Zhou Z.-H.,Nanjing Southeast University |
Zhou Z.-H.,Jiangsu Key Laboratory of Engineering Mechanics Analysis |
He Y.-L.,Shanghai University |
He Y.-L.,Shanghai Key Laboratory of Mechanics in Energy Engineering |
And 6 more authors.
Applied Mathematics and Mechanics (English Edition) | Year: 2012
In order to predict the mechanical performance of the polyvinyl chloride (PVC) at a high operating temperature, a series of short-term tensile creep tests (onetenth of the physical aging time) of the PVC are carried out at 63 °C with a small constant stress by a dynamic mechanical analyzer (DMA). The Struik-Kohlrausch (SK) formula and Struik shifting methods are used to describe these creep data for various physical aging time. A new phenomenological model based on the multiple relaxation mechanisms of an amorphous polymer is developed to quantitatively characterize the SK parameters (the initial creep compliance, the characteristic retardation time, and the shape factor) determined by the aging time. It is shown that the momentary creep compliance curve of the PVC at 63°C can be very well fitted by the SK formula for each aging time. However, the SK parameters for the creep curves are not constant during the aging process at the elevated temperatures, and the evolution of these parameters and the creep rate versus aging time curves at the double logarithmic coordinates have shown a nonlinear phenomenon. Moreover, the creep master curves obtained by the superposition with the Struik shifting methods are unsatisfactory in such a case. Finally, the predicted results calculated from the present model incorporating with the SK formula are in excellent agreement with the creep experimental data for the PVC isothermally aged at the temperature relatively close to the glass transition temperature. © Shanghai University and Springer-Verlag. Source
Zhou Z.,Nanjing Southeast University |
Zhou Z.,Jiangsu Key Laboratory of Engineering Mechanics Analysis |
Jiang D.,Nanjing Southeast University |
Jiang D.,Jiangsu Key Laboratory of Engineering Mechanics Analysis |
And 6 more authors.
Nanjing Hangkong Hangtian Daxue Xuebao/Journal of Nanjing University of Aeronautics and Astronautics | Year: 2010
A finite element model for a concrete-filled steel tubular arch bridge is established. The modal analysis is performed to obtain the computational modal frequencies. Dynamic testing based on environmental excitation is carried out to obtain the experimental modal frequencies. The sensitivity-based finite element model updating is adopted to update the elastic modulus and sectional areas to minimize the differences between computational and experimental modal frequencies. The maximum modal frequency error decreases from 22.6% to 3.3% after updating. Source