Experimental and Numerical Study on Dynamic Properties of Viscoelastic Microvibration Damper Considering Temperature and Frequency Effects

2016 ◽  
Vol 11 (6) ◽  
Author(s):  
Chao Xu ◽  
Zhao-Dong Xu ◽  
Teng Ge ◽  
Ya-Xin Liao
Keyword(s):  
Loss Factor ◽  
Numerical Study ◽  
Dynamic Properties ◽  
Frequency Effect ◽  
Solid Model ◽  
Temperature Dependent ◽  
Frequency Effects ◽  
Proposed Model ◽  
Different Temperatures ◽  
Increasing Temperature

This work presents an experimental and numerical study on the dynamic properties of viscoelastic (VE) microvibration damper under microvibration conditions at different frequencies and temperatures. The experimental results show that the storage modulus and the loss factor of VE microvibration damper both increase with increasing frequency but decrease with increasing temperature. To explicitly and accurately represent the temperature and frequency effects on the dynamic properties of VE microvibration damper, a modified standard solid model based on a phenomenological model and chain network model is proposed. A Gaussian chain spring and a temperature-dependent dashpot are employed to reflect the temperature effect in the model, and the frequency effect is considered with the nature of the standard solid model. Then, the proposed model is verified by comparing the numerical results with the experimental data. The results show that the proposed model can accurately describe the dynamic properties of VE microvibration damper at different temperatures and frequencies.

Permittivity Study of a CuCl Residue at 13–450 °C and Elucidation of the Microwave Intensification Mechanism for Its Dechlorination

2019 ◽  
Vol 38 (2019) ◽  
pp. 135-142
Author(s):  
Guo Zhanyong ◽  
Li Fachaung ◽  
Su Guang ◽  
Zhai Demei ◽  
Cheng Fang ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Microwave Irradiation ◽  
Loss Factor ◽  
Elevated Temperatures ◽  
Temperature Dependent ◽  
Positive Interaction ◽  
Increasing Temperature ◽  
Relationship Of ◽  
The Relationship ◽  
Metallurgy Process

AbstractPermittivity is a vitally important parameter for describing the absorbing and heating characteristics of a material under microwave irradiation, and it is also strongly dependent on temperature. However, the literature contains little information on this topic and even less particular permittivity data at elevated temperatures. In this paper, the permittivity of a CuCl residue at temperatures from 13 to 450 °C at 2.45 GHz was measured using the cavity perturbation method. The relationship of its real part (ε′) and imaginary part (ε″) with temperature (T) was deduced. In addition, the temperature-dependent tangent (tan δ) and the penetration depth (d) of microwaves into the material were calculated. The results of the permittivity study show that the dielectric constant (ε′) of the CuCl residue increased linearly with increasing temperature. In contrast, the dielectric loss factor (ε″) and loss tangent first maintained on a steady value between 13 and 300 °C and then substantially increased from 300 to 450 °C. The positive interaction of the dielectric property and temperature showed the reasonableness of our earlier metallurgy process, where the CuCl residue for dechlorination was roasted at 350–450 °C under microwave irradiation.

Strain-Dependent Properties of Polymers I

1966 ◽  
Vol 39 (5) ◽  
pp. 1421-1427 ◽  
Author(s):  
G. E. Warnaka ◽  
H. T. Miller
Keyword(s):  
Loss Factor ◽  
Elastic Moduli ◽  
Dynamic Properties ◽  
Amorphous Polymers ◽  
Temperature Dependent ◽  
Strain Dependence ◽  
Self Heating ◽  
Dynamic Elastic Moduli ◽  
Temperature Dependent Properties ◽  
Strain Dependent

Abstract Dynamic elastic moduli of homogeneous, amorphous polymers decrease at moderate to high strains. Under the same strain magnitudes the loss factor goes through a broad maximum. At low strains, dynamic properties are independent of strain amplitude. This paper shows that strain dependence is a basic property of homogeneous, amorphous polymers. Strain dependence is shown to occur in gum, as well as filled, vulcanizates. In addition it is shown that self heating due to flexing at high strains cannot fully explain strain dependent dynamic properties. Testing has been performed on specimens with greatly varying geometries (and, hence, different amounts of self-heating) and at controlled specimen temperatures. These tests have verified the existence of a basic strain-dependency. Strain dependence is here related to time-temperature dependent properties of polymers as described by the well-known work of Williams, Landel, and Ferry. The magnitude of strain dependence and the strain amplitudes at which strain dependence occurs appear to be controlled by the time-temperature dependence of polymers.

