The Response of a Double-Beam on a Nonlinear Foundation arising from a Moving Load

Author(s):  
Z. Hryniewicz ◽  
P. Koziol
Mechanika ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 80-87
Author(s):  
Hougui ZHANG ◽  
Ruixiang SONG ◽  
Jie YANG ◽  
Dan WU ◽  
Yingjie WANG

In this paper, a novel damage detection approach for the spring connection of the double beam system using the dynamic response of the beam and genetic algorithm is presented. The double beam system is regarded as both Bernoulli-Euler beams with simply supported ends, the upper and lower beams are connected by a series of linear springs with certain intervals. With the genetic algorithm, the dynamic acceleration response of double beam system under moving load, which can be solved by the Newmark-β integration procedure, is used as the input data to detect the connection damage. Thus the dynamic response of the double beam system with a certain damage pattern can be calculated employing the moving load model. If the calculated result is quite close to the recorded response of the damaged bridge, this damage pattern will be the solution. The connection damage detection process of the proposed approach is presented herein, and its feasibility is studied from the numerical investigation with simple and multiple damages detection. It is concluded that the sophisticated damage conditions need much longer time to detect successfully.


2018 ◽  
Vol 211 ◽  
pp. 11008 ◽  
Author(s):  
Piotr Koziol ◽  
Rafał Pilecki

In previous papers, the problem of double-beam system resting on viscoelastic foundation was solved with the assumption of nonlinear foundation stiffness. This multilayer model finds application in railway modelling, where rails are represented by the infinite Euler-Bernoulli beams and sleepers are modelled as a rigid body. In this paper, another assumption is made. The layer connecting two Euler-Bernoulli beams has nonlinear stiffness. This assumption is related to laboratory tests of fastening systems. These tests show that the stiffness of fasteners and rail pads is nonlinear and this factor should be taken into account in detailed analysis of dynamic features. Therefore inclusion of nonlinearity in double-beam system is justified. The physical model presented in this paper consists of two infinitely long beams connected by viscoelastic layer with nonlinear stiffness and resting on viscoelastic foundation. The mathematical model is described by two coupled fourth order partial differential equations of motion with homogeneous boundary conditions. The system is solved by using the Fourier transform and Adomian’s decomposition, combined with the wavelet based approximation of the response using Coiflet filters. The error index for Adomian series is proposed and the approximate solution for vertical vibrations is shown along with computational examples for some systems of parameters.


2019 ◽  
pp. 105-110
Author(s):  
Mikhail Yongon Lee ◽  
Sergei V. Fedorov

The article describes the structure and the operation principle of the spectrophotometer developed on the basis of a compact rapid monochromator with one input port and two output ports and a radiometric unit where upwelling radiation radiance and sea surface irradiance channels are located. A new approach to measurements of spectral characteristics of upwelling radiation of sea based on combination of advantages of a double beam photometer with a photomultiplier and a directreading photometer with a highstability silicon photodiode for its absolute adjustment in energy units is implemented.


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