پرویز ملک زاده

Various types of pipelines and risers used in oil and gas industry undergo dynamic instabilities (buckling and flutter) due to the internal fluid flows. This paper aims to study the possibility of increasing pipeline stability by using pipes made of composite materials and reinforced by carbon nanotubes. Hamilton principle for open systems is used to derive the equations of motion of the pipe based on a higher order shear deformation theory. The rule of mixture is implemented to express the change of the material properties of the pipe through the pipe thickness. Finite element analysis with super convergent elements is used to solve the governing differential equations of the problem. Static equilibrium equations of the pipe without fluid are used to develop the shape functions of the elements. The results of the present study are compared with those available in the literature for dynamic behavior of pipes with Euler-Bernoulli and Timoshenko beam theories. The effects of different parameters on (i) vibration characteristics and (ii) stability limits of composite pipes conveying fluid are also examined.