Impact of temperature on biodegradation of bulk and trace organics during soil passage in an indirect reuse system

2008 ◽  
Vol 57 (7) ◽  
pp. 987-994 ◽  
Author(s):  
S. Gruenheid ◽  
U. Huebner ◽  
M. Jekel
Keyword(s):  
Organic Compounds ◽  
Soil Column ◽  
Degradation Behavior ◽  
Trace Organic Compounds ◽  
Temperature Dependent ◽  
Column System ◽  
Trace Organics ◽  
Mineralization Potential ◽  
Different Temperatures ◽  
Increasing Temperature

Investigations on the behavior of bulk organics and trace organic compounds in a temperature controlled soil column system are reported. Objective of the research was to assess the importance of temperature for the degradation of bulk and trace organics. The analysis of the bulk organic behavior showed a fast mineralization of easily degradable organic carbon in the first few centimetres of the columns, which does not seem to be temperature-dependent. Along the further infiltration path an influence of the different temperatures on the bioactivity was clearly visible. However, a significant increase of mineralization potential of bulk organic compounds with increasing temperature was shown. The monitoring of the single organic pollutants Iopromide, Sulfamethoxazole and naphthalenedisulfonic acids showed that temperature has an influence on the degradation behavior of the monitored compounds. In most cases higher temperatures increased the mineralization potential.

Cononsolvency Phenomena of Poly(N-Isopropylacrylamide) in Mixed Solvents at Different Temperatures

2011 ◽  
Vol 332-334 ◽  
pp. 1752-1755
Author(s):  
Xiao Xia Qiu ◽  
Jie Sun ◽  
Shu Jie Tong ◽  
Shi Jia Wang ◽  
Li Yuan Wu ◽  
...  
Keyword(s):  
Mixed Solvents ◽  
Volume Ratio ◽  
Polymer Gels ◽  
High Water ◽  
Polymer Chains ◽  
Temperature Dependent ◽  
Different Temperatures ◽  
Ft Ir ◽  
Water Fractions ◽  
Increasing Temperature

N-isopropylacrylamide was synthesized in a mixture of DMF and THF ( 7:3 in volume ratio) and characterized by FT-IR. The behavior of poly(N-isopropylacrylamide) chain was studied by spectrometer in mixtures of water with DMF and THF. Cononsolvency phenomena were found to be temperature-dependent, as demixing occurred upon increasing temperature. A significant shrinkage of polymer chains and deswelling of polymer gels, followed by phase separation, were observed for high water fractions.

scholarly journals Study of the Effect of pH and Supersaturation on the Kinetics and Rate of Solid Layer Formation at External Sides of Thermal Heat Transfer Tubes

2015 ◽  
Vol 09 (2) ◽  
Keyword(s):  
Growth Rate ◽  
Calcium Carbonate ◽  
Layer Growth ◽  
Basic Medium ◽  
Temperature Dependent ◽  
Scale Layer ◽  
Different Temperatures ◽  
Increasing Temperature ◽  
Layer Composition ◽  
Scale Deposition

The formation of scale layers at the external sides of heated tubes at situations comparable with a Multi Effect Distiller (MED) desalination processes is experimentally studied. The growth of scale layer was measured at different temperatures, pH levels and salinities. The measured scale deposition rate data were correlated to the calcium carbonate supersaturation according to a power low kinetics. It was found that the growth rate order (n) with respect to supersaturation is strongly temperature dependent. It decreases with increasing temperature. The calculated value of activation energy of scale layer growth is Ea = 33360 J/mol. The scale layer growth was found to be strongly dependent on pH. It increases in the basic medium. The salinity was found to be significant in determining the growth rate of scale layer. The scale layer composition is affected by temperature. It was found that calcium carbonate is dominant at high temperatures (80 °C). calcium sulfate deposited besides calcium carbonate at lower temperatures (60-70 °C).

