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Inertial Effects of Moving Loads on the Dynamic Behavior of One and Two Dimensional Structures

Dehestani Kolagar, Mehdi | 2011

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 41443 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Vafai, Abolhassan
  7. Abstract:
  8. In this study the dynamic responses of finite Euler-Bernoulli beams and homogeneous isotropic 2D half-spaces, as one and two dimensional structures, under a moving object are investigated. First, the dynamic responses of finite beams with various boundary conditions were investigated. The results illustrated that the speed of a moving mass has direct influence on the entire structural dynamic response, depending on its boundary conditions. Critical influential speeds in the moving mass problems were introduced and obtained in numerical examples for various BC’s. Dynamic response of a half-space under an inertial foundation subjected to a time-harmonic loading was investigated in the next part of the study. Displacement potentials and the Fourier transformation were used to solve the Navier’s equation for the system. Direct contour integration has been employed to achieve the surface waves. Steepest descent method was also employed to obtain the approximate far-field displacements and stresses. The steady-state stresses in the half-space under a moving wheel-type load with constant subsonic speed, prescribed on a finite patch on the boundary, are investigated subsequently. The governing system of PDEs for the problem was solved utilizing a double Fourier-Laplace transformation. The effects of force transmission mechanism from the contact patch to the half-space have also been considered. The dynamic response of a half-space under a moving inertial load is investigated afterwards. The problem was first solved for a moving load, and, then, the procedure was extended to include the inertial effects. The governing wave-type PDEs were solved by utilizing a concurrent two-sided and one-sided Laplace transformation. The transformed dynamic responses and stresses were inverted by the Cagniard-de Hoop method. Effects of the inertia of the moving load were included using a numerical procedure. Numerical examples revealed the influences of the inertia of moving loads on the dynamic stresses and displacements in the half-space.
  9. Keywords:
  10. Traveling Mass ; Half Spaces ; Nonlinear Three Dimentional Euler-Bernoulli Beam Theory ; Wave Propagation ; Integral Transformation ; Cagniard-Dehoop Method

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