce the dynamic response of viscoelastic materials. Therefore, theviscoelastic damping properties of viscoelastic materials greatly affect the viscoelastic dampers. At present, viscoelastic materials mainly use rubber materials, but in this thesis, the excellent properties of polyurethaneelastomer materials are used to replace rubber materials and applied to viscoelastic dampers. However, purepolyurethane elastomer damping properties are related to poor performance, so it should be modified. Basedon the research of inorganic filler-modified polyurethane elastomer, the research group modified the threekinds of organic chemicals with hydroxyl silicone oil, HTPB liquid rubber and epoxy resin E-51, in the lowfrequency region of 0.025Hz-1.5Hz through the dynamic load test machine to test the dampingperformance.

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18

Seredyńska, M., and A. Hanyga. "Cones of material response functions in one-dimensional and anisotropic linear viscoelasticity." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 465, no. 2112 (September 25, 2009): 3751–70. http://dx.doi.org/10.1098/rspa.2009.0305.

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Viscoelastic materials have non-negative relaxation spectra. This property implies that viscoelastic response functions satisfy certain necessary and sufficient conditions. These conditions can be expressed in terms of each viscoelastic response function ranging over a cone. The elements of each cone are completely characterized by an integral representation. The 1:1 correspondence between the viscoelastic response functions is expressed in terms of cone-preserving mappings and their inverses. The theory covers scalar- and tensor-valued viscoelastic response functions.

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Wang, Xin, Yi Xia Zhang, and Yu Hong Cui. "Evaluation of Dentinal Viscoelastic Properties Based on its Microstructural Characters." Advanced Materials Research 32 (February 2008): 229–32. http://dx.doi.org/10.4028/www.scientific.net/amr.32.229.

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On the basis of the characters of dentinal microstructures, a new Three-Parameter-Solid viscoelastic mechanics model which can predict strain creep, stress relaxation and instant elasticity with anisotropic constitutive relation for the human dentin is developed in this paper. The porous protein-mineral model is adopted to obtain the independent dentinal viscoelastic moduli based on its microstructural characters. The influencing mechanisms and the viscoelastic properties of the microstructural dentin are also evaluated by the Three-Parameter-Solid viscoelastic model. The viscoelastic predictive results obtained from the Three-Parameter-Solid viscoelastic model agree well with those from the experimental investigation in both wet and dry situations.

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20

Zanj, Amir, Fangpo He, and Peter C. Breedveld. "Energy-based viscoelastic model: a physical approach for material an elastic behavior by the bond graph approach." SIMULATION 96, no. 1 (June 26, 2019): 111–27. http://dx.doi.org/10.1177/0037549719857136.

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Understanding the true nature of viscoelastic behaviors in multi-physical systems has always been a challenging issue in system dynamic investigations, as each existing physical subdomain of the system may follow a different attenuation pattern during the dynamic process. In this study, to generate a viscoelastic model suitable for multi-physical domain dynamic investigations, a physical combined viscoelastic model is proposed. To this aim, by means of the bond graph approach, an energy-based conventional viscoelastic model is first generated, and its embedded dispersive mechanisms are interpreted physically. By including the interpreted dissipative mechanisms into the relative subdomains of an elastic domain, an energy-based combined viscoelastic model is then proposed. The obtained simulation results indicate that the proposed viscoelastic model is able to capture a variety of viscoelastic behaviors in the system with respect to the true physical nature of the system.

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21

Hazanov, S. "Viscoelastic Minimum Principles Revisited." Journal of Applied Mechanics 63, no. 2 (June 1, 1996): 551–54. http://dx.doi.org/10.1115/1.2788903.

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A problem of viscoelastic counterparts for the elastic minimum theorems is considered. A theorem is proved that gives a general algorithm for the construction of such viscoelastic minimum functionals. The established results are applied for the theoretical evaluation of the effective properties of inhomogeneous viscoelastic materials. As an example, simple bounds on the effective properties of viscoelastic composites are obtained.