Numerical Study of Thermal Modeling of Resistance Spot Welding Utilizing Coupled Thermal-Electrical-Mechanical Analysis

1999 ◽  
Author(s):  
Lijun Xu ◽  
Jamil A. Khan ◽  
Yuh-Jin Chao ◽  
Kirkland Broach
Keyword(s):  
Resistance Spot Welding ◽  
Spot Welding ◽  
Numerical Study ◽  
Mechanical Analysis ◽  
Convective Transport ◽  
Temperature Dependent ◽  
Resistance Spot ◽  
Proposed Model ◽  
Nugget Formation ◽  
Surface Contact Area

Abstract This paper successfully proposes a novel model to predict nugget development during resistance spot welding (RSW) of binary Al-alloys. The model employs a coupled thermal-electrical-mechanical analysis, and also accounts for phase change and convective transport in weld pool. Faying surface contact area and its pressure distribution are simulated from coupled thermal-mechanical model using a finite element method. Temperature dependent thermal, electrical and mechanical properties are used. The proposed model can successfully calculate most of the RSW response in term of nugget diameter and thickness, the extent of heat affected zone, etc. The calculated nugget shape based on the thermal model agrees well with the experimental data. Convection effect due to the interactions between phases in the porous mushy zone and the buoyancy force arising from the temperature difference is determined to be not significant for the weld-nugget formation. The proposed model can be used to optimize RSW process parameters for industrial welding.

Study on experiment and modeling of viscoelastic damper considering interfacial effect of matrix rubber/carbon black

2021 ◽  
pp. 1-28
Author(s):  
Teng Ge ◽  
Zhao-Dong Xu ◽  
Fuh-Gwo Yuan
Keyword(s):  
Experimental Study ◽  
Dynamic Properties ◽  
Excitation Frequency ◽  
Control Device ◽  
Structural Vibration ◽  
Modeling Analysis ◽  
Proposed Model ◽  
Excited Vibration ◽  
Different Temperatures ◽  
Good Energy

Abstract Viscoelastic (VE) dampers are a kind of effective passive vibration control device and widely used to attenuate structural vibration. In this paper, experimental study and multi-scale modeling analysis on the VE damper for reducing wind-excited vibration are carried out. First, an experimental study on VE damper is conducted to reveal the dynamic properties of VE damper. The experimental results show that the dynamic properties of VE material are influenced by excitation frequency and insignificantly affected by displacement amplitude, and the VE material has good energy dissipation capacity. Second, the damping mechanism of VE damper is analyzed from micro-perspectives by considering the influence of cross-linked and free molecular chain networks. Then a novel type spherical chain network model based on the chain network microstructure is proposed. The proposed model is verified by comparing the experimental data and the mathematical results, which indicates that the proposed model can accurately describe the dynamic properties of VE damper affected by different temperatures, frequencies and displacements.

Oviposition model of Amblyseius swirskii Athias-Henriot in prey system (Tetranychus urticae Koch)

2020 ◽  
Vol 25 (10) ◽  
pp. 1857-1866
Author(s):  
Azadeh Farazmand ◽  
Masood Maafi Amir
Keyword(s):  
Survival Rate ◽  
Tetranychus Urticae ◽  
Mass Rearing ◽  
Weibull Function ◽  
Sigmoid Function ◽  
Amblyseius Swirskii ◽  
Temperature Dependent ◽  
Non Linear Equation ◽  
Different Temperatures ◽  
Increasing Temperature

