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NUMERICAL ANALYSIS AND EXPERI-MENT OF UNSTEADY THERMAL FIELD OF ROTOR PLATE FOR EDDY CURRENT RETARDER 被引量:10
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作者 LIU Chengye HE Ren 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2008年第4期71-75,共5页
The physical model based on heat transfer theory and virtual boundary method for analyzing unsteady thermal field of rotor plate for eddy current retarder used in automobile is established and boundary conditions are ... The physical model based on heat transfer theory and virtual boundary method for analyzing unsteady thermal field of rotor plate for eddy current retarder used in automobile is established and boundary conditions are also defined. The finite element governing equation is derived by Galerkin method. The time differential item is discrete based on Galerkin format that is stable at any condition. And a new style of varying time step method is used in iteration process. The thermal field on the rotor plate at the radial and axle directions is analyzed and varying temperature at appointed points on two side-surfaces is measured. The testing and analytical data are uniform approximately. Finite element method can be used for estimating thermal field of the rotor plate at initial design stage of eddy current retarder. 展开更多
关键词 Eddy current retarder Thermal field Numerical analysis Varying time step method
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TRANSVERSAL INERTIAL EFFECT ON RELAXATION/RETARDATION TIME OF CEMENT MORTAR UNDER HARMONIC WAVE
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作者 Jue Zhu Yonghui Cao Jiankang Chen 《Acta Mechanica Solida Sinica》 SCIE EI 2008年第1期44-50,共7页
Under dynamic loading, the constitutive relation of the cement mortar will be significantly affected by the transversal inertial effect of specimens with large diameters. In this paper, one-dimensional theoretical ana... Under dynamic loading, the constitutive relation of the cement mortar will be significantly affected by the transversal inertial effect of specimens with large diameters. In this paper, one-dimensional theoretical analysis is carried out to determine the transversal inertial effect on the relaxation/retardation time of the cement mortar under the harmonic wave. Relaxation time or retardation time is obtained by means of the wave velocity, attenuation coefficient and the frequency of the harmonic wave. Thus, the transversal inertial effect on the relaxation time from Maxwell model, as well as on retardation time from Voigt model is analyzed. The results show that the transversal inertial effect may lead to the increase of the relaxation time, but induce the decrease of the retardation time. Those should be taken into account when eliminating the transversal inertial effect in applications. 展开更多
关键词 cement mortar harmonic wave viscoelastic model relaxation/retardation time
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Coefficient of retardation time found out by polynomial fitting to predict creep behaviour of polystyrene
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作者 谢刚 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2005年第1期44-47,共4页
The universal creep function is successful in relating the creep (ε) to the ageing time (ta), coefficient of retardation time (β), and intrinsic time (t0). The relation was used to treat the creep experiment... The universal creep function is successful in relating the creep (ε) to the ageing time (ta), coefficient of retardation time (β), and intrinsic time (t0). The relation was used to treat the creep experimental data for polystyrene (PS) specimens at a given aged time and different stress levels. Comparing with “middle-point” method reported in the literatures, β is found out by another method “polynomial fitting” in this work. Then unified master lines were constructed with the treated data and curves according to the universal equation. The master lines can be used to predict the long-term creep behaviour and lifetime by extrapolating to a required ultimate strain. 展开更多
关键词 polystyrene(PS) PREDICT creep coefficient of retardation time united master line
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Application of retardation time spectra of asphalt
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作者 詹小丽 张肖宁 卢亮 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2008年第5期718-721,共4页
To improve the performance of asphalt pavement, the dynamic and static tests of asphalt were used to measure its viscoelastic properties under different time. Based on the obtained data of static creep compliances and... To improve the performance of asphalt pavement, the dynamic and static tests of asphalt were used to measure its viscoelastic properties under different time. Based on the obtained data of static creep compliances and dynamic compliances according to the static creep test and dynamic test of asphalt using the dynamic shear rheometer, the discrete retardation time spectra were attained using the non-linear regression method. All viscoelastic functions are mathematically equivalent and belong to the same retardation time spectra, so the dynamic compliances of asphalt were converted to the static creep compliance using the retardation time spectra. Good correlations were found between calculation results and measurement results. In accordance to these findings, the retardation time spectra can accurately transform static and dynamic viscoelastic functions. Therefore, we can obtain viscoelastic properties over much larger time or frequency region than measurement results. 展开更多
关键词 viscoelastic properties of asphalt retardation time spectra non-linear regression creep compli-ance dynamic compliance
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Instability of single-walled carbon nanotubes conveying Jeffrey fluid
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作者 Bei-Nan Jia Yong-Jun Jian 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第4期328-332,共5页
We report instability of the single-walled carbon nanotubes(SWCNT) filled with non-Newtonian Jeffrey fluid.Our objective is to get the influences of relaxation time and retardation time of the Jeffrey fluid on the vib... We report instability of the single-walled carbon nanotubes(SWCNT) filled with non-Newtonian Jeffrey fluid.Our objective is to get the influences of relaxation time and retardation time of the Jeffrey fluid on the vibration frequency and the decaying rate of the amplitude of carbon nanotubes.An elastic Euler-Bernoulli beam model is used to describe vibrations and structural instability of the carbon nanotubes.A new vibration equation of an SWCNT conveying Jeffrey fluid is first derived by employing Euler-Bernoulli beam equation and Cauchy momentum equation taking constitutive relation of Jeffrey fluid into account.The complex vibrating frequencies of the SWCNT are computed by solving a cubic eigenvalue problem based upon differential quadrature method(DQM).It is interesting to find from computational results that retardation time has significant influences on the vibration frequency and the decaying rate of the amplitude.Especially,the vibration frequency decreases and critical velocity increases with the retardation time.That is to say,longer retardation time makes the SWCNT more stable. 展开更多
关键词 single-walled carbon nanotubes Jeffrey fluid relaxation time retardation time
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