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22

Raghavan, Sathyanarayanan, Raphael I. Okereke, and Suresh K. Sitaraman. "An Efficient Implementation of Polymer Viscoelastic Behavior Through a Pseudo Viscoelastic Model." Journal of Microelectronics and Electronic Packaging 8, no. 2 (April 1, 2011): 83–87. http://dx.doi.org/10.4071/imaps.285.

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Modeling of viscoelastic relaxation of polymer materials is important to understand the thermo-mechanical behavior of organic microelectronic systems. However, incorporation of viscoelastic behavior into numerical models makes the models compute-intensive. This paper presents a different technique to incorporate the polymer viscoelastic behavior into the numerical models such that the computation time is not adversely affected without compromising the accuracy of the results obtained. In the proposed “pseudo viscoelastic” modeling technique, the modulus of the viscoelastic material is computed as a function of time and temperature loading history outside of the finite-element simulation, and is then input into the simulation as a thermo-elastic material incorporating the viscoelastic relaxation of the material. This paper compares the warpage results obtained through the proposed technique against a complete viscoelastic simulation model and experimental data, and it is seen that the maximum warpage predicted using the proposed technique agree within 10% compared with the results obtained from a “full” viscoelastic model. Also, it is shown through some of our simulations that the proposed technique could result in a computational time saving of more than 50% and hard disk space saving of 65%.

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Peihuo, Peng. "A method for calculating differential constitutive equation of linear viscoelastic composite model." Science Progress 104, no. 2 (April 2021): 003685042110232. http://dx.doi.org/10.1177/00368504211023289.

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The stress–strain behaviors of viscoelastic materials are often simulated using a model composed of various combinations of springs and dampers. With the increase in the number of springs and dampers, the viscoelastic characteristics of the model will approach those of the actual material. This study discusses how to obtain the differential constitutive equation of a viscoelastic model composed of any number of springs and dampers. First, the general viscoelastic model is regarded as the combination of various Kelvin units. The viscoelastic model is then transformed into a digraph. Based on the relationships between the independent path of the digraph and the strain equation of the viscoelastic model and between the closed enclosure and the stress equation, the derivation of the constitutive equation is transformed into operations involving the incidence matrix of the digraph. Finally, the coefficients of the linear differential operator of the constitutive equation of the viscoelastic model can be obtained by block matrix operations. This method is suitable for computer programming and has a certain significance for accurately constructing viscoelastic models of engineering materials.

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Mahi, Abderrahim El, Hajer Daoud, Jean-Luc Rebiere, Isabelle Gimenez, Mohamed Taktak, and Mohamed Haddar. "Damage mechanisms characterization of flax fibers–reinforced composites with interleaved natural viscoelastic layer using acoustic emission analysis." Journal of Composite Materials 53, no. 18 (March 13, 2019): 2623–37. http://dx.doi.org/10.1177/0021998319836236.

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In this paper, the static and fatigue behavior of flax fiber-reinforced composites with and without an interleaved natural viscoelastic layer are investigated. Viscoelastic composite plates consist of a soft natural viscoelastic layer which is confined between two identical flax fiber reinforced composites. Different stacking sequences of specimens are tested with uniaxial tensile loading until failure. The mechanical behavior and the acoustic activity of damage sources in various configurations with and without a viscoelastic layer are compared. The analysis of acoustic emission signals and the macroscopic and microscopic observations led to the identification of the main acoustic signatures of different damage modes dominant in each type of composites (with and without a viscoelastic layer). These results allow better identification of the influence of the impact of a viscoelastic layer on the mechanical behavior of different composites. In addition, static and fatigue flexural behavior of unidirectional composites with and without viscoelastic layer are characterized in 3-point bending tests. The effects of viscoelastic layer on the stiffness, hysteresis loops, and loss factor are studied for various numbers of cycles during cyclic fatigue.