In this study, temperature-dependent oviposition model of Amblyseius swirskii Athias-Henriot fed by Tetranychus urticae Koch as prey was developed. In order to obtain data for the model, the longevity, fecundity and survivorship of adult females of A. swirskii were recorded at seven different temperatures (15, 20, 25, 27.5, 30, 32.5 and 35 °C) all at 60±5% RH and a photoperiod of 16:8h (L; D) in growth chamber. The longevity of females decreased with increasing temperature; the maximum at 15°C (84±3.24 days) and the minimum at 32.5°C (22.48±0.31 days). The female adult developmental rates (1/median longevity) was described by Sharpe and DeMichele model (r2=0.99). The highest and the lowest fecundity were observed at 25°C (22.63±0.76 eggs/female) and 15°C (9.4±0.67 eggs/female), respectively. The oviposition model comprised of three functions: temperature-dependent fecundity, age-specific cumulative oviposition rate and age-specific survival rate. The best model of temperature-dependent fecundity was described by a non-linear equation (extreme value function) (r2=0.98). Similarly, the best model of age-specific cumulative oviposition was described by the two-parameter Weibull function (r2=0.94). Eventually, the best model of age-specific survival rate was described by sigmoid function (r2=0.97). Amblyseius swirskii has ability to control pests such as thrips, whiteflies and two-spotted spider mites and can grow even in low temperatures. Therefore, this mite can be active at the beginning of spring season. Temperature-dependent oviposition model of A. swirskii can determine optimal temperature for mass-rearing and predict seasonal population dynamic of this predatory mite in greenhouses. Finally, the greenhouse data can validate this model in future.

scholarly journals Temperature-dependent kinetics of aluminum leaching from peat clay

2020 ◽  
Vol 16 (2) ◽  
pp. 248-251
Author(s):  
Agus Mirwan ◽  
Susianto Susianto ◽  
Ali Altway ◽  
Renanto Handogo
Keyword(s):  
Leaching Kinetics ◽  
Particle Structure ◽  
Temperature Dependent ◽  
Reaction Rate Constants ◽  
Aluminum Recovery ◽  
Proposed Model ◽  
Shrinking Core ◽  
Increasing Temperature ◽  
Solid Liquid ◽  
Kinetics Of

The leaching kinetics of aluminum from peat clay using 4 M HCl at dissimilar leaching temperatures (30–90 °C) was investigated. The maximum of aluminum recovery was 91.27% after 60 min of leaching in agitated Pyrex reactor at 90 °C. The model involved the concept of shrinking core in order to describe aluminum that is located inside the core solid particle of peat clay that shrinks as the extracted solute, and it assumed the unchanged particle structure, a first-order leaching kinetics mechanism and a linear equilibrium at the interface of solid-liquid. The proposed model was corresponding to fit experimental data and to simulate the aluminum leaching from peat clay with four fitting parameters of temperature, which was confirmed with the mass transfer coefficient (kc, cm/s), diffusion coefficient (De, cm2/s), and reaction rate constants (k, cm/s) by following an increasing trend with increasing temperature. Moreover, it was validated by the correlation coefficient (ccoef ≥ 0.9794), the root means square error (RMSE ≤ 0.485), the mean relative deviation modulus (E ≤ 3.290%), and the activation energy value (Ea = 19.15 kJmol-1). This model could describe the aluminum leaching kinetics from peat clay that suitable with experiment parameters and statistical criteria, by giving useful information for optimization, scaling-up, and design.

Temperature-dependent heterojunction device characteristics of n-ZnO nanorods/p-Si assembly

2020 ◽  
Vol 10 (1) ◽  
pp. 29-36
Author(s):  
Rashad I. Badran ◽  
Yas Al-Hadeethi ◽  
Ahmad Umar ◽  
Saleh H. Al-Heniti ◽  
Bahaaudin M. Raffah ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Hexagonal Phase ◽  
Zno Nanorods ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Different Temperatures ◽  
Evaporation Technique ◽  
Wurtzite Hexagonal Phase ◽  
Heterojunction Device ◽  
Increasing Temperature

Heterojunction diode based on n-ZnO nanorods/p-Silicon (Si) assembly was fabricated, examined and reported here. Horizontal quartz tube thermal evaporation technique was used for the growth of ZnO nanorods on Si substrate. The nanorods were characterized by several techniques to examine the structural, morphological, scattering and electrical properties. Wurtzite hexagonal phase of the grown aligned nanorods was observed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The appearance of a sharp Raman peak at 438 cm–1 was observed and it is related to the E2(high) mode of the wurtzite hexagonal phase of ZnO. The electrical properties of the fabricated heterojunction assembly were examined at different temperatures (298∼398 K) in both reverse and forward biased conditions, and a good stability was observed over the entire temperature range. A reduction in the turn-on and breakdown voltage was observed with increasing temperature. By increasing the temperature, the effective potential barrier height was increased, while quality factor was decreased. The observed activation energy was found to be ∼93.4 meV, higher than the exciton binding energy of ZnO.

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