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Dynamic Modeling and Analysis of Delaminated Isotropic and Multi- Layered Composite Beam under the Action of Moving Force/Oscillatory Mass

Jafari Talookolaei, Ramazan Ali | 2013

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 44469 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Kargarnovin, Mohammad Hossein; Ahmadian, Mohammad Taghi
  7. Abstract:
  8. In this thesis, a laminated composite beam with single delamination under the action of moving force/oscillatory mass has been modeled and analyzed. The beam has been divided into four sub-beams and based on Bernoulli-Euler and also shear deformation theories and by applying the Hamilton’s principle, equations of motion along with boundary conditions and continuity and compatibility conditions are obtained. Primarily, based on the constrained mode model the delaminated layers have been analyzed then by implementing the Lagrange multipliers method, the nature of dynamic contact is incorporated. In the analysis of delaminated beam based on the constrained mode, by applying the mode summation technique the governing partial differential equations of motion were converted to the ordinary differential equations. Then the resulting equations have been solved by Runge-Kutta method. In order to include the problem of dynamic contact, the finite element method has been used and then the assembled equations of motion in the matrix form have been solved by employing the Newmark method. The obtained dynamic results initially have been verified for the special cases by those reported in the literatures. Then, the influences of different parameters on the dynamic response have been investigated. The in-depth study of the obtained results reveal that ignoring the axial, lateral and vertical displacements along with bending and torsional rotations result in higher stiffness and hence more rigidity for the beam. In addition, ignoring the Poisson’s effects and material couplings, restricts the analysis to the cross-ply layups while significant errors in the response of the beam with unsymmetric and angle ply layups have been detected. It is shown that the maximum error is occurred in the angle ply beam with fiber orientation 45°. It is shown that for the case of moving force traveling with low velocity, the dynamic deflection is approximately equal to the static deflection. By increasing the force velocity, the dynamic deflection has been increased accordingly and in the critical velocity the maximum deflection has been occurred. For the force velocity beyond this limit, the deflection has been reduced. Also, it is shown that for the delaminated beam, the maximum value of dynamic response decreases and occurs at a lower velocity when the location of delamination moves toward the midplane of the beam and the delamination length increases. It is to be mentioned that not only above analysis has been carried out using classical theory but also by first and third order shear deformation theories. Moreover, by applying the J-integral method, the stress intensity factor near the delamination tips has been calculated
  9. Keywords:
  10. Dynamic Analysis ; Lagrange Coefficient ; Laminated Composite Beam ; Moving Force/Oscillating Mass ; Dynamic Contact

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