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DiSilvestro,, Mark R., Qiliang Zhu,, and Jun-Kyo Francis Suh. "Biphasic Poroviscoelastic Simulation of the Unconfined Compression of Articular Cartilage: II—Effect of Variable Strain Rates." Journal of Biomechanical Engineering 123, no. 2 (October 1, 2000): 198–200. http://dx.doi.org/10.1115/1.1351887.

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This study investigated the abilities of the linear biphasic poroviscoelastic (BPVE) model and the linear biphasic poroelastic (BPE) model to simulate the effect of variable ramp strain rates on the unconfined compression stress relaxation response of articular cartilage. Curve fitting of experimental data showed that the BPVE model was able to successfully account for the ramp strain rate-dependent viscoelastic behavior of articular cartilage under unconfined compression, while the BPE model was able to account for the complete viscoelastic response at a slow strain rate, but only the long-term viscoelastic response at faster strain rates. We concluded that the short-term viscoelastic behavior of articular cartilage, when subjected to a fast ramp strain rate, is primarily governed by a fluid flow-independent (intrinsic) viscoelastic mechanism, whereas the long-term viscoelastic behavior is governed by a fluid flow-dependent (biphasic) viscoelastic mechanism. Furthermore, a linear viscoelastic representation of the solid stress was found to be a valid model assumption for the simulation of ramp strain rate-dependent relaxation behaviors of articular cartilage within the range of ramp strain rates investigated.

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Wu, Guangyuan, Haitao Zhang, Qixin Ge, Junfeng Sun, and Tengjiang Yu. "Evolution and comprehensive evaluation of viscoelastic characteristics of road asphalt in medium temperature region." Multidiscipline Modeling in Materials and Structures 18, no. 2 (April 14, 2022): 201–18. http://dx.doi.org/10.1108/mmms-08-2021-0139.

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PurposeIn order to determine the range of medium temperature zone of road asphalt, it is hoped that the evolution of viscoelastic characteristics of road asphalt under medium temperature state can be deeply explored.Design/methodology/approachIn this paper, the needle penetration test and temperature scanning test were designed for 90# and 70# bitumen as test materials, and the boundary of medium temperature zone of 90# and 70# bitumen was accurately determined by data analysis method. A mathematical model was established based on principal component analysis, and a comprehensive evaluation index was proposed to evaluate the evolution of temperature viscoelastic characteristics of road asphalt by means of standardization and rotational dimensionality reduction.FindingsThe test results show that the medium temperature zone of 90# asphalt is [−5 ± 1°C, 38 ± 1°C], and the medium temperature zone of 70# asphalt is [0 ± 1°C, 51 ± 1°C]. According to the viscoelastic response of road asphalt in the medium temperature zone, the medium temperature zone can be divided into three evolution stages: weak viscoelastic stage, viscoelastic equilibrium stage, strong viscoelastic weak stage. Analysis based on the intrinsic viscosity fillip target describing the various intrinsic viscoelastic index represents the viscoelastic properties of bitumen from different angles, and limitations inherent stick fillip for target put forward the integrated the inherent stick fillip mark information, as well as targeted and accurate evaluation of road asphalt temperature comprehensive evaluation indexes in the evolution of the viscoelastic properties of IM-T. Finally, the temperature data of asphalt pavement in several representative regions of China are compared with the determined medium temperature region, and it is proved that the research on the evolution of viscoelastic characteristics of asphalt pavement under the medium temperature condition has important practical significance.Originality/valueThe boundary of medium temperature zone of 90# and 70# base asphalt was determined, and the viscoelastic characteristic evolution of road asphalt under medium temperature state was studied deeply. Aiming at the limitation of intrinsic viscoelastic index, a comprehensive evaluation index IM-T which not only integrates the information of intrinsic viscoelastic index but also can accurately evaluate the evolution of temperature viscoelastic characteristics in road asphalt is proposed.

