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RISS 인기검색어
- 검색키워드
- 저자 : Changqing Bai (검색결과 5 건)
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Earthquake response analysis of series reactor
Bai, Changqing,Xu, Qingyu,Zhang, Hongyan Techno-Press 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.21 No.6
A direct transfer substructure method is presented in this paper for analyzing the dynamic characteristics and the seismic random responses of a series reactor. This method combines the concept of FRF (frequency response function) and the transfer matrix algorithm with the substructure approach. The inner degrees of freedom of each substructure are eliminated in the process of reconstruction and the computation cost is reduced greatly. With the convenient solution procedure, the dynamic characteristics analysis of the structure is valid and efficient. Associated with the pseudo excitation algorithm, the direct transfer substructure method is applied to investigating the seismic random responses of the series reactor. The numerical results demonstrate that the presented method is efficient and practicable in engineering. Finally, a precise time integration method is employed in performing a time-history analysis on the series reactor under El Centro and Taft earthquake waves.
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Stochastic elastic wave analysis of angled beams
Changqing Bai,Hualin Ma,Victor P.W. Shim 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.56 No.5
The stochastic finite element method is employed to obtain a stochastic dynamic model of angled beams subjected to impact loads when uncertain material properties are described by random fields. Using the perturbation technique in conjunction with a precise time integration method, a random analysis approach is developed for efficient analysis of random elastic waves. Formulas for the mean, variance and covariance of displacement, strain and stress are introduced. Statistics of displacement and stress waves is analyzed and effects of bend angle and material stochasticity on wave propagation are studied. It is found that the elastic wave correlation in the angled section is the most significant. The mean, variance and covariance of the stress wave amplitude decrease with an increase in bend angle. The standard deviation of the beam material density plays an important role in longitudinal displacement wave covariance.
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Hongyan Zhang,Changqing Bai,Yijun Mao 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.8
Random properties and random loads are highly important in rotor dynamic analysis because they cause system dynamic responses tobehave randomly. In this paper, a stochastical finite element of rotating shaft based on Timosheko beam theory is proposed for rotor systemmodeling, in which material and geometric random properties are considered one-dimensional stochastic field functions. A randomresponse analytical method is developed to determine the statistics of the dynamic responses of stochastical rotor systems under randomloads. The numerically obtained whirl speed of a turbopump rotor system is compared with the test data to validate the proposed model,and good agreement is observed. Linear and nonlinear turbopump rotor systems are employed to compare the results obtained from theproposed model and the Monte Carlo simulation. The numerically predicted results, which coincide well with Monte Carlo simulationdata, demonstrate the feasibility and efficiency of the proposed stochastic model and method for actual rotor system analysis and design.
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Influence of Polyurethane Polymer on the Strength and Mechanical Behavior of Sand-root Composite
Jin Liu,Zhihao Chen,Zhaojun Zeng,Debi Prasanna Kanungo,Fan Bu,Yuxia Bai,Changqing Qi,Wei Qian 한국섬유공학회 2020 Fibers and polymers Vol.21 No.4
Vegetation has good application in slope stabilization, but its beneficial effects on reinforcing topsoil are generallylimited by the soil properties it was cultivated in. This study aims at evaluating the strength improvements of sand-rootcomposite by treating with polyurethane polymer and hence investigating the mechanism of polymer-root-soil interactions. Vegetation roots were selected and mixed with dry sand and polymer solution to prepare remolded specimens. A series ofexperimental tests were then performed at different percentages of root content (0, 0.4, 0.8, 1.2, and 1.6 % by weight of drysand) and polymer content (1, 2, and 4 % by weight of dry sand) to evaluate the shear parameters and unconfinedcompressive strength (UCS). The combined mechanism was studied by scanning electron microscopy (SEM) images. Theresults showed that the strengthening effect has greater efficiency with higher polymer content. Through varying contents ofvegetation root, it was found that low root content induced an undesirable weakening effect on the strength of the treated soil. However, this situation was somewhat improved with the increase in root content. The good flexibility of polymers not onlypromote the capacity of soil to energy absorption, but also impart good ductility to soil. The presence of polymers greatlystrengthens soil stability due to its special network structure, by which the improved shear resistance at the root-soil interfaceprovides sufficient anchorage effect for the tensile strength of roots to be fully mobilized. Overall, the synergistic effect ofroot reinforcement and polymer treatment has the potential for its use in soil stabilization.
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