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Jingwei, Zhang, Li Jia, Huang Chuhao, and Chen Shuo. "Study on dynamic viscoelastic constitutive model of nonwater reacted polyurethane grouting materials based on DMA." REVIEWS ON ADVANCED MATERIALS SCIENCE 61, no. 1 (January 1, 2022): 238–49. http://dx.doi.org/10.1515/rams-2022-0004.

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Abstract Nonwater reacted polyurethane grouting materials are new materials developed to make up for the shortcomings of water-reactive materials in emergency rescue. However, its viscoelastic properties and constitutive model under dynamic loads have not been systematically studied. Based on dynamic thermal mechanical analysis (DMA), the dynamic viscoelastic indexes such as storage modulus, loss modulus, and loss factor of nonwater reacted polymer grouting material were obtained, and the frequency spectrum of polymer with different densities were analyzed. In addition, comparing and analyzing the classical viscoelastic constitutive models such as Maxewell model, Kelvin model, and Fractional model, the fourth-order generalized Maxwell model (GMM) was selected to construct the viscoelastic constitutive model of polyurethane grounding materials. Then, the parameters of the viscoelastic constitutive model of polyurethane grounding materials were obtained by using multi-objective shared parameter fitting method, and dynamic viscoelastic constitutive model of nonwater reacted polyurethane grouting materials was established. Furthermore, the viscoelastic constitutive model with different densities was verified by the DMA test. The results show that the dynamic viscoelastic constitutive model of nonwater reacted polyurethane grouting materials in the article can accurately and efficiently describe the dynamic viscoelastic properties of polyurethane grounding materials, which lays a foundation for the dynamic response analysis of polymer structures.

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Yang, Renhu, Weijian Mao, and Xu Chang. "An efficient seismic modeling in viscoelastic isotropic media." GEOPHYSICS 80, no. 1 (January 1, 2015): T63—T81. http://dx.doi.org/10.1190/geo2013-0439.1.

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Energy is absorbed and attenuated when seismic waves propagate in real earth media. Hence, the viscoelastic medium needs to be considered. There are many ways to construct the viscoelastic body, in which the generalized standard linear viscoelastic body is the most representative one. For viscoelastic wave propagation and imaging, it is very important to obtain a compact and efficient viscoelastic equation. Because of this, we derived a set of simplified viscoelastic equations in isotropic media on the basis of the standard linear solid body and the constitutive relation for a linear viscoelastic isotropic solid. The simplified equations were composed of the linear equations of momentum conservation, the stress-strain relations, and the memory variable equations. During the derivation of the equations, the Lamé differentiation matrix, which has a similar form to the stiffness matrix and indicates the relations between viscoelastic and elastic stiffness matrices, was introduced to simplify the memory variable equations. Analogous to the elastic equations, the simplified equations have symmetrically compact forms and are very useful for efficient viscoelastic modeling, migration, and inversion. Applied to a 2D simple model and the 2D SEG/EAGE salt model, the results show that our simplified equations are more efficient in computation than Carcione’s equations.

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bin Azizi, Muhammad Azim, Ahmad Kamal Ariffin bin Mohd Ihsan, and Nik Abdullah bin Nik Mohamed. "The peridynamic model of viscoelastic creep and recovery." Multidiscipline Modeling in Materials and Structures 11, no. 4 (November 9, 2015): 579–97. http://dx.doi.org/10.1108/mmms-03-2015-0017.

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Purpose – The purpose of this paper is to establish a peridynamic method in predicting viscoelastic creep behaviour with recovery stage and to find the suitable numerical parameters of peridynamic method. Design/methodology/approach – A rheological viscoelastic creep constitutive equation including recovery and an elastic peridynamic equation (with integral basis) are examined and used. The elasticity equation within the peridynamic equation is replaced by the viscoelastic equation. A new peridynamic method with two time parameters, i.e. numerical time and viscoelastic real time is designed. The two parameters of peridynamic method, horizon radius and number of nodes per unit volume are studied to get their optimal values. In validating this peridynamic method, comparisons are made between numerical and analytical result and between numerical and experimental data. Findings – The new peridynamic method for viscoelastic creep behaviour is approved by the good matching in numerical-analytical data comparison with difference of < 0.1 per cent and in numerical-experimental data comparison with difference of 4-6 per cent. It can be used for further creep test which may include non-linear viscoelastic behaviour and creep rupture. From this paper, the variation of constants in Burger’s viscoelastic model is also studied and groups of constants values that can simulate solid, fluid and solid-fluid viscoelastic behaviours were obtained. In addition, the numerical peridynamic parameters were also manipulated and examined to achieve the optimal values of the parameters. Research limitations/implications – The peridynamic model of viscoelastic creep behaviour preferably should have only one time parameter. This can only be done by solving the unstable fluctuation of dynamic results, which is not discussed in this paper. Another limitation is the tertiary region and creep rupture are not included in this paper. Practical implications – The viscoelastic peridynamic model in this paper can serve as an alternative for conventional numerical simulations in viscoelastic area. This model also is the initial step of developing peridynamic model of viscoelastic creep rupture properties (crack initiation, crack propagation, crack branching, etc.), where this future model has high potential in predicting failure behaviours of any components, tools or structures, and hence increase safety and reduce loss. Originality/value – The application of viscoelastic creep constitutive model on peridynamic formulation, effect of peridynamic parameters manipulation on numerical result, and optimization of constants of viscoelastic model in simulating three types of viscoelastic creep behaviours.

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Liu, Lin Chao, Lie Yu, and Huan Xin Yu. "Steady State Response of Compressible Fractional Derivative Viscoelastic Thick-Walled Cylinder." Applied Mechanics and Materials 166-169 (May 2012): 1510–13. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.1510.

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Many materials show viscoelastic properties under long term load, because of the complexity of viscoelastic problem, it is not enough for describing the characteristics of material and structure with classic viscoelastic model. The stress-strain constitutive relationship is described by fractional derivative viscoelastic model, the radial displacement and stress of thick-walled cylinder under internal pressure are obtained by using Fourier transform and the properties of fractional derivative, and we also investigated the steady state response of compressible fractional derivative viscoelastic thick-walled cylinder.

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31

Guillopé, Colette, and Jean-Claude Saut. "Existence and stability of steady flows of weakly viscoelastic fluids." Proceedings of the Royal Society of Edinburgh: Section A Mathematics 119, no. 1-2 (1991): 137–58. http://dx.doi.org/10.1017/s0308210500028377.

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SynopsisWe consider steady flows of viscoelastic fluids for which the extrastress tensor is given by a differential constitutive equation and is such that the retardation time is large (weakly viscoelastic fluids).We show the existence of a unique viscoelastic steady flow close to a given Newtonian flow and investigate its linear stability.As an example, we consider the Bénard problem for viscoelastic fluids and we prove that there exists a nontrivial linearly stable flow of a weakly viscoelastic fluid in a container heated from below.

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32

Li, Peng, and Hui Zhang. "A non-Fourier magneto-thermo-viscoelastic problem of a two-dimensional plate." Journal of Physics: Conference Series 2535, no. 1 (June 1, 2023): 012026. http://dx.doi.org/10.1088/1742-6596/2535/1/012026.

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Abstract Viscoelastic materials is a kind of damping materials which has been wildly applied in vibration control of ocean and civil engineering, and viscoelastic materials mostly work in a complex thermoelectric multi-field coupled environment. In this work, a two-dimensional viscoelastic plate is studied with stain relaxation time and viscoelastic relaxation time. The two-dimensional viscoelastic plate is placed in a magnetic field, and the upper surface is subjected to a thermal shock. The problem is investigated by a modified L-S thermo-viscoelastic model with stain, viscoelastic relaxation time, and magnetic field. Normal mode analysis is used to achieve exact analytical expressions of temperature distribution, displacement component and thermal stresses. Numerical computations are conducted for copper-like material and dimensionless results are illustrated graphically. Based on the results, the influence of magnetic field on the distributions of the nondimensional temperature, displacement and stresses are discussed.

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Teshaev, Muhsin, Ismoil Safarov, Dilshoda Ibragimova, Doniyor Rayimov, and Sharif Akhmedov. "Stationary response of the system “Cylindrical shell – viscoelastic filler” to the effect of a moving load." Journal of Physics: Conference Series 2697, no. 1 (February 1, 2024): 012004. http://dx.doi.org/10.1088/1742-6596/2697/1/012004.

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Abstract The paper considers the stationary response of the system “cylindrical shell - viscoelastic filler” to the action of a moving load. The filler and the shell were assumed to be viscoelastic. Using the principle of analogy of viscoelastic and elastic problems (elastic-viscoelastic analogy), a stationary solution of the action of mobile loads on a shell with a viscoelastic filler is obtained. It is shown that this principle makes it possible to generalize the class of problems obtained for the case of viscoelastic media. Since the viscoelastic filler has damping properties, the inversion integrals have no singularities on the real axis, and the elements of the determinants in integrals become complex since in this problem in the image space, the Lame coefficients are complex and depend on the speed of the load movement, as well as the Fourier transform parameter. Numerical results are obtained, and an analysis is made.

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34

Yanbarisov, Ruslan, Yuri Efremov, Nastasia Kosheleva, Peter Timashev, and Yuri Vassilevski. "Numerical Modelling of Multicellular Spheroid Compression: Viscoelastic Fluid vs. Viscoelastic Solid." Mathematics 9, no. 18 (September 20, 2021): 2333. http://dx.doi.org/10.3390/math9182333.

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Parallel-plate compression of multicellular spheroids (MCSs) is a promising and popular technique to quantify the viscoelastic properties of living tissues. This work presents two different approaches to the simulation of the MCS compression based on viscoelastic solid and viscoelastic fluid models. The first one is the standard linear solid model implemented in ABAQUS/CAE. The second one is the new model for 3D viscoelastic free surface fluid flow, which combines the Oldroyd-B incompressible fluid model and the incompressible neo-Hookean solid model via incorporation of an additional elastic tensor and a dynamic equation for it. The simulation results indicate that either approach can be applied to model the MCS compression with reasonable accuracy. Future application of the viscoelastic free surface fluid model is the MCSs fusion highly-demanded in bioprinting.

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He, Zi Ye, Fu Xue Liu, and Feng Lv. "Viscoelastic Properties Research of Sisal Fibre Asphalt Concrete." Applied Mechanics and Materials 505-506 (January 2014): 239–43. http://dx.doi.org/10.4028/www.scientific.net/amm.505-506.239.

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Asphalt concrete is a typical complex of viscous, elastic and plastic.So the raw materials should be fully considered, such as asphalt, aggregate, filler, etc, when research to viscoelastic. Viscoelastic can influence various properties, even to service life of the road and its performance. Therefore, if can improve the viscoelastic properties, it will have a lot of influence to asphalt concrete. Through to add 0.2% sisal fibre to common concrete to study the viscoelastic properties, this article seek to improve the viscoelastic method, in order to play the role of asphalt concrete better.

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Bahraini, Seyed Masoud Sotoodeh, Mohammad Eghtesad, and Mehrdad Farid. "Application of fractional-order control for vibration suppression of viscoelastic beams." International Journal of Computational Materials Science and Engineering 03, no. 01 (March 2014): 1450006. http://dx.doi.org/10.1142/s2047684114500067.

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There are several parameters required for viscoelastic material modeling to describe the material behavior. On the other hand, the parameter identification of viscoelastic materials often leads to difficult experimental procedures. Since the fractional controllers are robust to parameter uncertainties in the plant model, in this paper, this type of controller is proposed to avoid the difficulties of parameters identification in viscoelastic materials. As a prototype, a viscoelastic beam covered by piezoelectric patches is modeled for suppressing vibrations arising from transient excitations of viscoelastic materials. Different fractional-order PIλDμ controllers are used to illustrate the effect of fractional integral and fractional derivative orders separately. The results show that the fractional-order controllers are successful and effective for vibration suppression of viscoelastic beams.

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ZHANG, W., and C. Z. SONG. "HIGHER-DIMENSIONAL PERIODIC AND CHAOTIC OSCILLATIONS FOR VISCOELASTIC MOVING BELT WITH MULTIPLE INTERNAL RESONANCES." International Journal of Bifurcation and Chaos 17, no. 05 (May 2007): 1637–60. http://dx.doi.org/10.1142/s0218127407017963.

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In this paper, higher-dimensional periodic and chaotic oscillations for a parametrically excited viscoelastic moving belt with multiple internal resonances are investigated for the first time. The external damping and internal damping of the material for the viscoelastic moving belt are considered simultaneously. First, the nonlinear governing equation of planar motion for the viscoelastic moving belt with the external damping is given. Then, the transverse nonlinear oscillations of the viscoelastic moving belt are considered. The method of multiple scales and the Galerkin approach are applied directly to the governing partial differential equation of motion for the viscoelastic moving belt to obtain an eight-dimensional averaged equation for the case of 1:2:3:4 internal resonances for the first-, the second-, the third- and the fourth-order modes and primary parametric resonance of the first-order mode. Finally, numerical method is used to investigate higher-dimensional periodic and chaotic motions of the viscoelastic moving belt. The results of numerical simulation demonstrate that there exist the period, period 2, period 4, multiple period and chaotic motions of the viscoelastic moving belt. The multipulse chaotic motions of the viscoelastic moving belt are observed from numerical simulations.

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Ryazanov, A. A., P. V. Sklyuev, K. I. Babitskaya, and S. A. Bulgakov. "APPLICATION OF VISCOELASTIC SYSTEMS IN OIL PRODUCTION INTENSIFICATION PROCESSES." Petroleum Engineering 22, no. 1 (February 29, 2024): 99–111. http://dx.doi.org/10.17122/ngdelo-2024-1-99-111.

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This paper provides an overview of viscoelastic behavior and the use of viscoelastic fluids (VBLs) in various oil production intensification processes. The first part provides basic models describing viscoelastic behavior and corresponding equations of state. Describes the method of testing under the action of harmonic vibrations (method of dynamic tests), possible options for its implementation and the determined rheological properties of the viscoelastic sample. To interpret the results of dynamic tests, a complex module is most often introduced, which consists of two components — the elastic modulus (G’) and the loss modulus (G’’). These dynamic modules and their relationship describe the behavior of the viscoelastic sample. It is shown that with respect to modules, it is possible to conclude on the type of sample - viscoelastic liquid or viscoelastic body. It is also noted that dynamic tests should be carried out in the area of low amplitudes of oscillating loads, in which the rheological properties do not depend on the applied stress or strain. The second part provides examples of viscoelastic systems used in operations such as water flow isolation, hydraulic fracturing, and modified acid treatments. The most common viscoelastic systems used in various technologies are solutions of surfactants and polymers of different structures. It is noted that in order to obtain a viscoelastic gel, polymer solutions are used with a crosslinker, while the rheological properties of surfactant solutions are controlled by external factors — pH, temperature, water mineralization. Viscoelastic surfactant solutions have an advantage over polymer solutions ‑ they are able to recover their properties after mechanical or thermal exposure due to the formation of supramolecular structures as a result of selforganization of surfactant molecules. The surfactant-based HLT property of reversibly collapsing and recovering is used, in particular, to reduce pressure losses to overcome friction. In flow-deflecting acid compositions, viscoelastic surfactants are mainly used, the most common of which are given in the second part of the article.

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39

Epstein, Randy J., and Joel Sugar. "VISCOELASTIC AGENTS/REPLY." Ophthalmic Surgery, Lasers and Imaging Retina 22, no. 4 (April 1991): 240. http://dx.doi.org/10.3928/1542-8877-19910401-17.

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40

TAKAHARA, ATSUSHI. "Dynamic Viscoelastic Properties." FIBER 65, no. 12 (2009): P.472—P.476. http://dx.doi.org/10.2115/fiber.65.p_472.

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41

Lin, J. Y., and R. A. Westmann. "Viscoelastic Winding Mechanics." Journal of Applied Mechanics 56, no. 4 (December 1, 1989): 821–27. http://dx.doi.org/10.1115/1.3176177.

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The viscoelastic analysis of tape systems composed of rate-dependent materials is presented. Histories for winding, winding-pause, and winding-pause-unwinding are considered. The winding problem is reduced to determining the appropriate Green’s function by numerical solution of a Volterra integral equation of the second kind. This Green’s function and integral superposition permits the evaluation of the stress and displacement fields in the tape system for any winding history. Viscoelastic unwinding is treated by the superposition of two-states — one determined from the initial condition of the tape when unwinding begins and the second state given in terms of an arbitrary external pressure evaluated by solving an integral equation. Numerical results are presented for several histories and representative material properties.

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42

Smith, K. D., and W. L. Burt. "Fluorescent viscoelastic enhancement." Journal of Cataract & Refractive Surgery 18, no. 6 (November 1992): 572–76. http://dx.doi.org/10.1016/s0886-3350(13)80445-2.

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Melki, Samir A., Mona Harissi-Dagher, Simon Wu, and Mark A. Fava. "Viscoelastic-Assisted DSAEK." Ophthalmology 118, no. 5 (May 2011): 1003–4. http://dx.doi.org/10.1016/j.ophtha.2010.12.026.

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GOLDEN, J. M. "FRICTIONAL VISCOELASTIC CONTACT." Quarterly Journal of Mechanics and Applied Mathematics 39, no. 1 (1986): 125–38. http://dx.doi.org/10.1093/qjmam/39.1.125.

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45

Borg, Tommi, and Esko J. Pääkkönen. "Linear viscoelastic models." Journal of Non-Newtonian Fluid Mechanics 156, no. 1-2 (January 2009): 129–38. http://dx.doi.org/10.1016/j.jnnfm.2008.07.010.

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Borg, Tommi, and Esko J. Pääkkönen. "Linear viscoelastic models." Journal of Non-Newtonian Fluid Mechanics 156, no. 1-2 (January 2009): 121–28. http://dx.doi.org/10.1016/j.jnnfm.2008.07.011.

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Borg, Tommi, and Esko J. Pääkkönen. "Linear viscoelastic models." Journal of Non-Newtonian Fluid Mechanics 159, no. 1-3 (June 2009): 17–25. http://dx.doi.org/10.1016/j.jnnfm.2008.11.014.

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48

Borg, Tommi, and Esko J. Pääkkönen. "Linear viscoelastic models." Journal of Non-Newtonian Fluid Mechanics 165, no. 1-2 (January 2010): 24–31. http://dx.doi.org/10.1016/j.jnnfm.2009.08.008.

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49

Hong, Wei. "Modeling viscoelastic dielectrics." Journal of the Mechanics and Physics of Solids 59, no. 3 (March 2011): 637–50. http://dx.doi.org/10.1016/j.jmps.2010.12.003.

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Schapery, R. A. "Nonlinear viscoelastic solids." International Journal of Solids and Structures 37, no. 1-2 (January 2000): 359–66. http://dx.doi.org/10.1016/s0020-7683(99)00099-2.

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